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Diffstat (limited to 'gcc/tree-data-ref.cc')
| -rw-r--r-- | gcc/tree-data-ref.cc | 6386 |
1 files changed, 6386 insertions, 0 deletions
diff --git a/gcc/tree-data-ref.cc b/gcc/tree-data-ref.cc new file mode 100644 index 0000000..397792c --- /dev/null +++ b/gcc/tree-data-ref.cc @@ -0,0 +1,6386 @@ +/* Data references and dependences detectors. + Copyright (C) 2003-2022 Free Software Foundation, Inc. + Contributed by Sebastian Pop <pop@cri.ensmp.fr> + +This file is part of GCC. + +GCC is free software; you can redistribute it and/or modify it under +the terms of the GNU General Public License as published by the Free +Software Foundation; either version 3, or (at your option) any later +version. + +GCC is distributed in the hope that it will be useful, but WITHOUT ANY +WARRANTY; without even the implied warranty of MERCHANTABILITY or +FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License +for more details. + +You should have received a copy of the GNU General Public License +along with GCC; see the file COPYING3. If not see +<http://www.gnu.org/licenses/>. */ + +/* This pass walks a given loop structure searching for array + references. The information about the array accesses is recorded + in DATA_REFERENCE structures. + + The basic test for determining the dependences is: + given two access functions chrec1 and chrec2 to a same array, and + x and y two vectors from the iteration domain, the same element of + the array is accessed twice at iterations x and y if and only if: + | chrec1 (x) == chrec2 (y). + + The goals of this analysis are: + + - to determine the independence: the relation between two + independent accesses is qualified with the chrec_known (this + information allows a loop parallelization), + + - when two data references access the same data, to qualify the + dependence relation with classic dependence representations: + + - distance vectors + - direction vectors + - loop carried level dependence + - polyhedron dependence + or with the chains of recurrences based representation, + + - to define a knowledge base for storing the data dependence + information, + + - to define an interface to access this data. + + + Definitions: + + - subscript: given two array accesses a subscript is the tuple + composed of the access functions for a given dimension. Example: + Given A[f1][f2][f3] and B[g1][g2][g3], there are three subscripts: + (f1, g1), (f2, g2), (f3, g3). + + - Diophantine equation: an equation whose coefficients and + solutions are integer constants, for example the equation + | 3*x + 2*y = 1 + has an integer solution x = 1 and y = -1. + + References: + + - "Advanced Compilation for High Performance Computing" by Randy + Allen and Ken Kennedy. + http://citeseer.ist.psu.edu/goff91practical.html + + - "Loop Transformations for Restructuring Compilers - The Foundations" + by Utpal Banerjee. + + +*/ + +#include "config.h" +#include "system.h" +#include "coretypes.h" +#include "backend.h" +#include "rtl.h" +#include "tree.h" +#include "gimple.h" +#include "gimple-pretty-print.h" +#include "alias.h" +#include "fold-const.h" +#include "expr.h" +#include "gimple-iterator.h" +#include "tree-ssa-loop-niter.h" +#include "tree-ssa-loop.h" +#include "tree-ssa.h" +#include "cfgloop.h" +#include "tree-data-ref.h" +#include "tree-scalar-evolution.h" +#include "dumpfile.h" +#include "tree-affine.h" +#include "builtins.h" +#include "tree-eh.h" +#include "ssa.h" +#include "internal-fn.h" +#include "vr-values.h" +#include "range-op.h" +#include "tree-ssa-loop-ivopts.h" + +static struct datadep_stats +{ + int num_dependence_tests; + int num_dependence_dependent; + int num_dependence_independent; + int num_dependence_undetermined; + + int num_subscript_tests; + int num_subscript_undetermined; + int num_same_subscript_function; + + int num_ziv; + int num_ziv_independent; + int num_ziv_dependent; + int num_ziv_unimplemented; + + int num_siv; + int num_siv_independent; + int num_siv_dependent; + int num_siv_unimplemented; + + int num_miv; + int num_miv_independent; + int num_miv_dependent; + int num_miv_unimplemented; +} dependence_stats; + +static bool subscript_dependence_tester_1 (struct data_dependence_relation *, + unsigned int, unsigned int, + class loop *); +/* Returns true iff A divides B. */ + +static inline bool +tree_fold_divides_p (const_tree a, const_tree b) +{ + gcc_assert (TREE_CODE (a) == INTEGER_CST); + gcc_assert (TREE_CODE (b) == INTEGER_CST); + return integer_zerop (int_const_binop (TRUNC_MOD_EXPR, b, a)); +} + +/* Returns true iff A divides B. */ + +static inline bool +int_divides_p (lambda_int a, lambda_int b) +{ + return ((b % a) == 0); +} + +/* Return true if reference REF contains a union access. */ + +static bool +ref_contains_union_access_p (tree ref) +{ + while (handled_component_p (ref)) + { + ref = TREE_OPERAND (ref, 0); + if (TREE_CODE (TREE_TYPE (ref)) == UNION_TYPE + || TREE_CODE (TREE_TYPE (ref)) == QUAL_UNION_TYPE) + return true; + } + return false; +} + + + +/* Dump into FILE all the data references from DATAREFS. */ + +static void +dump_data_references (FILE *file, vec<data_reference_p> datarefs) +{ + for (data_reference *dr : datarefs) + dump_data_reference (file, dr); +} + +/* Unified dump into FILE all the data references from DATAREFS. */ + +DEBUG_FUNCTION void +debug (vec<data_reference_p> &ref) +{ + dump_data_references (stderr, ref); +} + +DEBUG_FUNCTION void +debug (vec<data_reference_p> *ptr) +{ + if (ptr) + debug (*ptr); + else + fprintf (stderr, "<nil>\n"); +} + + +/* Dump into STDERR all the data references from DATAREFS. */ + +DEBUG_FUNCTION void +debug_data_references (vec<data_reference_p> datarefs) +{ + dump_data_references (stderr, datarefs); +} + +/* Print to STDERR the data_reference DR. */ + +DEBUG_FUNCTION void +debug_data_reference (struct data_reference *dr) +{ + dump_data_reference (stderr, dr); +} + +/* Dump function for a DATA_REFERENCE structure. */ + +void +dump_data_reference (FILE *outf, + struct data_reference *dr) +{ + unsigned int i; + + fprintf (outf, "#(Data Ref: \n"); + fprintf (outf, "# bb: %d \n", gimple_bb (DR_STMT (dr))->index); + fprintf (outf, "# stmt: "); + print_gimple_stmt (outf, DR_STMT (dr), 0); + fprintf (outf, "# ref: "); + print_generic_stmt (outf, DR_REF (dr)); + fprintf (outf, "# base_object: "); + print_generic_stmt (outf, DR_BASE_OBJECT (dr)); + + for (i = 0; i < DR_NUM_DIMENSIONS (dr); i++) + { + fprintf (outf, "# Access function %d: ", i); + print_generic_stmt (outf, DR_ACCESS_FN (dr, i)); + } + fprintf (outf, "#)\n"); +} + +/* Unified dump function for a DATA_REFERENCE structure. */ + +DEBUG_FUNCTION void +debug (data_reference &ref) +{ + dump_data_reference (stderr, &ref); +} + +DEBUG_FUNCTION void +debug (data_reference *ptr) +{ + if (ptr) + debug (*ptr); + else + fprintf (stderr, "<nil>\n"); +} + + +/* Dumps the affine function described by FN to the file OUTF. */ + +DEBUG_FUNCTION void +dump_affine_function (FILE *outf, affine_fn fn) +{ + unsigned i; + tree coef; + + print_generic_expr (outf, fn[0], TDF_SLIM); + for (i = 1; fn.iterate (i, &coef); i++) + { + fprintf (outf, " + "); + print_generic_expr (outf, coef, TDF_SLIM); + fprintf (outf, " * x_%u", i); + } +} + +/* Dumps the conflict function CF to the file OUTF. */ + +DEBUG_FUNCTION void +dump_conflict_function (FILE *outf, conflict_function *cf) +{ + unsigned i; + + if (cf->n == NO_DEPENDENCE) + fprintf (outf, "no dependence"); + else if (cf->n == NOT_KNOWN) + fprintf (outf, "not known"); + else + { + for (i = 0; i < cf->n; i++) + { + if (i != 0) + fprintf (outf, " "); + fprintf (outf, "["); + dump_affine_function (outf, cf->fns[i]); + fprintf (outf, "]"); + } + } +} + +/* Dump function for a SUBSCRIPT structure. */ + +DEBUG_FUNCTION void +dump_subscript (FILE *outf, struct subscript *subscript) +{ + conflict_function *cf = SUB_CONFLICTS_IN_A (subscript); + + fprintf (outf, "\n (subscript \n"); + fprintf (outf, " iterations_that_access_an_element_twice_in_A: "); + dump_conflict_function (outf, cf); + if (CF_NONTRIVIAL_P (cf)) + { + tree last_iteration = SUB_LAST_CONFLICT (subscript); + fprintf (outf, "\n last_conflict: "); + print_generic_expr (outf, last_iteration); + } + + cf = SUB_CONFLICTS_IN_B (subscript); + fprintf (outf, "\n iterations_that_access_an_element_twice_in_B: "); + dump_conflict_function (outf, cf); + if (CF_NONTRIVIAL_P (cf)) + { + tree last_iteration = SUB_LAST_CONFLICT (subscript); + fprintf (outf, "\n last_conflict: "); + print_generic_expr (outf, last_iteration); + } + + fprintf (outf, "\n (Subscript distance: "); + print_generic_expr (outf, SUB_DISTANCE (subscript)); + fprintf (outf, " ))\n"); +} + +/* Print the classic direction vector DIRV to OUTF. */ + +DEBUG_FUNCTION void +print_direction_vector (FILE *outf, + lambda_vector dirv, + int length) +{ + int eq; + + for (eq = 0; eq < length; eq++) + { + enum data_dependence_direction dir = ((enum data_dependence_direction) + dirv[eq]); + + switch (dir) + { + case dir_positive: + fprintf (outf, " +"); + break; + case dir_negative: + fprintf (outf, " -"); + break; + case dir_equal: + fprintf (outf, " ="); + break; + case dir_positive_or_equal: + fprintf (outf, " +="); + break; + case dir_positive_or_negative: + fprintf (outf, " +-"); + break; + case dir_negative_or_equal: + fprintf (outf, " -="); + break; + case dir_star: + fprintf (outf, " *"); + break; + default: + fprintf (outf, "indep"); + break; + } + } + fprintf (outf, "\n"); +} + +/* Print a vector of direction vectors. */ + +DEBUG_FUNCTION void +print_dir_vectors (FILE *outf, vec<lambda_vector> dir_vects, + int length) +{ + for (lambda_vector v : dir_vects) + print_direction_vector (outf, v, length); +} + +/* Print out a vector VEC of length N to OUTFILE. */ + +DEBUG_FUNCTION void +print_lambda_vector (FILE * outfile, lambda_vector vector, int n) +{ + int i; + + for (i = 0; i < n; i++) + fprintf (outfile, HOST_WIDE_INT_PRINT_DEC " ", vector[i]); + fprintf (outfile, "\n"); +} + +/* Print a vector of distance vectors. */ + +DEBUG_FUNCTION void +print_dist_vectors (FILE *outf, vec<lambda_vector> dist_vects, + int length) +{ + for (lambda_vector v : dist_vects) + print_lambda_vector (outf, v, length); +} + +/* Dump function for a DATA_DEPENDENCE_RELATION structure. */ + +DEBUG_FUNCTION void +dump_data_dependence_relation (FILE *outf, const data_dependence_relation *ddr) +{ + struct data_reference *dra, *drb; + + fprintf (outf, "(Data Dep: \n"); + + if (!ddr || DDR_ARE_DEPENDENT (ddr) == chrec_dont_know) + { + if (ddr) + { + dra = DDR_A (ddr); + drb = DDR_B (ddr); + if (dra) + dump_data_reference (outf, dra); + else + fprintf (outf, " (nil)\n"); + if (drb) + dump_data_reference (outf, drb); + else + fprintf (outf, " (nil)\n"); + } + fprintf (outf, " (don't know)\n)\n"); + return; + } + + dra = DDR_A (ddr); + drb = DDR_B (ddr); + dump_data_reference (outf, dra); + dump_data_reference (outf, drb); + + if (DDR_ARE_DEPENDENT (ddr) == chrec_known) + fprintf (outf, " (no dependence)\n"); + + else if (DDR_ARE_DEPENDENT (ddr) == NULL_TREE) + { + unsigned int i; + class loop *loopi; + + subscript *sub; + FOR_EACH_VEC_ELT (DDR_SUBSCRIPTS (ddr), i, sub) + { + fprintf (outf, " access_fn_A: "); + print_generic_stmt (outf, SUB_ACCESS_FN (sub, 0)); + fprintf (outf, " access_fn_B: "); + print_generic_stmt (outf, SUB_ACCESS_FN (sub, 1)); + dump_subscript (outf, sub); + } + + fprintf (outf, " loop nest: ("); + FOR_EACH_VEC_ELT (DDR_LOOP_NEST (ddr), i, loopi) + fprintf (outf, "%d ", loopi->num); + fprintf (outf, ")\n"); + + for (i = 0; i < DDR_NUM_DIST_VECTS (ddr); i++) + { + fprintf (outf, " distance_vector: "); + print_lambda_vector (outf, DDR_DIST_VECT (ddr, i), + DDR_NB_LOOPS (ddr)); + } + + for (i = 0; i < DDR_NUM_DIR_VECTS (ddr); i++) + { + fprintf (outf, " direction_vector: "); + print_direction_vector (outf, DDR_DIR_VECT (ddr, i), + DDR_NB_LOOPS (ddr)); + } + } + + fprintf (outf, ")\n"); +} + +/* Debug version. */ + +DEBUG_FUNCTION void +debug_data_dependence_relation (const struct data_dependence_relation *ddr) +{ + dump_data_dependence_relation (stderr, ddr); +} + +/* Dump into FILE all the dependence relations from DDRS. */ + +DEBUG_FUNCTION void +dump_data_dependence_relations (FILE *file, const vec<ddr_p> &ddrs) +{ + for (auto ddr : ddrs) + dump_data_dependence_relation (file, ddr); +} + +DEBUG_FUNCTION void +debug (vec<ddr_p> &ref) +{ + dump_data_dependence_relations (stderr, ref); +} + +DEBUG_FUNCTION void +debug (vec<ddr_p> *ptr) +{ + if (ptr) + debug (*ptr); + else + fprintf (stderr, "<nil>\n"); +} + + +/* Dump to STDERR all the dependence relations from DDRS. */ + +DEBUG_FUNCTION void +debug_data_dependence_relations (vec<ddr_p> ddrs) +{ + dump_data_dependence_relations (stderr, ddrs); +} + +/* Dumps the distance and direction vectors in FILE. DDRS contains + the dependence relations, and VECT_SIZE is the size of the + dependence vectors, or in other words the number of loops in the + considered nest. */ + +DEBUG_FUNCTION void +dump_dist_dir_vectors (FILE *file, vec<ddr_p> ddrs) +{ + for (data_dependence_relation *ddr : ddrs) + if (DDR_ARE_DEPENDENT (ddr) == NULL_TREE && DDR_AFFINE_P (ddr)) + { + for (lambda_vector v : DDR_DIST_VECTS (ddr)) + { + fprintf (file, "DISTANCE_V ("); + print_lambda_vector (file, v, DDR_NB_LOOPS (ddr)); + fprintf (file, ")\n"); + } + + for (lambda_vector v : DDR_DIR_VECTS (ddr)) + { + fprintf (file, "DIRECTION_V ("); + print_direction_vector (file, v, DDR_NB_LOOPS (ddr)); + fprintf (file, ")\n"); + } + } + + fprintf (file, "\n\n"); +} + +/* Dumps the data dependence relations DDRS in FILE. */ + +DEBUG_FUNCTION void +dump_ddrs (FILE *file, vec<ddr_p> ddrs) +{ + for (data_dependence_relation *ddr : ddrs) + dump_data_dependence_relation (file, ddr); + + fprintf (file, "\n\n"); +} + +DEBUG_FUNCTION void +debug_ddrs (vec<ddr_p> ddrs) +{ + dump_ddrs (stderr, ddrs); +} + +/* If RESULT_RANGE is nonnull, set *RESULT_RANGE to the range of + OP0 CODE OP1, where: + + - OP0 CODE OP1 has integral type TYPE + - the range of OP0 is given by OP0_RANGE and + - the range of OP1 is given by OP1_RANGE. + + Independently of RESULT_RANGE, try to compute: + + DELTA = ((sizetype) OP0 CODE (sizetype) OP1) + - (sizetype) (OP0 CODE OP1) + + as a constant and subtract DELTA from the ssizetype constant in *OFF. + Return true on success, or false if DELTA is not known at compile time. + + Truncation and sign changes are known to distribute over CODE, i.e. + + (itype) (A CODE B) == (itype) A CODE (itype) B + + for any integral type ITYPE whose precision is no greater than the + precision of A and B. */ + +static bool +compute_distributive_range (tree type, value_range &op0_range, + tree_code code, value_range &op1_range, + tree *off, value_range *result_range) +{ + gcc_assert (INTEGRAL_TYPE_P (type) && !TYPE_OVERFLOW_TRAPS (type)); + if (result_range) + { + range_operator *op = range_op_handler (code, type); + op->fold_range (*result_range, type, op0_range, op1_range); + } + + /* The distributive property guarantees that if TYPE is no narrower + than SIZETYPE, + + (sizetype) (OP0 CODE OP1) == (sizetype) OP0 CODE (sizetype) OP1 + + and so we can treat DELTA as zero. */ + if (TYPE_PRECISION (type) >= TYPE_PRECISION (sizetype)) + return true; + + /* If overflow is undefined, we can assume that: + + X == (ssizetype) OP0 CODE (ssizetype) OP1 + + is within the range of TYPE, i.e.: + + X == (ssizetype) (TYPE) X + + Distributing the (TYPE) truncation over X gives: + + X == (ssizetype) (OP0 CODE OP1) + + Casting both sides to sizetype and distributing the sizetype cast + over X gives: + + (sizetype) OP0 CODE (sizetype) OP1 == (sizetype) (OP0 CODE OP1) + + and so we can treat DELTA as zero. */ + if (TYPE_OVERFLOW_UNDEFINED (type)) + return true; + + /* Compute the range of: + + (ssizetype) OP0 CODE (ssizetype) OP1 + + The distributive property guarantees that this has the same bitpattern as: + + (sizetype) OP0 CODE (sizetype) OP1 + + but its range is more conducive to analysis. */ + range_cast (op0_range, ssizetype); + range_cast (op1_range, ssizetype); + value_range wide_range; + range_operator *op = range_op_handler (code, ssizetype); + bool saved_flag_wrapv = flag_wrapv; + flag_wrapv = 1; + op->fold_range (wide_range, ssizetype, op0_range, op1_range); + flag_wrapv = saved_flag_wrapv; + if (wide_range.num_pairs () != 1 || !range_int_cst_p (&wide_range)) + return false; + + wide_int lb = wide_range.lower_bound (); + wide_int ub = wide_range.upper_bound (); + + /* Calculate the number of times that each end of the range overflows or + underflows TYPE. We can only calculate DELTA if the numbers match. */ + unsigned int precision = TYPE_PRECISION (type); + if (!TYPE_UNSIGNED (type)) + { + wide_int type_min = wi::mask (precision - 1, true, lb.get_precision ()); + lb -= type_min; + ub -= type_min; + } + wide_int upper_bits = wi::mask (precision, true, lb.get_precision ()); + lb &= upper_bits; + ub &= upper_bits; + if (lb != ub) + return false; + + /* OP0 CODE OP1 overflows exactly arshift (LB, PRECISION) times, with + negative values indicating underflow. The low PRECISION bits of LB + are clear, so DELTA is therefore LB (== UB). */ + *off = wide_int_to_tree (ssizetype, wi::to_wide (*off) - lb); + return true; +} + +/* Return true if (sizetype) OP == (sizetype) (TO_TYPE) OP, + given that OP has type FROM_TYPE and range RANGE. Both TO_TYPE and + FROM_TYPE are integral types. */ + +static bool +nop_conversion_for_offset_p (tree to_type, tree from_type, value_range &range) +{ + gcc_assert (INTEGRAL_TYPE_P (to_type) + && INTEGRAL_TYPE_P (from_type) + && !TYPE_OVERFLOW_TRAPS (to_type) + && !TYPE_OVERFLOW_TRAPS (from_type)); + + /* Converting to something no narrower than sizetype and then to sizetype + is equivalent to converting directly to sizetype. */ + if (TYPE_PRECISION (to_type) >= TYPE_PRECISION (sizetype)) + return true; + + /* Check whether TO_TYPE can represent all values that FROM_TYPE can. */ + if (TYPE_PRECISION (from_type) < TYPE_PRECISION (to_type) + && (TYPE_UNSIGNED (from_type) || !TYPE_UNSIGNED (to_type))) + return true; + + /* For narrowing conversions, we could in principle test whether + the bits in FROM_TYPE but not in TO_TYPE have a fixed value + and apply a constant adjustment. + + For other conversions (which involve a sign change) we could + check that the signs are always equal, and apply a constant + adjustment if the signs are negative. + + However, both cases should be rare. */ + return range_fits_type_p (&range, TYPE_PRECISION (to_type), + TYPE_SIGN (to_type)); +} + +static void +split_constant_offset (tree type, tree *var, tree *off, + value_range *result_range, + hash_map<tree, std::pair<tree, tree> > &cache, + unsigned *limit); + +/* Helper function for split_constant_offset. If TYPE is a pointer type, + try to express OP0 CODE OP1 as: + + POINTER_PLUS <*VAR, (sizetype) *OFF> + + where: + + - *VAR has type TYPE + - *OFF is a constant of type ssizetype. + + If TYPE is an integral type, try to express (sizetype) (OP0 CODE OP1) as: + + *VAR + (sizetype) *OFF + + where: + + - *VAR has type sizetype + - *OFF is a constant of type ssizetype. + + In both cases, OP0 CODE OP1 has type TYPE. + + Return true on success. A false return value indicates that we can't + do better than set *OFF to zero. + + When returning true, set RESULT_RANGE to the range of OP0 CODE OP1, + if RESULT_RANGE is nonnull and if we can do better than assume VR_VARYING. + + CACHE caches {*VAR, *OFF} pairs for SSA names that we've previously + visited. LIMIT counts down the number of SSA names that we are + allowed to process before giving up. */ + +static bool +split_constant_offset_1 (tree type, tree op0, enum tree_code code, tree op1, + tree *var, tree *off, value_range *result_range, + hash_map<tree, std::pair<tree, tree> > &cache, + unsigned *limit) +{ + tree var0, var1; + tree off0, off1; + value_range op0_range, op1_range; + + *var = NULL_TREE; + *off = NULL_TREE; + + if (INTEGRAL_TYPE_P (type) && TYPE_OVERFLOW_TRAPS (type)) + return false; + + switch (code) + { + case INTEGER_CST: + *var = size_int (0); + *off = fold_convert (ssizetype, op0); + if (result_range) + result_range->set (op0, op0); + return true; + + case POINTER_PLUS_EXPR: + split_constant_offset (op0, &var0, &off0, nullptr, cache, limit); + split_constant_offset (op1, &var1, &off1, nullptr, cache, limit); + *var = fold_build2 (POINTER_PLUS_EXPR, type, var0, var1); + *off = size_binop (PLUS_EXPR, off0, off1); + return true; + + case PLUS_EXPR: + case MINUS_EXPR: + split_constant_offset (op0, &var0, &off0, &op0_range, cache, limit); + split_constant_offset (op1, &var1, &off1, &op1_range, cache, limit); + *off = size_binop (code, off0, off1); + if (!compute_distributive_range (type, op0_range, code, op1_range, + off, result_range)) + return false; + *var = fold_build2 (code, sizetype, var0, var1); + return true; + + case MULT_EXPR: + if (TREE_CODE (op1) != INTEGER_CST) + return false; + + split_constant_offset (op0, &var0, &off0, &op0_range, cache, limit); + op1_range.set (op1, op1); + *off = size_binop (MULT_EXPR, off0, fold_convert (ssizetype, op1)); + if (!compute_distributive_range (type, op0_range, code, op1_range, + off, result_range)) + return false; + *var = fold_build2 (MULT_EXPR, sizetype, var0, + fold_convert (sizetype, op1)); + return true; + + case ADDR_EXPR: + { + tree base, poffset; + poly_int64 pbitsize, pbitpos, pbytepos; + machine_mode pmode; + int punsignedp, preversep, pvolatilep; + + op0 = TREE_OPERAND (op0, 0); + base + = get_inner_reference (op0, &pbitsize, &pbitpos, &poffset, &pmode, + &punsignedp, &preversep, &pvolatilep); + + if (!multiple_p (pbitpos, BITS_PER_UNIT, &pbytepos)) + return false; + base = build_fold_addr_expr (base); + off0 = ssize_int (pbytepos); + + if (poffset) + { + split_constant_offset (poffset, &poffset, &off1, nullptr, + cache, limit); + off0 = size_binop (PLUS_EXPR, off0, off1); + base = fold_build_pointer_plus (base, poffset); + } + + var0 = fold_convert (type, base); + + /* If variable length types are involved, punt, otherwise casts + might be converted into ARRAY_REFs in gimplify_conversion. + To compute that ARRAY_REF's element size TYPE_SIZE_UNIT, which + possibly no longer appears in current GIMPLE, might resurface. + This perhaps could run + if (CONVERT_EXPR_P (var0)) + { + gimplify_conversion (&var0); + // Attempt to fill in any within var0 found ARRAY_REF's + // element size from corresponding op embedded ARRAY_REF, + // if unsuccessful, just punt. + } */ + while (POINTER_TYPE_P (type)) + type = TREE_TYPE (type); + if (int_size_in_bytes (type) < 0) + return false; + + *var = var0; + *off = off0; + return true; + } + + case SSA_NAME: + { + if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op0)) + return false; + + gimple *def_stmt = SSA_NAME_DEF_STMT (op0); + enum tree_code subcode; + + if (gimple_code (def_stmt) != GIMPLE_ASSIGN) + return false; + + subcode = gimple_assign_rhs_code (def_stmt); + + /* We are using a cache to avoid un-CSEing large amounts of code. */ + bool use_cache = false; + if (!has_single_use (op0) + && (subcode == POINTER_PLUS_EXPR + || subcode == PLUS_EXPR + || subcode == MINUS_EXPR + || subcode == MULT_EXPR + || subcode == ADDR_EXPR + || CONVERT_EXPR_CODE_P (subcode))) + { + use_cache = true; + bool existed; + std::pair<tree, tree> &e = cache.get_or_insert (op0, &existed); + if (existed) + { + if (integer_zerop (e.second)) + return false; + *var = e.first; + *off = e.second; + /* The caller sets the range in this case. */ + return true; + } + e = std::make_pair (op0, ssize_int (0)); + } + + if (*limit == 0) + return false; + --*limit; + + var0 = gimple_assign_rhs1 (def_stmt); + var1 = gimple_assign_rhs2 (def_stmt); + + bool res = split_constant_offset_1 (type, var0, subcode, var1, + var, off, nullptr, cache, limit); + if (res && use_cache) + *cache.get (op0) = std::make_pair (*var, *off); + /* The caller sets the range in this case. */ + return res; + } + CASE_CONVERT: + { + /* We can only handle the following conversions: + + - Conversions from one pointer type to another pointer type. + + - Conversions from one non-trapping integral type to another + non-trapping integral type. In this case, the recursive + call makes sure that: + + (sizetype) OP0 + + can be expressed as a sizetype operation involving VAR and OFF, + and all we need to do is check whether: + + (sizetype) OP0 == (sizetype) (TYPE) OP0 + + - Conversions from a non-trapping sizetype-size integral type to + a like-sized pointer type. In this case, the recursive call + makes sure that: + + (sizetype) OP0 == *VAR + (sizetype) *OFF + + and we can convert that to: + + POINTER_PLUS <(TYPE) *VAR, (sizetype) *OFF> + + - Conversions from a sizetype-sized pointer type to a like-sized + non-trapping integral type. In this case, the recursive call + makes sure that: + + OP0 == POINTER_PLUS <*VAR, (sizetype) *OFF> + + where the POINTER_PLUS and *VAR have the same precision as + TYPE (and the same precision as sizetype). Then: + + (sizetype) (TYPE) OP0 == (sizetype) *VAR + (sizetype) *OFF. */ + tree itype = TREE_TYPE (op0); + if ((POINTER_TYPE_P (itype) + || (INTEGRAL_TYPE_P (itype) && !TYPE_OVERFLOW_TRAPS (itype))) + && (POINTER_TYPE_P (type) + || (INTEGRAL_TYPE_P (type) && !TYPE_OVERFLOW_TRAPS (type))) + && (POINTER_TYPE_P (type) == POINTER_TYPE_P (itype) + || (TYPE_PRECISION (type) == TYPE_PRECISION (sizetype) + && TYPE_PRECISION (itype) == TYPE_PRECISION (sizetype)))) + { + if (POINTER_TYPE_P (type)) + { + split_constant_offset (op0, var, off, nullptr, cache, limit); + *var = fold_convert (type, *var); + } + else if (POINTER_TYPE_P (itype)) + { + split_constant_offset (op0, var, off, nullptr, cache, limit); + *var = fold_convert (sizetype, *var); + } + else + { + split_constant_offset (op0, var, off, &op0_range, + cache, limit); + if (!nop_conversion_for_offset_p (type, itype, op0_range)) + return false; + if (result_range) + { + *result_range = op0_range; + range_cast (*result_range, type); + } + } + return true; + } + return false; + } + + default: + return false; + } +} + +/* If EXP has pointer type, try to express it as: + + POINTER_PLUS <*VAR, (sizetype) *OFF> + + where: + + - *VAR has the same type as EXP + - *OFF is a constant of type ssizetype. + + If EXP has an integral type, try to express (sizetype) EXP as: + + *VAR + (sizetype) *OFF + + where: + + - *VAR has type sizetype + - *OFF is a constant of type ssizetype. + + If EXP_RANGE is nonnull, set it to the range of EXP. + + CACHE caches {*VAR, *OFF} pairs for SSA names that we've previously + visited. LIMIT counts down the number of SSA names that we are + allowed to process before giving up. */ + +static void +split_constant_offset (tree exp, tree *var, tree *off, value_range *exp_range, + hash_map<tree, std::pair<tree, tree> > &cache, + unsigned *limit) +{ + tree type = TREE_TYPE (exp), op0, op1; + enum tree_code code; + + code = TREE_CODE (exp); + if (exp_range) + { + *exp_range = type; + if (code == SSA_NAME) + { + value_range vr; + get_range_query (cfun)->range_of_expr (vr, exp); + if (vr.undefined_p ()) + vr.set_varying (TREE_TYPE (exp)); + wide_int var_min = wi::to_wide (vr.min ()); + wide_int var_max = wi::to_wide (vr.max ()); + value_range_kind vr_kind = vr.kind (); + wide_int var_nonzero = get_nonzero_bits (exp); + vr_kind = intersect_range_with_nonzero_bits (vr_kind, + &var_min, &var_max, + var_nonzero, + TYPE_SIGN (type)); + /* This check for VR_VARYING is here because the old code + using get_range_info would return VR_RANGE for the entire + domain, instead of VR_VARYING. The new code normalizes + full-domain ranges to VR_VARYING. */ + if (vr_kind == VR_RANGE || vr_kind == VR_VARYING) + *exp_range = value_range (type, var_min, var_max); + } + } + + if (!tree_is_chrec (exp) + && get_gimple_rhs_class (TREE_CODE (exp)) != GIMPLE_TERNARY_RHS) + { + extract_ops_from_tree (exp, &code, &op0, &op1); + if (split_constant_offset_1 (type, op0, code, op1, var, off, + exp_range, cache, limit)) + return; + } + + *var = exp; + if (INTEGRAL_TYPE_P (type)) + *var = fold_convert (sizetype, *var); + *off = ssize_int (0); + + value_range r; + if (exp_range && code != SSA_NAME + && get_range_query (cfun)->range_of_expr (r, exp) + && !r.undefined_p ()) + *exp_range = r; +} + +/* Expresses EXP as VAR + OFF, where OFF is a constant. VAR has the same + type as EXP while OFF has type ssizetype. */ + +void +split_constant_offset (tree exp, tree *var, tree *off) +{ + unsigned limit = param_ssa_name_def_chain_limit; + static hash_map<tree, std::pair<tree, tree> > *cache; + if (!cache) + cache = new hash_map<tree, std::pair<tree, tree> > (37); + split_constant_offset (exp, var, off, nullptr, *cache, &limit); + *var = fold_convert (TREE_TYPE (exp), *var); + cache->empty (); +} + +/* Returns the address ADDR of an object in a canonical shape (without nop + casts, and with type of pointer to the object). */ + +static tree +canonicalize_base_object_address (tree addr) +{ + tree orig = addr; + + STRIP_NOPS (addr); + + /* The base address may be obtained by casting from integer, in that case + keep the cast. */ + if (!POINTER_TYPE_P (TREE_TYPE (addr))) + return orig; + + if (TREE_CODE (addr) != ADDR_EXPR) + return addr; + + return build_fold_addr_expr (TREE_OPERAND (addr, 0)); +} + +/* Analyze the behavior of memory reference REF within STMT. + There are two modes: + + - BB analysis. In this case we simply split the address into base, + init and offset components, without reference to any containing loop. + The resulting base and offset are general expressions and they can + vary arbitrarily from one iteration of the containing loop to the next. + The step is always zero. + + - loop analysis. In this case we analyze the reference both wrt LOOP + and on the basis that the reference occurs (is "used") in LOOP; + see the comment above analyze_scalar_evolution_in_loop for more + information about this distinction. The base, init, offset and + step fields are all invariant in LOOP. + + Perform BB analysis if LOOP is null, or if LOOP is the function's + dummy outermost loop. In other cases perform loop analysis. + + Return true if the analysis succeeded and store the results in DRB if so. + BB analysis can only fail for bitfield or reversed-storage accesses. */ + +opt_result +dr_analyze_innermost (innermost_loop_behavior *drb, tree ref, + class loop *loop, const gimple *stmt) +{ + poly_int64 pbitsize, pbitpos; + tree base, poffset; + machine_mode pmode; + int punsignedp, preversep, pvolatilep; + affine_iv base_iv, offset_iv; + tree init, dinit, step; + bool in_loop = (loop && loop->num); + + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "analyze_innermost: "); + + base = get_inner_reference (ref, &pbitsize, &pbitpos, &poffset, &pmode, + &punsignedp, &preversep, &pvolatilep); + gcc_assert (base != NULL_TREE); + + poly_int64 pbytepos; + if (!multiple_p (pbitpos, BITS_PER_UNIT, &pbytepos)) + return opt_result::failure_at (stmt, + "failed: bit offset alignment.\n"); + + if (preversep) + return opt_result::failure_at (stmt, + "failed: reverse storage order.\n"); + + /* Calculate the alignment and misalignment for the inner reference. */ + unsigned int HOST_WIDE_INT bit_base_misalignment; + unsigned int bit_base_alignment; + get_object_alignment_1 (base, &bit_base_alignment, &bit_base_misalignment); + + /* There are no bitfield references remaining in BASE, so the values + we got back must be whole bytes. */ + gcc_assert (bit_base_alignment % BITS_PER_UNIT == 0 + && bit_base_misalignment % BITS_PER_UNIT == 0); + unsigned int base_alignment = bit_base_alignment / BITS_PER_UNIT; + poly_int64 base_misalignment = bit_base_misalignment / BITS_PER_UNIT; + + if (TREE_CODE (base) == MEM_REF) + { + if (!integer_zerop (TREE_OPERAND (base, 1))) + { + /* Subtract MOFF from the base and add it to POFFSET instead. + Adjust the misalignment to reflect the amount we subtracted. */ + poly_offset_int moff = mem_ref_offset (base); + base_misalignment -= moff.force_shwi (); + tree mofft = wide_int_to_tree (sizetype, moff); + if (!poffset) + poffset = mofft; + else + poffset = size_binop (PLUS_EXPR, poffset, mofft); + } + base = TREE_OPERAND (base, 0); + } + else + base = build_fold_addr_expr (base); + + if (in_loop) + { + if (!simple_iv (loop, loop, base, &base_iv, true)) + return opt_result::failure_at + (stmt, "failed: evolution of base is not affine.\n"); + } + else + { + base_iv.base = base; + base_iv.step = ssize_int (0); + base_iv.no_overflow = true; + } + + if (!poffset) + { + offset_iv.base = ssize_int (0); + offset_iv.step = ssize_int (0); + } + else + { + if (!in_loop) + { + offset_iv.base = poffset; + offset_iv.step = ssize_int (0); + } + else if (!simple_iv (loop, loop, poffset, &offset_iv, true)) + return opt_result::failure_at + (stmt, "failed: evolution of offset is not affine.\n"); + } + + init = ssize_int (pbytepos); + + /* Subtract any constant component from the base and add it to INIT instead. + Adjust the misalignment to reflect the amount we subtracted. */ + split_constant_offset (base_iv.base, &base_iv.base, &dinit); + init = size_binop (PLUS_EXPR, init, dinit); + base_misalignment -= TREE_INT_CST_LOW (dinit); + + split_constant_offset (offset_iv.base, &offset_iv.base, &dinit); + init = size_binop (PLUS_EXPR, init, dinit); + + step = size_binop (PLUS_EXPR, + fold_convert (ssizetype, base_iv.step), + fold_convert (ssizetype, offset_iv.step)); + + base = canonicalize_base_object_address (base_iv.base); + + /* See if get_pointer_alignment can guarantee a higher alignment than + the one we calculated above. */ + unsigned int HOST_WIDE_INT alt_misalignment; + unsigned int alt_alignment; + get_pointer_alignment_1 (base, &alt_alignment, &alt_misalignment); + + /* As above, these values must be whole bytes. */ + gcc_assert (alt_alignment % BITS_PER_UNIT == 0 + && alt_misalignment % BITS_PER_UNIT == 0); + alt_alignment /= BITS_PER_UNIT; + alt_misalignment /= BITS_PER_UNIT; + + if (base_alignment < alt_alignment) + { + base_alignment = alt_alignment; + base_misalignment = alt_misalignment; + } + + drb->base_address = base; + drb->offset = fold_convert (ssizetype, offset_iv.base); + drb->init = init; + drb->step = step; + if (known_misalignment (base_misalignment, base_alignment, + &drb->base_misalignment)) + drb->base_alignment = base_alignment; + else + { + drb->base_alignment = known_alignment (base_misalignment); + drb->base_misalignment = 0; + } + drb->offset_alignment = highest_pow2_factor (offset_iv.base); + drb->step_alignment = highest_pow2_factor (step); + + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "success.\n"); + + return opt_result::success (); +} + +/* Return true if OP is a valid component reference for a DR access + function. This accepts a subset of what handled_component_p accepts. */ + +static bool +access_fn_component_p (tree op) +{ + switch (TREE_CODE (op)) + { + case REALPART_EXPR: + case IMAGPART_EXPR: + case ARRAY_REF: + return true; + + case COMPONENT_REF: + return TREE_CODE (TREE_TYPE (TREE_OPERAND (op, 0))) == RECORD_TYPE; + + default: + return false; + } +} + +/* Returns whether BASE can have a access_fn_component_p with BASE + as base. */ + +static bool +base_supports_access_fn_components_p (tree base) +{ + switch (TREE_CODE (TREE_TYPE (base))) + { + case COMPLEX_TYPE: + case ARRAY_TYPE: + case RECORD_TYPE: + return true; + default: + return false; + } +} + +/* Determines the base object and the list of indices of memory reference + DR, analyzed in LOOP and instantiated before NEST. */ + +static void +dr_analyze_indices (struct indices *dri, tree ref, edge nest, loop_p loop) +{ + /* If analyzing a basic-block there are no indices to analyze + and thus no access functions. */ + if (!nest) + { + dri->base_object = ref; + dri->access_fns.create (0); + return; + } + + vec<tree> access_fns = vNULL; + + /* REALPART_EXPR and IMAGPART_EXPR can be handled like accesses + into a two element array with a constant index. The base is + then just the immediate underlying object. */ + if (TREE_CODE (ref) == REALPART_EXPR) + { + ref = TREE_OPERAND (ref, 0); + access_fns.safe_push (integer_zero_node); + } + else if (TREE_CODE (ref) == IMAGPART_EXPR) + { + ref = TREE_OPERAND (ref, 0); + access_fns.safe_push (integer_one_node); + } + + /* Analyze access functions of dimensions we know to be independent. + The list of component references handled here should be kept in + sync with access_fn_component_p. */ + while (handled_component_p (ref)) + { + if (TREE_CODE (ref) == ARRAY_REF) + { + tree op = TREE_OPERAND (ref, 1); + tree access_fn = analyze_scalar_evolution (loop, op); + access_fn = instantiate_scev (nest, loop, access_fn); + access_fns.safe_push (access_fn); + } + else if (TREE_CODE (ref) == COMPONENT_REF + && TREE_CODE (TREE_TYPE (TREE_OPERAND (ref, 0))) == RECORD_TYPE) + { + /* For COMPONENT_REFs of records (but not unions!) use the + FIELD_DECL offset as constant access function so we can + disambiguate a[i].f1 and a[i].f2. */ + tree off = component_ref_field_offset (ref); + off = size_binop (PLUS_EXPR, + size_binop (MULT_EXPR, + fold_convert (bitsizetype, off), + bitsize_int (BITS_PER_UNIT)), + DECL_FIELD_BIT_OFFSET (TREE_OPERAND (ref, 1))); + access_fns.safe_push (off); + } + else + /* If we have an unhandled component we could not translate + to an access function stop analyzing. We have determined + our base object in this case. */ + break; + + ref = TREE_OPERAND (ref, 0); + } + + /* If the address operand of a MEM_REF base has an evolution in the + analyzed nest, add it as an additional independent access-function. */ + if (TREE_CODE (ref) == MEM_REF) + { + tree op = TREE_OPERAND (ref, 0); + tree access_fn = analyze_scalar_evolution (loop, op); + access_fn = instantiate_scev (nest, loop, access_fn); + STRIP_NOPS (access_fn); + if (TREE_CODE (access_fn) == POLYNOMIAL_CHREC) + { + tree memoff = TREE_OPERAND (ref, 1); + tree base = initial_condition (access_fn); + tree orig_type = TREE_TYPE (base); + STRIP_USELESS_TYPE_CONVERSION (base); + tree off; + split_constant_offset (base, &base, &off); + STRIP_USELESS_TYPE_CONVERSION (base); + /* Fold the MEM_REF offset into the evolutions initial + value to make more bases comparable. */ + if (!integer_zerop (memoff)) + { + off = size_binop (PLUS_EXPR, off, + fold_convert (ssizetype, memoff)); + memoff = build_int_cst (TREE_TYPE (memoff), 0); + } + /* Adjust the offset so it is a multiple of the access type + size and thus we separate bases that can possibly be used + to produce partial overlaps (which the access_fn machinery + cannot handle). */ + wide_int rem; + if (TYPE_SIZE_UNIT (TREE_TYPE (ref)) + && TREE_CODE (TYPE_SIZE_UNIT (TREE_TYPE (ref))) == INTEGER_CST + && !integer_zerop (TYPE_SIZE_UNIT (TREE_TYPE (ref)))) + rem = wi::mod_trunc + (wi::to_wide (off), + wi::to_wide (TYPE_SIZE_UNIT (TREE_TYPE (ref))), + SIGNED); + else + /* If we can't compute the remainder simply force the initial + condition to zero. */ + rem = wi::to_wide (off); + off = wide_int_to_tree (ssizetype, wi::to_wide (off) - rem); + memoff = wide_int_to_tree (TREE_TYPE (memoff), rem); + /* And finally replace the initial condition. */ + access_fn = chrec_replace_initial_condition + (access_fn, fold_convert (orig_type, off)); + /* ??? This is still not a suitable base object for + dr_may_alias_p - the base object needs to be an + access that covers the object as whole. With + an evolution in the pointer this cannot be + guaranteed. + As a band-aid, mark the access so we can special-case + it in dr_may_alias_p. */ + tree old = ref; + ref = fold_build2_loc (EXPR_LOCATION (ref), + MEM_REF, TREE_TYPE (ref), + base, memoff); + MR_DEPENDENCE_CLIQUE (ref) = MR_DEPENDENCE_CLIQUE (old); + MR_DEPENDENCE_BASE (ref) = MR_DEPENDENCE_BASE (old); + dri->unconstrained_base = true; + access_fns.safe_push (access_fn); + } + } + else if (DECL_P (ref)) + { + /* Canonicalize DR_BASE_OBJECT to MEM_REF form. */ + ref = build2 (MEM_REF, TREE_TYPE (ref), + build_fold_addr_expr (ref), + build_int_cst (reference_alias_ptr_type (ref), 0)); + } + + dri->base_object = ref; + dri->access_fns = access_fns; +} + +/* Extracts the alias analysis information from the memory reference DR. */ + +static void +dr_analyze_alias (struct data_reference *dr) +{ + tree ref = DR_REF (dr); + tree base = get_base_address (ref), addr; + + if (INDIRECT_REF_P (base) + || TREE_CODE (base) == MEM_REF) + { + addr = TREE_OPERAND (base, 0); + if (TREE_CODE (addr) == SSA_NAME) + DR_PTR_INFO (dr) = SSA_NAME_PTR_INFO (addr); + } +} + +/* Frees data reference DR. */ + +void +free_data_ref (data_reference_p dr) +{ + DR_ACCESS_FNS (dr).release (); + if (dr->alt_indices.base_object) + dr->alt_indices.access_fns.release (); + free (dr); +} + +/* Analyze memory reference MEMREF, which is accessed in STMT. + The reference is a read if IS_READ is true, otherwise it is a write. + IS_CONDITIONAL_IN_STMT indicates that the reference is conditional + within STMT, i.e. that it might not occur even if STMT is executed + and runs to completion. + + Return the data_reference description of MEMREF. NEST is the outermost + loop in which the reference should be instantiated, LOOP is the loop + in which the data reference should be analyzed. */ + +struct data_reference * +create_data_ref (edge nest, loop_p loop, tree memref, gimple *stmt, + bool is_read, bool is_conditional_in_stmt) +{ + struct data_reference *dr; + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, "Creating dr for "); + print_generic_expr (dump_file, memref, TDF_SLIM); + fprintf (dump_file, "\n"); + } + + dr = XCNEW (struct data_reference); + DR_STMT (dr) = stmt; + DR_REF (dr) = memref; + DR_IS_READ (dr) = is_read; + DR_IS_CONDITIONAL_IN_STMT (dr) = is_conditional_in_stmt; + + dr_analyze_innermost (&DR_INNERMOST (dr), memref, + nest != NULL ? loop : NULL, stmt); + dr_analyze_indices (&dr->indices, DR_REF (dr), nest, loop); + dr_analyze_alias (dr); + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + unsigned i; + fprintf (dump_file, "\tbase_address: "); + print_generic_expr (dump_file, DR_BASE_ADDRESS (dr), TDF_SLIM); + fprintf (dump_file, "\n\toffset from base address: "); + print_generic_expr (dump_file, DR_OFFSET (dr), TDF_SLIM); + fprintf (dump_file, "\n\tconstant offset from base address: "); + print_generic_expr (dump_file, DR_INIT (dr), TDF_SLIM); + fprintf (dump_file, "\n\tstep: "); + print_generic_expr (dump_file, DR_STEP (dr), TDF_SLIM); + fprintf (dump_file, "\n\tbase alignment: %d", DR_BASE_ALIGNMENT (dr)); + fprintf (dump_file, "\n\tbase misalignment: %d", + DR_BASE_MISALIGNMENT (dr)); + fprintf (dump_file, "\n\toffset alignment: %d", + DR_OFFSET_ALIGNMENT (dr)); + fprintf (dump_file, "\n\tstep alignment: %d", DR_STEP_ALIGNMENT (dr)); + fprintf (dump_file, "\n\tbase_object: "); + print_generic_expr (dump_file, DR_BASE_OBJECT (dr), TDF_SLIM); + fprintf (dump_file, "\n"); + for (i = 0; i < DR_NUM_DIMENSIONS (dr); i++) + { + fprintf (dump_file, "\tAccess function %d: ", i); + print_generic_stmt (dump_file, DR_ACCESS_FN (dr, i), TDF_SLIM); + } + } + + return dr; +} + +/* A helper function computes order between two tree expressions T1 and T2. + This is used in comparator functions sorting objects based on the order + of tree expressions. The function returns -1, 0, or 1. */ + +int +data_ref_compare_tree (tree t1, tree t2) +{ + int i, cmp; + enum tree_code code; + char tclass; + + if (t1 == t2) + return 0; + if (t1 == NULL) + return -1; + if (t2 == NULL) + return 1; + + STRIP_USELESS_TYPE_CONVERSION (t1); + STRIP_USELESS_TYPE_CONVERSION (t2); + if (t1 == t2) + return 0; + + if (TREE_CODE (t1) != TREE_CODE (t2) + && ! (CONVERT_EXPR_P (t1) && CONVERT_EXPR_P (t2))) + return TREE_CODE (t1) < TREE_CODE (t2) ? -1 : 1; + + code = TREE_CODE (t1); + switch (code) + { + case INTEGER_CST: + return tree_int_cst_compare (t1, t2); + + case STRING_CST: + if (TREE_STRING_LENGTH (t1) != TREE_STRING_LENGTH (t2)) + return TREE_STRING_LENGTH (t1) < TREE_STRING_LENGTH (t2) ? -1 : 1; + return memcmp (TREE_STRING_POINTER (t1), TREE_STRING_POINTER (t2), + TREE_STRING_LENGTH (t1)); + + case SSA_NAME: + if (SSA_NAME_VERSION (t1) != SSA_NAME_VERSION (t2)) + return SSA_NAME_VERSION (t1) < SSA_NAME_VERSION (t2) ? -1 : 1; + break; + + default: + if (POLY_INT_CST_P (t1)) + return compare_sizes_for_sort (wi::to_poly_widest (t1), + wi::to_poly_widest (t2)); + + tclass = TREE_CODE_CLASS (code); + + /* For decls, compare their UIDs. */ + if (tclass == tcc_declaration) + { + if (DECL_UID (t1) != DECL_UID (t2)) + return DECL_UID (t1) < DECL_UID (t2) ? -1 : 1; + break; + } + /* For expressions, compare their operands recursively. */ + else if (IS_EXPR_CODE_CLASS (tclass)) + { + for (i = TREE_OPERAND_LENGTH (t1) - 1; i >= 0; --i) + { + cmp = data_ref_compare_tree (TREE_OPERAND (t1, i), + TREE_OPERAND (t2, i)); + if (cmp != 0) + return cmp; + } + } + else + gcc_unreachable (); + } + + return 0; +} + +/* Return TRUE it's possible to resolve data dependence DDR by runtime alias + check. */ + +opt_result +runtime_alias_check_p (ddr_p ddr, class loop *loop, bool speed_p) +{ + if (dump_enabled_p ()) + dump_printf (MSG_NOTE, + "consider run-time aliasing test between %T and %T\n", + DR_REF (DDR_A (ddr)), DR_REF (DDR_B (ddr))); + + if (!speed_p) + return opt_result::failure_at (DR_STMT (DDR_A (ddr)), + "runtime alias check not supported when" + " optimizing for size.\n"); + + /* FORNOW: We don't support versioning with outer-loop in either + vectorization or loop distribution. */ + if (loop != NULL && loop->inner != NULL) + return opt_result::failure_at (DR_STMT (DDR_A (ddr)), + "runtime alias check not supported for" + " outer loop.\n"); + + return opt_result::success (); +} + +/* Operator == between two dr_with_seg_len objects. + + This equality operator is used to make sure two data refs + are the same one so that we will consider to combine the + aliasing checks of those two pairs of data dependent data + refs. */ + +static bool +operator == (const dr_with_seg_len& d1, + const dr_with_seg_len& d2) +{ + return (operand_equal_p (DR_BASE_ADDRESS (d1.dr), + DR_BASE_ADDRESS (d2.dr), 0) + && data_ref_compare_tree (DR_OFFSET (d1.dr), DR_OFFSET (d2.dr)) == 0 + && data_ref_compare_tree (DR_INIT (d1.dr), DR_INIT (d2.dr)) == 0 + && data_ref_compare_tree (d1.seg_len, d2.seg_len) == 0 + && known_eq (d1.access_size, d2.access_size) + && d1.align == d2.align); +} + +/* Comparison function for sorting objects of dr_with_seg_len_pair_t + so that we can combine aliasing checks in one scan. */ + +static int +comp_dr_with_seg_len_pair (const void *pa_, const void *pb_) +{ + const dr_with_seg_len_pair_t* pa = (const dr_with_seg_len_pair_t *) pa_; + const dr_with_seg_len_pair_t* pb = (const dr_with_seg_len_pair_t *) pb_; + const dr_with_seg_len &a1 = pa->first, &a2 = pa->second; + const dr_with_seg_len &b1 = pb->first, &b2 = pb->second; + + /* For DR pairs (a, b) and (c, d), we only consider to merge the alias checks + if a and c have the same basic address snd step, and b and d have the same + address and step. Therefore, if any a&c or b&d don't have the same address + and step, we don't care the order of those two pairs after sorting. */ + int comp_res; + + if ((comp_res = data_ref_compare_tree (DR_BASE_ADDRESS (a1.dr), + DR_BASE_ADDRESS (b1.dr))) != 0) + return comp_res; + if ((comp_res = data_ref_compare_tree (DR_BASE_ADDRESS (a2.dr), + DR_BASE_ADDRESS (b2.dr))) != 0) + return comp_res; + if ((comp_res = data_ref_compare_tree (DR_STEP (a1.dr), + DR_STEP (b1.dr))) != 0) + return comp_res; + if ((comp_res = data_ref_compare_tree (DR_STEP (a2.dr), + DR_STEP (b2.dr))) != 0) + return comp_res; + if ((comp_res = data_ref_compare_tree (DR_OFFSET (a1.dr), + DR_OFFSET (b1.dr))) != 0) + return comp_res; + if ((comp_res = data_ref_compare_tree (DR_INIT (a1.dr), + DR_INIT (b1.dr))) != 0) + return comp_res; + if ((comp_res = data_ref_compare_tree (DR_OFFSET (a2.dr), + DR_OFFSET (b2.dr))) != 0) + return comp_res; + if ((comp_res = data_ref_compare_tree (DR_INIT (a2.dr), + DR_INIT (b2.dr))) != 0) + return comp_res; + + return 0; +} + +/* Dump information about ALIAS_PAIR, indenting each line by INDENT. */ + +static void +dump_alias_pair (dr_with_seg_len_pair_t *alias_pair, const char *indent) +{ + dump_printf (MSG_NOTE, "%sreference: %T vs. %T\n", indent, + DR_REF (alias_pair->first.dr), + DR_REF (alias_pair->second.dr)); + + dump_printf (MSG_NOTE, "%ssegment length: %T", indent, + alias_pair->first.seg_len); + if (!operand_equal_p (alias_pair->first.seg_len, + alias_pair->second.seg_len, 0)) + dump_printf (MSG_NOTE, " vs. %T", alias_pair->second.seg_len); + + dump_printf (MSG_NOTE, "\n%saccess size: ", indent); + dump_dec (MSG_NOTE, alias_pair->first.access_size); + if (maybe_ne (alias_pair->first.access_size, alias_pair->second.access_size)) + { + dump_printf (MSG_NOTE, " vs. "); + dump_dec (MSG_NOTE, alias_pair->second.access_size); + } + + dump_printf (MSG_NOTE, "\n%salignment: %d", indent, + alias_pair->first.align); + if (alias_pair->first.align != alias_pair->second.align) + dump_printf (MSG_NOTE, " vs. %d", alias_pair->second.align); + + dump_printf (MSG_NOTE, "\n%sflags: ", indent); + if (alias_pair->flags & DR_ALIAS_RAW) + dump_printf (MSG_NOTE, " RAW"); + if (alias_pair->flags & DR_ALIAS_WAR) + dump_printf (MSG_NOTE, " WAR"); + if (alias_pair->flags & DR_ALIAS_WAW) + dump_printf (MSG_NOTE, " WAW"); + if (alias_pair->flags & DR_ALIAS_ARBITRARY) + dump_printf (MSG_NOTE, " ARBITRARY"); + if (alias_pair->flags & DR_ALIAS_SWAPPED) + dump_printf (MSG_NOTE, " SWAPPED"); + if (alias_pair->flags & DR_ALIAS_UNSWAPPED) + dump_printf (MSG_NOTE, " UNSWAPPED"); + if (alias_pair->flags & DR_ALIAS_MIXED_STEPS) + dump_printf (MSG_NOTE, " MIXED_STEPS"); + if (alias_pair->flags == 0) + dump_printf (MSG_NOTE, " <none>"); + dump_printf (MSG_NOTE, "\n"); +} + +/* Merge alias checks recorded in ALIAS_PAIRS and remove redundant ones. + FACTOR is number of iterations that each data reference is accessed. + + Basically, for each pair of dependent data refs store_ptr_0 & load_ptr_0, + we create an expression: + + ((store_ptr_0 + store_segment_length_0) <= load_ptr_0) + || (load_ptr_0 + load_segment_length_0) <= store_ptr_0)) + + for aliasing checks. However, in some cases we can decrease the number + of checks by combining two checks into one. For example, suppose we have + another pair of data refs store_ptr_0 & load_ptr_1, and if the following + condition is satisfied: + + load_ptr_0 < load_ptr_1 && + load_ptr_1 - load_ptr_0 - load_segment_length_0 < store_segment_length_0 + + (this condition means, in each iteration of vectorized loop, the accessed + memory of store_ptr_0 cannot be between the memory of load_ptr_0 and + load_ptr_1.) + + we then can use only the following expression to finish the alising checks + between store_ptr_0 & load_ptr_0 and store_ptr_0 & load_ptr_1: + + ((store_ptr_0 + store_segment_length_0) <= load_ptr_0) + || (load_ptr_1 + load_segment_length_1 <= store_ptr_0)) + + Note that we only consider that load_ptr_0 and load_ptr_1 have the same + basic address. */ + +void +prune_runtime_alias_test_list (vec<dr_with_seg_len_pair_t> *alias_pairs, + poly_uint64) +{ + if (alias_pairs->is_empty ()) + return; + + /* Canonicalize each pair so that the base components are ordered wrt + data_ref_compare_tree. This allows the loop below to merge more + cases. */ + unsigned int i; + dr_with_seg_len_pair_t *alias_pair; + FOR_EACH_VEC_ELT (*alias_pairs, i, alias_pair) + { + data_reference_p dr_a = alias_pair->first.dr; + data_reference_p dr_b = alias_pair->second.dr; + int comp_res = data_ref_compare_tree (DR_BASE_ADDRESS (dr_a), + DR_BASE_ADDRESS (dr_b)); + if (comp_res == 0) + comp_res = data_ref_compare_tree (DR_OFFSET (dr_a), DR_OFFSET (dr_b)); + if (comp_res == 0) + comp_res = data_ref_compare_tree (DR_INIT (dr_a), DR_INIT (dr_b)); + if (comp_res > 0) + { + std::swap (alias_pair->first, alias_pair->second); + alias_pair->flags |= DR_ALIAS_SWAPPED; + } + else + alias_pair->flags |= DR_ALIAS_UNSWAPPED; + } + + /* Sort the collected data ref pairs so that we can scan them once to + combine all possible aliasing checks. */ + alias_pairs->qsort (comp_dr_with_seg_len_pair); + + /* Scan the sorted dr pairs and check if we can combine alias checks + of two neighboring dr pairs. */ + unsigned int last = 0; + for (i = 1; i < alias_pairs->length (); ++i) + { + /* Deal with two ddrs (dr_a1, dr_b1) and (dr_a2, dr_b2). */ + dr_with_seg_len_pair_t *alias_pair1 = &(*alias_pairs)[last]; + dr_with_seg_len_pair_t *alias_pair2 = &(*alias_pairs)[i]; + + dr_with_seg_len *dr_a1 = &alias_pair1->first; + dr_with_seg_len *dr_b1 = &alias_pair1->second; + dr_with_seg_len *dr_a2 = &alias_pair2->first; + dr_with_seg_len *dr_b2 = &alias_pair2->second; + + /* Remove duplicate data ref pairs. */ + if (*dr_a1 == *dr_a2 && *dr_b1 == *dr_b2) + { + if (dump_enabled_p ()) + dump_printf (MSG_NOTE, "found equal ranges %T, %T and %T, %T\n", + DR_REF (dr_a1->dr), DR_REF (dr_b1->dr), + DR_REF (dr_a2->dr), DR_REF (dr_b2->dr)); + alias_pair1->flags |= alias_pair2->flags; + continue; + } + + /* Assume that we won't be able to merge the pairs, then correct + if we do. */ + last += 1; + if (last != i) + (*alias_pairs)[last] = (*alias_pairs)[i]; + + if (*dr_a1 == *dr_a2 || *dr_b1 == *dr_b2) + { + /* We consider the case that DR_B1 and DR_B2 are same memrefs, + and DR_A1 and DR_A2 are two consecutive memrefs. */ + if (*dr_a1 == *dr_a2) + { + std::swap (dr_a1, dr_b1); + std::swap (dr_a2, dr_b2); + } + + poly_int64 init_a1, init_a2; + /* Only consider cases in which the distance between the initial + DR_A1 and the initial DR_A2 is known at compile time. */ + if (!operand_equal_p (DR_BASE_ADDRESS (dr_a1->dr), + DR_BASE_ADDRESS (dr_a2->dr), 0) + || !operand_equal_p (DR_OFFSET (dr_a1->dr), + DR_OFFSET (dr_a2->dr), 0) + || !poly_int_tree_p (DR_INIT (dr_a1->dr), &init_a1) + || !poly_int_tree_p (DR_INIT (dr_a2->dr), &init_a2)) + continue; + + /* Don't combine if we can't tell which one comes first. */ + if (!ordered_p (init_a1, init_a2)) + continue; + + /* Work out what the segment length would be if we did combine + DR_A1 and DR_A2: + + - If DR_A1 and DR_A2 have equal lengths, that length is + also the combined length. + + - If DR_A1 and DR_A2 both have negative "lengths", the combined + length is the lower bound on those lengths. + + - If DR_A1 and DR_A2 both have positive lengths, the combined + length is the upper bound on those lengths. + + Other cases are unlikely to give a useful combination. + + The lengths both have sizetype, so the sign is taken from + the step instead. */ + poly_uint64 new_seg_len = 0; + bool new_seg_len_p = !operand_equal_p (dr_a1->seg_len, + dr_a2->seg_len, 0); + if (new_seg_len_p) + { + poly_uint64 seg_len_a1, seg_len_a2; + if (!poly_int_tree_p (dr_a1->seg_len, &seg_len_a1) + || !poly_int_tree_p (dr_a2->seg_len, &seg_len_a2)) + continue; + + tree indicator_a = dr_direction_indicator (dr_a1->dr); + if (TREE_CODE (indicator_a) != INTEGER_CST) + continue; + + tree indicator_b = dr_direction_indicator (dr_a2->dr); + if (TREE_CODE (indicator_b) != INTEGER_CST) + continue; + + int sign_a = tree_int_cst_sgn (indicator_a); + int sign_b = tree_int_cst_sgn (indicator_b); + + if (sign_a <= 0 && sign_b <= 0) + new_seg_len = lower_bound (seg_len_a1, seg_len_a2); + else if (sign_a >= 0 && sign_b >= 0) + new_seg_len = upper_bound (seg_len_a1, seg_len_a2); + else + continue; + } + /* At this point we're committed to merging the refs. */ + + /* Make sure dr_a1 starts left of dr_a2. */ + if (maybe_gt (init_a1, init_a2)) + { + std::swap (*dr_a1, *dr_a2); + std::swap (init_a1, init_a2); + } + + /* The DR_Bs are equal, so only the DR_As can introduce + mixed steps. */ + if (!operand_equal_p (DR_STEP (dr_a1->dr), DR_STEP (dr_a2->dr), 0)) + alias_pair1->flags |= DR_ALIAS_MIXED_STEPS; + + if (new_seg_len_p) + { + dr_a1->seg_len = build_int_cst (TREE_TYPE (dr_a1->seg_len), + new_seg_len); + dr_a1->align = MIN (dr_a1->align, known_alignment (new_seg_len)); + } + + /* This is always positive due to the swap above. */ + poly_uint64 diff = init_a2 - init_a1; + + /* The new check will start at DR_A1. Make sure that its access + size encompasses the initial DR_A2. */ + if (maybe_lt (dr_a1->access_size, diff + dr_a2->access_size)) + { + dr_a1->access_size = upper_bound (dr_a1->access_size, + diff + dr_a2->access_size); + unsigned int new_align = known_alignment (dr_a1->access_size); + dr_a1->align = MIN (dr_a1->align, new_align); + } + if (dump_enabled_p ()) + dump_printf (MSG_NOTE, "merging ranges for %T, %T and %T, %T\n", + DR_REF (dr_a1->dr), DR_REF (dr_b1->dr), + DR_REF (dr_a2->dr), DR_REF (dr_b2->dr)); + alias_pair1->flags |= alias_pair2->flags; + last -= 1; + } + } + alias_pairs->truncate (last + 1); + + /* Try to restore the original dr_with_seg_len order within each + dr_with_seg_len_pair_t. If we ended up combining swapped and + unswapped pairs into the same check, we have to invalidate any + RAW, WAR and WAW information for it. */ + if (dump_enabled_p ()) + dump_printf (MSG_NOTE, "merged alias checks:\n"); + FOR_EACH_VEC_ELT (*alias_pairs, i, alias_pair) + { + unsigned int swap_mask = (DR_ALIAS_SWAPPED | DR_ALIAS_UNSWAPPED); + unsigned int swapped = (alias_pair->flags & swap_mask); + if (swapped == DR_ALIAS_SWAPPED) + std::swap (alias_pair->first, alias_pair->second); + else if (swapped != DR_ALIAS_UNSWAPPED) + alias_pair->flags |= DR_ALIAS_ARBITRARY; + alias_pair->flags &= ~swap_mask; + if (dump_enabled_p ()) + dump_alias_pair (alias_pair, " "); + } +} + +/* A subroutine of create_intersect_range_checks, with a subset of the + same arguments. Try to use IFN_CHECK_RAW_PTRS and IFN_CHECK_WAR_PTRS + to optimize cases in which the references form a simple RAW, WAR or + WAR dependence. */ + +static bool +create_ifn_alias_checks (tree *cond_expr, + const dr_with_seg_len_pair_t &alias_pair) +{ + const dr_with_seg_len& dr_a = alias_pair.first; + const dr_with_seg_len& dr_b = alias_pair.second; + + /* Check for cases in which: + + (a) we have a known RAW, WAR or WAR dependence + (b) the accesses are well-ordered in both the original and new code + (see the comment above the DR_ALIAS_* flags for details); and + (c) the DR_STEPs describe all access pairs covered by ALIAS_PAIR. */ + if (alias_pair.flags & ~(DR_ALIAS_RAW | DR_ALIAS_WAR | DR_ALIAS_WAW)) + return false; + + /* Make sure that both DRs access the same pattern of bytes, + with a constant length and step. */ + poly_uint64 seg_len; + if (!operand_equal_p (dr_a.seg_len, dr_b.seg_len, 0) + || !poly_int_tree_p (dr_a.seg_len, &seg_len) + || maybe_ne (dr_a.access_size, dr_b.access_size) + || !operand_equal_p (DR_STEP (dr_a.dr), DR_STEP (dr_b.dr), 0) + || !tree_fits_uhwi_p (DR_STEP (dr_a.dr))) + return false; + + unsigned HOST_WIDE_INT bytes = tree_to_uhwi (DR_STEP (dr_a.dr)); + tree addr_a = DR_BASE_ADDRESS (dr_a.dr); + tree addr_b = DR_BASE_ADDRESS (dr_b.dr); + + /* See whether the target suports what we want to do. WAW checks are + equivalent to WAR checks here. */ + internal_fn ifn = (alias_pair.flags & DR_ALIAS_RAW + ? IFN_CHECK_RAW_PTRS + : IFN_CHECK_WAR_PTRS); + unsigned int align = MIN (dr_a.align, dr_b.align); + poly_uint64 full_length = seg_len + bytes; + if (!internal_check_ptrs_fn_supported_p (ifn, TREE_TYPE (addr_a), + full_length, align)) + { + full_length = seg_len + dr_a.access_size; + if (!internal_check_ptrs_fn_supported_p (ifn, TREE_TYPE (addr_a), + full_length, align)) + return false; + } + + /* Commit to using this form of test. */ + addr_a = fold_build_pointer_plus (addr_a, DR_OFFSET (dr_a.dr)); + addr_a = fold_build_pointer_plus (addr_a, DR_INIT (dr_a.dr)); + + addr_b = fold_build_pointer_plus (addr_b, DR_OFFSET (dr_b.dr)); + addr_b = fold_build_pointer_plus (addr_b, DR_INIT (dr_b.dr)); + + *cond_expr = build_call_expr_internal_loc (UNKNOWN_LOCATION, + ifn, boolean_type_node, + 4, addr_a, addr_b, + size_int (full_length), + size_int (align)); + + if (dump_enabled_p ()) + { + if (ifn == IFN_CHECK_RAW_PTRS) + dump_printf (MSG_NOTE, "using an IFN_CHECK_RAW_PTRS test\n"); + else + dump_printf (MSG_NOTE, "using an IFN_CHECK_WAR_PTRS test\n"); + } + return true; +} + +/* Try to generate a runtime condition that is true if ALIAS_PAIR is + free of aliases, using a condition based on index values instead + of a condition based on addresses. Return true on success, + storing the condition in *COND_EXPR. + + This can only be done if the two data references in ALIAS_PAIR access + the same array object and the index is the only difference. For example, + if the two data references are DR_A and DR_B: + + DR_A DR_B + data-ref arr[i] arr[j] + base_object arr arr + index {i_0, +, 1}_loop {j_0, +, 1}_loop + + The addresses and their index are like: + + |<- ADDR_A ->| |<- ADDR_B ->| + -------------------------------------------------------> + | | | | | | | | | | + -------------------------------------------------------> + i_0 ... i_0+4 j_0 ... j_0+4 + + We can create expression based on index rather than address: + + (unsigned) (i_0 - j_0 + 3) <= 6 + + i.e. the indices are less than 4 apart. + + Note evolution step of index needs to be considered in comparison. */ + +static bool +create_intersect_range_checks_index (class loop *loop, tree *cond_expr, + const dr_with_seg_len_pair_t &alias_pair) +{ + const dr_with_seg_len &dr_a = alias_pair.first; + const dr_with_seg_len &dr_b = alias_pair.second; + if ((alias_pair.flags & DR_ALIAS_MIXED_STEPS) + || integer_zerop (DR_STEP (dr_a.dr)) + || integer_zerop (DR_STEP (dr_b.dr)) + || DR_NUM_DIMENSIONS (dr_a.dr) != DR_NUM_DIMENSIONS (dr_b.dr)) + return false; + + poly_uint64 seg_len1, seg_len2; + if (!poly_int_tree_p (dr_a.seg_len, &seg_len1) + || !poly_int_tree_p (dr_b.seg_len, &seg_len2)) + return false; + + if (!tree_fits_shwi_p (DR_STEP (dr_a.dr))) + return false; + + if (!operand_equal_p (DR_BASE_OBJECT (dr_a.dr), DR_BASE_OBJECT (dr_b.dr), 0)) + return false; + + if (!operand_equal_p (DR_STEP (dr_a.dr), DR_STEP (dr_b.dr), 0)) + return false; + + gcc_assert (TREE_CODE (DR_STEP (dr_a.dr)) == INTEGER_CST); + + bool neg_step = tree_int_cst_compare (DR_STEP (dr_a.dr), size_zero_node) < 0; + unsigned HOST_WIDE_INT abs_step = tree_to_shwi (DR_STEP (dr_a.dr)); + if (neg_step) + { + abs_step = -abs_step; + seg_len1 = (-wi::to_poly_wide (dr_a.seg_len)).force_uhwi (); + seg_len2 = (-wi::to_poly_wide (dr_b.seg_len)).force_uhwi (); + } + + /* Infer the number of iterations with which the memory segment is accessed + by DR. In other words, alias is checked if memory segment accessed by + DR_A in some iterations intersect with memory segment accessed by DR_B + in the same amount iterations. + Note segnment length is a linear function of number of iterations with + DR_STEP as the coefficient. */ + poly_uint64 niter_len1, niter_len2; + if (!can_div_trunc_p (seg_len1 + abs_step - 1, abs_step, &niter_len1) + || !can_div_trunc_p (seg_len2 + abs_step - 1, abs_step, &niter_len2)) + return false; + + /* Divide each access size by the byte step, rounding up. */ + poly_uint64 niter_access1, niter_access2; + if (!can_div_trunc_p (dr_a.access_size + abs_step - 1, + abs_step, &niter_access1) + || !can_div_trunc_p (dr_b.access_size + abs_step - 1, + abs_step, &niter_access2)) + return false; + + bool waw_or_war_p = (alias_pair.flags & ~(DR_ALIAS_WAR | DR_ALIAS_WAW)) == 0; + + int found = -1; + for (unsigned int i = 0; i < DR_NUM_DIMENSIONS (dr_a.dr); i++) + { + tree access1 = DR_ACCESS_FN (dr_a.dr, i); + tree access2 = DR_ACCESS_FN (dr_b.dr, i); + /* Two indices must be the same if they are not scev, or not scev wrto + current loop being vecorized. */ + if (TREE_CODE (access1) != POLYNOMIAL_CHREC + || TREE_CODE (access2) != POLYNOMIAL_CHREC + || CHREC_VARIABLE (access1) != (unsigned)loop->num + || CHREC_VARIABLE (access2) != (unsigned)loop->num) + { + if (operand_equal_p (access1, access2, 0)) + continue; + + return false; + } + if (found >= 0) + return false; + found = i; + } + + /* Ought not to happen in practice, since if all accesses are equal then the + alias should be decidable at compile time. */ + if (found < 0) + return false; + + /* The two indices must have the same step. */ + tree access1 = DR_ACCESS_FN (dr_a.dr, found); + tree access2 = DR_ACCESS_FN (dr_b.dr, found); + if (!operand_equal_p (CHREC_RIGHT (access1), CHREC_RIGHT (access2), 0)) + return false; + + tree idx_step = CHREC_RIGHT (access1); + /* Index must have const step, otherwise DR_STEP won't be constant. */ + gcc_assert (TREE_CODE (idx_step) == INTEGER_CST); + /* Index must evaluate in the same direction as DR. */ + gcc_assert (!neg_step || tree_int_cst_sign_bit (idx_step) == 1); + + tree min1 = CHREC_LEFT (access1); + tree min2 = CHREC_LEFT (access2); + if (!types_compatible_p (TREE_TYPE (min1), TREE_TYPE (min2))) + return false; + + /* Ideally, alias can be checked against loop's control IV, but we + need to prove linear mapping between control IV and reference + index. Although that should be true, we check against (array) + index of data reference. Like segment length, index length is + linear function of the number of iterations with index_step as + the coefficient, i.e, niter_len * idx_step. */ + offset_int abs_idx_step = offset_int::from (wi::to_wide (idx_step), + SIGNED); + if (neg_step) + abs_idx_step = -abs_idx_step; + poly_offset_int idx_len1 = abs_idx_step * niter_len1; + poly_offset_int idx_len2 = abs_idx_step * niter_len2; + poly_offset_int idx_access1 = abs_idx_step * niter_access1; + poly_offset_int idx_access2 = abs_idx_step * niter_access2; + + gcc_assert (known_ge (idx_len1, 0) + && known_ge (idx_len2, 0) + && known_ge (idx_access1, 0) + && known_ge (idx_access2, 0)); + + /* Each access has the following pattern, with lengths measured + in units of INDEX: + + <-- idx_len --> + <--- A: -ve step ---> + +-----+-------+-----+-------+-----+ + | n-1 | ..... | 0 | ..... | n-1 | + +-----+-------+-----+-------+-----+ + <--- B: +ve step ---> + <-- idx_len --> + | + min + + where "n" is the number of scalar iterations covered by the segment + and where each access spans idx_access units. + + A is the range of bytes accessed when the step is negative, + B is the range when the step is positive. + + When checking for general overlap, we need to test whether + the range: + + [min1 + low_offset1, min1 + high_offset1 + idx_access1 - 1] + + overlaps: + + [min2 + low_offset2, min2 + high_offset2 + idx_access2 - 1] + + where: + + low_offsetN = +ve step ? 0 : -idx_lenN; + high_offsetN = +ve step ? idx_lenN : 0; + + This is equivalent to testing whether: + + min1 + low_offset1 <= min2 + high_offset2 + idx_access2 - 1 + && min2 + low_offset2 <= min1 + high_offset1 + idx_access1 - 1 + + Converting this into a single test, there is an overlap if: + + 0 <= min2 - min1 + bias <= limit + + where bias = high_offset2 + idx_access2 - 1 - low_offset1 + limit = (high_offset1 - low_offset1 + idx_access1 - 1) + + (high_offset2 - low_offset2 + idx_access2 - 1) + i.e. limit = idx_len1 + idx_access1 - 1 + idx_len2 + idx_access2 - 1 + + Combining the tests requires limit to be computable in an unsigned + form of the index type; if it isn't, we fall back to the usual + pointer-based checks. + + We can do better if DR_B is a write and if DR_A and DR_B are + well-ordered in both the original and the new code (see the + comment above the DR_ALIAS_* flags for details). In this case + we know that for each i in [0, n-1], the write performed by + access i of DR_B occurs after access numbers j<=i of DR_A in + both the original and the new code. Any write or anti + dependencies wrt those DR_A accesses are therefore maintained. + + We just need to make sure that each individual write in DR_B does not + overlap any higher-indexed access in DR_A; such DR_A accesses happen + after the DR_B access in the original code but happen before it in + the new code. + + We know the steps for both accesses are equal, so by induction, we + just need to test whether the first write of DR_B overlaps a later + access of DR_A. In other words, we need to move min1 along by + one iteration: + + min1' = min1 + idx_step + + and use the ranges: + + [min1' + low_offset1', min1' + high_offset1' + idx_access1 - 1] + + and: + + [min2, min2 + idx_access2 - 1] + + where: + + low_offset1' = +ve step ? 0 : -(idx_len1 - |idx_step|) + high_offset1' = +ve_step ? idx_len1 - |idx_step| : 0. */ + if (waw_or_war_p) + idx_len1 -= abs_idx_step; + + poly_offset_int limit = idx_len1 + idx_access1 - 1 + idx_access2 - 1; + if (!waw_or_war_p) + limit += idx_len2; + + tree utype = unsigned_type_for (TREE_TYPE (min1)); + if (!wi::fits_to_tree_p (limit, utype)) + return false; + + poly_offset_int low_offset1 = neg_step ? -idx_len1 : 0; + poly_offset_int high_offset2 = neg_step || waw_or_war_p ? 0 : idx_len2; + poly_offset_int bias = high_offset2 + idx_access2 - 1 - low_offset1; + /* Equivalent to adding IDX_STEP to MIN1. */ + if (waw_or_war_p) + bias -= wi::to_offset (idx_step); + + tree subject = fold_build2 (MINUS_EXPR, utype, + fold_convert (utype, min2), + fold_convert (utype, min1)); + subject = fold_build2 (PLUS_EXPR, utype, subject, + wide_int_to_tree (utype, bias)); + tree part_cond_expr = fold_build2 (GT_EXPR, boolean_type_node, subject, + wide_int_to_tree (utype, limit)); + if (*cond_expr) + *cond_expr = fold_build2 (TRUTH_AND_EXPR, boolean_type_node, + *cond_expr, part_cond_expr); + else + *cond_expr = part_cond_expr; + if (dump_enabled_p ()) + { + if (waw_or_war_p) + dump_printf (MSG_NOTE, "using an index-based WAR/WAW test\n"); + else + dump_printf (MSG_NOTE, "using an index-based overlap test\n"); + } + return true; +} + +/* A subroutine of create_intersect_range_checks, with a subset of the + same arguments. Try to optimize cases in which the second access + is a write and in which some overlap is valid. */ + +static bool +create_waw_or_war_checks (tree *cond_expr, + const dr_with_seg_len_pair_t &alias_pair) +{ + const dr_with_seg_len& dr_a = alias_pair.first; + const dr_with_seg_len& dr_b = alias_pair.second; + + /* Check for cases in which: + + (a) DR_B is always a write; + (b) the accesses are well-ordered in both the original and new code + (see the comment above the DR_ALIAS_* flags for details); and + (c) the DR_STEPs describe all access pairs covered by ALIAS_PAIR. */ + if (alias_pair.flags & ~(DR_ALIAS_WAR | DR_ALIAS_WAW)) + return false; + + /* Check for equal (but possibly variable) steps. */ + tree step = DR_STEP (dr_a.dr); + if (!operand_equal_p (step, DR_STEP (dr_b.dr))) + return false; + + /* Make sure that we can operate on sizetype without loss of precision. */ + tree addr_type = TREE_TYPE (DR_BASE_ADDRESS (dr_a.dr)); + if (TYPE_PRECISION (addr_type) != TYPE_PRECISION (sizetype)) + return false; + + /* All addresses involved are known to have a common alignment ALIGN. + We can therefore subtract ALIGN from an exclusive endpoint to get + an inclusive endpoint. In the best (and common) case, ALIGN is the + same as the access sizes of both DRs, and so subtracting ALIGN + cancels out the addition of an access size. */ + unsigned int align = MIN (dr_a.align, dr_b.align); + poly_uint64 last_chunk_a = dr_a.access_size - align; + poly_uint64 last_chunk_b = dr_b.access_size - align; + + /* Get a boolean expression that is true when the step is negative. */ + tree indicator = dr_direction_indicator (dr_a.dr); + tree neg_step = fold_build2 (LT_EXPR, boolean_type_node, + fold_convert (ssizetype, indicator), + ssize_int (0)); + + /* Get lengths in sizetype. */ + tree seg_len_a + = fold_convert (sizetype, rewrite_to_non_trapping_overflow (dr_a.seg_len)); + step = fold_convert (sizetype, rewrite_to_non_trapping_overflow (step)); + + /* Each access has the following pattern: + + <- |seg_len| -> + <--- A: -ve step ---> + +-----+-------+-----+-------+-----+ + | n-1 | ..... | 0 | ..... | n-1 | + +-----+-------+-----+-------+-----+ + <--- B: +ve step ---> + <- |seg_len| -> + | + base address + + where "n" is the number of scalar iterations covered by the segment. + + A is the range of bytes accessed when the step is negative, + B is the range when the step is positive. + + We know that DR_B is a write. We also know (from checking that + DR_A and DR_B are well-ordered) that for each i in [0, n-1], + the write performed by access i of DR_B occurs after access numbers + j<=i of DR_A in both the original and the new code. Any write or + anti dependencies wrt those DR_A accesses are therefore maintained. + + We just need to make sure that each individual write in DR_B does not + overlap any higher-indexed access in DR_A; such DR_A accesses happen + after the DR_B access in the original code but happen before it in + the new code. + + We know the steps for both accesses are equal, so by induction, we + just need to test whether the first write of DR_B overlaps a later + access of DR_A. In other words, we need to move addr_a along by + one iteration: + + addr_a' = addr_a + step + + and check whether: + + [addr_b, addr_b + last_chunk_b] + + overlaps: + + [addr_a' + low_offset_a, addr_a' + high_offset_a + last_chunk_a] + + where [low_offset_a, high_offset_a] spans accesses [1, n-1]. I.e.: + + low_offset_a = +ve step ? 0 : seg_len_a - step + high_offset_a = +ve step ? seg_len_a - step : 0 + + This is equivalent to testing whether: + + addr_a' + low_offset_a <= addr_b + last_chunk_b + && addr_b <= addr_a' + high_offset_a + last_chunk_a + + Converting this into a single test, there is an overlap if: + + 0 <= addr_b + last_chunk_b - addr_a' - low_offset_a <= limit + + where limit = high_offset_a - low_offset_a + last_chunk_a + last_chunk_b + + If DR_A is performed, limit + |step| - last_chunk_b is known to be + less than the size of the object underlying DR_A. We also know + that last_chunk_b <= |step|; this is checked elsewhere if it isn't + guaranteed at compile time. There can therefore be no overflow if + "limit" is calculated in an unsigned type with pointer precision. */ + tree addr_a = fold_build_pointer_plus (DR_BASE_ADDRESS (dr_a.dr), + DR_OFFSET (dr_a.dr)); + addr_a = fold_build_pointer_plus (addr_a, DR_INIT (dr_a.dr)); + + tree addr_b = fold_build_pointer_plus (DR_BASE_ADDRESS (dr_b.dr), + DR_OFFSET (dr_b.dr)); + addr_b = fold_build_pointer_plus (addr_b, DR_INIT (dr_b.dr)); + + /* Advance ADDR_A by one iteration and adjust the length to compensate. */ + addr_a = fold_build_pointer_plus (addr_a, step); + tree seg_len_a_minus_step = fold_build2 (MINUS_EXPR, sizetype, + seg_len_a, step); + if (!CONSTANT_CLASS_P (seg_len_a_minus_step)) + seg_len_a_minus_step = build1 (SAVE_EXPR, sizetype, seg_len_a_minus_step); + + tree low_offset_a = fold_build3 (COND_EXPR, sizetype, neg_step, + seg_len_a_minus_step, size_zero_node); + if (!CONSTANT_CLASS_P (low_offset_a)) + low_offset_a = build1 (SAVE_EXPR, sizetype, low_offset_a); + + /* We could use COND_EXPR <neg_step, size_zero_node, seg_len_a_minus_step>, + but it's usually more efficient to reuse the LOW_OFFSET_A result. */ + tree high_offset_a = fold_build2 (MINUS_EXPR, sizetype, seg_len_a_minus_step, + low_offset_a); + + /* The amount added to addr_b - addr_a'. */ + tree bias = fold_build2 (MINUS_EXPR, sizetype, + size_int (last_chunk_b), low_offset_a); + + tree limit = fold_build2 (MINUS_EXPR, sizetype, high_offset_a, low_offset_a); + limit = fold_build2 (PLUS_EXPR, sizetype, limit, + size_int (last_chunk_a + last_chunk_b)); + + tree subject = fold_build2 (POINTER_DIFF_EXPR, ssizetype, addr_b, addr_a); + subject = fold_build2 (PLUS_EXPR, sizetype, + fold_convert (sizetype, subject), bias); + + *cond_expr = fold_build2 (GT_EXPR, boolean_type_node, subject, limit); + if (dump_enabled_p ()) + dump_printf (MSG_NOTE, "using an address-based WAR/WAW test\n"); + return true; +} + +/* If ALIGN is nonzero, set up *SEQ_MIN_OUT and *SEQ_MAX_OUT so that for + every address ADDR accessed by D: + + *SEQ_MIN_OUT <= ADDR (== ADDR & -ALIGN) <= *SEQ_MAX_OUT + + In this case, every element accessed by D is aligned to at least + ALIGN bytes. + + If ALIGN is zero then instead set *SEG_MAX_OUT so that: + + *SEQ_MIN_OUT <= ADDR < *SEQ_MAX_OUT. */ + +static void +get_segment_min_max (const dr_with_seg_len &d, tree *seg_min_out, + tree *seg_max_out, HOST_WIDE_INT align) +{ + /* Each access has the following pattern: + + <- |seg_len| -> + <--- A: -ve step ---> + +-----+-------+-----+-------+-----+ + | n-1 | ,.... | 0 | ..... | n-1 | + +-----+-------+-----+-------+-----+ + <--- B: +ve step ---> + <- |seg_len| -> + | + base address + + where "n" is the number of scalar iterations covered by the segment. + (This should be VF for a particular pair if we know that both steps + are the same, otherwise it will be the full number of scalar loop + iterations.) + + A is the range of bytes accessed when the step is negative, + B is the range when the step is positive. + + If the access size is "access_size" bytes, the lowest addressed byte is: + + base + (step < 0 ? seg_len : 0) [LB] + + and the highest addressed byte is always below: + + base + (step < 0 ? 0 : seg_len) + access_size [UB] + + Thus: + + LB <= ADDR < UB + + If ALIGN is nonzero, all three values are aligned to at least ALIGN + bytes, so: + + LB <= ADDR <= UB - ALIGN + + where "- ALIGN" folds naturally with the "+ access_size" and often + cancels it out. + + We don't try to simplify LB and UB beyond this (e.g. by using + MIN and MAX based on whether seg_len rather than the stride is + negative) because it is possible for the absolute size of the + segment to overflow the range of a ssize_t. + + Keeping the pointer_plus outside of the cond_expr should allow + the cond_exprs to be shared with other alias checks. */ + tree indicator = dr_direction_indicator (d.dr); + tree neg_step = fold_build2 (LT_EXPR, boolean_type_node, + fold_convert (ssizetype, indicator), + ssize_int (0)); + tree addr_base = fold_build_pointer_plus (DR_BASE_ADDRESS (d.dr), + DR_OFFSET (d.dr)); + addr_base = fold_build_pointer_plus (addr_base, DR_INIT (d.dr)); + tree seg_len + = fold_convert (sizetype, rewrite_to_non_trapping_overflow (d.seg_len)); + + tree min_reach = fold_build3 (COND_EXPR, sizetype, neg_step, + seg_len, size_zero_node); + tree max_reach = fold_build3 (COND_EXPR, sizetype, neg_step, + size_zero_node, seg_len); + max_reach = fold_build2 (PLUS_EXPR, sizetype, max_reach, + size_int (d.access_size - align)); + + *seg_min_out = fold_build_pointer_plus (addr_base, min_reach); + *seg_max_out = fold_build_pointer_plus (addr_base, max_reach); +} + +/* Generate a runtime condition that is true if ALIAS_PAIR is free of aliases, + storing the condition in *COND_EXPR. The fallback is to generate a + a test that the two accesses do not overlap: + + end_a <= start_b || end_b <= start_a. */ + +static void +create_intersect_range_checks (class loop *loop, tree *cond_expr, + const dr_with_seg_len_pair_t &alias_pair) +{ + const dr_with_seg_len& dr_a = alias_pair.first; + const dr_with_seg_len& dr_b = alias_pair.second; + *cond_expr = NULL_TREE; + if (create_intersect_range_checks_index (loop, cond_expr, alias_pair)) + return; + + if (create_ifn_alias_checks (cond_expr, alias_pair)) + return; + + if (create_waw_or_war_checks (cond_expr, alias_pair)) + return; + + unsigned HOST_WIDE_INT min_align; + tree_code cmp_code; + /* We don't have to check DR_ALIAS_MIXED_STEPS here, since both versions + are equivalent. This is just an optimization heuristic. */ + if (TREE_CODE (DR_STEP (dr_a.dr)) == INTEGER_CST + && TREE_CODE (DR_STEP (dr_b.dr)) == INTEGER_CST) + { + /* In this case adding access_size to seg_len is likely to give + a simple X * step, where X is either the number of scalar + iterations or the vectorization factor. We're better off + keeping that, rather than subtracting an alignment from it. + + In this case the maximum values are exclusive and so there is + no alias if the maximum of one segment equals the minimum + of another. */ + min_align = 0; + cmp_code = LE_EXPR; + } + else + { + /* Calculate the minimum alignment shared by all four pointers, + then arrange for this alignment to be subtracted from the + exclusive maximum values to get inclusive maximum values. + This "- min_align" is cumulative with a "+ access_size" + in the calculation of the maximum values. In the best + (and common) case, the two cancel each other out, leaving + us with an inclusive bound based only on seg_len. In the + worst case we're simply adding a smaller number than before. + + Because the maximum values are inclusive, there is an alias + if the maximum value of one segment is equal to the minimum + value of the other. */ + min_align = MIN (dr_a.align, dr_b.align); + cmp_code = LT_EXPR; + } + + tree seg_a_min, seg_a_max, seg_b_min, seg_b_max; + get_segment_min_max (dr_a, &seg_a_min, &seg_a_max, min_align); + get_segment_min_max (dr_b, &seg_b_min, &seg_b_max, min_align); + + *cond_expr + = fold_build2 (TRUTH_OR_EXPR, boolean_type_node, + fold_build2 (cmp_code, boolean_type_node, seg_a_max, seg_b_min), + fold_build2 (cmp_code, boolean_type_node, seg_b_max, seg_a_min)); + if (dump_enabled_p ()) + dump_printf (MSG_NOTE, "using an address-based overlap test\n"); +} + +/* Create a conditional expression that represents the run-time checks for + overlapping of address ranges represented by a list of data references + pairs passed in ALIAS_PAIRS. Data references are in LOOP. The returned + COND_EXPR is the conditional expression to be used in the if statement + that controls which version of the loop gets executed at runtime. */ + +void +create_runtime_alias_checks (class loop *loop, + const vec<dr_with_seg_len_pair_t> *alias_pairs, + tree * cond_expr) +{ + tree part_cond_expr; + + fold_defer_overflow_warnings (); + for (const dr_with_seg_len_pair_t &alias_pair : alias_pairs) + { + gcc_assert (alias_pair.flags); + if (dump_enabled_p ()) + dump_printf (MSG_NOTE, + "create runtime check for data references %T and %T\n", + DR_REF (alias_pair.first.dr), + DR_REF (alias_pair.second.dr)); + + /* Create condition expression for each pair data references. */ + create_intersect_range_checks (loop, &part_cond_expr, alias_pair); + if (*cond_expr) + *cond_expr = fold_build2 (TRUTH_AND_EXPR, boolean_type_node, + *cond_expr, part_cond_expr); + else + *cond_expr = part_cond_expr; + } + fold_undefer_and_ignore_overflow_warnings (); +} + +/* Check if OFFSET1 and OFFSET2 (DR_OFFSETs of some data-refs) are identical + expressions. */ +static bool +dr_equal_offsets_p1 (tree offset1, tree offset2) +{ + bool res; + + STRIP_NOPS (offset1); + STRIP_NOPS (offset2); + + if (offset1 == offset2) + return true; + + if (TREE_CODE (offset1) != TREE_CODE (offset2) + || (!BINARY_CLASS_P (offset1) && !UNARY_CLASS_P (offset1))) + return false; + + res = dr_equal_offsets_p1 (TREE_OPERAND (offset1, 0), + TREE_OPERAND (offset2, 0)); + + if (!res || !BINARY_CLASS_P (offset1)) + return res; + + res = dr_equal_offsets_p1 (TREE_OPERAND (offset1, 1), + TREE_OPERAND (offset2, 1)); + + return res; +} + +/* Check if DRA and DRB have equal offsets. */ +bool +dr_equal_offsets_p (struct data_reference *dra, + struct data_reference *drb) +{ + tree offset1, offset2; + + offset1 = DR_OFFSET (dra); + offset2 = DR_OFFSET (drb); + + return dr_equal_offsets_p1 (offset1, offset2); +} + +/* Returns true if FNA == FNB. */ + +static bool +affine_function_equal_p (affine_fn fna, affine_fn fnb) +{ + unsigned i, n = fna.length (); + + if (n != fnb.length ()) + return false; + + for (i = 0; i < n; i++) + if (!operand_equal_p (fna[i], fnb[i], 0)) + return false; + + return true; +} + +/* If all the functions in CF are the same, returns one of them, + otherwise returns NULL. */ + +static affine_fn +common_affine_function (conflict_function *cf) +{ + unsigned i; + affine_fn comm; + + if (!CF_NONTRIVIAL_P (cf)) + return affine_fn (); + + comm = cf->fns[0]; + + for (i = 1; i < cf->n; i++) + if (!affine_function_equal_p (comm, cf->fns[i])) + return affine_fn (); + + return comm; +} + +/* Returns the base of the affine function FN. */ + +static tree +affine_function_base (affine_fn fn) +{ + return fn[0]; +} + +/* Returns true if FN is a constant. */ + +static bool +affine_function_constant_p (affine_fn fn) +{ + unsigned i; + tree coef; + + for (i = 1; fn.iterate (i, &coef); i++) + if (!integer_zerop (coef)) + return false; + + return true; +} + +/* Returns true if FN is the zero constant function. */ + +static bool +affine_function_zero_p (affine_fn fn) +{ + return (integer_zerop (affine_function_base (fn)) + && affine_function_constant_p (fn)); +} + +/* Returns a signed integer type with the largest precision from TA + and TB. */ + +static tree +signed_type_for_types (tree ta, tree tb) +{ + if (TYPE_PRECISION (ta) > TYPE_PRECISION (tb)) + return signed_type_for (ta); + else + return signed_type_for (tb); +} + +/* Applies operation OP on affine functions FNA and FNB, and returns the + result. */ + +static affine_fn +affine_fn_op (enum tree_code op, affine_fn fna, affine_fn fnb) +{ + unsigned i, n, m; + affine_fn ret; + tree coef; + + if (fnb.length () > fna.length ()) + { + n = fna.length (); + m = fnb.length (); + } + else + { + n = fnb.length (); + m = fna.length (); + } + + ret.create (m); + for (i = 0; i < n; i++) + { + tree type = signed_type_for_types (TREE_TYPE (fna[i]), + TREE_TYPE (fnb[i])); + ret.quick_push (fold_build2 (op, type, fna[i], fnb[i])); + } + + for (; fna.iterate (i, &coef); i++) + ret.quick_push (fold_build2 (op, signed_type_for (TREE_TYPE (coef)), + coef, integer_zero_node)); + for (; fnb.iterate (i, &coef); i++) + ret.quick_push (fold_build2 (op, signed_type_for (TREE_TYPE (coef)), + integer_zero_node, coef)); + + return ret; +} + +/* Returns the sum of affine functions FNA and FNB. */ + +static affine_fn +affine_fn_plus (affine_fn fna, affine_fn fnb) +{ + return affine_fn_op (PLUS_EXPR, fna, fnb); +} + +/* Returns the difference of affine functions FNA and FNB. */ + +static affine_fn +affine_fn_minus (affine_fn fna, affine_fn fnb) +{ + return affine_fn_op (MINUS_EXPR, fna, fnb); +} + +/* Frees affine function FN. */ + +static void +affine_fn_free (affine_fn fn) +{ + fn.release (); +} + +/* Determine for each subscript in the data dependence relation DDR + the distance. */ + +static void +compute_subscript_distance (struct data_dependence_relation *ddr) +{ + conflict_function *cf_a, *cf_b; + affine_fn fn_a, fn_b, diff; + + if (DDR_ARE_DEPENDENT (ddr) == NULL_TREE) + { + unsigned int i; + + for (i = 0; i < DDR_NUM_SUBSCRIPTS (ddr); i++) + { + struct subscript *subscript; + + subscript = DDR_SUBSCRIPT (ddr, i); + cf_a = SUB_CONFLICTS_IN_A (subscript); + cf_b = SUB_CONFLICTS_IN_B (subscript); + + fn_a = common_affine_function (cf_a); + fn_b = common_affine_function (cf_b); + if (!fn_a.exists () || !fn_b.exists ()) + { + SUB_DISTANCE (subscript) = chrec_dont_know; + return; + } + diff = affine_fn_minus (fn_a, fn_b); + + if (affine_function_constant_p (diff)) + SUB_DISTANCE (subscript) = affine_function_base (diff); + else + SUB_DISTANCE (subscript) = chrec_dont_know; + + affine_fn_free (diff); + } + } +} + +/* Returns the conflict function for "unknown". */ + +static conflict_function * +conflict_fn_not_known (void) +{ + conflict_function *fn = XCNEW (conflict_function); + fn->n = NOT_KNOWN; + + return fn; +} + +/* Returns the conflict function for "independent". */ + +static conflict_function * +conflict_fn_no_dependence (void) +{ + conflict_function *fn = XCNEW (conflict_function); + fn->n = NO_DEPENDENCE; + + return fn; +} + +/* Returns true if the address of OBJ is invariant in LOOP. */ + +static bool +object_address_invariant_in_loop_p (const class loop *loop, const_tree obj) +{ + while (handled_component_p (obj)) + { + if (TREE_CODE (obj) == ARRAY_REF) + { + for (int i = 1; i < 4; ++i) + if (chrec_contains_symbols_defined_in_loop (TREE_OPERAND (obj, i), + loop->num)) + return false; + } + else if (TREE_CODE (obj) == COMPONENT_REF) + { + if (chrec_contains_symbols_defined_in_loop (TREE_OPERAND (obj, 2), + loop->num)) + return false; + } + obj = TREE_OPERAND (obj, 0); + } + + if (!INDIRECT_REF_P (obj) + && TREE_CODE (obj) != MEM_REF) + return true; + + return !chrec_contains_symbols_defined_in_loop (TREE_OPERAND (obj, 0), + loop->num); +} + +/* Returns false if we can prove that data references A and B do not alias, + true otherwise. If LOOP_NEST is false no cross-iteration aliases are + considered. */ + +bool +dr_may_alias_p (const struct data_reference *a, const struct data_reference *b, + class loop *loop_nest) +{ + tree addr_a = DR_BASE_OBJECT (a); + tree addr_b = DR_BASE_OBJECT (b); + + /* If we are not processing a loop nest but scalar code we + do not need to care about possible cross-iteration dependences + and thus can process the full original reference. Do so, + similar to how loop invariant motion applies extra offset-based + disambiguation. */ + if (!loop_nest) + { + aff_tree off1, off2; + poly_widest_int size1, size2; + get_inner_reference_aff (DR_REF (a), &off1, &size1); + get_inner_reference_aff (DR_REF (b), &off2, &size2); + aff_combination_scale (&off1, -1); + aff_combination_add (&off2, &off1); + if (aff_comb_cannot_overlap_p (&off2, size1, size2)) + return false; + } + + if ((TREE_CODE (addr_a) == MEM_REF || TREE_CODE (addr_a) == TARGET_MEM_REF) + && (TREE_CODE (addr_b) == MEM_REF || TREE_CODE (addr_b) == TARGET_MEM_REF) + /* For cross-iteration dependences the cliques must be valid for the + whole loop, not just individual iterations. */ + && (!loop_nest + || MR_DEPENDENCE_CLIQUE (addr_a) == 1 + || MR_DEPENDENCE_CLIQUE (addr_a) == loop_nest->owned_clique) + && MR_DEPENDENCE_CLIQUE (addr_a) == MR_DEPENDENCE_CLIQUE (addr_b) + && MR_DEPENDENCE_BASE (addr_a) != MR_DEPENDENCE_BASE (addr_b)) + return false; + + /* If we had an evolution in a pointer-based MEM_REF BASE_OBJECT we + do not know the size of the base-object. So we cannot do any + offset/overlap based analysis but have to rely on points-to + information only. */ + if (TREE_CODE (addr_a) == MEM_REF + && (DR_UNCONSTRAINED_BASE (a) + || TREE_CODE (TREE_OPERAND (addr_a, 0)) == SSA_NAME)) + { + /* For true dependences we can apply TBAA. */ + if (flag_strict_aliasing + && DR_IS_WRITE (a) && DR_IS_READ (b) + && !alias_sets_conflict_p (get_alias_set (DR_REF (a)), + get_alias_set (DR_REF (b)))) + return false; + if (TREE_CODE (addr_b) == MEM_REF) + return ptr_derefs_may_alias_p (TREE_OPERAND (addr_a, 0), + TREE_OPERAND (addr_b, 0)); + else + return ptr_derefs_may_alias_p (TREE_OPERAND (addr_a, 0), + build_fold_addr_expr (addr_b)); + } + else if (TREE_CODE (addr_b) == MEM_REF + && (DR_UNCONSTRAINED_BASE (b) + || TREE_CODE (TREE_OPERAND (addr_b, 0)) == SSA_NAME)) + { + /* For true dependences we can apply TBAA. */ + if (flag_strict_aliasing + && DR_IS_WRITE (a) && DR_IS_READ (b) + && !alias_sets_conflict_p (get_alias_set (DR_REF (a)), + get_alias_set (DR_REF (b)))) + return false; + if (TREE_CODE (addr_a) == MEM_REF) + return ptr_derefs_may_alias_p (TREE_OPERAND (addr_a, 0), + TREE_OPERAND (addr_b, 0)); + else + return ptr_derefs_may_alias_p (build_fold_addr_expr (addr_a), + TREE_OPERAND (addr_b, 0)); + } + + /* Otherwise DR_BASE_OBJECT is an access that covers the whole object + that is being subsetted in the loop nest. */ + if (DR_IS_WRITE (a) && DR_IS_WRITE (b)) + return refs_output_dependent_p (addr_a, addr_b); + else if (DR_IS_READ (a) && DR_IS_WRITE (b)) + return refs_anti_dependent_p (addr_a, addr_b); + return refs_may_alias_p (addr_a, addr_b); +} + +/* REF_A and REF_B both satisfy access_fn_component_p. Return true + if it is meaningful to compare their associated access functions + when checking for dependencies. */ + +static bool +access_fn_components_comparable_p (tree ref_a, tree ref_b) +{ + /* Allow pairs of component refs from the following sets: + + { REALPART_EXPR, IMAGPART_EXPR } + { COMPONENT_REF } + { ARRAY_REF }. */ + tree_code code_a = TREE_CODE (ref_a); + tree_code code_b = TREE_CODE (ref_b); + if (code_a == IMAGPART_EXPR) + code_a = REALPART_EXPR; + if (code_b == IMAGPART_EXPR) + code_b = REALPART_EXPR; + if (code_a != code_b) + return false; + + if (TREE_CODE (ref_a) == COMPONENT_REF) + /* ??? We cannot simply use the type of operand #0 of the refs here as + the Fortran compiler smuggles type punning into COMPONENT_REFs. + Use the DECL_CONTEXT of the FIELD_DECLs instead. */ + return (DECL_CONTEXT (TREE_OPERAND (ref_a, 1)) + == DECL_CONTEXT (TREE_OPERAND (ref_b, 1))); + + return types_compatible_p (TREE_TYPE (TREE_OPERAND (ref_a, 0)), + TREE_TYPE (TREE_OPERAND (ref_b, 0))); +} + +/* Initialize a data dependence relation RES in LOOP_NEST. USE_ALT_INDICES + is true when the main indices of A and B were not comparable so we try again + with alternate indices computed on an indirect reference. */ + +struct data_dependence_relation * +initialize_data_dependence_relation (struct data_dependence_relation *res, + vec<loop_p> loop_nest, + bool use_alt_indices) +{ + struct data_reference *a = DDR_A (res); + struct data_reference *b = DDR_B (res); + unsigned int i; + + struct indices *indices_a = &a->indices; + struct indices *indices_b = &b->indices; + if (use_alt_indices) + { + if (TREE_CODE (DR_REF (a)) != MEM_REF) + indices_a = &a->alt_indices; + if (TREE_CODE (DR_REF (b)) != MEM_REF) + indices_b = &b->alt_indices; + } + unsigned int num_dimensions_a = indices_a->access_fns.length (); + unsigned int num_dimensions_b = indices_b->access_fns.length (); + if (num_dimensions_a == 0 || num_dimensions_b == 0) + { + DDR_ARE_DEPENDENT (res) = chrec_dont_know; + return res; + } + + /* For unconstrained bases, the root (highest-indexed) subscript + describes a variation in the base of the original DR_REF rather + than a component access. We have no type that accurately describes + the new DR_BASE_OBJECT (whose TREE_TYPE describes the type *after* + applying this subscript) so limit the search to the last real + component access. + + E.g. for: + + void + f (int a[][8], int b[][8]) + { + for (int i = 0; i < 8; ++i) + a[i * 2][0] = b[i][0]; + } + + the a and b accesses have a single ARRAY_REF component reference [0] + but have two subscripts. */ + if (indices_a->unconstrained_base) + num_dimensions_a -= 1; + if (indices_b->unconstrained_base) + num_dimensions_b -= 1; + + /* These structures describe sequences of component references in + DR_REF (A) and DR_REF (B). Each component reference is tied to a + specific access function. */ + struct { + /* The sequence starts at DR_ACCESS_FN (A, START_A) of A and + DR_ACCESS_FN (B, START_B) of B (inclusive) and extends to higher + indices. In C notation, these are the indices of the rightmost + component references; e.g. for a sequence .b.c.d, the start + index is for .d. */ + unsigned int start_a; + unsigned int start_b; + + /* The sequence contains LENGTH consecutive access functions from + each DR. */ + unsigned int length; + + /* The enclosing objects for the A and B sequences respectively, + i.e. the objects to which DR_ACCESS_FN (A, START_A + LENGTH - 1) + and DR_ACCESS_FN (B, START_B + LENGTH - 1) are applied. */ + tree object_a; + tree object_b; + } full_seq = {}, struct_seq = {}; + + /* Before each iteration of the loop: + + - REF_A is what you get after applying DR_ACCESS_FN (A, INDEX_A) and + - REF_B is what you get after applying DR_ACCESS_FN (B, INDEX_B). */ + unsigned int index_a = 0; + unsigned int index_b = 0; + tree ref_a = DR_REF (a); + tree ref_b = DR_REF (b); + + /* Now walk the component references from the final DR_REFs back up to + the enclosing base objects. Each component reference corresponds + to one access function in the DR, with access function 0 being for + the final DR_REF and the highest-indexed access function being the + one that is applied to the base of the DR. + + Look for a sequence of component references whose access functions + are comparable (see access_fn_components_comparable_p). If more + than one such sequence exists, pick the one nearest the base + (which is the leftmost sequence in C notation). Store this sequence + in FULL_SEQ. + + For example, if we have: + + struct foo { struct bar s; ... } (*a)[10], (*b)[10]; + + A: a[0][i].s.c.d + B: __real b[0][i].s.e[i].f + + (where d is the same type as the real component of f) then the access + functions would be: + + 0 1 2 3 + A: .d .c .s [i] + + 0 1 2 3 4 5 + B: __real .f [i] .e .s [i] + + The A0/B2 column isn't comparable, since .d is a COMPONENT_REF + and [i] is an ARRAY_REF. However, the A1/B3 column contains two + COMPONENT_REF accesses for struct bar, so is comparable. Likewise + the A2/B4 column contains two COMPONENT_REF accesses for struct foo, + so is comparable. The A3/B5 column contains two ARRAY_REFs that + index foo[10] arrays, so is again comparable. The sequence is + therefore: + + A: [1, 3] (i.e. [i].s.c) + B: [3, 5] (i.e. [i].s.e) + + Also look for sequences of component references whose access + functions are comparable and whose enclosing objects have the same + RECORD_TYPE. Store this sequence in STRUCT_SEQ. In the above + example, STRUCT_SEQ would be: + + A: [1, 2] (i.e. s.c) + B: [3, 4] (i.e. s.e) */ + while (index_a < num_dimensions_a && index_b < num_dimensions_b) + { + /* The alternate indices form always has a single dimension + with unconstrained base. */ + gcc_assert (!use_alt_indices); + + /* REF_A and REF_B must be one of the component access types + allowed by dr_analyze_indices. */ + gcc_checking_assert (access_fn_component_p (ref_a)); + gcc_checking_assert (access_fn_component_p (ref_b)); + + /* Get the immediately-enclosing objects for REF_A and REF_B, + i.e. the references *before* applying DR_ACCESS_FN (A, INDEX_A) + and DR_ACCESS_FN (B, INDEX_B). */ + tree object_a = TREE_OPERAND (ref_a, 0); + tree object_b = TREE_OPERAND (ref_b, 0); + + tree type_a = TREE_TYPE (object_a); + tree type_b = TREE_TYPE (object_b); + if (access_fn_components_comparable_p (ref_a, ref_b)) + { + /* This pair of component accesses is comparable for dependence + analysis, so we can include DR_ACCESS_FN (A, INDEX_A) and + DR_ACCESS_FN (B, INDEX_B) in the sequence. */ + if (full_seq.start_a + full_seq.length != index_a + || full_seq.start_b + full_seq.length != index_b) + { + /* The accesses don't extend the current sequence, + so start a new one here. */ + full_seq.start_a = index_a; + full_seq.start_b = index_b; + full_seq.length = 0; + } + + /* Add this pair of references to the sequence. */ + full_seq.length += 1; + full_seq.object_a = object_a; + full_seq.object_b = object_b; + + /* If the enclosing objects are structures (and thus have the + same RECORD_TYPE), record the new sequence in STRUCT_SEQ. */ + if (TREE_CODE (type_a) == RECORD_TYPE) + struct_seq = full_seq; + + /* Move to the next containing reference for both A and B. */ + ref_a = object_a; + ref_b = object_b; + index_a += 1; + index_b += 1; + continue; + } + + /* Try to approach equal type sizes. */ + if (!COMPLETE_TYPE_P (type_a) + || !COMPLETE_TYPE_P (type_b) + || !tree_fits_uhwi_p (TYPE_SIZE_UNIT (type_a)) + || !tree_fits_uhwi_p (TYPE_SIZE_UNIT (type_b))) + break; + + unsigned HOST_WIDE_INT size_a = tree_to_uhwi (TYPE_SIZE_UNIT (type_a)); + unsigned HOST_WIDE_INT size_b = tree_to_uhwi (TYPE_SIZE_UNIT (type_b)); + if (size_a <= size_b) + { + index_a += 1; + ref_a = object_a; + } + if (size_b <= size_a) + { + index_b += 1; + ref_b = object_b; + } + } + + /* See whether FULL_SEQ ends at the base and whether the two bases + are equal. We do not care about TBAA or alignment info so we can + use OEP_ADDRESS_OF to avoid false negatives. */ + tree base_a = indices_a->base_object; + tree base_b = indices_b->base_object; + bool same_base_p = (full_seq.start_a + full_seq.length == num_dimensions_a + && full_seq.start_b + full_seq.length == num_dimensions_b + && (indices_a->unconstrained_base + == indices_b->unconstrained_base) + && operand_equal_p (base_a, base_b, OEP_ADDRESS_OF) + && (types_compatible_p (TREE_TYPE (base_a), + TREE_TYPE (base_b)) + || (!base_supports_access_fn_components_p (base_a) + && !base_supports_access_fn_components_p (base_b) + && operand_equal_p + (TYPE_SIZE (TREE_TYPE (base_a)), + TYPE_SIZE (TREE_TYPE (base_b)), 0))) + && (!loop_nest.exists () + || (object_address_invariant_in_loop_p + (loop_nest[0], base_a)))); + + /* If the bases are the same, we can include the base variation too. + E.g. the b accesses in: + + for (int i = 0; i < n; ++i) + b[i + 4][0] = b[i][0]; + + have a definite dependence distance of 4, while for: + + for (int i = 0; i < n; ++i) + a[i + 4][0] = b[i][0]; + + the dependence distance depends on the gap between a and b. + + If the bases are different then we can only rely on the sequence + rooted at a structure access, since arrays are allowed to overlap + arbitrarily and change shape arbitrarily. E.g. we treat this as + valid code: + + int a[256]; + ... + ((int (*)[4][3]) &a[1])[i][0] += ((int (*)[4][3]) &a[2])[i][0]; + + where two lvalues with the same int[4][3] type overlap, and where + both lvalues are distinct from the object's declared type. */ + if (same_base_p) + { + if (indices_a->unconstrained_base) + full_seq.length += 1; + } + else + full_seq = struct_seq; + + /* Punt if we didn't find a suitable sequence. */ + if (full_seq.length == 0) + { + if (use_alt_indices + || (TREE_CODE (DR_REF (a)) == MEM_REF + && TREE_CODE (DR_REF (b)) == MEM_REF) + || may_be_nonaddressable_p (DR_REF (a)) + || may_be_nonaddressable_p (DR_REF (b))) + { + /* Fully exhausted possibilities. */ + DDR_ARE_DEPENDENT (res) = chrec_dont_know; + return res; + } + + /* Try evaluating both DRs as dereferences of pointers. */ + if (!a->alt_indices.base_object + && TREE_CODE (DR_REF (a)) != MEM_REF) + { + tree alt_ref = build2 (MEM_REF, TREE_TYPE (DR_REF (a)), + build1 (ADDR_EXPR, ptr_type_node, DR_REF (a)), + build_int_cst + (reference_alias_ptr_type (DR_REF (a)), 0)); + dr_analyze_indices (&a->alt_indices, alt_ref, + loop_preheader_edge (loop_nest[0]), + loop_containing_stmt (DR_STMT (a))); + } + if (!b->alt_indices.base_object + && TREE_CODE (DR_REF (b)) != MEM_REF) + { + tree alt_ref = build2 (MEM_REF, TREE_TYPE (DR_REF (b)), + build1 (ADDR_EXPR, ptr_type_node, DR_REF (b)), + build_int_cst + (reference_alias_ptr_type (DR_REF (b)), 0)); + dr_analyze_indices (&b->alt_indices, alt_ref, + loop_preheader_edge (loop_nest[0]), + loop_containing_stmt (DR_STMT (b))); + } + return initialize_data_dependence_relation (res, loop_nest, true); + } + + if (!same_base_p) + { + /* Partial overlap is possible for different bases when strict aliasing + is not in effect. It's also possible if either base involves a union + access; e.g. for: + + struct s1 { int a[2]; }; + struct s2 { struct s1 b; int c; }; + struct s3 { int d; struct s1 e; }; + union u { struct s2 f; struct s3 g; } *p, *q; + + the s1 at "p->f.b" (base "p->f") partially overlaps the s1 at + "p->g.e" (base "p->g") and might partially overlap the s1 at + "q->g.e" (base "q->g"). */ + if (!flag_strict_aliasing + || ref_contains_union_access_p (full_seq.object_a) + || ref_contains_union_access_p (full_seq.object_b)) + { + DDR_ARE_DEPENDENT (res) = chrec_dont_know; + return res; + } + + DDR_COULD_BE_INDEPENDENT_P (res) = true; + if (!loop_nest.exists () + || (object_address_invariant_in_loop_p (loop_nest[0], + full_seq.object_a) + && object_address_invariant_in_loop_p (loop_nest[0], + full_seq.object_b))) + { + DDR_OBJECT_A (res) = full_seq.object_a; + DDR_OBJECT_B (res) = full_seq.object_b; + } + } + + DDR_AFFINE_P (res) = true; + DDR_ARE_DEPENDENT (res) = NULL_TREE; + DDR_SUBSCRIPTS (res).create (full_seq.length); + DDR_LOOP_NEST (res) = loop_nest; + DDR_SELF_REFERENCE (res) = false; + + for (i = 0; i < full_seq.length; ++i) + { + struct subscript *subscript; + + subscript = XNEW (struct subscript); + SUB_ACCESS_FN (subscript, 0) = indices_a->access_fns[full_seq.start_a + i]; + SUB_ACCESS_FN (subscript, 1) = indices_b->access_fns[full_seq.start_b + i]; + SUB_CONFLICTS_IN_A (subscript) = conflict_fn_not_known (); + SUB_CONFLICTS_IN_B (subscript) = conflict_fn_not_known (); + SUB_LAST_CONFLICT (subscript) = chrec_dont_know; + SUB_DISTANCE (subscript) = chrec_dont_know; + DDR_SUBSCRIPTS (res).safe_push (subscript); + } + + return res; +} + +/* Initialize a data dependence relation between data accesses A and + B. NB_LOOPS is the number of loops surrounding the references: the + size of the classic distance/direction vectors. */ + +struct data_dependence_relation * +initialize_data_dependence_relation (struct data_reference *a, + struct data_reference *b, + vec<loop_p> loop_nest) +{ + data_dependence_relation *res = XCNEW (struct data_dependence_relation); + DDR_A (res) = a; + DDR_B (res) = b; + DDR_LOOP_NEST (res).create (0); + DDR_SUBSCRIPTS (res).create (0); + DDR_DIR_VECTS (res).create (0); + DDR_DIST_VECTS (res).create (0); + + if (a == NULL || b == NULL) + { + DDR_ARE_DEPENDENT (res) = chrec_dont_know; + return res; + } + + /* If the data references do not alias, then they are independent. */ + if (!dr_may_alias_p (a, b, loop_nest.exists () ? loop_nest[0] : NULL)) + { + DDR_ARE_DEPENDENT (res) = chrec_known; + return res; + } + + return initialize_data_dependence_relation (res, loop_nest, false); +} + + +/* Frees memory used by the conflict function F. */ + +static void +free_conflict_function (conflict_function *f) +{ + unsigned i; + + if (CF_NONTRIVIAL_P (f)) + { + for (i = 0; i < f->n; i++) + affine_fn_free (f->fns[i]); + } + free (f); +} + +/* Frees memory used by SUBSCRIPTS. */ + +static void +free_subscripts (vec<subscript_p> subscripts) +{ + for (subscript_p s : subscripts) + { + free_conflict_function (s->conflicting_iterations_in_a); + free_conflict_function (s->conflicting_iterations_in_b); + free (s); + } + subscripts.release (); +} + +/* Set DDR_ARE_DEPENDENT to CHREC and finalize the subscript overlap + description. */ + +static inline void +finalize_ddr_dependent (struct data_dependence_relation *ddr, + tree chrec) +{ + DDR_ARE_DEPENDENT (ddr) = chrec; + free_subscripts (DDR_SUBSCRIPTS (ddr)); + DDR_SUBSCRIPTS (ddr).create (0); +} + +/* The dependence relation DDR cannot be represented by a distance + vector. */ + +static inline void +non_affine_dependence_relation (struct data_dependence_relation *ddr) +{ + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "(Dependence relation cannot be represented by distance vector.) \n"); + + DDR_AFFINE_P (ddr) = false; +} + + + +/* This section contains the classic Banerjee tests. */ + +/* Returns true iff CHREC_A and CHREC_B are not dependent on any index + variables, i.e., if the ZIV (Zero Index Variable) test is true. */ + +static inline bool +ziv_subscript_p (const_tree chrec_a, const_tree chrec_b) +{ + return (evolution_function_is_constant_p (chrec_a) + && evolution_function_is_constant_p (chrec_b)); +} + +/* Returns true iff CHREC_A and CHREC_B are dependent on an index + variable, i.e., if the SIV (Single Index Variable) test is true. */ + +static bool +siv_subscript_p (const_tree chrec_a, const_tree chrec_b) +{ + if ((evolution_function_is_constant_p (chrec_a) + && evolution_function_is_univariate_p (chrec_b)) + || (evolution_function_is_constant_p (chrec_b) + && evolution_function_is_univariate_p (chrec_a))) + return true; + + if (evolution_function_is_univariate_p (chrec_a) + && evolution_function_is_univariate_p (chrec_b)) + { + switch (TREE_CODE (chrec_a)) + { + case POLYNOMIAL_CHREC: + switch (TREE_CODE (chrec_b)) + { + case POLYNOMIAL_CHREC: + if (CHREC_VARIABLE (chrec_a) != CHREC_VARIABLE (chrec_b)) + return false; + /* FALLTHRU */ + + default: + return true; + } + + default: + return true; + } + } + + return false; +} + +/* Creates a conflict function with N dimensions. The affine functions + in each dimension follow. */ + +static conflict_function * +conflict_fn (unsigned n, ...) +{ + unsigned i; + conflict_function *ret = XCNEW (conflict_function); + va_list ap; + + gcc_assert (n > 0 && n <= MAX_DIM); + va_start (ap, n); + + ret->n = n; + for (i = 0; i < n; i++) + ret->fns[i] = va_arg (ap, affine_fn); + va_end (ap); + + return ret; +} + +/* Returns constant affine function with value CST. */ + +static affine_fn +affine_fn_cst (tree cst) +{ + affine_fn fn; + fn.create (1); + fn.quick_push (cst); + return fn; +} + +/* Returns affine function with single variable, CST + COEF * x_DIM. */ + +static affine_fn +affine_fn_univar (tree cst, unsigned dim, tree coef) +{ + affine_fn fn; + fn.create (dim + 1); + unsigned i; + + gcc_assert (dim > 0); + fn.quick_push (cst); + for (i = 1; i < dim; i++) + fn.quick_push (integer_zero_node); + fn.quick_push (coef); + return fn; +} + +/* Analyze a ZIV (Zero Index Variable) subscript. *OVERLAPS_A and + *OVERLAPS_B are initialized to the functions that describe the + relation between the elements accessed twice by CHREC_A and + CHREC_B. For k >= 0, the following property is verified: + + CHREC_A (*OVERLAPS_A (k)) = CHREC_B (*OVERLAPS_B (k)). */ + +static void +analyze_ziv_subscript (tree chrec_a, + tree chrec_b, + conflict_function **overlaps_a, + conflict_function **overlaps_b, + tree *last_conflicts) +{ + tree type, difference; + dependence_stats.num_ziv++; + + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "(analyze_ziv_subscript \n"); + + type = signed_type_for_types (TREE_TYPE (chrec_a), TREE_TYPE (chrec_b)); + chrec_a = chrec_convert (type, chrec_a, NULL); + chrec_b = chrec_convert (type, chrec_b, NULL); + difference = chrec_fold_minus (type, chrec_a, chrec_b); + + switch (TREE_CODE (difference)) + { + case INTEGER_CST: + if (integer_zerop (difference)) + { + /* The difference is equal to zero: the accessed index + overlaps for each iteration in the loop. */ + *overlaps_a = conflict_fn (1, affine_fn_cst (integer_zero_node)); + *overlaps_b = conflict_fn (1, affine_fn_cst (integer_zero_node)); + *last_conflicts = chrec_dont_know; + dependence_stats.num_ziv_dependent++; + } + else + { + /* The accesses do not overlap. */ + *overlaps_a = conflict_fn_no_dependence (); + *overlaps_b = conflict_fn_no_dependence (); + *last_conflicts = integer_zero_node; + dependence_stats.num_ziv_independent++; + } + break; + + default: + /* We're not sure whether the indexes overlap. For the moment, + conservatively answer "don't know". */ + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "ziv test failed: difference is non-integer.\n"); + + *overlaps_a = conflict_fn_not_known (); + *overlaps_b = conflict_fn_not_known (); + *last_conflicts = chrec_dont_know; + dependence_stats.num_ziv_unimplemented++; + break; + } + + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, ")\n"); +} + +/* Similar to max_stmt_executions_int, but returns the bound as a tree, + and only if it fits to the int type. If this is not the case, or the + bound on the number of iterations of LOOP could not be derived, returns + chrec_dont_know. */ + +static tree +max_stmt_executions_tree (class loop *loop) +{ + widest_int nit; + + if (!max_stmt_executions (loop, &nit)) + return chrec_dont_know; + + if (!wi::fits_to_tree_p (nit, unsigned_type_node)) + return chrec_dont_know; + + return wide_int_to_tree (unsigned_type_node, nit); +} + +/* Determine whether the CHREC is always positive/negative. If the expression + cannot be statically analyzed, return false, otherwise set the answer into + VALUE. */ + +static bool +chrec_is_positive (tree chrec, bool *value) +{ + bool value0, value1, value2; + tree end_value, nb_iter; + + switch (TREE_CODE (chrec)) + { + case POLYNOMIAL_CHREC: + if (!chrec_is_positive (CHREC_LEFT (chrec), &value0) + || !chrec_is_positive (CHREC_RIGHT (chrec), &value1)) + return false; + + /* FIXME -- overflows. */ + if (value0 == value1) + { + *value = value0; + return true; + } + + /* Otherwise the chrec is under the form: "{-197, +, 2}_1", + and the proof consists in showing that the sign never + changes during the execution of the loop, from 0 to + loop->nb_iterations. */ + if (!evolution_function_is_affine_p (chrec)) + return false; + + nb_iter = number_of_latch_executions (get_chrec_loop (chrec)); + if (chrec_contains_undetermined (nb_iter)) + return false; + +#if 0 + /* TODO -- If the test is after the exit, we may decrease the number of + iterations by one. */ + if (after_exit) + nb_iter = chrec_fold_minus (type, nb_iter, build_int_cst (type, 1)); +#endif + + end_value = chrec_apply (CHREC_VARIABLE (chrec), chrec, nb_iter); + + if (!chrec_is_positive (end_value, &value2)) + return false; + + *value = value0; + return value0 == value1; + + case INTEGER_CST: + switch (tree_int_cst_sgn (chrec)) + { + case -1: + *value = false; + break; + case 1: + *value = true; + break; + default: + return false; + } + return true; + + default: + return false; + } +} + + +/* Analyze a SIV (Single Index Variable) subscript where CHREC_A is a + constant, and CHREC_B is an affine function. *OVERLAPS_A and + *OVERLAPS_B are initialized to the functions that describe the + relation between the elements accessed twice by CHREC_A and + CHREC_B. For k >= 0, the following property is verified: + + CHREC_A (*OVERLAPS_A (k)) = CHREC_B (*OVERLAPS_B (k)). */ + +static void +analyze_siv_subscript_cst_affine (tree chrec_a, + tree chrec_b, + conflict_function **overlaps_a, + conflict_function **overlaps_b, + tree *last_conflicts) +{ + bool value0, value1, value2; + tree type, difference, tmp; + + type = signed_type_for_types (TREE_TYPE (chrec_a), TREE_TYPE (chrec_b)); + chrec_a = chrec_convert (type, chrec_a, NULL); + chrec_b = chrec_convert (type, chrec_b, NULL); + difference = chrec_fold_minus (type, initial_condition (chrec_b), chrec_a); + + /* Special case overlap in the first iteration. */ + if (integer_zerop (difference)) + { + *overlaps_a = conflict_fn (1, affine_fn_cst (integer_zero_node)); + *overlaps_b = conflict_fn (1, affine_fn_cst (integer_zero_node)); + *last_conflicts = integer_one_node; + return; + } + + if (!chrec_is_positive (initial_condition (difference), &value0)) + { + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "siv test failed: chrec is not positive.\n"); + + dependence_stats.num_siv_unimplemented++; + *overlaps_a = conflict_fn_not_known (); + *overlaps_b = conflict_fn_not_known (); + *last_conflicts = chrec_dont_know; + return; + } + else + { + if (value0 == false) + { + if (TREE_CODE (chrec_b) != POLYNOMIAL_CHREC + || !chrec_is_positive (CHREC_RIGHT (chrec_b), &value1)) + { + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "siv test failed: chrec not positive.\n"); + + *overlaps_a = conflict_fn_not_known (); + *overlaps_b = conflict_fn_not_known (); + *last_conflicts = chrec_dont_know; + dependence_stats.num_siv_unimplemented++; + return; + } + else + { + if (value1 == true) + { + /* Example: + chrec_a = 12 + chrec_b = {10, +, 1} + */ + + if (tree_fold_divides_p (CHREC_RIGHT (chrec_b), difference)) + { + HOST_WIDE_INT numiter; + class loop *loop = get_chrec_loop (chrec_b); + + *overlaps_a = conflict_fn (1, affine_fn_cst (integer_zero_node)); + tmp = fold_build2 (EXACT_DIV_EXPR, type, + fold_build1 (ABS_EXPR, type, difference), + CHREC_RIGHT (chrec_b)); + *overlaps_b = conflict_fn (1, affine_fn_cst (tmp)); + *last_conflicts = integer_one_node; + + + /* Perform weak-zero siv test to see if overlap is + outside the loop bounds. */ + numiter = max_stmt_executions_int (loop); + + if (numiter >= 0 + && compare_tree_int (tmp, numiter) > 0) + { + free_conflict_function (*overlaps_a); + free_conflict_function (*overlaps_b); + *overlaps_a = conflict_fn_no_dependence (); + *overlaps_b = conflict_fn_no_dependence (); + *last_conflicts = integer_zero_node; + dependence_stats.num_siv_independent++; + return; + } + dependence_stats.num_siv_dependent++; + return; + } + + /* When the step does not divide the difference, there are + no overlaps. */ + else + { + *overlaps_a = conflict_fn_no_dependence (); + *overlaps_b = conflict_fn_no_dependence (); + *last_conflicts = integer_zero_node; + dependence_stats.num_siv_independent++; + return; + } + } + + else + { + /* Example: + chrec_a = 12 + chrec_b = {10, +, -1} + + In this case, chrec_a will not overlap with chrec_b. */ + *overlaps_a = conflict_fn_no_dependence (); + *overlaps_b = conflict_fn_no_dependence (); + *last_conflicts = integer_zero_node; + dependence_stats.num_siv_independent++; + return; + } + } + } + else + { + if (TREE_CODE (chrec_b) != POLYNOMIAL_CHREC + || !chrec_is_positive (CHREC_RIGHT (chrec_b), &value2)) + { + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "siv test failed: chrec not positive.\n"); + + *overlaps_a = conflict_fn_not_known (); + *overlaps_b = conflict_fn_not_known (); + *last_conflicts = chrec_dont_know; + dependence_stats.num_siv_unimplemented++; + return; + } + else + { + if (value2 == false) + { + /* Example: + chrec_a = 3 + chrec_b = {10, +, -1} + */ + if (tree_fold_divides_p (CHREC_RIGHT (chrec_b), difference)) + { + HOST_WIDE_INT numiter; + class loop *loop = get_chrec_loop (chrec_b); + + *overlaps_a = conflict_fn (1, affine_fn_cst (integer_zero_node)); + tmp = fold_build2 (EXACT_DIV_EXPR, type, difference, + CHREC_RIGHT (chrec_b)); + *overlaps_b = conflict_fn (1, affine_fn_cst (tmp)); + *last_conflicts = integer_one_node; + + /* Perform weak-zero siv test to see if overlap is + outside the loop bounds. */ + numiter = max_stmt_executions_int (loop); + + if (numiter >= 0 + && compare_tree_int (tmp, numiter) > 0) + { + free_conflict_function (*overlaps_a); + free_conflict_function (*overlaps_b); + *overlaps_a = conflict_fn_no_dependence (); + *overlaps_b = conflict_fn_no_dependence (); + *last_conflicts = integer_zero_node; + dependence_stats.num_siv_independent++; + return; + } + dependence_stats.num_siv_dependent++; + return; + } + + /* When the step does not divide the difference, there + are no overlaps. */ + else + { + *overlaps_a = conflict_fn_no_dependence (); + *overlaps_b = conflict_fn_no_dependence (); + *last_conflicts = integer_zero_node; + dependence_stats.num_siv_independent++; + return; + } + } + else + { + /* Example: + chrec_a = 3 + chrec_b = {4, +, 1} + + In this case, chrec_a will not overlap with chrec_b. */ + *overlaps_a = conflict_fn_no_dependence (); + *overlaps_b = conflict_fn_no_dependence (); + *last_conflicts = integer_zero_node; + dependence_stats.num_siv_independent++; + return; + } + } + } + } +} + +/* Helper recursive function for initializing the matrix A. Returns + the initial value of CHREC. */ + +static tree +initialize_matrix_A (lambda_matrix A, tree chrec, unsigned index, int mult) +{ + gcc_assert (chrec); + + switch (TREE_CODE (chrec)) + { + case POLYNOMIAL_CHREC: + HOST_WIDE_INT chrec_right; + if (!cst_and_fits_in_hwi (CHREC_RIGHT (chrec))) + return chrec_dont_know; + chrec_right = int_cst_value (CHREC_RIGHT (chrec)); + /* We want to be able to negate without overflow. */ + if (chrec_right == HOST_WIDE_INT_MIN) + return chrec_dont_know; + A[index][0] = mult * chrec_right; + return initialize_matrix_A (A, CHREC_LEFT (chrec), index + 1, mult); + + case PLUS_EXPR: + case MULT_EXPR: + case MINUS_EXPR: + { + tree op0 = initialize_matrix_A (A, TREE_OPERAND (chrec, 0), index, mult); + tree op1 = initialize_matrix_A (A, TREE_OPERAND (chrec, 1), index, mult); + + return chrec_fold_op (TREE_CODE (chrec), chrec_type (chrec), op0, op1); + } + + CASE_CONVERT: + { + tree op = initialize_matrix_A (A, TREE_OPERAND (chrec, 0), index, mult); + return chrec_convert (chrec_type (chrec), op, NULL); + } + + case BIT_NOT_EXPR: + { + /* Handle ~X as -1 - X. */ + tree op = initialize_matrix_A (A, TREE_OPERAND (chrec, 0), index, mult); + return chrec_fold_op (MINUS_EXPR, chrec_type (chrec), + build_int_cst (TREE_TYPE (chrec), -1), op); + } + + case INTEGER_CST: + return chrec; + + default: + gcc_unreachable (); + return NULL_TREE; + } +} + +#define FLOOR_DIV(x,y) ((x) / (y)) + +/* Solves the special case of the Diophantine equation: + | {0, +, STEP_A}_x (OVERLAPS_A) = {0, +, STEP_B}_y (OVERLAPS_B) + + Computes the descriptions OVERLAPS_A and OVERLAPS_B. NITER is the + number of iterations that loops X and Y run. The overlaps will be + constructed as evolutions in dimension DIM. */ + +static void +compute_overlap_steps_for_affine_univar (HOST_WIDE_INT niter, + HOST_WIDE_INT step_a, + HOST_WIDE_INT step_b, + affine_fn *overlaps_a, + affine_fn *overlaps_b, + tree *last_conflicts, int dim) +{ + if (((step_a > 0 && step_b > 0) + || (step_a < 0 && step_b < 0))) + { + HOST_WIDE_INT step_overlaps_a, step_overlaps_b; + HOST_WIDE_INT gcd_steps_a_b, last_conflict, tau2; + + gcd_steps_a_b = gcd (step_a, step_b); + step_overlaps_a = step_b / gcd_steps_a_b; + step_overlaps_b = step_a / gcd_steps_a_b; + + if (niter > 0) + { + tau2 = FLOOR_DIV (niter, step_overlaps_a); + tau2 = MIN (tau2, FLOOR_DIV (niter, step_overlaps_b)); + last_conflict = tau2; + *last_conflicts = build_int_cst (NULL_TREE, last_conflict); + } + else + *last_conflicts = chrec_dont_know; + + *overlaps_a = affine_fn_univar (integer_zero_node, dim, + build_int_cst (NULL_TREE, + step_overlaps_a)); + *overlaps_b = affine_fn_univar (integer_zero_node, dim, + build_int_cst (NULL_TREE, + step_overlaps_b)); + } + + else + { + *overlaps_a = affine_fn_cst (integer_zero_node); + *overlaps_b = affine_fn_cst (integer_zero_node); + *last_conflicts = integer_zero_node; + } +} + +/* Solves the special case of a Diophantine equation where CHREC_A is + an affine bivariate function, and CHREC_B is an affine univariate + function. For example, + + | {{0, +, 1}_x, +, 1335}_y = {0, +, 1336}_z + + has the following overlapping functions: + + | x (t, u, v) = {{0, +, 1336}_t, +, 1}_v + | y (t, u, v) = {{0, +, 1336}_u, +, 1}_v + | z (t, u, v) = {{{0, +, 1}_t, +, 1335}_u, +, 1}_v + + FORNOW: This is a specialized implementation for a case occurring in + a common benchmark. Implement the general algorithm. */ + +static void +compute_overlap_steps_for_affine_1_2 (tree chrec_a, tree chrec_b, + conflict_function **overlaps_a, + conflict_function **overlaps_b, + tree *last_conflicts) +{ + bool xz_p, yz_p, xyz_p; + HOST_WIDE_INT step_x, step_y, step_z; + HOST_WIDE_INT niter_x, niter_y, niter_z, niter; + affine_fn overlaps_a_xz, overlaps_b_xz; + affine_fn overlaps_a_yz, overlaps_b_yz; + affine_fn overlaps_a_xyz, overlaps_b_xyz; + affine_fn ova1, ova2, ovb; + tree last_conflicts_xz, last_conflicts_yz, last_conflicts_xyz; + + step_x = int_cst_value (CHREC_RIGHT (CHREC_LEFT (chrec_a))); + step_y = int_cst_value (CHREC_RIGHT (chrec_a)); + step_z = int_cst_value (CHREC_RIGHT (chrec_b)); + + niter_x = max_stmt_executions_int (get_chrec_loop (CHREC_LEFT (chrec_a))); + niter_y = max_stmt_executions_int (get_chrec_loop (chrec_a)); + niter_z = max_stmt_executions_int (get_chrec_loop (chrec_b)); + + if (niter_x < 0 || niter_y < 0 || niter_z < 0) + { + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "overlap steps test failed: no iteration counts.\n"); + + *overlaps_a = conflict_fn_not_known (); + *overlaps_b = conflict_fn_not_known (); + *last_conflicts = chrec_dont_know; + return; + } + + niter = MIN (niter_x, niter_z); + compute_overlap_steps_for_affine_univar (niter, step_x, step_z, + &overlaps_a_xz, + &overlaps_b_xz, + &last_conflicts_xz, 1); + niter = MIN (niter_y, niter_z); + compute_overlap_steps_for_affine_univar (niter, step_y, step_z, + &overlaps_a_yz, + &overlaps_b_yz, + &last_conflicts_yz, 2); + niter = MIN (niter_x, niter_z); + niter = MIN (niter_y, niter); + compute_overlap_steps_for_affine_univar (niter, step_x + step_y, step_z, + &overlaps_a_xyz, + &overlaps_b_xyz, + &last_conflicts_xyz, 3); + + xz_p = !integer_zerop (last_conflicts_xz); + yz_p = !integer_zerop (last_conflicts_yz); + xyz_p = !integer_zerop (last_conflicts_xyz); + + if (xz_p || yz_p || xyz_p) + { + ova1 = affine_fn_cst (integer_zero_node); + ova2 = affine_fn_cst (integer_zero_node); + ovb = affine_fn_cst (integer_zero_node); + if (xz_p) + { + affine_fn t0 = ova1; + affine_fn t2 = ovb; + + ova1 = affine_fn_plus (ova1, overlaps_a_xz); + ovb = affine_fn_plus (ovb, overlaps_b_xz); + affine_fn_free (t0); + affine_fn_free (t2); + *last_conflicts = last_conflicts_xz; + } + if (yz_p) + { + affine_fn t0 = ova2; + affine_fn t2 = ovb; + + ova2 = affine_fn_plus (ova2, overlaps_a_yz); + ovb = affine_fn_plus (ovb, overlaps_b_yz); + affine_fn_free (t0); + affine_fn_free (t2); + *last_conflicts = last_conflicts_yz; + } + if (xyz_p) + { + affine_fn t0 = ova1; + affine_fn t2 = ova2; + affine_fn t4 = ovb; + + ova1 = affine_fn_plus (ova1, overlaps_a_xyz); + ova2 = affine_fn_plus (ova2, overlaps_a_xyz); + ovb = affine_fn_plus (ovb, overlaps_b_xyz); + affine_fn_free (t0); + affine_fn_free (t2); + affine_fn_free (t4); + *last_conflicts = last_conflicts_xyz; + } + *overlaps_a = conflict_fn (2, ova1, ova2); + *overlaps_b = conflict_fn (1, ovb); + } + else + { + *overlaps_a = conflict_fn (1, affine_fn_cst (integer_zero_node)); + *overlaps_b = conflict_fn (1, affine_fn_cst (integer_zero_node)); + *last_conflicts = integer_zero_node; + } + + affine_fn_free (overlaps_a_xz); + affine_fn_free (overlaps_b_xz); + affine_fn_free (overlaps_a_yz); + affine_fn_free (overlaps_b_yz); + affine_fn_free (overlaps_a_xyz); + affine_fn_free (overlaps_b_xyz); +} + +/* Copy the elements of vector VEC1 with length SIZE to VEC2. */ + +static void +lambda_vector_copy (lambda_vector vec1, lambda_vector vec2, + int size) +{ + memcpy (vec2, vec1, size * sizeof (*vec1)); +} + +/* Copy the elements of M x N matrix MAT1 to MAT2. */ + +static void +lambda_matrix_copy (lambda_matrix mat1, lambda_matrix mat2, + int m, int n) +{ + int i; + + for (i = 0; i < m; i++) + lambda_vector_copy (mat1[i], mat2[i], n); +} + +/* Store the N x N identity matrix in MAT. */ + +static void +lambda_matrix_id (lambda_matrix mat, int size) +{ + int i, j; + + for (i = 0; i < size; i++) + for (j = 0; j < size; j++) + mat[i][j] = (i == j) ? 1 : 0; +} + +/* Return the index of the first nonzero element of vector VEC1 between + START and N. We must have START <= N. + Returns N if VEC1 is the zero vector. */ + +static int +lambda_vector_first_nz (lambda_vector vec1, int n, int start) +{ + int j = start; + while (j < n && vec1[j] == 0) + j++; + return j; +} + +/* Add a multiple of row R1 of matrix MAT with N columns to row R2: + R2 = R2 + CONST1 * R1. */ + +static bool +lambda_matrix_row_add (lambda_matrix mat, int n, int r1, int r2, + lambda_int const1) +{ + int i; + + if (const1 == 0) + return true; + + for (i = 0; i < n; i++) + { + bool ovf; + lambda_int tem = mul_hwi (mat[r1][i], const1, &ovf); + if (ovf) + return false; + lambda_int tem2 = add_hwi (mat[r2][i], tem, &ovf); + if (ovf || tem2 == HOST_WIDE_INT_MIN) + return false; + mat[r2][i] = tem2; + } + + return true; +} + +/* Multiply vector VEC1 of length SIZE by a constant CONST1, + and store the result in VEC2. */ + +static void +lambda_vector_mult_const (lambda_vector vec1, lambda_vector vec2, + int size, lambda_int const1) +{ + int i; + + if (const1 == 0) + lambda_vector_clear (vec2, size); + else + for (i = 0; i < size; i++) + vec2[i] = const1 * vec1[i]; +} + +/* Negate vector VEC1 with length SIZE and store it in VEC2. */ + +static void +lambda_vector_negate (lambda_vector vec1, lambda_vector vec2, + int size) +{ + lambda_vector_mult_const (vec1, vec2, size, -1); +} + +/* Negate row R1 of matrix MAT which has N columns. */ + +static void +lambda_matrix_row_negate (lambda_matrix mat, int n, int r1) +{ + lambda_vector_negate (mat[r1], mat[r1], n); +} + +/* Return true if two vectors are equal. */ + +static bool +lambda_vector_equal (lambda_vector vec1, lambda_vector vec2, int size) +{ + int i; + for (i = 0; i < size; i++) + if (vec1[i] != vec2[i]) + return false; + return true; +} + +/* Given an M x N integer matrix A, this function determines an M x + M unimodular matrix U, and an M x N echelon matrix S such that + "U.A = S". This decomposition is also known as "right Hermite". + + Ref: Algorithm 2.1 page 33 in "Loop Transformations for + Restructuring Compilers" Utpal Banerjee. */ + +static bool +lambda_matrix_right_hermite (lambda_matrix A, int m, int n, + lambda_matrix S, lambda_matrix U) +{ + int i, j, i0 = 0; + + lambda_matrix_copy (A, S, m, n); + lambda_matrix_id (U, m); + + for (j = 0; j < n; j++) + { + if (lambda_vector_first_nz (S[j], m, i0) < m) + { + ++i0; + for (i = m - 1; i >= i0; i--) + { + while (S[i][j] != 0) + { + lambda_int factor, a, b; + + a = S[i-1][j]; + b = S[i][j]; + gcc_assert (a != HOST_WIDE_INT_MIN); + factor = a / b; + + if (!lambda_matrix_row_add (S, n, i, i-1, -factor)) + return false; + std::swap (S[i], S[i-1]); + + if (!lambda_matrix_row_add (U, m, i, i-1, -factor)) + return false; + std::swap (U[i], U[i-1]); + } + } + } + } + + return true; +} + +/* Determines the overlapping elements due to accesses CHREC_A and + CHREC_B, that are affine functions. This function cannot handle + symbolic evolution functions, ie. when initial conditions are + parameters, because it uses lambda matrices of integers. */ + +static void +analyze_subscript_affine_affine (tree chrec_a, + tree chrec_b, + conflict_function **overlaps_a, + conflict_function **overlaps_b, + tree *last_conflicts) +{ + unsigned nb_vars_a, nb_vars_b, dim; + lambda_int gamma, gcd_alpha_beta; + lambda_matrix A, U, S; + struct obstack scratch_obstack; + + if (eq_evolutions_p (chrec_a, chrec_b)) + { + /* The accessed index overlaps for each iteration in the + loop. */ + *overlaps_a = conflict_fn (1, affine_fn_cst (integer_zero_node)); + *overlaps_b = conflict_fn (1, affine_fn_cst (integer_zero_node)); + *last_conflicts = chrec_dont_know; + return; + } + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "(analyze_subscript_affine_affine \n"); + + /* For determining the initial intersection, we have to solve a + Diophantine equation. This is the most time consuming part. + + For answering to the question: "Is there a dependence?" we have + to prove that there exists a solution to the Diophantine + equation, and that the solution is in the iteration domain, + i.e. the solution is positive or zero, and that the solution + happens before the upper bound loop.nb_iterations. Otherwise + there is no dependence. This function outputs a description of + the iterations that hold the intersections. */ + + nb_vars_a = nb_vars_in_chrec (chrec_a); + nb_vars_b = nb_vars_in_chrec (chrec_b); + + gcc_obstack_init (&scratch_obstack); + + dim = nb_vars_a + nb_vars_b; + U = lambda_matrix_new (dim, dim, &scratch_obstack); + A = lambda_matrix_new (dim, 1, &scratch_obstack); + S = lambda_matrix_new (dim, 1, &scratch_obstack); + + tree init_a = initialize_matrix_A (A, chrec_a, 0, 1); + tree init_b = initialize_matrix_A (A, chrec_b, nb_vars_a, -1); + if (init_a == chrec_dont_know + || init_b == chrec_dont_know) + { + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "affine-affine test failed: " + "representation issue.\n"); + *overlaps_a = conflict_fn_not_known (); + *overlaps_b = conflict_fn_not_known (); + *last_conflicts = chrec_dont_know; + goto end_analyze_subs_aa; + } + gamma = int_cst_value (init_b) - int_cst_value (init_a); + + /* Don't do all the hard work of solving the Diophantine equation + when we already know the solution: for example, + | {3, +, 1}_1 + | {3, +, 4}_2 + | gamma = 3 - 3 = 0. + Then the first overlap occurs during the first iterations: + | {3, +, 1}_1 ({0, +, 4}_x) = {3, +, 4}_2 ({0, +, 1}_x) + */ + if (gamma == 0) + { + if (nb_vars_a == 1 && nb_vars_b == 1) + { + HOST_WIDE_INT step_a, step_b; + HOST_WIDE_INT niter, niter_a, niter_b; + affine_fn ova, ovb; + + niter_a = max_stmt_executions_int (get_chrec_loop (chrec_a)); + niter_b = max_stmt_executions_int (get_chrec_loop (chrec_b)); + niter = MIN (niter_a, niter_b); + step_a = int_cst_value (CHREC_RIGHT (chrec_a)); + step_b = int_cst_value (CHREC_RIGHT (chrec_b)); + + compute_overlap_steps_for_affine_univar (niter, step_a, step_b, + &ova, &ovb, + last_conflicts, 1); + *overlaps_a = conflict_fn (1, ova); + *overlaps_b = conflict_fn (1, ovb); + } + + else if (nb_vars_a == 2 && nb_vars_b == 1) + compute_overlap_steps_for_affine_1_2 + (chrec_a, chrec_b, overlaps_a, overlaps_b, last_conflicts); + + else if (nb_vars_a == 1 && nb_vars_b == 2) + compute_overlap_steps_for_affine_1_2 + (chrec_b, chrec_a, overlaps_b, overlaps_a, last_conflicts); + + else + { + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "affine-affine test failed: too many variables.\n"); + *overlaps_a = conflict_fn_not_known (); + *overlaps_b = conflict_fn_not_known (); + *last_conflicts = chrec_dont_know; + } + goto end_analyze_subs_aa; + } + + /* U.A = S */ + if (!lambda_matrix_right_hermite (A, dim, 1, S, U)) + { + *overlaps_a = conflict_fn_not_known (); + *overlaps_b = conflict_fn_not_known (); + *last_conflicts = chrec_dont_know; + goto end_analyze_subs_aa; + } + + if (S[0][0] < 0) + { + S[0][0] *= -1; + lambda_matrix_row_negate (U, dim, 0); + } + gcd_alpha_beta = S[0][0]; + + /* Something went wrong: for example in {1, +, 0}_5 vs. {0, +, 0}_5, + but that is a quite strange case. Instead of ICEing, answer + don't know. */ + if (gcd_alpha_beta == 0) + { + *overlaps_a = conflict_fn_not_known (); + *overlaps_b = conflict_fn_not_known (); + *last_conflicts = chrec_dont_know; + goto end_analyze_subs_aa; + } + + /* The classic "gcd-test". */ + if (!int_divides_p (gcd_alpha_beta, gamma)) + { + /* The "gcd-test" has determined that there is no integer + solution, i.e. there is no dependence. */ + *overlaps_a = conflict_fn_no_dependence (); + *overlaps_b = conflict_fn_no_dependence (); + *last_conflicts = integer_zero_node; + } + + /* Both access functions are univariate. This includes SIV and MIV cases. */ + else if (nb_vars_a == 1 && nb_vars_b == 1) + { + /* Both functions should have the same evolution sign. */ + if (((A[0][0] > 0 && -A[1][0] > 0) + || (A[0][0] < 0 && -A[1][0] < 0))) + { + /* The solutions are given by: + | + | [GAMMA/GCD_ALPHA_BETA t].[u11 u12] = [x0] + | [u21 u22] [y0] + + For a given integer t. Using the following variables, + + | i0 = u11 * gamma / gcd_alpha_beta + | j0 = u12 * gamma / gcd_alpha_beta + | i1 = u21 + | j1 = u22 + + the solutions are: + + | x0 = i0 + i1 * t, + | y0 = j0 + j1 * t. */ + HOST_WIDE_INT i0, j0, i1, j1; + + i0 = U[0][0] * gamma / gcd_alpha_beta; + j0 = U[0][1] * gamma / gcd_alpha_beta; + i1 = U[1][0]; + j1 = U[1][1]; + + if ((i1 == 0 && i0 < 0) + || (j1 == 0 && j0 < 0)) + { + /* There is no solution. + FIXME: The case "i0 > nb_iterations, j0 > nb_iterations" + falls in here, but for the moment we don't look at the + upper bound of the iteration domain. */ + *overlaps_a = conflict_fn_no_dependence (); + *overlaps_b = conflict_fn_no_dependence (); + *last_conflicts = integer_zero_node; + goto end_analyze_subs_aa; + } + + if (i1 > 0 && j1 > 0) + { + HOST_WIDE_INT niter_a + = max_stmt_executions_int (get_chrec_loop (chrec_a)); + HOST_WIDE_INT niter_b + = max_stmt_executions_int (get_chrec_loop (chrec_b)); + HOST_WIDE_INT niter = MIN (niter_a, niter_b); + + /* (X0, Y0) is a solution of the Diophantine equation: + "chrec_a (X0) = chrec_b (Y0)". */ + HOST_WIDE_INT tau1 = MAX (CEIL (-i0, i1), + CEIL (-j0, j1)); + HOST_WIDE_INT x0 = i1 * tau1 + i0; + HOST_WIDE_INT y0 = j1 * tau1 + j0; + + /* (X1, Y1) is the smallest positive solution of the eq + "chrec_a (X1) = chrec_b (Y1)", i.e. this is where the + first conflict occurs. */ + HOST_WIDE_INT min_multiple = MIN (x0 / i1, y0 / j1); + HOST_WIDE_INT x1 = x0 - i1 * min_multiple; + HOST_WIDE_INT y1 = y0 - j1 * min_multiple; + + if (niter > 0) + { + /* If the overlap occurs outside of the bounds of the + loop, there is no dependence. */ + if (x1 >= niter_a || y1 >= niter_b) + { + *overlaps_a = conflict_fn_no_dependence (); + *overlaps_b = conflict_fn_no_dependence (); + *last_conflicts = integer_zero_node; + goto end_analyze_subs_aa; + } + + /* max stmt executions can get quite large, avoid + overflows by using wide ints here. */ + widest_int tau2 + = wi::smin (wi::sdiv_floor (wi::sub (niter_a, i0), i1), + wi::sdiv_floor (wi::sub (niter_b, j0), j1)); + widest_int last_conflict = wi::sub (tau2, (x1 - i0)/i1); + if (wi::min_precision (last_conflict, SIGNED) + <= TYPE_PRECISION (integer_type_node)) + *last_conflicts + = build_int_cst (integer_type_node, + last_conflict.to_shwi ()); + else + *last_conflicts = chrec_dont_know; + } + else + *last_conflicts = chrec_dont_know; + + *overlaps_a + = conflict_fn (1, + affine_fn_univar (build_int_cst (NULL_TREE, x1), + 1, + build_int_cst (NULL_TREE, i1))); + *overlaps_b + = conflict_fn (1, + affine_fn_univar (build_int_cst (NULL_TREE, y1), + 1, + build_int_cst (NULL_TREE, j1))); + } + else + { + /* FIXME: For the moment, the upper bound of the + iteration domain for i and j is not checked. */ + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "affine-affine test failed: unimplemented.\n"); + *overlaps_a = conflict_fn_not_known (); + *overlaps_b = conflict_fn_not_known (); + *last_conflicts = chrec_dont_know; + } + } + else + { + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "affine-affine test failed: unimplemented.\n"); + *overlaps_a = conflict_fn_not_known (); + *overlaps_b = conflict_fn_not_known (); + *last_conflicts = chrec_dont_know; + } + } + else + { + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "affine-affine test failed: unimplemented.\n"); + *overlaps_a = conflict_fn_not_known (); + *overlaps_b = conflict_fn_not_known (); + *last_conflicts = chrec_dont_know; + } + +end_analyze_subs_aa: + obstack_free (&scratch_obstack, NULL); + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, " (overlaps_a = "); + dump_conflict_function (dump_file, *overlaps_a); + fprintf (dump_file, ")\n (overlaps_b = "); + dump_conflict_function (dump_file, *overlaps_b); + fprintf (dump_file, "))\n"); + } +} + +/* Returns true when analyze_subscript_affine_affine can be used for + determining the dependence relation between chrec_a and chrec_b, + that contain symbols. This function modifies chrec_a and chrec_b + such that the analysis result is the same, and such that they don't + contain symbols, and then can safely be passed to the analyzer. + + Example: The analysis of the following tuples of evolutions produce + the same results: {x+1, +, 1}_1 vs. {x+3, +, 1}_1, and {-2, +, 1}_1 + vs. {0, +, 1}_1 + + {x+1, +, 1}_1 ({2, +, 1}_1) = {x+3, +, 1}_1 ({0, +, 1}_1) + {-2, +, 1}_1 ({2, +, 1}_1) = {0, +, 1}_1 ({0, +, 1}_1) +*/ + +static bool +can_use_analyze_subscript_affine_affine (tree *chrec_a, tree *chrec_b) +{ + tree diff, type, left_a, left_b, right_b; + + if (chrec_contains_symbols (CHREC_RIGHT (*chrec_a)) + || chrec_contains_symbols (CHREC_RIGHT (*chrec_b))) + /* FIXME: For the moment not handled. Might be refined later. */ + return false; + + type = chrec_type (*chrec_a); + left_a = CHREC_LEFT (*chrec_a); + left_b = chrec_convert (type, CHREC_LEFT (*chrec_b), NULL); + diff = chrec_fold_minus (type, left_a, left_b); + + if (!evolution_function_is_constant_p (diff)) + return false; + + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "can_use_subscript_aff_aff_for_symbolic \n"); + + *chrec_a = build_polynomial_chrec (CHREC_VARIABLE (*chrec_a), + diff, CHREC_RIGHT (*chrec_a)); + right_b = chrec_convert (type, CHREC_RIGHT (*chrec_b), NULL); + *chrec_b = build_polynomial_chrec (CHREC_VARIABLE (*chrec_b), + build_int_cst (type, 0), + right_b); + return true; +} + +/* Analyze a SIV (Single Index Variable) subscript. *OVERLAPS_A and + *OVERLAPS_B are initialized to the functions that describe the + relation between the elements accessed twice by CHREC_A and + CHREC_B. For k >= 0, the following property is verified: + + CHREC_A (*OVERLAPS_A (k)) = CHREC_B (*OVERLAPS_B (k)). */ + +static void +analyze_siv_subscript (tree chrec_a, + tree chrec_b, + conflict_function **overlaps_a, + conflict_function **overlaps_b, + tree *last_conflicts, + int loop_nest_num) +{ + dependence_stats.num_siv++; + + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "(analyze_siv_subscript \n"); + + if (evolution_function_is_constant_p (chrec_a) + && evolution_function_is_affine_in_loop (chrec_b, loop_nest_num)) + analyze_siv_subscript_cst_affine (chrec_a, chrec_b, + overlaps_a, overlaps_b, last_conflicts); + + else if (evolution_function_is_affine_in_loop (chrec_a, loop_nest_num) + && evolution_function_is_constant_p (chrec_b)) + analyze_siv_subscript_cst_affine (chrec_b, chrec_a, + overlaps_b, overlaps_a, last_conflicts); + + else if (evolution_function_is_affine_in_loop (chrec_a, loop_nest_num) + && evolution_function_is_affine_in_loop (chrec_b, loop_nest_num)) + { + if (!chrec_contains_symbols (chrec_a) + && !chrec_contains_symbols (chrec_b)) + { + analyze_subscript_affine_affine (chrec_a, chrec_b, + overlaps_a, overlaps_b, + last_conflicts); + + if (CF_NOT_KNOWN_P (*overlaps_a) + || CF_NOT_KNOWN_P (*overlaps_b)) + dependence_stats.num_siv_unimplemented++; + else if (CF_NO_DEPENDENCE_P (*overlaps_a) + || CF_NO_DEPENDENCE_P (*overlaps_b)) + dependence_stats.num_siv_independent++; + else + dependence_stats.num_siv_dependent++; + } + else if (can_use_analyze_subscript_affine_affine (&chrec_a, + &chrec_b)) + { + analyze_subscript_affine_affine (chrec_a, chrec_b, + overlaps_a, overlaps_b, + last_conflicts); + + if (CF_NOT_KNOWN_P (*overlaps_a) + || CF_NOT_KNOWN_P (*overlaps_b)) + dependence_stats.num_siv_unimplemented++; + else if (CF_NO_DEPENDENCE_P (*overlaps_a) + || CF_NO_DEPENDENCE_P (*overlaps_b)) + dependence_stats.num_siv_independent++; + else + dependence_stats.num_siv_dependent++; + } + else + goto siv_subscript_dontknow; + } + + else + { + siv_subscript_dontknow:; + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, " siv test failed: unimplemented"); + *overlaps_a = conflict_fn_not_known (); + *overlaps_b = conflict_fn_not_known (); + *last_conflicts = chrec_dont_know; + dependence_stats.num_siv_unimplemented++; + } + + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, ")\n"); +} + +/* Returns false if we can prove that the greatest common divisor of the steps + of CHREC does not divide CST, false otherwise. */ + +static bool +gcd_of_steps_may_divide_p (const_tree chrec, const_tree cst) +{ + HOST_WIDE_INT cd = 0, val; + tree step; + + if (!tree_fits_shwi_p (cst)) + return true; + val = tree_to_shwi (cst); + + while (TREE_CODE (chrec) == POLYNOMIAL_CHREC) + { + step = CHREC_RIGHT (chrec); + if (!tree_fits_shwi_p (step)) + return true; + cd = gcd (cd, tree_to_shwi (step)); + chrec = CHREC_LEFT (chrec); + } + + return val % cd == 0; +} + +/* Analyze a MIV (Multiple Index Variable) subscript with respect to + LOOP_NEST. *OVERLAPS_A and *OVERLAPS_B are initialized to the + functions that describe the relation between the elements accessed + twice by CHREC_A and CHREC_B. For k >= 0, the following property + is verified: + + CHREC_A (*OVERLAPS_A (k)) = CHREC_B (*OVERLAPS_B (k)). */ + +static void +analyze_miv_subscript (tree chrec_a, + tree chrec_b, + conflict_function **overlaps_a, + conflict_function **overlaps_b, + tree *last_conflicts, + class loop *loop_nest) +{ + tree type, difference; + + dependence_stats.num_miv++; + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "(analyze_miv_subscript \n"); + + type = signed_type_for_types (TREE_TYPE (chrec_a), TREE_TYPE (chrec_b)); + chrec_a = chrec_convert (type, chrec_a, NULL); + chrec_b = chrec_convert (type, chrec_b, NULL); + difference = chrec_fold_minus (type, chrec_a, chrec_b); + + if (eq_evolutions_p (chrec_a, chrec_b)) + { + /* Access functions are the same: all the elements are accessed + in the same order. */ + *overlaps_a = conflict_fn (1, affine_fn_cst (integer_zero_node)); + *overlaps_b = conflict_fn (1, affine_fn_cst (integer_zero_node)); + *last_conflicts = max_stmt_executions_tree (get_chrec_loop (chrec_a)); + dependence_stats.num_miv_dependent++; + } + + else if (evolution_function_is_constant_p (difference) + && evolution_function_is_affine_multivariate_p (chrec_a, + loop_nest->num) + && !gcd_of_steps_may_divide_p (chrec_a, difference)) + { + /* testsuite/.../ssa-chrec-33.c + {{21, +, 2}_1, +, -2}_2 vs. {{20, +, 2}_1, +, -2}_2 + + The difference is 1, and all the evolution steps are multiples + of 2, consequently there are no overlapping elements. */ + *overlaps_a = conflict_fn_no_dependence (); + *overlaps_b = conflict_fn_no_dependence (); + *last_conflicts = integer_zero_node; + dependence_stats.num_miv_independent++; + } + + else if (evolution_function_is_affine_in_loop (chrec_a, loop_nest->num) + && !chrec_contains_symbols (chrec_a, loop_nest) + && evolution_function_is_affine_in_loop (chrec_b, loop_nest->num) + && !chrec_contains_symbols (chrec_b, loop_nest)) + { + /* testsuite/.../ssa-chrec-35.c + {0, +, 1}_2 vs. {0, +, 1}_3 + the overlapping elements are respectively located at iterations: + {0, +, 1}_x and {0, +, 1}_x, + in other words, we have the equality: + {0, +, 1}_2 ({0, +, 1}_x) = {0, +, 1}_3 ({0, +, 1}_x) + + Other examples: + {{0, +, 1}_1, +, 2}_2 ({0, +, 1}_x, {0, +, 1}_y) = + {0, +, 1}_1 ({{0, +, 1}_x, +, 2}_y) + + {{0, +, 2}_1, +, 3}_2 ({0, +, 1}_y, {0, +, 1}_x) = + {{0, +, 3}_1, +, 2}_2 ({0, +, 1}_x, {0, +, 1}_y) + */ + analyze_subscript_affine_affine (chrec_a, chrec_b, + overlaps_a, overlaps_b, last_conflicts); + + if (CF_NOT_KNOWN_P (*overlaps_a) + || CF_NOT_KNOWN_P (*overlaps_b)) + dependence_stats.num_miv_unimplemented++; + else if (CF_NO_DEPENDENCE_P (*overlaps_a) + || CF_NO_DEPENDENCE_P (*overlaps_b)) + dependence_stats.num_miv_independent++; + else + dependence_stats.num_miv_dependent++; + } + + else + { + /* When the analysis is too difficult, answer "don't know". */ + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "analyze_miv_subscript test failed: unimplemented.\n"); + + *overlaps_a = conflict_fn_not_known (); + *overlaps_b = conflict_fn_not_known (); + *last_conflicts = chrec_dont_know; + dependence_stats.num_miv_unimplemented++; + } + + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, ")\n"); +} + +/* Determines the iterations for which CHREC_A is equal to CHREC_B in + with respect to LOOP_NEST. OVERLAP_ITERATIONS_A and + OVERLAP_ITERATIONS_B are initialized with two functions that + describe the iterations that contain conflicting elements. + + Remark: For an integer k >= 0, the following equality is true: + + CHREC_A (OVERLAP_ITERATIONS_A (k)) == CHREC_B (OVERLAP_ITERATIONS_B (k)). +*/ + +static void +analyze_overlapping_iterations (tree chrec_a, + tree chrec_b, + conflict_function **overlap_iterations_a, + conflict_function **overlap_iterations_b, + tree *last_conflicts, class loop *loop_nest) +{ + unsigned int lnn = loop_nest->num; + + dependence_stats.num_subscript_tests++; + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, "(analyze_overlapping_iterations \n"); + fprintf (dump_file, " (chrec_a = "); + print_generic_expr (dump_file, chrec_a); + fprintf (dump_file, ")\n (chrec_b = "); + print_generic_expr (dump_file, chrec_b); + fprintf (dump_file, ")\n"); + } + + if (chrec_a == NULL_TREE + || chrec_b == NULL_TREE + || chrec_contains_undetermined (chrec_a) + || chrec_contains_undetermined (chrec_b)) + { + dependence_stats.num_subscript_undetermined++; + + *overlap_iterations_a = conflict_fn_not_known (); + *overlap_iterations_b = conflict_fn_not_known (); + } + + /* If they are the same chrec, and are affine, they overlap + on every iteration. */ + else if (eq_evolutions_p (chrec_a, chrec_b) + && (evolution_function_is_affine_multivariate_p (chrec_a, lnn) + || operand_equal_p (chrec_a, chrec_b, 0))) + { + dependence_stats.num_same_subscript_function++; + *overlap_iterations_a = conflict_fn (1, affine_fn_cst (integer_zero_node)); + *overlap_iterations_b = conflict_fn (1, affine_fn_cst (integer_zero_node)); + *last_conflicts = chrec_dont_know; + } + + /* If they aren't the same, and aren't affine, we can't do anything + yet. */ + else if ((chrec_contains_symbols (chrec_a) + || chrec_contains_symbols (chrec_b)) + && (!evolution_function_is_affine_multivariate_p (chrec_a, lnn) + || !evolution_function_is_affine_multivariate_p (chrec_b, lnn))) + { + dependence_stats.num_subscript_undetermined++; + *overlap_iterations_a = conflict_fn_not_known (); + *overlap_iterations_b = conflict_fn_not_known (); + } + + else if (ziv_subscript_p (chrec_a, chrec_b)) + analyze_ziv_subscript (chrec_a, chrec_b, + overlap_iterations_a, overlap_iterations_b, + last_conflicts); + + else if (siv_subscript_p (chrec_a, chrec_b)) + analyze_siv_subscript (chrec_a, chrec_b, + overlap_iterations_a, overlap_iterations_b, + last_conflicts, lnn); + + else + analyze_miv_subscript (chrec_a, chrec_b, + overlap_iterations_a, overlap_iterations_b, + last_conflicts, loop_nest); + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, " (overlap_iterations_a = "); + dump_conflict_function (dump_file, *overlap_iterations_a); + fprintf (dump_file, ")\n (overlap_iterations_b = "); + dump_conflict_function (dump_file, *overlap_iterations_b); + fprintf (dump_file, "))\n"); + } +} + +/* Helper function for uniquely inserting distance vectors. */ + +static void +save_dist_v (struct data_dependence_relation *ddr, lambda_vector dist_v) +{ + for (lambda_vector v : DDR_DIST_VECTS (ddr)) + if (lambda_vector_equal (v, dist_v, DDR_NB_LOOPS (ddr))) + return; + + DDR_DIST_VECTS (ddr).safe_push (dist_v); +} + +/* Helper function for uniquely inserting direction vectors. */ + +static void +save_dir_v (struct data_dependence_relation *ddr, lambda_vector dir_v) +{ + for (lambda_vector v : DDR_DIR_VECTS (ddr)) + if (lambda_vector_equal (v, dir_v, DDR_NB_LOOPS (ddr))) + return; + + DDR_DIR_VECTS (ddr).safe_push (dir_v); +} + +/* Add a distance of 1 on all the loops outer than INDEX. If we + haven't yet determined a distance for this outer loop, push a new + distance vector composed of the previous distance, and a distance + of 1 for this outer loop. Example: + + | loop_1 + | loop_2 + | A[10] + | endloop_2 + | endloop_1 + + Saved vectors are of the form (dist_in_1, dist_in_2). First, we + save (0, 1), then we have to save (1, 0). */ + +static void +add_outer_distances (struct data_dependence_relation *ddr, + lambda_vector dist_v, int index) +{ + /* For each outer loop where init_v is not set, the accesses are + in dependence of distance 1 in the loop. */ + while (--index >= 0) + { + lambda_vector save_v = lambda_vector_new (DDR_NB_LOOPS (ddr)); + lambda_vector_copy (dist_v, save_v, DDR_NB_LOOPS (ddr)); + save_v[index] = 1; + save_dist_v (ddr, save_v); + } +} + +/* Return false when fail to represent the data dependence as a + distance vector. A_INDEX is the index of the first reference + (0 for DDR_A, 1 for DDR_B) and B_INDEX is the index of the + second reference. INIT_B is set to true when a component has been + added to the distance vector DIST_V. INDEX_CARRY is then set to + the index in DIST_V that carries the dependence. */ + +static bool +build_classic_dist_vector_1 (struct data_dependence_relation *ddr, + unsigned int a_index, unsigned int b_index, + lambda_vector dist_v, bool *init_b, + int *index_carry) +{ + unsigned i; + lambda_vector init_v = lambda_vector_new (DDR_NB_LOOPS (ddr)); + class loop *loop = DDR_LOOP_NEST (ddr)[0]; + + for (i = 0; i < DDR_NUM_SUBSCRIPTS (ddr); i++) + { + tree access_fn_a, access_fn_b; + struct subscript *subscript = DDR_SUBSCRIPT (ddr, i); + + if (chrec_contains_undetermined (SUB_DISTANCE (subscript))) + { + non_affine_dependence_relation (ddr); + return false; + } + + access_fn_a = SUB_ACCESS_FN (subscript, a_index); + access_fn_b = SUB_ACCESS_FN (subscript, b_index); + + if (TREE_CODE (access_fn_a) == POLYNOMIAL_CHREC + && TREE_CODE (access_fn_b) == POLYNOMIAL_CHREC) + { + HOST_WIDE_INT dist; + int index; + int var_a = CHREC_VARIABLE (access_fn_a); + int var_b = CHREC_VARIABLE (access_fn_b); + + if (var_a != var_b + || chrec_contains_undetermined (SUB_DISTANCE (subscript))) + { + non_affine_dependence_relation (ddr); + return false; + } + + /* When data references are collected in a loop while data + dependences are analyzed in loop nest nested in the loop, we + would have more number of access functions than number of + loops. Skip access functions of loops not in the loop nest. + + See PR89725 for more information. */ + if (flow_loop_nested_p (get_loop (cfun, var_a), loop)) + continue; + + dist = int_cst_value (SUB_DISTANCE (subscript)); + index = index_in_loop_nest (var_a, DDR_LOOP_NEST (ddr)); + *index_carry = MIN (index, *index_carry); + + /* This is the subscript coupling test. If we have already + recorded a distance for this loop (a distance coming from + another subscript), it should be the same. For example, + in the following code, there is no dependence: + + | loop i = 0, N, 1 + | T[i+1][i] = ... + | ... = T[i][i] + | endloop + */ + if (init_v[index] != 0 && dist_v[index] != dist) + { + finalize_ddr_dependent (ddr, chrec_known); + return false; + } + + dist_v[index] = dist; + init_v[index] = 1; + *init_b = true; + } + else if (!operand_equal_p (access_fn_a, access_fn_b, 0)) + { + /* This can be for example an affine vs. constant dependence + (T[i] vs. T[3]) that is not an affine dependence and is + not representable as a distance vector. */ + non_affine_dependence_relation (ddr); + return false; + } + else + *init_b = true; + } + + return true; +} + +/* Return true when the DDR contains only invariant access functions wrto. loop + number LNUM. */ + +static bool +invariant_access_functions (const struct data_dependence_relation *ddr, + int lnum) +{ + for (subscript *sub : DDR_SUBSCRIPTS (ddr)) + if (!evolution_function_is_invariant_p (SUB_ACCESS_FN (sub, 0), lnum) + || !evolution_function_is_invariant_p (SUB_ACCESS_FN (sub, 1), lnum)) + return false; + + return true; +} + +/* Helper function for the case where DDR_A and DDR_B are the same + multivariate access function with a constant step. For an example + see pr34635-1.c. */ + +static void +add_multivariate_self_dist (struct data_dependence_relation *ddr, tree c_2) +{ + int x_1, x_2; + tree c_1 = CHREC_LEFT (c_2); + tree c_0 = CHREC_LEFT (c_1); + lambda_vector dist_v; + HOST_WIDE_INT v1, v2, cd; + + /* Polynomials with more than 2 variables are not handled yet. When + the evolution steps are parameters, it is not possible to + represent the dependence using classical distance vectors. */ + if (TREE_CODE (c_0) != INTEGER_CST + || TREE_CODE (CHREC_RIGHT (c_1)) != INTEGER_CST + || TREE_CODE (CHREC_RIGHT (c_2)) != INTEGER_CST) + { + DDR_AFFINE_P (ddr) = false; + return; + } + + x_2 = index_in_loop_nest (CHREC_VARIABLE (c_2), DDR_LOOP_NEST (ddr)); + x_1 = index_in_loop_nest (CHREC_VARIABLE (c_1), DDR_LOOP_NEST (ddr)); + + /* For "{{0, +, 2}_1, +, 3}_2" the distance vector is (3, -2). */ + dist_v = lambda_vector_new (DDR_NB_LOOPS (ddr)); + v1 = int_cst_value (CHREC_RIGHT (c_1)); + v2 = int_cst_value (CHREC_RIGHT (c_2)); + cd = gcd (v1, v2); + v1 /= cd; + v2 /= cd; + + if (v2 < 0) + { + v2 = -v2; + v1 = -v1; + } + + dist_v[x_1] = v2; + dist_v[x_2] = -v1; + save_dist_v (ddr, dist_v); + + add_outer_distances (ddr, dist_v, x_1); +} + +/* Helper function for the case where DDR_A and DDR_B are the same + access functions. */ + +static void +add_other_self_distances (struct data_dependence_relation *ddr) +{ + lambda_vector dist_v; + unsigned i; + int index_carry = DDR_NB_LOOPS (ddr); + subscript *sub; + class loop *loop = DDR_LOOP_NEST (ddr)[0]; + + FOR_EACH_VEC_ELT (DDR_SUBSCRIPTS (ddr), i, sub) + { + tree access_fun = SUB_ACCESS_FN (sub, 0); + + if (TREE_CODE (access_fun) == POLYNOMIAL_CHREC) + { + if (!evolution_function_is_univariate_p (access_fun, loop->num)) + { + if (DDR_NUM_SUBSCRIPTS (ddr) != 1) + { + DDR_ARE_DEPENDENT (ddr) = chrec_dont_know; + return; + } + + access_fun = SUB_ACCESS_FN (DDR_SUBSCRIPT (ddr, 0), 0); + + if (TREE_CODE (CHREC_LEFT (access_fun)) == POLYNOMIAL_CHREC) + add_multivariate_self_dist (ddr, access_fun); + else + /* The evolution step is not constant: it varies in + the outer loop, so this cannot be represented by a + distance vector. For example in pr34635.c the + evolution is {0, +, {0, +, 4}_1}_2. */ + DDR_AFFINE_P (ddr) = false; + + return; + } + + /* When data references are collected in a loop while data + dependences are analyzed in loop nest nested in the loop, we + would have more number of access functions than number of + loops. Skip access functions of loops not in the loop nest. + + See PR89725 for more information. */ + if (flow_loop_nested_p (get_loop (cfun, CHREC_VARIABLE (access_fun)), + loop)) + continue; + + index_carry = MIN (index_carry, + index_in_loop_nest (CHREC_VARIABLE (access_fun), + DDR_LOOP_NEST (ddr))); + } + } + + dist_v = lambda_vector_new (DDR_NB_LOOPS (ddr)); + add_outer_distances (ddr, dist_v, index_carry); +} + +static void +insert_innermost_unit_dist_vector (struct data_dependence_relation *ddr) +{ + lambda_vector dist_v = lambda_vector_new (DDR_NB_LOOPS (ddr)); + + dist_v[0] = 1; + save_dist_v (ddr, dist_v); +} + +/* Adds a unit distance vector to DDR when there is a 0 overlap. This + is the case for example when access functions are the same and + equal to a constant, as in: + + | loop_1 + | A[3] = ... + | ... = A[3] + | endloop_1 + + in which case the distance vectors are (0) and (1). */ + +static void +add_distance_for_zero_overlaps (struct data_dependence_relation *ddr) +{ + unsigned i, j; + + for (i = 0; i < DDR_NUM_SUBSCRIPTS (ddr); i++) + { + subscript_p sub = DDR_SUBSCRIPT (ddr, i); + conflict_function *ca = SUB_CONFLICTS_IN_A (sub); + conflict_function *cb = SUB_CONFLICTS_IN_B (sub); + + for (j = 0; j < ca->n; j++) + if (affine_function_zero_p (ca->fns[j])) + { + insert_innermost_unit_dist_vector (ddr); + return; + } + + for (j = 0; j < cb->n; j++) + if (affine_function_zero_p (cb->fns[j])) + { + insert_innermost_unit_dist_vector (ddr); + return; + } + } +} + +/* Return true when the DDR contains two data references that have the + same access functions. */ + +static inline bool +same_access_functions (const struct data_dependence_relation *ddr) +{ + for (subscript *sub : DDR_SUBSCRIPTS (ddr)) + if (!eq_evolutions_p (SUB_ACCESS_FN (sub, 0), + SUB_ACCESS_FN (sub, 1))) + return false; + + return true; +} + +/* Compute the classic per loop distance vector. DDR is the data + dependence relation to build a vector from. Return false when fail + to represent the data dependence as a distance vector. */ + +static bool +build_classic_dist_vector (struct data_dependence_relation *ddr, + class loop *loop_nest) +{ + bool init_b = false; + int index_carry = DDR_NB_LOOPS (ddr); + lambda_vector dist_v; + + if (DDR_ARE_DEPENDENT (ddr) != NULL_TREE) + return false; + + if (same_access_functions (ddr)) + { + /* Save the 0 vector. */ + dist_v = lambda_vector_new (DDR_NB_LOOPS (ddr)); + save_dist_v (ddr, dist_v); + + if (invariant_access_functions (ddr, loop_nest->num)) + add_distance_for_zero_overlaps (ddr); + + if (DDR_NB_LOOPS (ddr) > 1) + add_other_self_distances (ddr); + + return true; + } + + dist_v = lambda_vector_new (DDR_NB_LOOPS (ddr)); + if (!build_classic_dist_vector_1 (ddr, 0, 1, dist_v, &init_b, &index_carry)) + return false; + + /* Save the distance vector if we initialized one. */ + if (init_b) + { + /* Verify a basic constraint: classic distance vectors should + always be lexicographically positive. + + Data references are collected in the order of execution of + the program, thus for the following loop + + | for (i = 1; i < 100; i++) + | for (j = 1; j < 100; j++) + | { + | t = T[j+1][i-1]; // A + | T[j][i] = t + 2; // B + | } + + references are collected following the direction of the wind: + A then B. The data dependence tests are performed also + following this order, such that we're looking at the distance + separating the elements accessed by A from the elements later + accessed by B. But in this example, the distance returned by + test_dep (A, B) is lexicographically negative (-1, 1), that + means that the access A occurs later than B with respect to + the outer loop, ie. we're actually looking upwind. In this + case we solve test_dep (B, A) looking downwind to the + lexicographically positive solution, that returns the + distance vector (1, -1). */ + if (!lambda_vector_lexico_pos (dist_v, DDR_NB_LOOPS (ddr))) + { + lambda_vector save_v = lambda_vector_new (DDR_NB_LOOPS (ddr)); + if (!subscript_dependence_tester_1 (ddr, 1, 0, loop_nest)) + return false; + compute_subscript_distance (ddr); + if (!build_classic_dist_vector_1 (ddr, 1, 0, save_v, &init_b, + &index_carry)) + return false; + save_dist_v (ddr, save_v); + DDR_REVERSED_P (ddr) = true; + + /* In this case there is a dependence forward for all the + outer loops: + + | for (k = 1; k < 100; k++) + | for (i = 1; i < 100; i++) + | for (j = 1; j < 100; j++) + | { + | t = T[j+1][i-1]; // A + | T[j][i] = t + 2; // B + | } + + the vectors are: + (0, 1, -1) + (1, 1, -1) + (1, -1, 1) + */ + if (DDR_NB_LOOPS (ddr) > 1) + { + add_outer_distances (ddr, save_v, index_carry); + add_outer_distances (ddr, dist_v, index_carry); + } + } + else + { + lambda_vector save_v = lambda_vector_new (DDR_NB_LOOPS (ddr)); + lambda_vector_copy (dist_v, save_v, DDR_NB_LOOPS (ddr)); + + if (DDR_NB_LOOPS (ddr) > 1) + { + lambda_vector opposite_v = lambda_vector_new (DDR_NB_LOOPS (ddr)); + + if (!subscript_dependence_tester_1 (ddr, 1, 0, loop_nest)) + return false; + compute_subscript_distance (ddr); + if (!build_classic_dist_vector_1 (ddr, 1, 0, opposite_v, &init_b, + &index_carry)) + return false; + + save_dist_v (ddr, save_v); + add_outer_distances (ddr, dist_v, index_carry); + add_outer_distances (ddr, opposite_v, index_carry); + } + else + save_dist_v (ddr, save_v); + } + } + else + { + /* There is a distance of 1 on all the outer loops: Example: + there is a dependence of distance 1 on loop_1 for the array A. + + | loop_1 + | A[5] = ... + | endloop + */ + add_outer_distances (ddr, dist_v, + lambda_vector_first_nz (dist_v, + DDR_NB_LOOPS (ddr), 0)); + } + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + unsigned i; + + fprintf (dump_file, "(build_classic_dist_vector\n"); + for (i = 0; i < DDR_NUM_DIST_VECTS (ddr); i++) + { + fprintf (dump_file, " dist_vector = ("); + print_lambda_vector (dump_file, DDR_DIST_VECT (ddr, i), + DDR_NB_LOOPS (ddr)); + fprintf (dump_file, " )\n"); + } + fprintf (dump_file, ")\n"); + } + + return true; +} + +/* Return the direction for a given distance. + FIXME: Computing dir this way is suboptimal, since dir can catch + cases that dist is unable to represent. */ + +static inline enum data_dependence_direction +dir_from_dist (int dist) +{ + if (dist > 0) + return dir_positive; + else if (dist < 0) + return dir_negative; + else + return dir_equal; +} + +/* Compute the classic per loop direction vector. DDR is the data + dependence relation to build a vector from. */ + +static void +build_classic_dir_vector (struct data_dependence_relation *ddr) +{ + unsigned i, j; + lambda_vector dist_v; + + FOR_EACH_VEC_ELT (DDR_DIST_VECTS (ddr), i, dist_v) + { + lambda_vector dir_v = lambda_vector_new (DDR_NB_LOOPS (ddr)); + + for (j = 0; j < DDR_NB_LOOPS (ddr); j++) + dir_v[j] = dir_from_dist (dist_v[j]); + + save_dir_v (ddr, dir_v); + } +} + +/* Helper function. Returns true when there is a dependence between the + data references. A_INDEX is the index of the first reference (0 for + DDR_A, 1 for DDR_B) and B_INDEX is the index of the second reference. */ + +static bool +subscript_dependence_tester_1 (struct data_dependence_relation *ddr, + unsigned int a_index, unsigned int b_index, + class loop *loop_nest) +{ + unsigned int i; + tree last_conflicts; + struct subscript *subscript; + tree res = NULL_TREE; + + for (i = 0; DDR_SUBSCRIPTS (ddr).iterate (i, &subscript); i++) + { + conflict_function *overlaps_a, *overlaps_b; + + analyze_overlapping_iterations (SUB_ACCESS_FN (subscript, a_index), + SUB_ACCESS_FN (subscript, b_index), + &overlaps_a, &overlaps_b, + &last_conflicts, loop_nest); + + if (SUB_CONFLICTS_IN_A (subscript)) + free_conflict_function (SUB_CONFLICTS_IN_A (subscript)); + if (SUB_CONFLICTS_IN_B (subscript)) + free_conflict_function (SUB_CONFLICTS_IN_B (subscript)); + + SUB_CONFLICTS_IN_A (subscript) = overlaps_a; + SUB_CONFLICTS_IN_B (subscript) = overlaps_b; + SUB_LAST_CONFLICT (subscript) = last_conflicts; + + /* If there is any undetermined conflict function we have to + give a conservative answer in case we cannot prove that + no dependence exists when analyzing another subscript. */ + if (CF_NOT_KNOWN_P (overlaps_a) + || CF_NOT_KNOWN_P (overlaps_b)) + { + res = chrec_dont_know; + continue; + } + + /* When there is a subscript with no dependence we can stop. */ + else if (CF_NO_DEPENDENCE_P (overlaps_a) + || CF_NO_DEPENDENCE_P (overlaps_b)) + { + res = chrec_known; + break; + } + } + + if (res == NULL_TREE) + return true; + + if (res == chrec_known) + dependence_stats.num_dependence_independent++; + else + dependence_stats.num_dependence_undetermined++; + finalize_ddr_dependent (ddr, res); + return false; +} + +/* Computes the conflicting iterations in LOOP_NEST, and initialize DDR. */ + +static void +subscript_dependence_tester (struct data_dependence_relation *ddr, + class loop *loop_nest) +{ + if (subscript_dependence_tester_1 (ddr, 0, 1, loop_nest)) + dependence_stats.num_dependence_dependent++; + + compute_subscript_distance (ddr); + if (build_classic_dist_vector (ddr, loop_nest)) + build_classic_dir_vector (ddr); +} + +/* Returns true when all the access functions of A are affine or + constant with respect to LOOP_NEST. */ + +static bool +access_functions_are_affine_or_constant_p (const struct data_reference *a, + const class loop *loop_nest) +{ + vec<tree> fns = DR_ACCESS_FNS (a); + for (tree t : fns) + if (!evolution_function_is_invariant_p (t, loop_nest->num) + && !evolution_function_is_affine_multivariate_p (t, loop_nest->num)) + return false; + + return true; +} + +/* This computes the affine dependence relation between A and B with + respect to LOOP_NEST. CHREC_KNOWN is used for representing the + independence between two accesses, while CHREC_DONT_KNOW is used + for representing the unknown relation. + + Note that it is possible to stop the computation of the dependence + relation the first time we detect a CHREC_KNOWN element for a given + subscript. */ + +void +compute_affine_dependence (struct data_dependence_relation *ddr, + class loop *loop_nest) +{ + struct data_reference *dra = DDR_A (ddr); + struct data_reference *drb = DDR_B (ddr); + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, "(compute_affine_dependence\n"); + fprintf (dump_file, " ref_a: "); + print_generic_expr (dump_file, DR_REF (dra)); + fprintf (dump_file, ", stmt_a: "); + print_gimple_stmt (dump_file, DR_STMT (dra), 0, TDF_SLIM); + fprintf (dump_file, " ref_b: "); + print_generic_expr (dump_file, DR_REF (drb)); + fprintf (dump_file, ", stmt_b: "); + print_gimple_stmt (dump_file, DR_STMT (drb), 0, TDF_SLIM); + } + + /* Analyze only when the dependence relation is not yet known. */ + if (DDR_ARE_DEPENDENT (ddr) == NULL_TREE) + { + dependence_stats.num_dependence_tests++; + + if (access_functions_are_affine_or_constant_p (dra, loop_nest) + && access_functions_are_affine_or_constant_p (drb, loop_nest)) + subscript_dependence_tester (ddr, loop_nest); + + /* As a last case, if the dependence cannot be determined, or if + the dependence is considered too difficult to determine, answer + "don't know". */ + else + { + dependence_stats.num_dependence_undetermined++; + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, "Data ref a:\n"); + dump_data_reference (dump_file, dra); + fprintf (dump_file, "Data ref b:\n"); + dump_data_reference (dump_file, drb); + fprintf (dump_file, "affine dependence test not usable: access function not affine or constant.\n"); + } + finalize_ddr_dependent (ddr, chrec_dont_know); + } + } + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + if (DDR_ARE_DEPENDENT (ddr) == chrec_known) + fprintf (dump_file, ") -> no dependence\n"); + else if (DDR_ARE_DEPENDENT (ddr) == chrec_dont_know) + fprintf (dump_file, ") -> dependence analysis failed\n"); + else + fprintf (dump_file, ")\n"); + } +} + +/* Compute in DEPENDENCE_RELATIONS the data dependence graph for all + the data references in DATAREFS, in the LOOP_NEST. When + COMPUTE_SELF_AND_RR is FALSE, don't compute read-read and self + relations. Return true when successful, i.e. data references number + is small enough to be handled. */ + +bool +compute_all_dependences (const vec<data_reference_p> &datarefs, + vec<ddr_p> *dependence_relations, + const vec<loop_p> &loop_nest, + bool compute_self_and_rr) +{ + struct data_dependence_relation *ddr; + struct data_reference *a, *b; + unsigned int i, j; + + if ((int) datarefs.length () + > param_loop_max_datarefs_for_datadeps) + { + struct data_dependence_relation *ddr; + + /* Insert a single relation into dependence_relations: + chrec_dont_know. */ + ddr = initialize_data_dependence_relation (NULL, NULL, loop_nest); + dependence_relations->safe_push (ddr); + return false; + } + + FOR_EACH_VEC_ELT (datarefs, i, a) + for (j = i + 1; datarefs.iterate (j, &b); j++) + if (DR_IS_WRITE (a) || DR_IS_WRITE (b) || compute_self_and_rr) + { + ddr = initialize_data_dependence_relation (a, b, loop_nest); + dependence_relations->safe_push (ddr); + if (loop_nest.exists ()) + compute_affine_dependence (ddr, loop_nest[0]); + } + + if (compute_self_and_rr) + FOR_EACH_VEC_ELT (datarefs, i, a) + { + ddr = initialize_data_dependence_relation (a, a, loop_nest); + dependence_relations->safe_push (ddr); + if (loop_nest.exists ()) + compute_affine_dependence (ddr, loop_nest[0]); + } + + return true; +} + +/* Describes a location of a memory reference. */ + +struct data_ref_loc +{ + /* The memory reference. */ + tree ref; + + /* True if the memory reference is read. */ + bool is_read; + + /* True if the data reference is conditional within the containing + statement, i.e. if it might not occur even when the statement + is executed and runs to completion. */ + bool is_conditional_in_stmt; +}; + + +/* Stores the locations of memory references in STMT to REFERENCES. Returns + true if STMT clobbers memory, false otherwise. */ + +static bool +get_references_in_stmt (gimple *stmt, vec<data_ref_loc, va_heap> *references) +{ + bool clobbers_memory = false; + data_ref_loc ref; + tree op0, op1; + enum gimple_code stmt_code = gimple_code (stmt); + + /* ASM_EXPR and CALL_EXPR may embed arbitrary side effects. + As we cannot model data-references to not spelled out + accesses give up if they may occur. */ + if (stmt_code == GIMPLE_CALL + && !(gimple_call_flags (stmt) & ECF_CONST)) + { + /* Allow IFN_GOMP_SIMD_LANE in their own loops. */ + if (gimple_call_internal_p (stmt)) + switch (gimple_call_internal_fn (stmt)) + { + case IFN_GOMP_SIMD_LANE: + { + class loop *loop = gimple_bb (stmt)->loop_father; + tree uid = gimple_call_arg (stmt, 0); + gcc_assert (TREE_CODE (uid) == SSA_NAME); + if (loop == NULL + || loop->simduid != SSA_NAME_VAR (uid)) + clobbers_memory = true; + break; + } + case IFN_MASK_LOAD: + case IFN_MASK_STORE: + break; + default: + clobbers_memory = true; + break; + } + else + clobbers_memory = true; + } + else if (stmt_code == GIMPLE_ASM + && (gimple_asm_volatile_p (as_a <gasm *> (stmt)) + || gimple_vuse (stmt))) + clobbers_memory = true; + + if (!gimple_vuse (stmt)) + return clobbers_memory; + + if (stmt_code == GIMPLE_ASSIGN) + { + tree base; + op0 = gimple_assign_lhs (stmt); + op1 = gimple_assign_rhs1 (stmt); + + if (DECL_P (op1) + || (REFERENCE_CLASS_P (op1) + && (base = get_base_address (op1)) + && TREE_CODE (base) != SSA_NAME + && !is_gimple_min_invariant (base))) + { + ref.ref = op1; + ref.is_read = true; + ref.is_conditional_in_stmt = false; + references->safe_push (ref); + } + } + else if (stmt_code == GIMPLE_CALL) + { + unsigned i, n; + tree ptr, type; + unsigned int align; + + ref.is_read = false; + if (gimple_call_internal_p (stmt)) + switch (gimple_call_internal_fn (stmt)) + { + case IFN_MASK_LOAD: + if (gimple_call_lhs (stmt) == NULL_TREE) + break; + ref.is_read = true; + /* FALLTHRU */ + case IFN_MASK_STORE: + ptr = build_int_cst (TREE_TYPE (gimple_call_arg (stmt, 1)), 0); + align = tree_to_shwi (gimple_call_arg (stmt, 1)); + if (ref.is_read) + type = TREE_TYPE (gimple_call_lhs (stmt)); + else + type = TREE_TYPE (gimple_call_arg (stmt, 3)); + if (TYPE_ALIGN (type) != align) + type = build_aligned_type (type, align); + ref.is_conditional_in_stmt = true; + ref.ref = fold_build2 (MEM_REF, type, gimple_call_arg (stmt, 0), + ptr); + references->safe_push (ref); + return false; + default: + break; + } + + op0 = gimple_call_lhs (stmt); + n = gimple_call_num_args (stmt); + for (i = 0; i < n; i++) + { + op1 = gimple_call_arg (stmt, i); + + if (DECL_P (op1) + || (REFERENCE_CLASS_P (op1) && get_base_address (op1))) + { + ref.ref = op1; + ref.is_read = true; + ref.is_conditional_in_stmt = false; + references->safe_push (ref); + } + } + } + else + return clobbers_memory; + + if (op0 + && (DECL_P (op0) + || (REFERENCE_CLASS_P (op0) && get_base_address (op0)))) + { + ref.ref = op0; + ref.is_read = false; + ref.is_conditional_in_stmt = false; + references->safe_push (ref); + } + return clobbers_memory; +} + + +/* Returns true if the loop-nest has any data reference. */ + +bool +loop_nest_has_data_refs (loop_p loop) +{ + basic_block *bbs = get_loop_body (loop); + auto_vec<data_ref_loc, 3> references; + + for (unsigned i = 0; i < loop->num_nodes; i++) + { + basic_block bb = bbs[i]; + gimple_stmt_iterator bsi; + + for (bsi = gsi_start_bb (bb); !gsi_end_p (bsi); gsi_next (&bsi)) + { + gimple *stmt = gsi_stmt (bsi); + get_references_in_stmt (stmt, &references); + if (references.length ()) + { + free (bbs); + return true; + } + } + } + free (bbs); + return false; +} + +/* Stores the data references in STMT to DATAREFS. If there is an unanalyzable + reference, returns false, otherwise returns true. NEST is the outermost + loop of the loop nest in which the references should be analyzed. */ + +opt_result +find_data_references_in_stmt (class loop *nest, gimple *stmt, + vec<data_reference_p> *datarefs) +{ + auto_vec<data_ref_loc, 2> references; + data_reference_p dr; + + if (get_references_in_stmt (stmt, &references)) + return opt_result::failure_at (stmt, "statement clobbers memory: %G", + stmt); + + for (const data_ref_loc &ref : references) + { + dr = create_data_ref (nest ? loop_preheader_edge (nest) : NULL, + loop_containing_stmt (stmt), ref.ref, + stmt, ref.is_read, ref.is_conditional_in_stmt); + gcc_assert (dr != NULL); + datarefs->safe_push (dr); + } + + return opt_result::success (); +} + +/* Stores the data references in STMT to DATAREFS. If there is an + unanalyzable reference, returns false, otherwise returns true. + NEST is the outermost loop of the loop nest in which the references + should be instantiated, LOOP is the loop in which the references + should be analyzed. */ + +bool +graphite_find_data_references_in_stmt (edge nest, loop_p loop, gimple *stmt, + vec<data_reference_p> *datarefs) +{ + auto_vec<data_ref_loc, 2> references; + bool ret = true; + data_reference_p dr; + + if (get_references_in_stmt (stmt, &references)) + return false; + + for (const data_ref_loc &ref : references) + { + dr = create_data_ref (nest, loop, ref.ref, stmt, ref.is_read, + ref.is_conditional_in_stmt); + gcc_assert (dr != NULL); + datarefs->safe_push (dr); + } + + return ret; +} + +/* Search the data references in LOOP, and record the information into + DATAREFS. Returns chrec_dont_know when failing to analyze a + difficult case, returns NULL_TREE otherwise. */ + +tree +find_data_references_in_bb (class loop *loop, basic_block bb, + vec<data_reference_p> *datarefs) +{ + gimple_stmt_iterator bsi; + + for (bsi = gsi_start_bb (bb); !gsi_end_p (bsi); gsi_next (&bsi)) + { + gimple *stmt = gsi_stmt (bsi); + + if (!find_data_references_in_stmt (loop, stmt, datarefs)) + { + struct data_reference *res; + res = XCNEW (struct data_reference); + datarefs->safe_push (res); + + return chrec_dont_know; + } + } + + return NULL_TREE; +} + +/* Search the data references in LOOP, and record the information into + DATAREFS. Returns chrec_dont_know when failing to analyze a + difficult case, returns NULL_TREE otherwise. + + TODO: This function should be made smarter so that it can handle address + arithmetic as if they were array accesses, etc. */ + +tree +find_data_references_in_loop (class loop *loop, + vec<data_reference_p> *datarefs) +{ + basic_block bb, *bbs; + unsigned int i; + + bbs = get_loop_body_in_dom_order (loop); + + for (i = 0; i < loop->num_nodes; i++) + { + bb = bbs[i]; + + if (find_data_references_in_bb (loop, bb, datarefs) == chrec_dont_know) + { + free (bbs); + return chrec_dont_know; + } + } + free (bbs); + + return NULL_TREE; +} + +/* Return the alignment in bytes that DRB is guaranteed to have at all + times. */ + +unsigned int +dr_alignment (innermost_loop_behavior *drb) +{ + /* Get the alignment of BASE_ADDRESS + INIT. */ + unsigned int alignment = drb->base_alignment; + unsigned int misalignment = (drb->base_misalignment + + TREE_INT_CST_LOW (drb->init)); + if (misalignment != 0) + alignment = MIN (alignment, misalignment & -misalignment); + + /* Cap it to the alignment of OFFSET. */ + if (!integer_zerop (drb->offset)) + alignment = MIN (alignment, drb->offset_alignment); + + /* Cap it to the alignment of STEP. */ + if (!integer_zerop (drb->step)) + alignment = MIN (alignment, drb->step_alignment); + + return alignment; +} + +/* If BASE is a pointer-typed SSA name, try to find the object that it + is based on. Return this object X on success and store the alignment + in bytes of BASE - &X in *ALIGNMENT_OUT. */ + +static tree +get_base_for_alignment_1 (tree base, unsigned int *alignment_out) +{ + if (TREE_CODE (base) != SSA_NAME || !POINTER_TYPE_P (TREE_TYPE (base))) + return NULL_TREE; + + gimple *def = SSA_NAME_DEF_STMT (base); + base = analyze_scalar_evolution (loop_containing_stmt (def), base); + + /* Peel chrecs and record the minimum alignment preserved by + all steps. */ + unsigned int alignment = MAX_OFILE_ALIGNMENT / BITS_PER_UNIT; + while (TREE_CODE (base) == POLYNOMIAL_CHREC) + { + unsigned int step_alignment = highest_pow2_factor (CHREC_RIGHT (base)); + alignment = MIN (alignment, step_alignment); + base = CHREC_LEFT (base); + } + + /* Punt if the expression is too complicated to handle. */ + if (tree_contains_chrecs (base, NULL) || !POINTER_TYPE_P (TREE_TYPE (base))) + return NULL_TREE; + + /* The only useful cases are those for which a dereference folds to something + other than an INDIRECT_REF. */ + tree ref_type = TREE_TYPE (TREE_TYPE (base)); + tree ref = fold_indirect_ref_1 (UNKNOWN_LOCATION, ref_type, base); + if (!ref) + return NULL_TREE; + + /* Analyze the base to which the steps we peeled were applied. */ + poly_int64 bitsize, bitpos, bytepos; + machine_mode mode; + int unsignedp, reversep, volatilep; + tree offset; + base = get_inner_reference (ref, &bitsize, &bitpos, &offset, &mode, + &unsignedp, &reversep, &volatilep); + if (!base || !multiple_p (bitpos, BITS_PER_UNIT, &bytepos)) + return NULL_TREE; + + /* Restrict the alignment to that guaranteed by the offsets. */ + unsigned int bytepos_alignment = known_alignment (bytepos); + if (bytepos_alignment != 0) + alignment = MIN (alignment, bytepos_alignment); + if (offset) + { + unsigned int offset_alignment = highest_pow2_factor (offset); + alignment = MIN (alignment, offset_alignment); + } + + *alignment_out = alignment; + return base; +} + +/* Return the object whose alignment would need to be changed in order + to increase the alignment of ADDR. Store the maximum achievable + alignment in *MAX_ALIGNMENT. */ + +tree +get_base_for_alignment (tree addr, unsigned int *max_alignment) +{ + tree base = get_base_for_alignment_1 (addr, max_alignment); + if (base) + return base; + + if (TREE_CODE (addr) == ADDR_EXPR) + addr = TREE_OPERAND (addr, 0); + *max_alignment = MAX_OFILE_ALIGNMENT / BITS_PER_UNIT; + return addr; +} + +/* Recursive helper function. */ + +static bool +find_loop_nest_1 (class loop *loop, vec<loop_p> *loop_nest) +{ + /* Inner loops of the nest should not contain siblings. Example: + when there are two consecutive loops, + + | loop_0 + | loop_1 + | A[{0, +, 1}_1] + | endloop_1 + | loop_2 + | A[{0, +, 1}_2] + | endloop_2 + | endloop_0 + + the dependence relation cannot be captured by the distance + abstraction. */ + if (loop->next) + return false; + + loop_nest->safe_push (loop); + if (loop->inner) + return find_loop_nest_1 (loop->inner, loop_nest); + return true; +} + +/* Return false when the LOOP is not well nested. Otherwise return + true and insert in LOOP_NEST the loops of the nest. LOOP_NEST will + contain the loops from the outermost to the innermost, as they will + appear in the classic distance vector. */ + +bool +find_loop_nest (class loop *loop, vec<loop_p> *loop_nest) +{ + loop_nest->safe_push (loop); + if (loop->inner) + return find_loop_nest_1 (loop->inner, loop_nest); + return true; +} + +/* Returns true when the data dependences have been computed, false otherwise. + Given a loop nest LOOP, the following vectors are returned: + DATAREFS is initialized to all the array elements contained in this loop, + DEPENDENCE_RELATIONS contains the relations between the data references. + Compute read-read and self relations if + COMPUTE_SELF_AND_READ_READ_DEPENDENCES is TRUE. */ + +bool +compute_data_dependences_for_loop (class loop *loop, + bool compute_self_and_read_read_dependences, + vec<loop_p> *loop_nest, + vec<data_reference_p> *datarefs, + vec<ddr_p> *dependence_relations) +{ + bool res = true; + + memset (&dependence_stats, 0, sizeof (dependence_stats)); + + /* If the loop nest is not well formed, or one of the data references + is not computable, give up without spending time to compute other + dependences. */ + if (!loop + || !find_loop_nest (loop, loop_nest) + || find_data_references_in_loop (loop, datarefs) == chrec_dont_know + || !compute_all_dependences (*datarefs, dependence_relations, *loop_nest, + compute_self_and_read_read_dependences)) + res = false; + + if (dump_file && (dump_flags & TDF_STATS)) + { + fprintf (dump_file, "Dependence tester statistics:\n"); + + fprintf (dump_file, "Number of dependence tests: %d\n", + dependence_stats.num_dependence_tests); + fprintf (dump_file, "Number of dependence tests classified dependent: %d\n", + dependence_stats.num_dependence_dependent); + fprintf (dump_file, "Number of dependence tests classified independent: %d\n", + dependence_stats.num_dependence_independent); + fprintf (dump_file, "Number of undetermined dependence tests: %d\n", + dependence_stats.num_dependence_undetermined); + + fprintf (dump_file, "Number of subscript tests: %d\n", + dependence_stats.num_subscript_tests); + fprintf (dump_file, "Number of undetermined subscript tests: %d\n", + dependence_stats.num_subscript_undetermined); + fprintf (dump_file, "Number of same subscript function: %d\n", + dependence_stats.num_same_subscript_function); + + fprintf (dump_file, "Number of ziv tests: %d\n", + dependence_stats.num_ziv); + fprintf (dump_file, "Number of ziv tests returning dependent: %d\n", + dependence_stats.num_ziv_dependent); + fprintf (dump_file, "Number of ziv tests returning independent: %d\n", + dependence_stats.num_ziv_independent); + fprintf (dump_file, "Number of ziv tests unimplemented: %d\n", + dependence_stats.num_ziv_unimplemented); + + fprintf (dump_file, "Number of siv tests: %d\n", + dependence_stats.num_siv); + fprintf (dump_file, "Number of siv tests returning dependent: %d\n", + dependence_stats.num_siv_dependent); + fprintf (dump_file, "Number of siv tests returning independent: %d\n", + dependence_stats.num_siv_independent); + fprintf (dump_file, "Number of siv tests unimplemented: %d\n", + dependence_stats.num_siv_unimplemented); + + fprintf (dump_file, "Number of miv tests: %d\n", + dependence_stats.num_miv); + fprintf (dump_file, "Number of miv tests returning dependent: %d\n", + dependence_stats.num_miv_dependent); + fprintf (dump_file, "Number of miv tests returning independent: %d\n", + dependence_stats.num_miv_independent); + fprintf (dump_file, "Number of miv tests unimplemented: %d\n", + dependence_stats.num_miv_unimplemented); + } + + return res; +} + +/* Free the memory used by a data dependence relation DDR. */ + +void +free_dependence_relation (struct data_dependence_relation *ddr) +{ + if (ddr == NULL) + return; + + if (DDR_SUBSCRIPTS (ddr).exists ()) + free_subscripts (DDR_SUBSCRIPTS (ddr)); + DDR_DIST_VECTS (ddr).release (); + DDR_DIR_VECTS (ddr).release (); + + free (ddr); +} + +/* Free the memory used by the data dependence relations from + DEPENDENCE_RELATIONS. */ + +void +free_dependence_relations (vec<ddr_p>& dependence_relations) +{ + for (data_dependence_relation *ddr : dependence_relations) + if (ddr) + free_dependence_relation (ddr); + + dependence_relations.release (); +} + +/* Free the memory used by the data references from DATAREFS. */ + +void +free_data_refs (vec<data_reference_p>& datarefs) +{ + for (data_reference *dr : datarefs) + free_data_ref (dr); + datarefs.release (); +} + +/* Common routine implementing both dr_direction_indicator and + dr_zero_step_indicator. Return USEFUL_MIN if the indicator is known + to be >= USEFUL_MIN and -1 if the indicator is known to be negative. + Return the step as the indicator otherwise. */ + +static tree +dr_step_indicator (struct data_reference *dr, int useful_min) +{ + tree step = DR_STEP (dr); + if (!step) + return NULL_TREE; + STRIP_NOPS (step); + /* Look for cases where the step is scaled by a positive constant + integer, which will often be the access size. If the multiplication + doesn't change the sign (due to overflow effects) then we can + test the unscaled value instead. */ + if (TREE_CODE (step) == MULT_EXPR + && TREE_CODE (TREE_OPERAND (step, 1)) == INTEGER_CST + && tree_int_cst_sgn (TREE_OPERAND (step, 1)) > 0) + { + tree factor = TREE_OPERAND (step, 1); + step = TREE_OPERAND (step, 0); + + /* Strip widening and truncating conversions as well as nops. */ + if (CONVERT_EXPR_P (step) + && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (step, 0)))) + step = TREE_OPERAND (step, 0); + tree type = TREE_TYPE (step); + + /* Get the range of step values that would not cause overflow. */ + widest_int minv = (wi::to_widest (TYPE_MIN_VALUE (ssizetype)) + / wi::to_widest (factor)); + widest_int maxv = (wi::to_widest (TYPE_MAX_VALUE (ssizetype)) + / wi::to_widest (factor)); + + /* Get the range of values that the unconverted step actually has. */ + wide_int step_min, step_max; + value_range vr; + if (TREE_CODE (step) != SSA_NAME + || !get_range_query (cfun)->range_of_expr (vr, step) + || vr.kind () != VR_RANGE) + { + step_min = wi::to_wide (TYPE_MIN_VALUE (type)); + step_max = wi::to_wide (TYPE_MAX_VALUE (type)); + } + else + { + step_min = vr.lower_bound (); + step_max = vr.upper_bound (); + } + + /* Check whether the unconverted step has an acceptable range. */ + signop sgn = TYPE_SIGN (type); + if (wi::les_p (minv, widest_int::from (step_min, sgn)) + && wi::ges_p (maxv, widest_int::from (step_max, sgn))) + { + if (wi::ge_p (step_min, useful_min, sgn)) + return ssize_int (useful_min); + else if (wi::lt_p (step_max, 0, sgn)) + return ssize_int (-1); + else + return fold_convert (ssizetype, step); + } + } + return DR_STEP (dr); +} + +/* Return a value that is negative iff DR has a negative step. */ + +tree +dr_direction_indicator (struct data_reference *dr) +{ + return dr_step_indicator (dr, 0); +} + +/* Return a value that is zero iff DR has a zero step. */ + +tree +dr_zero_step_indicator (struct data_reference *dr) +{ + return dr_step_indicator (dr, 1); +} + +/* Return true if DR is known to have a nonnegative (but possibly zero) + step. */ + +bool +dr_known_forward_stride_p (struct data_reference *dr) +{ + tree indicator = dr_direction_indicator (dr); + tree neg_step_val = fold_binary (LT_EXPR, boolean_type_node, + fold_convert (ssizetype, indicator), + ssize_int (0)); + return neg_step_val && integer_zerop (neg_step_val); +} |