diff options
Diffstat (limited to 'gcc/tree-ssa-structalias.c')
| -rw-r--r-- | gcc/tree-ssa-structalias.c | 117 |
1 files changed, 108 insertions, 9 deletions
diff --git a/gcc/tree-ssa-structalias.c b/gcc/tree-ssa-structalias.c index 3be76ac..46781b8 100644 --- a/gcc/tree-ssa-structalias.c +++ b/gcc/tree-ssa-structalias.c @@ -31,14 +31,14 @@ #include "hard-reg-set.h" #include "basic-block.h" #include "output.h" -#include "errors.h" -#include "diagnostic.h" #include "tree.h" #include "c-common.h" #include "tree-flow.h" #include "tree-inline.h" #include "varray.h" #include "c-tree.h" +#include "diagnostic.h" +#include "toplev.h" #include "gimple.h" #include "hashtab.h" #include "function.h" @@ -4648,14 +4648,15 @@ shared_bitmap_add (bitmap pt_vars) IS_DEREFED is true if PTR was directly dereferenced, which we use to help determine whether we are we are allowed to prune using TBAA. If NO_TBAA_PRUNING is true, we do not perform any TBAA pruning of - the from set. */ + the from set. Returns the number of pruned variables. */ -static void +static unsigned set_uids_in_ptset (tree ptr, bitmap into, bitmap from, bool is_derefed, bool no_tbaa_pruning) { unsigned int i; bitmap_iterator bi; + unsigned pruned = 0; gcc_assert (POINTER_TYPE_P (TREE_TYPE (ptr))); @@ -4688,14 +4689,97 @@ set_uids_in_ptset (tree ptr, bitmap into, bitmap from, bool is_derefed, if (may_alias_p (SSA_NAME_VAR (ptr), mem_alias_set, vi->decl, var_alias_set, true)) bitmap_set_bit (into, DECL_UID (vi->decl)); + else + ++pruned; } } } + + return pruned; } static bool have_alias_info = false; +/* Emit a note for the pointer initialization point DEF. */ + +static void +emit_pointer_definition (gimple def) +{ + if (gimple_code (def) == GIMPLE_PHI) + { + use_operand_p argp; + ssa_op_iter oi; + + FOR_EACH_PHI_ARG (argp, def, oi, SSA_OP_USE) + { + tree arg = USE_FROM_PTR (argp); + if (TREE_CODE (arg) == SSA_NAME) + emit_pointer_definition (SSA_NAME_DEF_STMT (arg)); + else + inform (0, "initialized from %qE", arg); + } + } + else if (!gimple_nop_p (def)) + inform (gimple_location (def), "initialized from here"); +} + +/* Emit a strict aliasing warning for dereferencing the pointer PTR. */ + +static void +emit_alias_warning (tree ptr) +{ + gimple def = SSA_NAME_DEF_STMT (ptr); + gimple use; + imm_use_iterator ui; + unsigned warned = 0; + + FOR_EACH_IMM_USE_STMT (use, ui, ptr) + { + tree deref = NULL_TREE; + + if (gimple_has_lhs (use)) + { + tree lhs = get_base_address (gimple_get_lhs (use)); + if (lhs + && INDIRECT_REF_P (lhs) + && TREE_OPERAND (lhs, 0) == ptr) + deref = lhs; + } + if (gimple_assign_single_p (use)) + { + tree rhs = get_base_address (gimple_assign_rhs1 (use)); + if (rhs + && INDIRECT_REF_P (rhs) + && TREE_OPERAND (rhs, 0) == ptr) + deref = rhs; + } + else if (is_gimple_call (use)) + { + unsigned i; + for (i = 0; i < gimple_call_num_args (use); ++i) + { + tree op = get_base_address (gimple_call_arg (use, i)); + if (op + && INDIRECT_REF_P (op) + && TREE_OPERAND (op, 0) == ptr) + deref = op; + } + } + if (deref + && !TREE_NO_WARNING (deref)) + { + TREE_NO_WARNING (deref) = 1; + warning_at (gimple_location (use), OPT_Wstrict_aliasing, + "dereferencing pointer %qD does break strict-aliasing " + "rules", SSA_NAME_VAR (ptr)); + ++warned; + } + } + if (warned > 0) + emit_pointer_definition (def); +} + /* Given a pointer variable P, fill in its points-to set, or return false if we can't. Rather than return false for variables that point-to anything, we @@ -4740,7 +4824,7 @@ find_what_p_points_to (tree p) else { struct ptr_info_def *pi = get_ptr_info (p); - unsigned int i; + unsigned int i, pruned; bitmap_iterator bi; bool was_pt_anything = false; bitmap finished_solution; @@ -4792,9 +4876,9 @@ find_what_p_points_to (tree p) finished_solution = BITMAP_GGC_ALLOC (); stats.points_to_sets_created++; - set_uids_in_ptset (p, finished_solution, vi->solution, - pi->is_dereferenced, - vi->no_tbaa_pruning); + pruned = set_uids_in_ptset (p, finished_solution, vi->solution, + pi->is_dereferenced, + vi->no_tbaa_pruning); result = shared_bitmap_lookup (finished_solution); if (!result) @@ -4809,7 +4893,22 @@ find_what_p_points_to (tree p) } if (bitmap_empty_p (pi->pt_vars)) - pi->pt_vars = NULL; + { + pi->pt_vars = NULL; + if (pruned > 0 + && pi->is_dereferenced + && warn_strict_aliasing > 0 + && !SSA_NAME_IS_DEFAULT_DEF (p)) + { + if (dump_file && dump_flags & TDF_DETAILS) + { + fprintf (dump_file, "alias warning for "); + print_generic_expr (dump_file, p, 0); + fprintf (dump_file, "\n"); + } + emit_alias_warning (p); + } + } return true; } |