diff options
Diffstat (limited to 'gcc/rust/backend/rust-constexpr.cc')
| -rw-r--r-- | gcc/rust/backend/rust-constexpr.cc | 6112 |
1 files changed, 6086 insertions, 26 deletions
diff --git a/gcc/rust/backend/rust-constexpr.cc b/gcc/rust/backend/rust-constexpr.cc index 53c6ef6..f2e3e51 100644 --- a/gcc/rust/backend/rust-constexpr.cc +++ b/gcc/rust/backend/rust-constexpr.cc @@ -18,29 +18,449 @@ #include "rust-location.h" #include "rust-diagnostics.h" #include "rust-tree.h" - #include "fold-const.h" #include "realmpfr.h" #include "convert.h" #include "print-tree.h" #include "gimplify.h" #include "tree-iterator.h" +#include "timevar.h" +#include "varasm.h" +#include "cgraph.h" +#include "tree-inline.h" +#include "vec.h" +#include "function.h" +#include "diagnostic.h" +#include "target.h" +#include "builtins.h" + +#define VERIFY_CONSTANT(X) \ + do \ + { \ + if (verify_constant ((X), ctx->quiet, non_constant_p, overflow_p)) \ + return t; \ + } \ + while (0) namespace Rust { namespace Compile { +/* Returns true iff FUN is an instantiation of a constexpr function + template or a defaulted constexpr function. */ + +bool +is_instantiation_of_constexpr (tree fun) +{ + return DECL_DECLARED_CONSTEXPR_P (fun); +} + +/* Return true if T is a literal type. */ + +bool +literal_type_p (tree t) +{ + if (SCALAR_TYPE_P (t) || VECTOR_TYPE_P (t) || TYPE_REF_P (t) + || (VOID_TYPE_P (t))) + return true; + + if (TREE_CODE (t) == ARRAY_TYPE) + return literal_type_p (strip_array_types (t)); + return false; +} + +static bool +verify_constant (tree, bool, bool *, bool *); + +static HOST_WIDE_INT +find_array_ctor_elt (tree ary, tree dindex, bool insert = false); +static int +array_index_cmp (tree key, tree index); +static bool +potential_constant_expression_1 (tree t, bool want_rval, bool strict, bool now, + tsubst_flags_t flags, tree *jump_target); +bool +potential_constant_expression_1 (tree t, bool want_rval, bool strict, bool now, + tsubst_flags_t flags); +inline tree +get_nth_callarg (tree t, int n); +tree +unshare_constructor (tree t MEM_STAT_DECL); +void +maybe_save_constexpr_fundef (tree fun); + +static bool +returns (tree *jump_target); +static bool +breaks (tree *jump_target); +static bool +continues (tree *jump_target); +static bool +switches (tree *jump_target); + struct constexpr_global_ctx { + /* Values for any temporaries or local variables within the + constant-expression. */ + hash_map<tree, tree> values; + /* Number of cxx_eval_constant_expression calls (except skipped ones, + on simple constants or location wrappers) encountered during current + cxx_eval_outermost_constant_expr call. */ HOST_WIDE_INT constexpr_ops_count; + /* Heap VAR_DECLs created during the evaluation of the outermost constant + expression. */ + auto_vec<tree, 16> heap_vars; + /* Cleanups that need to be evaluated at the end of CLEANUP_POINT_EXPR. */ + vec<tree> *cleanups; + /* Number of heap VAR_DECL deallocations. */ + unsigned heap_dealloc_count; + /* Constructor. */ + constexpr_global_ctx () + : constexpr_ops_count (0), cleanups (NULL), heap_dealloc_count (0) + {} +}; + +/* In constexpr.cc */ +/* Representation of entries in the constexpr function definition table. */ + +struct GTY ((for_user)) constexpr_fundef +{ + tree decl; + tree body; + tree parms; + tree result; +}; + +/* Objects of this type represent calls to constexpr functions + along with the bindings of parameters to their arguments, for + the purpose of compile time evaluation. */ + +struct GTY ((for_user)) constexpr_call +{ + /* Description of the constexpr function definition. */ + constexpr_fundef *fundef; + /* Parameter bindings environment. A TREE_VEC of arguments. */ + tree bindings; + /* Result of the call. + NULL means the call is being evaluated. + error_mark_node means that the evaluation was erroneous; + otherwise, the actuall value of the call. */ + tree result; + /* The hash of this call; we remember it here to avoid having to + recalculate it when expanding the hash table. */ + hashval_t hash; + /* Whether __builtin_is_constant_evaluated() should evaluate to true. */ + bool manifestly_const_eval; +}; - constexpr_global_ctx () : constexpr_ops_count (0) {} +struct constexpr_call_hasher : ggc_ptr_hash<constexpr_call> +{ + static hashval_t hash (constexpr_call *); + static bool equal (constexpr_call *, constexpr_call *); +}; + +enum constexpr_switch_state +{ + /* Used when processing a switch for the first time by cxx_eval_switch_expr + and default: label for that switch has not been seen yet. */ + css_default_not_seen, + /* Used when processing a switch for the first time by cxx_eval_switch_expr + and default: label for that switch has been seen already. */ + css_default_seen, + /* Used when processing a switch for the second time by + cxx_eval_switch_expr, where default: label should match. */ + css_default_processing }; struct constexpr_ctx { + /* The part of the context that needs to be unique to the whole + cxx_eval_outermost_constant_expr invocation. */ constexpr_global_ctx *global; + /* The innermost call we're evaluating. */ + constexpr_call *call; + /* SAVE_EXPRs and TARGET_EXPR_SLOT vars of TARGET_EXPRs that we've seen + within the current LOOP_EXPR. NULL if we aren't inside a loop. */ + vec<tree> *save_exprs; + /* The CONSTRUCTOR we're currently building up for an aggregate + initializer. */ + tree ctor; + /* The object we're building the CONSTRUCTOR for. */ + tree object; + /* If inside SWITCH_EXPR. */ + constexpr_switch_state *css_state; + /* The aggregate initialization context inside which this one is nested. This + is used by lookup_placeholder to resolve PLACEHOLDER_EXPRs. */ + const constexpr_ctx *parent; + + /* Whether we should error on a non-constant expression or fail quietly. + This flag needs to be here, but some of the others could move to global + if they get larger than a word. */ + bool quiet; + /* Whether we are strictly conforming to constant expression rules or + trying harder to get a constant value. */ + bool strict; + /* Whether __builtin_is_constant_evaluated () should be true. */ + bool manifestly_const_eval; }; +struct constexpr_fundef_hasher : ggc_ptr_hash<constexpr_fundef> +{ + static hashval_t hash (const constexpr_fundef *); + static bool equal (const constexpr_fundef *, const constexpr_fundef *); +}; + +/* This table holds all constexpr function definitions seen in + the current translation unit. */ + +static GTY (()) hash_table<constexpr_fundef_hasher> *constexpr_fundef_table; + +/* Utility function used for managing the constexpr function table. + Return true if the entries pointed to by P and Q are for the + same constexpr function. */ + +inline bool +constexpr_fundef_hasher::equal (const constexpr_fundef *lhs, + const constexpr_fundef *rhs) +{ + return lhs->decl == rhs->decl; +} + +/* Utility function used for managing the constexpr function table. + Return a hash value for the entry pointed to by Q. */ + +inline hashval_t +constexpr_fundef_hasher::hash (const constexpr_fundef *fundef) +{ + return DECL_UID (fundef->decl); +} + +/* Return a previously saved definition of function FUN. */ + +constexpr_fundef * +retrieve_constexpr_fundef (tree fun) +{ + if (constexpr_fundef_table == NULL) + return NULL; + + constexpr_fundef fundef = {fun, NULL_TREE, NULL_TREE, NULL_TREE}; + return constexpr_fundef_table->find (&fundef); +} + +/* This internal flag controls whether we should avoid doing anything during + constexpr evaluation that would cause extra DECL_UID generation, such as + template instantiation and function body copying. */ + +static bool uid_sensitive_constexpr_evaluation_value; + +/* An internal counter that keeps track of the number of times + uid_sensitive_constexpr_evaluation_p returned true. */ + +static unsigned uid_sensitive_constexpr_evaluation_true_counter; + +/* The accessor for uid_sensitive_constexpr_evaluation_value which also + increments the corresponding counter. */ + +static bool +uid_sensitive_constexpr_evaluation_p () +{ + if (uid_sensitive_constexpr_evaluation_value) + { + ++uid_sensitive_constexpr_evaluation_true_counter; + return true; + } + else + return false; +} + +/* RAII sentinel that saves the value of a variable, optionally + overrides it right away, and restores its value when the sentinel + id destructed. */ + +template <typename T> class temp_override +{ + T &overridden_variable; + T saved_value; + +public: + temp_override (T &var) : overridden_variable (var), saved_value (var) {} + temp_override (T &var, T overrider) + : overridden_variable (var), saved_value (var) + { + overridden_variable = overrider; + } + ~temp_override () { overridden_variable = saved_value; } +}; + +/* An RAII sentinel used to restrict constexpr evaluation so that it + doesn't do anything that causes extra DECL_UID generation. */ + +struct uid_sensitive_constexpr_evaluation_sentinel +{ + temp_override<bool> ovr; + uid_sensitive_constexpr_evaluation_sentinel (); +}; + +/* Used to determine whether uid_sensitive_constexpr_evaluation_p was + called and returned true, indicating that we've restricted constexpr + evaluation in order to avoid UID generation. We use this to control + updates to the fold_cache and cv_cache. */ + +struct uid_sensitive_constexpr_evaluation_checker +{ + const unsigned saved_counter; + uid_sensitive_constexpr_evaluation_checker (); + bool evaluation_restricted_p () const; +}; + +/* The default constructor for uid_sensitive_constexpr_evaluation_sentinel + enables the internal flag for uid_sensitive_constexpr_evaluation_p + during the lifetime of the sentinel object. Upon its destruction, the + previous value of uid_sensitive_constexpr_evaluation_p is restored. */ + +uid_sensitive_constexpr_evaluation_sentinel :: + uid_sensitive_constexpr_evaluation_sentinel () + : ovr (uid_sensitive_constexpr_evaluation_value, true) +{} + +/* The default constructor for uid_sensitive_constexpr_evaluation_checker + records the current number of times that uid_sensitive_constexpr_evaluation_p + has been called and returned true. */ + +uid_sensitive_constexpr_evaluation_checker :: + uid_sensitive_constexpr_evaluation_checker () + : saved_counter (uid_sensitive_constexpr_evaluation_true_counter) +{} + +/* Returns true iff uid_sensitive_constexpr_evaluation_p is true, and + some constexpr evaluation was restricted due to u_s_c_e_p being called + and returning true during the lifetime of this checker object. */ + +bool +uid_sensitive_constexpr_evaluation_checker::evaluation_restricted_p () const +{ + return (uid_sensitive_constexpr_evaluation_value + && saved_counter != uid_sensitive_constexpr_evaluation_true_counter); +} + +/* A table of all constexpr calls that have been evaluated by the + compiler in this translation unit. */ + +static GTY (()) hash_table<constexpr_call_hasher> *constexpr_call_table; + +/* Compute a hash value for a constexpr call representation. */ + +inline hashval_t +constexpr_call_hasher::hash (constexpr_call *info) +{ + return info->hash; +} + +/* Return true if the objects pointed to by P and Q represent calls + to the same constexpr function with the same arguments. + Otherwise, return false. */ + +bool +constexpr_call_hasher::equal (constexpr_call *lhs, constexpr_call *rhs) +{ + if (lhs == rhs) + return true; + if (lhs->hash != rhs->hash) + return false; + if (lhs->manifestly_const_eval != rhs->manifestly_const_eval) + return false; + if (!constexpr_fundef_hasher::equal (lhs->fundef, rhs->fundef)) + return false; + return rs_tree_equal (lhs->bindings, rhs->bindings); +} + +/* Initialize the constexpr call table, if needed. */ + +static void +maybe_initialize_constexpr_call_table (void) +{ + if (constexpr_call_table == NULL) + constexpr_call_table = hash_table<constexpr_call_hasher>::create_ggc (101); +} + +/* During constexpr CALL_EXPR evaluation, to avoid issues with sharing when + a function happens to get called recursively, we unshare the callee + function's body and evaluate this unshared copy instead of evaluating the + original body. + + FUNDEF_COPIES_TABLE is a per-function freelist of these unshared function + copies. The underlying data structure of FUNDEF_COPIES_TABLE is a hash_map + that's keyed off of the original FUNCTION_DECL and whose value is a + TREE_LIST of this function's unused copies awaiting reuse. + + This is not GC-deletable to avoid GC affecting UID generation. */ + +static GTY (()) decl_tree_map *fundef_copies_table; + +/* Reuse a copy or create a new unshared copy of the function FUN. + Return this copy. We use a TREE_LIST whose PURPOSE is body, VALUE + is parms, TYPE is result. */ + +static tree +get_fundef_copy (constexpr_fundef *fundef) +{ + tree copy; + bool existed; + tree *slot + = &(hash_map_safe_get_or_insert<hm_ggc> (fundef_copies_table, fundef->decl, + &existed, 127)); + + if (!existed) + { + /* There is no cached function available, or in use. We can use + the function directly. That the slot is now created records + that this function is now in use. */ + copy = build_tree_list (fundef->body, fundef->parms); + TREE_TYPE (copy) = fundef->result; + } + else if (*slot == NULL_TREE) + { + if (uid_sensitive_constexpr_evaluation_p ()) + return NULL_TREE; + + /* We've already used the function itself, so make a copy. */ + copy = build_tree_list (NULL, NULL); + tree saved_body = DECL_SAVED_TREE (fundef->decl); + tree saved_parms = DECL_ARGUMENTS (fundef->decl); + tree saved_result = DECL_RESULT (fundef->decl); + tree saved_fn = current_function_decl; + DECL_SAVED_TREE (fundef->decl) = fundef->body; + DECL_ARGUMENTS (fundef->decl) = fundef->parms; + DECL_RESULT (fundef->decl) = fundef->result; + current_function_decl = fundef->decl; + TREE_PURPOSE (copy) + = copy_fn (fundef->decl, TREE_VALUE (copy), TREE_TYPE (copy)); + current_function_decl = saved_fn; + DECL_RESULT (fundef->decl) = saved_result; + DECL_ARGUMENTS (fundef->decl) = saved_parms; + DECL_SAVED_TREE (fundef->decl) = saved_body; + } + else + { + /* We have a cached function available. */ + copy = *slot; + *slot = TREE_CHAIN (copy); + } + + return copy; +} + +/* Save the copy COPY of function FUN for later reuse by + get_fundef_copy(). By construction, there will always be an entry + to find. */ + +static void +save_fundef_copy (tree fun, tree copy) +{ + tree *slot = fundef_copies_table->get (fun); + TREE_CHAIN (copy) = *slot; + *slot = copy; +} + static tree constant_value_1 (tree decl, bool strict_p, bool return_aggregate_cst_ok_p, bool unshare_p); @@ -51,37 +471,1433 @@ static void non_const_var_error (location_t loc, tree r); static tree -constexpr_expression (const constexpr_ctx *ctx, tree); +eval_constant_expression (const constexpr_ctx *ctx, tree, bool, bool *, bool *, + tree * = NULL); static tree constexpr_fn_retval (const constexpr_ctx *ctx, tree r); static tree -eval_store_expression (const constexpr_ctx *ctx, tree r); +eval_store_expression (const constexpr_ctx *ctx, tree r, bool, bool *, bool *); static tree -eval_call_expression (const constexpr_ctx *ctx, tree r); +eval_call_expression (const constexpr_ctx *ctx, tree r, bool, bool *, bool *); static tree -eval_binary_expression (const constexpr_ctx *ctx, tree r); +eval_binary_expression (const constexpr_ctx *ctx, tree r, bool, bool *, bool *); static tree get_function_named_in_call (tree t); +static tree +eval_statement_list (const constexpr_ctx *ctx, tree t, bool *non_constant_p, + bool *overflow_p, tree *jump_target); +static tree +extract_string_elt (tree string, unsigned chars_per_elt, unsigned index); + +static tree +eval_conditional_expression (const constexpr_ctx *ctx, tree t, bool lval, + bool *non_constant_p, bool *overflow_p, + tree *jump_target); + +static tree +eval_bit_field_ref (const constexpr_ctx *ctx, tree t, bool lval, + bool *non_constant_p, bool *overflow_p); + +static tree +eval_loop_expr (const constexpr_ctx *ctx, tree t, bool *non_constant_p, + bool *overflow_p, tree *jump_target); + +static tree +eval_switch_expr (const constexpr_ctx *ctx, tree t, bool *non_constant_p, + bool *overflow_p, tree *jump_target); + +static tree +eval_unary_expression (const constexpr_ctx *ctx, tree t, bool /*lval*/, + bool *non_constant_p, bool *overflow_p); + +/* Variables and functions to manage constexpr call expansion context. + These do not need to be marked for PCH or GC. */ + +/* FIXME remember and print actual constant arguments. */ +static vec<tree> call_stack; +static int call_stack_tick; +static int last_cx_error_tick; + +static int +push_cx_call_context (tree call) +{ + ++call_stack_tick; + if (!EXPR_HAS_LOCATION (call)) + SET_EXPR_LOCATION (call, input_location); + call_stack.safe_push (call); + int len = call_stack.length (); + if (len > max_constexpr_depth) + return false; + return len; +} + +static void +pop_cx_call_context (void) +{ + ++call_stack_tick; + call_stack.pop (); +} + +vec<tree> +cx_error_context (void) +{ + vec<tree> r = vNULL; + if (call_stack_tick != last_cx_error_tick && !call_stack.is_empty ()) + r = call_stack; + last_cx_error_tick = call_stack_tick; + return r; +} + +// this is ported from cxx_eval_outermost_constant_expr tree fold_expr (tree expr) { + bool allow_non_constant = false; + bool strict = true; + bool manifestly_const_eval = false; + constexpr_global_ctx global_ctx; - constexpr_ctx ctx = {&global_ctx}; + constexpr_ctx ctx + = {&global_ctx, NULL, + NULL, NULL, + NULL, NULL, + NULL, allow_non_constant, + strict, manifestly_const_eval || !allow_non_constant}; - tree folded = constexpr_expression (&ctx, expr); + auto_vec<tree, 16> cleanups; + global_ctx.cleanups = &cleanups; + + bool non_constant_p = false; + bool overflow_p = false; + + tree folded = eval_constant_expression (&ctx, expr, false, &non_constant_p, + &overflow_p); rust_assert (folded != NULL_TREE); + + // more logic here to possibly port return folded; } +static bool +same_type_ignoring_tlq_and_bounds_p (tree type1, tree type2) +{ + while (TREE_CODE (type1) == ARRAY_TYPE && TREE_CODE (type2) == ARRAY_TYPE + && (!TYPE_DOMAIN (type1) || !TYPE_DOMAIN (type2))) + { + type1 = TREE_TYPE (type1); + type2 = TREE_TYPE (type2); + } + return same_type_ignoring_top_level_qualifiers_p (type1, type2); +} + +// forked from gcc/cp/constexpr.cc cxx_union_active_member + +/* Try to determine the currently active union member for an expression + with UNION_TYPE. If it can be determined, return the FIELD_DECL, + otherwise return NULL_TREE. */ + static tree -constexpr_expression (const constexpr_ctx *ctx, tree t) +union_active_member (const constexpr_ctx *ctx, tree t) { + constexpr_ctx new_ctx = *ctx; + new_ctx.quiet = true; + bool non_constant_p = false, overflow_p = false; + tree ctor = eval_constant_expression (&new_ctx, t, false, &non_constant_p, + &overflow_p); + if (TREE_CODE (ctor) == CONSTRUCTOR && CONSTRUCTOR_NELTS (ctor) == 1 + && CONSTRUCTOR_ELT (ctor, 0)->index + && TREE_CODE (CONSTRUCTOR_ELT (ctor, 0)->index) == FIELD_DECL) + return CONSTRUCTOR_ELT (ctor, 0)->index; + return NULL_TREE; +} + +// forked from gcc/cp/constexpr.cc cxx_fold_indirect_ref_1 + +static tree +fold_indirect_ref_1 (const constexpr_ctx *ctx, location_t loc, tree type, + tree op, unsigned HOST_WIDE_INT off, bool *empty_base) +{ + tree optype = TREE_TYPE (op); + unsigned HOST_WIDE_INT const_nunits; + if (off == 0 && similar_type_p (optype, type)) + return op; + else if (TREE_CODE (optype) == COMPLEX_TYPE + && similar_type_p (type, TREE_TYPE (optype))) + { + /* *(foo *)&complexfoo => __real__ complexfoo */ + if (off == 0) + return build1_loc (loc, REALPART_EXPR, type, op); + /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */ + else if (tree_to_uhwi (TYPE_SIZE_UNIT (type)) == off) + return build1_loc (loc, IMAGPART_EXPR, type, op); + } + /* ((foo*)&vectorfoo)[x] => BIT_FIELD_REF<vectorfoo,...> */ + else if (VECTOR_TYPE_P (optype) && similar_type_p (type, TREE_TYPE (optype)) + && TYPE_VECTOR_SUBPARTS (optype).is_constant (&const_nunits)) + { + unsigned HOST_WIDE_INT part_width = tree_to_uhwi (TYPE_SIZE_UNIT (type)); + unsigned HOST_WIDE_INT max_offset = part_width * const_nunits; + if (off < max_offset && off % part_width == 0) + { + tree index = bitsize_int (off * BITS_PER_UNIT); + return build3_loc (loc, BIT_FIELD_REF, type, op, TYPE_SIZE (type), + index); + } + } + /* ((foo *)&fooarray)[x] => fooarray[x] */ + else if (TREE_CODE (optype) == ARRAY_TYPE + && tree_fits_uhwi_p (TYPE_SIZE_UNIT (TREE_TYPE (optype))) + && !integer_zerop (TYPE_SIZE_UNIT (TREE_TYPE (optype)))) + { + tree type_domain = TYPE_DOMAIN (optype); + tree min_val = size_zero_node; + if (type_domain && TYPE_MIN_VALUE (type_domain)) + min_val = TYPE_MIN_VALUE (type_domain); + unsigned HOST_WIDE_INT el_sz + = tree_to_uhwi (TYPE_SIZE_UNIT (TREE_TYPE (optype))); + unsigned HOST_WIDE_INT idx = off / el_sz; + unsigned HOST_WIDE_INT rem = off % el_sz; + if (tree_fits_uhwi_p (min_val)) + { + tree index = size_int (idx + tree_to_uhwi (min_val)); + op = build4_loc (loc, ARRAY_REF, TREE_TYPE (optype), op, index, + NULL_TREE, NULL_TREE); + return fold_indirect_ref_1 (ctx, loc, type, op, rem, empty_base); + } + } + /* ((foo *)&struct_with_foo_field)[x] => COMPONENT_REF */ + else if (TREE_CODE (optype) == RECORD_TYPE + || TREE_CODE (optype) == UNION_TYPE) + { + if (TREE_CODE (optype) == UNION_TYPE) + /* For unions prefer the currently active member. */ + if (tree field = union_active_member (ctx, op)) + { + unsigned HOST_WIDE_INT el_sz + = tree_to_uhwi (TYPE_SIZE_UNIT (TREE_TYPE (field))); + if (off < el_sz) + { + tree cop = build3 (COMPONENT_REF, TREE_TYPE (field), op, field, + NULL_TREE); + if (tree ret = fold_indirect_ref_1 (ctx, loc, type, cop, off, + empty_base)) + return ret; + } + } + for (tree field = TYPE_FIELDS (optype); field; field = DECL_CHAIN (field)) + if (TREE_CODE (field) == FIELD_DECL + && TREE_TYPE (field) != error_mark_node + && tree_fits_uhwi_p (TYPE_SIZE_UNIT (TREE_TYPE (field)))) + { + tree pos = byte_position (field); + if (!tree_fits_uhwi_p (pos)) + continue; + unsigned HOST_WIDE_INT upos = tree_to_uhwi (pos); + unsigned HOST_WIDE_INT el_sz + = tree_to_uhwi (TYPE_SIZE_UNIT (TREE_TYPE (field))); + if (upos <= off && off < upos + el_sz) + { + tree cop = build3 (COMPONENT_REF, TREE_TYPE (field), op, field, + NULL_TREE); + if (tree ret = fold_indirect_ref_1 (ctx, loc, type, cop, + off - upos, empty_base)) + return ret; + } + } + /* Also handle conversion to an empty base class, which + is represented with a NOP_EXPR. */ + if (is_empty_class (type) && CLASS_TYPE_P (optype)) + { + *empty_base = true; + return op; + } + } + + return NULL_TREE; +} + +// forked from gcc/cp/constexpr.cc cxx_fold_indirect_ref + +/* A less strict version of fold_indirect_ref_1, which requires cv-quals to + match. We want to be less strict for simple *& folding; if we have a + non-const temporary that we access through a const pointer, that should + work. We handle this here rather than change fold_indirect_ref_1 + because we're dealing with things like ADDR_EXPR of INTEGER_CST which + don't really make sense outside of constant expression evaluation. Also + we want to allow folding to COMPONENT_REF, which could cause trouble + with TBAA in fold_indirect_ref_1. */ + +static tree +rs_fold_indirect_ref (const constexpr_ctx *ctx, location_t loc, tree type, + tree op0, bool *empty_base) +{ + tree sub = op0; + tree subtype; + poly_uint64 const_op01; + + /* STRIP_NOPS, but stop if REINTERPRET_CAST_P. */ + while (CONVERT_EXPR_P (sub) || TREE_CODE (sub) == NON_LVALUE_EXPR + || TREE_CODE (sub) == VIEW_CONVERT_EXPR) + { + if (TREE_CODE (sub) == NOP_EXPR && REINTERPRET_CAST_P (sub)) + return NULL_TREE; + sub = TREE_OPERAND (sub, 0); + } + + subtype = TREE_TYPE (sub); + if (!INDIRECT_TYPE_P (subtype)) + return NULL_TREE; + + /* Canonicalizes the given OBJ/OFF pair by iteratively absorbing + the innermost component into the offset until it would make the + offset positive, so that cxx_fold_indirect_ref_1 can identify + more folding opportunities. */ + auto canonicalize_obj_off = [] (tree &obj, tree &off) { + while (TREE_CODE (obj) == COMPONENT_REF + && (tree_int_cst_sign_bit (off) || integer_zerop (off))) + { + tree field = TREE_OPERAND (obj, 1); + tree pos = byte_position (field); + if (integer_zerop (off) && integer_nonzerop (pos)) + /* If the offset is already 0, keep going as long as the + component is at position 0. */ + break; + off = int_const_binop (PLUS_EXPR, off, pos); + obj = TREE_OPERAND (obj, 0); + } + }; + + if (TREE_CODE (sub) == ADDR_EXPR) + { + tree op = TREE_OPERAND (sub, 0); + tree optype = TREE_TYPE (op); + + /* *&CONST_DECL -> to the value of the const decl. */ + if (TREE_CODE (op) == CONST_DECL) + return DECL_INITIAL (op); + /* *&p => p; make sure to handle *&"str"[cst] here. */ + if (similar_type_p (optype, type)) + { + tree fop = fold_read_from_constant_string (op); + if (fop) + return fop; + else + return op; + } + else + { + tree off = integer_zero_node; + canonicalize_obj_off (op, off); + gcc_assert (integer_zerop (off)); + return fold_indirect_ref_1 (ctx, loc, type, op, 0, empty_base); + } + } + else if (TREE_CODE (sub) == POINTER_PLUS_EXPR + && tree_fits_uhwi_p (TREE_OPERAND (sub, 1))) + { + tree op00 = TREE_OPERAND (sub, 0); + tree off = TREE_OPERAND (sub, 1); + + STRIP_NOPS (op00); + if (TREE_CODE (op00) == ADDR_EXPR) + { + tree obj = TREE_OPERAND (op00, 0); + canonicalize_obj_off (obj, off); + return fold_indirect_ref_1 (ctx, loc, type, obj, tree_to_uhwi (off), + empty_base); + } + } + /* *(foo *)fooarrptr => (*fooarrptr)[0] */ + else if (TREE_CODE (TREE_TYPE (subtype)) == ARRAY_TYPE + && similar_type_p (type, TREE_TYPE (TREE_TYPE (subtype)))) + { + tree type_domain; + tree min_val = size_zero_node; + tree newsub + = rs_fold_indirect_ref (ctx, loc, TREE_TYPE (subtype), sub, NULL); + if (newsub) + sub = newsub; + else + sub = build1_loc (loc, INDIRECT_REF, TREE_TYPE (subtype), sub); + type_domain = TYPE_DOMAIN (TREE_TYPE (sub)); + if (type_domain && TYPE_MIN_VALUE (type_domain)) + min_val = TYPE_MIN_VALUE (type_domain); + return build4_loc (loc, ARRAY_REF, type, sub, min_val, NULL_TREE, + NULL_TREE); + } + + return NULL_TREE; +} + +// forked from gcc/cp/constexpr.cc cxx_eval_indirect_ref + +static tree +rs_eval_indirect_ref (const constexpr_ctx *ctx, tree t, bool lval, + bool *non_constant_p, bool *overflow_p) +{ + tree orig_op0 = TREE_OPERAND (t, 0); + bool empty_base = false; + + /* We can handle a MEM_REF like an INDIRECT_REF, if MEM_REF's second + operand is an integer-zero. Otherwise reject the MEM_REF for now. */ + + if (TREE_CODE (t) == MEM_REF + && (!TREE_OPERAND (t, 1) || !integer_zerop (TREE_OPERAND (t, 1)))) + { + gcc_assert (ctx->quiet); + *non_constant_p = true; + return t; + } + + /* First try to simplify it directly. */ + tree r = rs_fold_indirect_ref (ctx, EXPR_LOCATION (t), TREE_TYPE (t), + orig_op0, &empty_base); + if (!r) + { + /* If that didn't work, evaluate the operand first. */ + tree op0 + = eval_constant_expression (ctx, orig_op0, + /*lval*/ false, non_constant_p, overflow_p); + /* Don't VERIFY_CONSTANT here. */ + if (*non_constant_p) + return t; + + if (!lval && integer_zerop (op0)) + { + if (!ctx->quiet) + error ("dereferencing a null pointer"); + *non_constant_p = true; + return t; + } + + r = rs_fold_indirect_ref (ctx, EXPR_LOCATION (t), TREE_TYPE (t), op0, + &empty_base); + if (r == NULL_TREE) + { + /* We couldn't fold to a constant value. Make sure it's not + something we should have been able to fold. */ + tree sub = op0; + STRIP_NOPS (sub); + if (TREE_CODE (sub) == ADDR_EXPR) + { + gcc_assert ( + !similar_type_p (TREE_TYPE (TREE_TYPE (sub)), TREE_TYPE (t))); + /* DR 1188 says we don't have to deal with this. */ + if (!ctx->quiet) + error_at (rs_expr_loc_or_input_loc (t), + "accessing value of %qE through a %qT glvalue in a " + "constant expression", + build_fold_indirect_ref (sub), TREE_TYPE (t)); + *non_constant_p = true; + return t; + } + + if (lval && op0 != orig_op0) + return build1 (INDIRECT_REF, TREE_TYPE (t), op0); + if (!lval) + VERIFY_CONSTANT (t); + return t; + } + } + + r = eval_constant_expression (ctx, r, lval, non_constant_p, overflow_p); + if (*non_constant_p) + return t; + + /* If we're pulling out the value of an empty base, just return an empty + CONSTRUCTOR. */ + if (empty_base && !lval) + { + r = build_constructor (TREE_TYPE (t), NULL); + TREE_CONSTANT (r) = true; + } + + return r; +} + +// forked from gcc/cp/constexpr.cc cxx_eval_logical_expression + +/* Subroutine of cxx_eval_constant_expression. + Evaluate a short-circuited logical expression T in the context + of a given constexpr CALL. BAILOUT_VALUE is the value for + early return. CONTINUE_VALUE is used here purely for + sanity check purposes. */ + +static tree +eval_logical_expression (const constexpr_ctx *ctx, tree t, tree bailout_value, + tree continue_value, bool lval, bool *non_constant_p, + bool *overflow_p) +{ + tree r; + tree lhs = eval_constant_expression (ctx, TREE_OPERAND (t, 0), lval, + non_constant_p, overflow_p); + VERIFY_CONSTANT (lhs); + if (tree_int_cst_equal (lhs, bailout_value)) + return lhs; + gcc_assert (tree_int_cst_equal (lhs, continue_value)); + r = eval_constant_expression (ctx, TREE_OPERAND (t, 1), lval, non_constant_p, + overflow_p); + VERIFY_CONSTANT (r); + return r; +} + +// forked from gcc/cp/constexp.rcc lookup_placeholder + +/* Find the object of TYPE under initialization in CTX. */ + +static tree +lookup_placeholder (const constexpr_ctx *ctx, bool lval, tree type) +{ + if (!ctx) + return NULL_TREE; + + /* Prefer the outermost matching object, but don't cross + CONSTRUCTOR_PLACEHOLDER_BOUNDARY constructors. */ + if (ctx->ctor && !CONSTRUCTOR_PLACEHOLDER_BOUNDARY (ctx->ctor)) + if (tree outer_ob = lookup_placeholder (ctx->parent, lval, type)) + return outer_ob; + + /* We could use ctx->object unconditionally, but using ctx->ctor when we + can is a minor optimization. */ + if (!lval && ctx->ctor && same_type_p (TREE_TYPE (ctx->ctor), type)) + return ctx->ctor; + + if (!ctx->object) + return NULL_TREE; + + /* Since an object cannot have a field of its own type, we can search outward + from ctx->object to find the unique containing object of TYPE. */ + tree ob = ctx->object; + while (ob) + { + if (same_type_ignoring_top_level_qualifiers_p (TREE_TYPE (ob), type)) + break; + if (handled_component_p (ob)) + ob = TREE_OPERAND (ob, 0); + else + ob = NULL_TREE; + } + + return ob; +} + +// forked from gcc/cp/constexp.rcc inline_asm_in_constexpr_error + +/* Complain about an attempt to evaluate inline assembly. */ + +static void +inline_asm_in_constexpr_error (location_t loc) +{ + auto_diagnostic_group d; + error_at (loc, "inline assembly is not a constant expression"); + inform (loc, "only unevaluated inline assembly is allowed in a " + "%<constexpr%> function in C++20"); +} + +// forked from gcc/cp/constexpr.cc verify_ctor_sanity + +/* We're about to process an initializer for a class or array TYPE. Make + sure that CTX is set up appropriately. */ + +static void +verify_ctor_sanity (const constexpr_ctx *ctx, tree type) +{ + /* We don't bother building a ctor for an empty base subobject. */ + if (is_empty_class (type)) + return; + + /* We're in the middle of an initializer that might involve placeholders; + our caller should have created a CONSTRUCTOR for us to put the + initializer into. We will either return that constructor or T. */ + gcc_assert (ctx->ctor); + gcc_assert ( + same_type_ignoring_top_level_qualifiers_p (type, TREE_TYPE (ctx->ctor))); + /* We used to check that ctx->ctor was empty, but that isn't the case when + the object is zero-initialized before calling the constructor. */ + if (ctx->object) + { + tree otype = TREE_TYPE (ctx->object); + gcc_assert (same_type_ignoring_top_level_qualifiers_p (type, otype) + /* Handle flexible array members. */ + || (TREE_CODE (otype) == ARRAY_TYPE + && TYPE_DOMAIN (otype) == NULL_TREE + && TREE_CODE (type) == ARRAY_TYPE + && (same_type_ignoring_top_level_qualifiers_p ( + TREE_TYPE (type), TREE_TYPE (otype))))); + } + gcc_assert (!ctx->object || !DECL_P (ctx->object) + || *(ctx->global->values.get (ctx->object)) == ctx->ctor); +} + +// forked from gcc/cp/constexpr.cc array_index_cmp + +/* Some of the expressions fed to the constexpr mechanism are calls to + constructors, which have type void. In that case, return the type being + initialized by the constructor. */ + +static tree +initialized_type (tree t) +{ + if (TYPE_P (t)) + return t; + tree type = TREE_TYPE (t); + if (TREE_CODE (t) == CALL_EXPR) + { + /* A constructor call has void type, so we need to look deeper. */ + tree fn = get_function_named_in_call (t); + if (fn && TREE_CODE (fn) == FUNCTION_DECL && DECL_CXX_CONSTRUCTOR_P (fn)) + type = DECL_CONTEXT (fn); + } + else if (TREE_CODE (t) == COMPOUND_EXPR) + return initialized_type (TREE_OPERAND (t, 1)); + + return cv_unqualified (type); +} + +// forked from gcc/cp/constexpr.cc init_subob_ctx + +/* We're about to initialize element INDEX of an array or class from VALUE. + Set up NEW_CTX appropriately by adjusting .object to refer to the + subobject and creating a new CONSTRUCTOR if the element is itself + a class or array. */ + +static void +init_subob_ctx (const constexpr_ctx *ctx, constexpr_ctx &new_ctx, tree index, + tree &value) +{ + new_ctx = *ctx; + + if (index && TREE_CODE (index) != INTEGER_CST + && TREE_CODE (index) != FIELD_DECL && TREE_CODE (index) != RANGE_EXPR) + /* This won't have an element in the new CONSTRUCTOR. */ + return; + + tree type = initialized_type (value); + if (!AGGREGATE_TYPE_P (type) && !VECTOR_TYPE_P (type)) + /* A non-aggregate member doesn't get its own CONSTRUCTOR. */ + return; + + /* The sub-aggregate initializer might contain a placeholder; + update object to refer to the subobject and ctor to refer to + the (newly created) sub-initializer. */ + if (ctx->object) + { + if (index == NULL_TREE || TREE_CODE (index) == RANGE_EXPR) + /* There's no well-defined subobject for this index. */ + new_ctx.object = NULL_TREE; + else + { + // Faisal: commenting this out as not sure if it's needed and it's + // huge new_ctx.object = build_ctor_subob_ref (index, type, + // ctx->object); + } + } + tree elt = build_constructor (type, NULL); + CONSTRUCTOR_NO_CLEARING (elt) = true; + new_ctx.ctor = elt; + + if (TREE_CODE (value) == TARGET_EXPR) + /* Avoid creating another CONSTRUCTOR when we expand the TARGET_EXPR. */ + value = TARGET_EXPR_INITIAL (value); +} + +// forked from gcc/cp/constexpr.cc base_field_constructor_elt + +/* REF is a COMPONENT_REF designating a particular field. V is a vector of + CONSTRUCTOR elements to initialize (part of) an object containing that + field. Return a pointer to the constructor_elt corresponding to the + initialization of the field. */ + +static constructor_elt * +base_field_constructor_elt (vec<constructor_elt, va_gc> *v, tree ref) +{ + tree aggr = TREE_OPERAND (ref, 0); + tree field = TREE_OPERAND (ref, 1); + HOST_WIDE_INT i; + constructor_elt *ce; + + gcc_assert (TREE_CODE (ref) == COMPONENT_REF); + + if (TREE_CODE (aggr) == COMPONENT_REF) + { + constructor_elt *base_ce = base_field_constructor_elt (v, aggr); + v = CONSTRUCTOR_ELTS (base_ce->value); + } + + for (i = 0; vec_safe_iterate (v, i, &ce); ++i) + if (ce->index == field) + return ce; + + gcc_unreachable (); + return NULL; +} + +/* Return a pointer to the constructor_elt of CTOR which matches INDEX. If no + matching constructor_elt exists, then add one to CTOR. + + As an optimization, if POS_HINT is non-negative then it is used as a guess + for the (integer) index of the matching constructor_elt within CTOR. */ + +static constructor_elt * +get_or_insert_ctor_field (tree ctor, tree index, int pos_hint = -1) +{ + /* Check the hint first. */ + if (pos_hint >= 0 && (unsigned) pos_hint < CONSTRUCTOR_NELTS (ctor) + && CONSTRUCTOR_ELT (ctor, pos_hint)->index == index) + return CONSTRUCTOR_ELT (ctor, pos_hint); + + tree type = TREE_TYPE (ctor); + if (TREE_CODE (type) == VECTOR_TYPE && index == NULL_TREE) + { + CONSTRUCTOR_APPEND_ELT (CONSTRUCTOR_ELTS (ctor), index, NULL_TREE); + return &CONSTRUCTOR_ELTS (ctor)->last (); + } + else if (TREE_CODE (type) == ARRAY_TYPE || TREE_CODE (type) == VECTOR_TYPE) + { + if (TREE_CODE (index) == RANGE_EXPR) + { + /* Support for RANGE_EXPR index lookups is currently limited to + accessing an existing element via POS_HINT, or appending a new + element to the end of CTOR. ??? Support for other access + patterns may also be needed. */ + vec<constructor_elt, va_gc> *elts = CONSTRUCTOR_ELTS (ctor); + if (vec_safe_length (elts)) + { + tree lo = TREE_OPERAND (index, 0); + gcc_assert (array_index_cmp (elts->last ().index, lo) < 0); + } + CONSTRUCTOR_APPEND_ELT (elts, index, NULL_TREE); + return &elts->last (); + } + + HOST_WIDE_INT i = find_array_ctor_elt (ctor, index, /*insert*/ true); + gcc_assert (i >= 0); + constructor_elt *cep = CONSTRUCTOR_ELT (ctor, i); + gcc_assert (cep->index == NULL_TREE + || TREE_CODE (cep->index) != RANGE_EXPR); + return cep; + } + else + { + gcc_assert ( + TREE_CODE (index) == FIELD_DECL + && (same_type_ignoring_top_level_qualifiers_p (DECL_CONTEXT (index), + TREE_TYPE (ctor)))); + + /* We must keep the CONSTRUCTOR's ELTS in FIELD order. + Usually we meet initializers in that order, but it is + possible for base types to be placed not in program + order. */ + tree fields = TYPE_FIELDS (DECL_CONTEXT (index)); + unsigned HOST_WIDE_INT idx = 0; + constructor_elt *cep = NULL; + + /* Check if we're changing the active member of a union. */ + if (TREE_CODE (type) == UNION_TYPE && CONSTRUCTOR_NELTS (ctor) + && CONSTRUCTOR_ELT (ctor, 0)->index != index) + vec_safe_truncate (CONSTRUCTOR_ELTS (ctor), 0); + /* If the bit offset of INDEX is larger than that of the last + constructor_elt, then we can just immediately append a new + constructor_elt to the end of CTOR. */ + else if (CONSTRUCTOR_NELTS (ctor) + && tree_int_cst_compare ( + bit_position (index), + bit_position (CONSTRUCTOR_ELTS (ctor)->last ().index)) + > 0) + { + idx = CONSTRUCTOR_NELTS (ctor); + goto insert; + } + + /* Otherwise, we need to iterate over CTOR to find or insert INDEX + appropriately. */ + + for (; vec_safe_iterate (CONSTRUCTOR_ELTS (ctor), idx, &cep); + idx++, fields = DECL_CHAIN (fields)) + { + if (index == cep->index) + goto found; + + /* The field we're initializing must be on the field + list. Look to see if it is present before the + field the current ELT initializes. */ + for (; fields != cep->index; fields = DECL_CHAIN (fields)) + if (index == fields) + goto insert; + } + /* We fell off the end of the CONSTRUCTOR, so insert a new + entry at the end. */ + + insert : { + constructor_elt ce = {index, NULL_TREE}; + + vec_safe_insert (CONSTRUCTOR_ELTS (ctor), idx, ce); + cep = CONSTRUCTOR_ELT (ctor, idx); + } + found:; + + return cep; + } +} + +// forked from gcc/cp/constexpr.cc cxx_eval_vector_conditional_expression + +/* Subroutine of cxx_eval_constant_expression. + Attempt to evaluate vector condition expressions. Unlike + cxx_eval_conditional_expression, VEC_COND_EXPR acts like a normal + ternary arithmetics operation, where all 3 arguments have to be + evaluated as constants and then folding computes the result from + them. */ + +static tree +eval_vector_conditional_expression (const constexpr_ctx *ctx, tree t, + bool *non_constant_p, bool *overflow_p) +{ + tree arg1 + = eval_constant_expression (ctx, TREE_OPERAND (t, 0), + /*lval*/ false, non_constant_p, overflow_p); + VERIFY_CONSTANT (arg1); + tree arg2 + = eval_constant_expression (ctx, TREE_OPERAND (t, 1), + /*lval*/ false, non_constant_p, overflow_p); + VERIFY_CONSTANT (arg2); + tree arg3 + = eval_constant_expression (ctx, TREE_OPERAND (t, 2), + /*lval*/ false, non_constant_p, overflow_p); + VERIFY_CONSTANT (arg3); + location_t loc = EXPR_LOCATION (t); + tree type = TREE_TYPE (t); + tree r = fold_ternary_loc (loc, VEC_COND_EXPR, type, arg1, arg2, arg3); + if (r == NULL_TREE) + { + if (arg1 == TREE_OPERAND (t, 0) && arg2 == TREE_OPERAND (t, 1) + && arg3 == TREE_OPERAND (t, 2)) + r = t; + else + r = build3_loc (loc, VEC_COND_EXPR, type, arg1, arg2, arg3); + } + VERIFY_CONSTANT (r); + return r; +} + +// forked from gcc/cp/constexpr.cc cxx_eval_bare_aggregate + +/* Subroutine of cxx_eval_constant_expression. + The expression tree T denotes a C-style array or a C-style + aggregate. Reduce it to a constant expression. */ + +static tree +eval_bare_aggregate (const constexpr_ctx *ctx, tree t, bool lval, + bool *non_constant_p, bool *overflow_p) +{ + vec<constructor_elt, va_gc> *v = CONSTRUCTOR_ELTS (t); + bool changed = false; + gcc_assert (!BRACE_ENCLOSED_INITIALIZER_P (t)); + tree type = TREE_TYPE (t); + + constexpr_ctx new_ctx; + if (TYPE_PTRMEMFUNC_P (type) || VECTOR_TYPE_P (type)) + { + /* We don't really need the ctx->ctor business for a PMF or + vector, but it's simpler to use the same code. */ + new_ctx = *ctx; + new_ctx.ctor = build_constructor (type, NULL); + new_ctx.object = NULL_TREE; + ctx = &new_ctx; + }; + verify_ctor_sanity (ctx, type); + vec<constructor_elt, va_gc> **p = &CONSTRUCTOR_ELTS (ctx->ctor); + vec_alloc (*p, vec_safe_length (v)); + + if (CONSTRUCTOR_PLACEHOLDER_BOUNDARY (t)) + CONSTRUCTOR_PLACEHOLDER_BOUNDARY (ctx->ctor) = 1; + + unsigned i; + tree index, value; + bool constant_p = true; + bool side_effects_p = false; + FOR_EACH_CONSTRUCTOR_ELT (v, i, index, value) + { + tree orig_value = value; + /* Like in cxx_eval_store_expression, omit entries for empty fields. */ + bool no_slot = TREE_CODE (type) == RECORD_TYPE && is_empty_field (index); + if (no_slot) + new_ctx = *ctx; + else + init_subob_ctx (ctx, new_ctx, index, value); + int pos_hint = -1; + if (new_ctx.ctor != ctx->ctor) + { + /* If we built a new CONSTRUCTOR, attach it now so that other + initializers can refer to it. */ + constructor_elt *cep = get_or_insert_ctor_field (ctx->ctor, index); + cep->value = new_ctx.ctor; + pos_hint = cep - (*p)->begin (); + } + else if (TREE_CODE (type) == UNION_TYPE) + /* Otherwise if we're constructing a non-aggregate union member, set + the active union member now so that we can later detect and diagnose + if its initializer attempts to activate another member. */ + get_or_insert_ctor_field (ctx->ctor, index); + tree elt = eval_constant_expression (&new_ctx, value, lval, + non_constant_p, overflow_p); + /* Don't VERIFY_CONSTANT here. */ + if (ctx->quiet && *non_constant_p) + break; + if (elt != orig_value) + changed = true; + + if (!TREE_CONSTANT (elt)) + constant_p = false; + if (TREE_SIDE_EFFECTS (elt)) + side_effects_p = true; + if (index && TREE_CODE (index) == COMPONENT_REF) + { + /* This is an initialization of a vfield inside a base + subaggregate that we already initialized; push this + initialization into the previous initialization. */ + constructor_elt *inner = base_field_constructor_elt (*p, index); + inner->value = elt; + changed = true; + } + else if (index + && (TREE_CODE (index) == NOP_EXPR + || TREE_CODE (index) == POINTER_PLUS_EXPR)) + { + /* This is an initializer for an empty base; now that we've + checked that it's constant, we can ignore it. */ + gcc_assert (is_empty_class (TREE_TYPE (TREE_TYPE (index)))); + changed = true; + } + else if (no_slot) + changed = true; + else + { + if (TREE_CODE (type) == UNION_TYPE && (*p)->last ().index != index) + /* The initializer erroneously changed the active union member that + we're initializing. */ + gcc_assert (*non_constant_p); + else + { + /* The initializer might have mutated the underlying CONSTRUCTOR, + so recompute the location of the target constructer_elt. */ + constructor_elt *cep + = get_or_insert_ctor_field (ctx->ctor, index, pos_hint); + cep->value = elt; + } + + /* Adding or replacing an element might change the ctor's flags. */ + TREE_CONSTANT (ctx->ctor) = constant_p; + TREE_SIDE_EFFECTS (ctx->ctor) = side_effects_p; + } + } + if (*non_constant_p || !changed) + return t; + t = ctx->ctor; + /* We're done building this CONSTRUCTOR, so now we can interpret an + element without an explicit initializer as value-initialized. */ + CONSTRUCTOR_NO_CLEARING (t) = false; + TREE_CONSTANT (t) = constant_p; + TREE_SIDE_EFFECTS (t) = side_effects_p; + if (VECTOR_TYPE_P (type)) + t = fold (t); + return t; +} + +/* Subroutine of cxx_eval_constant_expression. + Like cxx_eval_unary_expression, except for trinary expressions. */ + +static tree +cxx_eval_trinary_expression (const constexpr_ctx *ctx, tree t, bool lval, + bool *non_constant_p, bool *overflow_p) +{ + int i; + tree args[3]; + tree val; + + for (i = 0; i < 3; i++) + { + args[i] = eval_constant_expression (ctx, TREE_OPERAND (t, i), lval, + non_constant_p, overflow_p); + VERIFY_CONSTANT (args[i]); + } + + val = fold_ternary_loc (EXPR_LOCATION (t), TREE_CODE (t), TREE_TYPE (t), + args[0], args[1], args[2]); + if (val == NULL_TREE) + return t; + VERIFY_CONSTANT (val); + return val; +} + +/* Return true if T is a valid constant initializer. If a CONSTRUCTOR + initializes all the members, the CONSTRUCTOR_NO_CLEARING flag will be + cleared. + FIXME speed this up, it's taking 16% of compile time on sieve testcase. */ + +bool +reduced_constant_expression_p (tree t) +{ + if (t == NULL_TREE) + return false; + + switch (TREE_CODE (t)) + { + case PTRMEM_CST: + /* Even if we can't lower this yet, it's constant. */ + return true; + + case CONSTRUCTOR: + /* And we need to handle PTRMEM_CST wrapped in a CONSTRUCTOR. */ + tree field; + if (CONSTRUCTOR_NO_CLEARING (t)) + { + if (TREE_CODE (TREE_TYPE (t)) == VECTOR_TYPE) + /* An initialized vector would have a VECTOR_CST. */ + return false; + else if (TREE_CODE (TREE_TYPE (t)) == ARRAY_TYPE) + { + /* There must be a valid constant initializer at every array + index. */ + tree min = TYPE_MIN_VALUE (TYPE_DOMAIN (TREE_TYPE (t))); + tree max = TYPE_MAX_VALUE (TYPE_DOMAIN (TREE_TYPE (t))); + tree cursor = min; + for (auto &e : CONSTRUCTOR_ELTS (t)) + { + if (!reduced_constant_expression_p (e.value)) + return false; + if (array_index_cmp (cursor, e.index) != 0) + return false; + if (TREE_CODE (e.index) == RANGE_EXPR) + cursor = TREE_OPERAND (e.index, 1); + cursor = int_const_binop (PLUS_EXPR, cursor, size_one_node); + } + if (find_array_ctor_elt (t, max) == -1) + return false; + goto ok; + } + else if (TREE_CODE (TREE_TYPE (t)) == UNION_TYPE) + { + if (CONSTRUCTOR_NELTS (t) == 0) + /* An initialized union has a constructor element. */ + return false; + /* And it only initializes one member. */ + field = NULL_TREE; + } + else + field = next_initializable_field (TYPE_FIELDS (TREE_TYPE (t))); + } + else + field = NULL_TREE; + for (auto &e : CONSTRUCTOR_ELTS (t)) + { + /* If VAL is null, we're in the middle of initializing this + element. */ + if (!reduced_constant_expression_p (e.value)) + return false; + /* Empty class field may or may not have an initializer. */ + for (; field && e.index != field; + field = next_initializable_field (DECL_CHAIN (field))) + if (!is_really_empty_class (TREE_TYPE (field), + /*ignore_vptr*/ false)) + return false; + if (field) + field = next_initializable_field (DECL_CHAIN (field)); + } + /* There could be a non-empty field at the end. */ + for (; field; field = next_initializable_field (DECL_CHAIN (field))) + if (!is_really_empty_class (TREE_TYPE (field), /*ignore_vptr*/ false)) + return false; + ok: + if (CONSTRUCTOR_NO_CLEARING (t)) + /* All the fields are initialized. */ + CONSTRUCTOR_NO_CLEARING (t) = false; + return true; + + default: + /* FIXME are we calling this too much? */ + return initializer_constant_valid_p (t, TREE_TYPE (t)) != NULL_TREE; + } +} + +/* TEMP is the constant value of a temporary object of type TYPE. Adjust + the type of the value to match. */ + +static tree +adjust_temp_type (tree type, tree temp) +{ + if (same_type_p (TREE_TYPE (temp), type)) + return temp; + + gcc_assert (scalarish_type_p (type)); + /* Now we know we're dealing with a scalar, and a prvalue of non-class + type is cv-unqualified. */ + return fold_convert (cv_unqualified (type), temp); +} + +// forked from gcc/cp/constexpr.cc free_constructor + +/* If T is a CONSTRUCTOR, ggc_free T and any sub-CONSTRUCTORs. */ + +static void +free_constructor (tree t) +{ + if (!t || TREE_CODE (t) != CONSTRUCTOR) + return; + releasing_vec ctors; + vec_safe_push (ctors, t); + while (!ctors->is_empty ()) + { + tree c = ctors->pop (); + if (vec<constructor_elt, va_gc> *elts = CONSTRUCTOR_ELTS (c)) + { + constructor_elt *ce; + for (HOST_WIDE_INT i = 0; vec_safe_iterate (elts, i, &ce); ++i) + if (TREE_CODE (ce->value) == CONSTRUCTOR) + vec_safe_push (ctors, ce->value); + ggc_free (elts); + } + ggc_free (c); + } +} + +static tree +eval_and_check_array_index (const constexpr_ctx *ctx, tree t, + bool allow_one_past, bool *non_constant_p, + bool *overflow_p); + +// forked from gcc/cp/constexpr.cc cxx_eval_array_reference + +/* Subroutine of cxx_eval_constant_expression. + Attempt to reduce a reference to an array slot. */ + +static tree +eval_array_reference (const constexpr_ctx *ctx, tree t, bool lval, + bool *non_constant_p, bool *overflow_p) +{ + tree oldary = TREE_OPERAND (t, 0); + tree ary + = eval_constant_expression (ctx, oldary, lval, non_constant_p, overflow_p); + if (*non_constant_p) + return t; + if (!lval && TREE_CODE (ary) == VIEW_CONVERT_EXPR + && VECTOR_TYPE_P (TREE_TYPE (TREE_OPERAND (ary, 0))) + && TREE_TYPE (t) == TREE_TYPE (TREE_TYPE (TREE_OPERAND (ary, 0)))) + ary = TREE_OPERAND (ary, 0); + + tree oldidx = TREE_OPERAND (t, 1); + tree index + = eval_and_check_array_index (ctx, t, lval, non_constant_p, overflow_p); + if (*non_constant_p) + return t; + + if (lval && ary == oldary && index == oldidx) + return t; + else if (lval) + return build4 (ARRAY_REF, TREE_TYPE (t), ary, index, NULL, NULL); + + unsigned len = 0, elem_nchars = 1; + tree elem_type = TREE_TYPE (TREE_TYPE (ary)); + if (TREE_CODE (ary) == CONSTRUCTOR) + len = CONSTRUCTOR_NELTS (ary); + else if (TREE_CODE (ary) == STRING_CST) + { + elem_nchars + = (TYPE_PRECISION (elem_type) / TYPE_PRECISION (char_type_node)); + len = (unsigned) TREE_STRING_LENGTH (ary) / elem_nchars; + } + else if (TREE_CODE (ary) == VECTOR_CST) + /* We don't create variable-length VECTOR_CSTs. */ + len = VECTOR_CST_NELTS (ary).to_constant (); + else + { + /* We can't do anything with other tree codes, so use + VERIFY_CONSTANT to complain and fail. */ + VERIFY_CONSTANT (ary); + gcc_unreachable (); + } + + bool found; + HOST_WIDE_INT i = 0; + if (TREE_CODE (ary) == CONSTRUCTOR) + { + HOST_WIDE_INT ix = find_array_ctor_elt (ary, index); + found = (ix >= 0); + if (found) + i = ix; + } + else + { + i = tree_to_shwi (index); + found = (i < len); + } + + if (found) + { + tree r; + if (TREE_CODE (ary) == CONSTRUCTOR) + r = (*CONSTRUCTOR_ELTS (ary))[i].value; + else if (TREE_CODE (ary) == VECTOR_CST) + r = VECTOR_CST_ELT (ary, i); + else + r = extract_string_elt (ary, elem_nchars, i); + + if (r) + /* Don't VERIFY_CONSTANT here. */ + return r; + + /* Otherwise the element doesn't have a value yet. */ + } + + /* Not found. */ + + if (TREE_CODE (ary) == CONSTRUCTOR && CONSTRUCTOR_NO_CLEARING (ary)) + { + /* 'ary' is part of the aggregate initializer we're currently + building; if there's no initializer for this element yet, + that's an error. */ + if (!ctx->quiet) + error ("accessing uninitialized array element"); + *non_constant_p = true; + return t; + } + + /* If it's within the array bounds but doesn't have an explicit + initializer, it's initialized from {}. But use build_value_init + directly for non-aggregates to avoid creating a garbage CONSTRUCTOR. */ + tree val = NULL_TREE; + sorry ("array size expression is not supported yet."); + + constexpr_ctx new_ctx; + if (is_really_empty_class (elem_type, /*ignore_vptr*/ false)) + return build_constructor (elem_type, NULL); + // else if (CP_AGGREGATE_TYPE_P (elem_type)) + // { + // tree empty_ctor = build_constructor (init_list_type_node, NULL); + // //val = digest_init (elem_type, empty_ctor, tf_warning_or_error); + // } + // else + // val = build_value_init (elem_type, tf_warning_or_error); + + if (!SCALAR_TYPE_P (elem_type)) + { + new_ctx = *ctx; + if (ctx->object) + /* If there was no object, don't add one: it could confuse us + into thinking we're modifying a const object. */ + new_ctx.object = t; + new_ctx.ctor = build_constructor (elem_type, NULL); + ctx = &new_ctx; + } + t = eval_constant_expression (ctx, val, lval, non_constant_p, overflow_p); + if (!SCALAR_TYPE_P (elem_type) && t != ctx->ctor) + free_constructor (ctx->ctor); + return t; +} + +// forked from gcc/cp/constexpr.cc cxx_eval_component_reference + +/* Subroutine of cxx_eval_constant_expression. + Attempt to reduce a field access of a value of class type. */ + +static tree +eval_component_reference (const constexpr_ctx *ctx, tree t, bool lval, + bool *non_constant_p, bool *overflow_p) +{ + unsigned HOST_WIDE_INT i; + tree field; + tree value; + tree part = TREE_OPERAND (t, 1); + tree orig_whole = TREE_OPERAND (t, 0); + tree whole = eval_constant_expression (ctx, orig_whole, lval, non_constant_p, + overflow_p); + if (INDIRECT_REF_P (whole) && integer_zerop (TREE_OPERAND (whole, 0))) + { + if (!ctx->quiet) + error ("dereferencing a null pointer in %qE", orig_whole); + *non_constant_p = true; + return t; + } + + if (whole == orig_whole) + return t; + if (lval) + return fold_build3 (COMPONENT_REF, TREE_TYPE (t), whole, part, NULL_TREE); + /* Don't VERIFY_CONSTANT here; we only want to check that we got a + CONSTRUCTOR. */ + if (!*non_constant_p && TREE_CODE (whole) != CONSTRUCTOR) + { + if (!ctx->quiet) + error ("%qE is not a constant expression", orig_whole); + *non_constant_p = true; + } + if (DECL_MUTABLE_P (part)) + { + if (!ctx->quiet) + error ("mutable %qD is not usable in a constant expression", part); + *non_constant_p = true; + } + if (*non_constant_p) + return t; + bool pmf = TYPE_PTRMEMFUNC_P (TREE_TYPE (whole)); + FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (whole), i, field, value) + { + /* Use name match for PMF fields, as a variant will have a + different FIELD_DECL with a different type. */ + if (pmf ? DECL_NAME (field) == DECL_NAME (part) : field == part) + { + if (value) + { + STRIP_ANY_LOCATION_WRAPPER (value); + return value; + } + else + /* We're in the middle of initializing it. */ + break; + } + } + if (TREE_CODE (TREE_TYPE (whole)) == UNION_TYPE + && CONSTRUCTOR_NELTS (whole) > 0) + { + /* DR 1188 says we don't have to deal with this. */ + if (!ctx->quiet) + { + constructor_elt *cep = CONSTRUCTOR_ELT (whole, 0); + if (cep->value == NULL_TREE) + error ("accessing uninitialized member %qD", part); + else + error ("accessing %qD member instead of initialized %qD member in " + "constant expression", + part, cep->index); + } + *non_constant_p = true; + return t; + } + + /* We only create a CONSTRUCTOR for a subobject when we modify it, so empty + classes never get represented; throw together a value now. */ + if (is_really_empty_class (TREE_TYPE (t), /*ignore_vptr*/ false)) + return build_constructor (TREE_TYPE (t), NULL); + + gcc_assert (DECL_CONTEXT (part) == TYPE_MAIN_VARIANT (TREE_TYPE (whole))); + + if (CONSTRUCTOR_NO_CLEARING (whole)) + { + /* 'whole' is part of the aggregate initializer we're currently + building; if there's no initializer for this member yet, that's an + error. */ + if (!ctx->quiet) + error ("accessing uninitialized member %qD", part); + *non_constant_p = true; + return t; + } + + value = NULL_TREE; + sorry ("constant folding not supported for this tree code"); + /* If there's no explicit init for this field, it's value-initialized. */ + // Faisal: commenting this out as not sure if we need this but we need to come + // back to handle this to assign suitable value to value before sending it in + // eval_constant_expression below + // value = build_value_init (TREE_TYPE (t), tf_warning_or_error); + return eval_constant_expression (ctx, value, lval, non_constant_p, + overflow_p); +} + +/* Subroutine of cxx_eval_statement_list. Determine whether the statement + STMT matches *jump_target. If we're looking for a case label and we see + the default label, note it in ctx->css_state. */ + +static bool +label_matches (const constexpr_ctx *ctx, tree *jump_target, tree stmt) +{ + switch (TREE_CODE (*jump_target)) + { + case LABEL_DECL: + if (TREE_CODE (stmt) == LABEL_EXPR + && LABEL_EXPR_LABEL (stmt) == *jump_target) + return true; + break; + + case INTEGER_CST: + if (TREE_CODE (stmt) == CASE_LABEL_EXPR) + { + gcc_assert (ctx->css_state != NULL); + if (!CASE_LOW (stmt)) + { + /* default: should appear just once in a SWITCH_EXPR + body (excluding nested SWITCH_EXPR). */ + gcc_assert (*ctx->css_state != css_default_seen); + /* When evaluating SWITCH_EXPR body for the second time, + return true for the default: label. */ + if (*ctx->css_state == css_default_processing) + return true; + *ctx->css_state = css_default_seen; + } + else if (CASE_HIGH (stmt)) + { + if (tree_int_cst_le (CASE_LOW (stmt), *jump_target) + && tree_int_cst_le (*jump_target, CASE_HIGH (stmt))) + return true; + } + else if (tree_int_cst_equal (*jump_target, CASE_LOW (stmt))) + return true; + } + break; + + case BREAK_STMT: + case CONTINUE_STMT: + /* These two are handled directly in cxx_eval_loop_expr by testing + breaks (jump_target) or continues (jump_target). */ + break; + + default: + gcc_unreachable (); + } + return false; +} + +static tree +eval_constant_expression (const constexpr_ctx *ctx, tree t, bool lval, + bool *non_constant_p, bool *overflow_p, + tree *jump_target /* = NULL */) +{ + if (jump_target && *jump_target) + { + /* If we are jumping, ignore all statements/expressions except those + that could have LABEL_EXPR or CASE_LABEL_EXPR in their bodies. */ + switch (TREE_CODE (t)) + { + case BIND_EXPR: + case STATEMENT_LIST: + case LOOP_EXPR: + case COND_EXPR: + case IF_STMT: + case DO_STMT: + case WHILE_STMT: + case FOR_STMT: + break; + case LABEL_EXPR: + case CASE_LABEL_EXPR: + if (label_matches (ctx, jump_target, t)) + /* Found it. */ + *jump_target = NULL_TREE; + return NULL_TREE; + default: + return NULL_TREE; + } + } + if (error_operand_p (t)) + { + *non_constant_p = true; + return t; + } + location_t loc = EXPR_LOCATION (t); if (CONSTANT_CLASS_P (t)) @@ -107,11 +1923,33 @@ constexpr_expression (const constexpr_ctx *ctx, tree t) return t; } + constexpr_ctx new_ctx; tree r = t; tree_code tcode = TREE_CODE (t); switch (tcode) { + case VAR_DECL: + if (DECL_HAS_VALUE_EXPR_P (t)) + { + r = DECL_VALUE_EXPR (t); + return eval_constant_expression (ctx, r, lval, non_constant_p, + overflow_p); + } + /* fall through */ case CONST_DECL: { + /* We used to not check lval for CONST_DECL, but darwin.cc uses + CONST_DECL for aggregate constants. */ + if (lval) + return t; + else if (t == ctx->object) + return ctx->ctor; + if (VAR_P (t)) + if (tree *p = ctx->global->values.get (t)) + if (*p != NULL_TREE) + { + r = *p; + break; + } r = decl_constant_value (t, /*unshare_p=*/false); if (TREE_CODE (r) == TARGET_EXPR && TREE_CODE (TARGET_EXPR_INITIAL (r)) == CONSTRUCTOR) @@ -124,6 +1962,28 @@ constexpr_expression (const constexpr_ctx *ctx, tree t) } break; + case PARM_DECL: + if (lval && !TYPE_REF_P (TREE_TYPE (t))) + /* glvalue use. */; + else if (tree *p = ctx->global->values.get (r)) + r = *p; + else if (lval) + /* Defer in case this is only used for its type. */; + else if (COMPLETE_TYPE_P (TREE_TYPE (t)) + && is_really_empty_class (TREE_TYPE (t), /*ignore_vptr*/ false)) + { + /* If the class is empty, we aren't actually loading anything. */ + r = build_constructor (TREE_TYPE (t), NULL); + TREE_CONSTANT (r) = true; + } + else + { + if (!ctx->quiet) + error ("%qE is not a constant expression", t); + *non_constant_p = true; + } + break; + case POINTER_PLUS_EXPR: case POINTER_DIFF_EXPR: case PLUS_EXPR: @@ -165,22 +2025,577 @@ constexpr_expression (const constexpr_ctx *ctx, tree t) case LTGT_EXPR: case RANGE_EXPR: case COMPLEX_EXPR: - r = eval_binary_expression (ctx, t); + r = eval_binary_expression (ctx, t, lval, non_constant_p, overflow_p); + break; + + /* fold can introduce non-IF versions of these; still treat them as + short-circuiting. */ + case TRUTH_AND_EXPR: + case TRUTH_ANDIF_EXPR: + r = eval_logical_expression (ctx, t, boolean_false_node, + boolean_true_node, lval, non_constant_p, + overflow_p); + break; + + case TRUTH_OR_EXPR: + case TRUTH_ORIF_EXPR: + r = eval_logical_expression (ctx, t, boolean_true_node, + boolean_false_node, lval, non_constant_p, + overflow_p); + break; + + case TARGET_EXPR: { + tree type = TREE_TYPE (t); + + if (!literal_type_p (type)) + { + if (!ctx->quiet) + { + auto_diagnostic_group d; + error ("temporary of non-literal type %qT in a " + "constant expression", + type); + explain_non_literal_class (type); + } + *non_constant_p = true; + break; + } + gcc_checking_assert (!TARGET_EXPR_DIRECT_INIT_P (t)); + /* Avoid evaluating a TARGET_EXPR more than once. */ + tree slot = TARGET_EXPR_SLOT (t); + if (tree *p = ctx->global->values.get (slot)) + { + if (lval) + return slot; + r = *p; + break; + } + if ((AGGREGATE_TYPE_P (type) || VECTOR_TYPE_P (type))) + { + /* We're being expanded without an explicit target, so start + initializing a new object; expansion with an explicit target + strips the TARGET_EXPR before we get here. */ + new_ctx = *ctx; + /* Link CTX to NEW_CTX so that lookup_placeholder can resolve + any PLACEHOLDER_EXPR within the initializer that refers to the + former object under construction. */ + new_ctx.parent = ctx; + new_ctx.ctor = build_constructor (type, NULL); + CONSTRUCTOR_NO_CLEARING (new_ctx.ctor) = true; + new_ctx.object = slot; + ctx->global->values.put (new_ctx.object, new_ctx.ctor); + ctx = &new_ctx; + } + /* Pass false for 'lval' because this indicates + initialization of a temporary. */ + r = eval_constant_expression (ctx, TREE_OPERAND (t, 1), false, + non_constant_p, overflow_p); + if (*non_constant_p) + break; + /* Adjust the type of the result to the type of the temporary. */ + r = adjust_temp_type (type, r); + if (TARGET_EXPR_CLEANUP (t) && !CLEANUP_EH_ONLY (t)) + ctx->global->cleanups->safe_push (TARGET_EXPR_CLEANUP (t)); + r = unshare_constructor (r); + ctx->global->values.put (slot, r); + if (ctx->save_exprs) + ctx->save_exprs->safe_push (slot); + if (lval) + return slot; + } break; case CALL_EXPR: - r = eval_call_expression (ctx, t); + r = eval_call_expression (ctx, t, lval, non_constant_p, overflow_p); break; case RETURN_EXPR: - rust_assert (TREE_OPERAND (t, 0) != NULL_TREE); - r = constexpr_expression (ctx, TREE_OPERAND (t, 0)); + if (TREE_OPERAND (t, 0) != NULL_TREE) + r = eval_constant_expression (ctx, TREE_OPERAND (t, 0), lval, + non_constant_p, overflow_p); + /* FALLTHRU */ + case BREAK_STMT: + case CONTINUE_STMT: + if (jump_target) + *jump_target = t; + else + { + /* Can happen with ({ return true; }) && false; passed to + maybe_constant_value. There is nothing to jump over in this + case, and the bug will be diagnosed later. */ + gcc_assert (ctx->quiet); + *non_constant_p = true; + } + break; + + case DECL_EXPR: { + r = DECL_EXPR_DECL (t); + + if (AGGREGATE_TYPE_P (TREE_TYPE (r)) || VECTOR_TYPE_P (TREE_TYPE (r))) + { + new_ctx = *ctx; + new_ctx.object = r; + new_ctx.ctor = build_constructor (TREE_TYPE (r), NULL); + CONSTRUCTOR_NO_CLEARING (new_ctx.ctor) = true; + ctx->global->values.put (r, new_ctx.ctor); + ctx = &new_ctx; + } + + if (tree init = DECL_INITIAL (r)) + { + init = eval_constant_expression (ctx, init, false, non_constant_p, + overflow_p); + /* Don't share a CONSTRUCTOR that might be changed. */ + init = unshare_constructor (init); + /* Remember that a constant object's constructor has already + run. */ + if (CLASS_TYPE_P (TREE_TYPE (r)) && RS_TYPE_CONST_P (TREE_TYPE (r))) + TREE_READONLY (init) = true; + ctx->global->values.put (r, init); + } + else if (ctx == &new_ctx) + /* We gave it a CONSTRUCTOR above. */; + else + ctx->global->values.put (r, NULL_TREE); + } + break; + + /* These differ from cxx_eval_unary_expression in that this doesn't + check for a constant operand or result; an address can be + constant without its operand being, and vice versa. */ + case MEM_REF: + case INDIRECT_REF: + r = rs_eval_indirect_ref (ctx, t, lval, non_constant_p, overflow_p); + break; + + case VEC_PERM_EXPR: + r = cxx_eval_trinary_expression (ctx, t, lval, non_constant_p, + overflow_p); + break; + + case PAREN_EXPR: + gcc_assert (!REF_PARENTHESIZED_P (t)); + /* A PAREN_EXPR resulting from __builtin_assoc_barrier has no effect in + constant expressions since it's unaffected by -fassociative-math. */ + r = eval_constant_expression (ctx, TREE_OPERAND (t, 0), lval, + non_constant_p, overflow_p); break; case MODIFY_EXPR: - r = eval_store_expression (ctx, t); + r = eval_store_expression (ctx, t, false, non_constant_p, overflow_p); + break; + + case STATEMENT_LIST: + new_ctx = *ctx; + new_ctx.ctor = new_ctx.object = NULL_TREE; + return eval_statement_list (&new_ctx, t, non_constant_p, overflow_p, + jump_target); + + case BIND_EXPR: + return eval_constant_expression (ctx, BIND_EXPR_BODY (t), lval, + non_constant_p, overflow_p, jump_target); + + case OBJ_TYPE_REF: + /* Virtual function lookup. We don't need to do anything fancy. */ + return eval_constant_expression (ctx, OBJ_TYPE_REF_EXPR (t), lval, + non_constant_p, overflow_p); + + case EXIT_EXPR: { + tree cond = TREE_OPERAND (t, 0); + cond = eval_constant_expression (ctx, cond, /*lval*/ false, + non_constant_p, overflow_p); + VERIFY_CONSTANT (cond); + if (integer_nonzerop (cond)) + *jump_target = t; + } + break; + + case RESULT_DECL: + if (lval) + return t; + /* We ask for an rvalue for the RESULT_DECL when indirecting + through an invisible reference, or in named return value + optimization. */ + if (tree *p = ctx->global->values.get (t)) + return *p; + else + { + if (!ctx->quiet) + error ("%qE is not a constant expression", t); + *non_constant_p = true; + } + break; + + case SAVE_EXPR: + /* Avoid evaluating a SAVE_EXPR more than once. */ + if (tree *p = ctx->global->values.get (t)) + r = *p; + else + { + r = eval_constant_expression (ctx, TREE_OPERAND (t, 0), false, + non_constant_p, overflow_p); + if (*non_constant_p) + break; + ctx->global->values.put (t, r); + if (ctx->save_exprs) + ctx->save_exprs->safe_push (t); + } + break; + + case ADDR_EXPR: { + tree oldop = TREE_OPERAND (t, 0); + tree op = eval_constant_expression (ctx, oldop, + /*lval*/ true, non_constant_p, + overflow_p); + /* Don't VERIFY_CONSTANT here. */ + if (*non_constant_p) + return t; + gcc_checking_assert (TREE_CODE (op) != CONSTRUCTOR); + /* This function does more aggressive folding than fold itself. */ + r = build_fold_addr_expr_with_type (op, TREE_TYPE (t)); + if (TREE_CODE (r) == ADDR_EXPR && TREE_OPERAND (r, 0) == oldop) + { + ggc_free (r); + return t; + } + break; + } + + case COMPOUND_EXPR: { + /* check_return_expr sometimes wraps a TARGET_EXPR in a + COMPOUND_EXPR; don't get confused. Also handle EMPTY_CLASS_EXPR + introduced by build_call_a. */ + tree op0 = TREE_OPERAND (t, 0); + tree op1 = TREE_OPERAND (t, 1); + STRIP_NOPS (op1); + if ((TREE_CODE (op0) == TARGET_EXPR && op1 == TARGET_EXPR_SLOT (op0)) + || TREE_CODE (op1) == EMPTY_CLASS_EXPR) + r = eval_constant_expression (ctx, op0, lval, non_constant_p, + overflow_p, jump_target); + else + { + /* Check that the LHS is constant and then discard it. */ + eval_constant_expression (ctx, op0, true, non_constant_p, + overflow_p, jump_target); + if (*non_constant_p) + return t; + op1 = TREE_OPERAND (t, 1); + r = eval_constant_expression (ctx, op1, lval, non_constant_p, + overflow_p, jump_target); + } + } + break; + + case REALPART_EXPR: + case IMAGPART_EXPR: + if (lval) + { + r = eval_constant_expression (ctx, TREE_OPERAND (t, 0), lval, + non_constant_p, overflow_p); + if (r == error_mark_node) + ; + else if (r == TREE_OPERAND (t, 0)) + r = t; + else + r = fold_build1 (TREE_CODE (t), TREE_TYPE (t), r); + break; + } + /* FALLTHRU */ + case CONJ_EXPR: + case FIX_TRUNC_EXPR: + case FLOAT_EXPR: + case NEGATE_EXPR: + case ABS_EXPR: + case ABSU_EXPR: + case BIT_NOT_EXPR: + case TRUTH_NOT_EXPR: + case FIXED_CONVERT_EXPR: + r = eval_unary_expression (ctx, t, lval, non_constant_p, overflow_p); + break; + + case LOOP_EXPR: + case WHILE_STMT: + case FOR_STMT: + eval_loop_expr (ctx, t, non_constant_p, overflow_p, jump_target); + break; + + case SWITCH_EXPR: + case SWITCH_STMT: + eval_switch_expr (ctx, t, non_constant_p, overflow_p, jump_target); + break; + + case ARRAY_REF: + r = eval_array_reference (ctx, t, lval, non_constant_p, overflow_p); + break; + + case COMPONENT_REF: + if (is_overloaded_fn (t)) + { + /* We can only get here in checking mode via + build_non_dependent_expr, because any expression that + calls or takes the address of the function will have + pulled a FUNCTION_DECL out of the COMPONENT_REF. */ + gcc_checking_assert (ctx->quiet || errorcount); + *non_constant_p = true; + return t; + } + r = eval_component_reference (ctx, t, lval, non_constant_p, overflow_p); + break; + + case BIT_FIELD_REF: + r = eval_bit_field_ref (ctx, t, lval, non_constant_p, overflow_p); + break; + + case COND_EXPR: + case IF_STMT: // comes from cp-tree.def + if (jump_target && *jump_target) + { + tree orig_jump = *jump_target; + tree arg = ((TREE_CODE (t) != IF_STMT || TREE_OPERAND (t, 1)) + ? TREE_OPERAND (t, 1) + : void_node); + /* When jumping to a label, the label might be either in the + then or else blocks, so process then block first in skipping + mode first, and if we are still in the skipping mode at its end, + process the else block too. */ + r = eval_constant_expression (ctx, arg, lval, non_constant_p, + overflow_p, jump_target); + /* It's possible that we found the label in the then block. But + it could have been followed by another jumping statement, e.g. + say we're looking for case 1: + if (cond) + { + // skipped statements + case 1:; // clears up *jump_target + return 1; // and sets it to a RETURN_EXPR + } + else { ... } + in which case we need not go looking to the else block. + (goto is not allowed in a constexpr function.) */ + if (*jump_target == orig_jump) + { + arg = ((TREE_CODE (t) != IF_STMT || TREE_OPERAND (t, 2)) + ? TREE_OPERAND (t, 2) + : void_node); + r = eval_constant_expression (ctx, arg, lval, non_constant_p, + overflow_p, jump_target); + } + break; + } + r = eval_conditional_expression (ctx, t, lval, non_constant_p, overflow_p, + jump_target); + break; + + case VEC_COND_EXPR: + r = eval_vector_conditional_expression (ctx, t, non_constant_p, + overflow_p); + break; + + case TRY_CATCH_EXPR: + if (TREE_OPERAND (t, 0) == NULL_TREE) + { + r = void_node; + break; + } + r = eval_constant_expression (ctx, TREE_OPERAND (t, 0), lval, + non_constant_p, overflow_p, jump_target); + break; + + case CLEANUP_POINT_EXPR: { + auto_vec<tree, 2> cleanups; + vec<tree> *prev_cleanups = ctx->global->cleanups; + ctx->global->cleanups = &cleanups; + r = eval_constant_expression (ctx, TREE_OPERAND (t, 0), lval, + non_constant_p, overflow_p, jump_target); + ctx->global->cleanups = prev_cleanups; + unsigned int i; + tree cleanup; + /* Evaluate the cleanups. */ + FOR_EACH_VEC_ELT_REVERSE (cleanups, i, cleanup) + eval_constant_expression (ctx, cleanup, false, non_constant_p, + overflow_p); + } + break; + + case TRY_FINALLY_EXPR: + r = eval_constant_expression (ctx, TREE_OPERAND (t, 0), lval, + non_constant_p, overflow_p, jump_target); + if (!*non_constant_p) + /* Also evaluate the cleanup. */ + eval_constant_expression (ctx, TREE_OPERAND (t, 1), true, + non_constant_p, overflow_p); break; + case CONSTRUCTOR: + if (TREE_CONSTANT (t) && reduced_constant_expression_p (t)) + { + /* Don't re-process a constant CONSTRUCTOR, but do fold it to + VECTOR_CST if applicable. */ + verify_constructor_flags (t); + if (TREE_CONSTANT (t)) + return fold (t); + } + r = eval_bare_aggregate (ctx, t, lval, non_constant_p, overflow_p); + break; + + /* FALLTHROUGH. */ + case NOP_EXPR: + case CONVERT_EXPR: + case VIEW_CONVERT_EXPR: { + tree oldop = TREE_OPERAND (t, 0); + + tree op = eval_constant_expression (ctx, oldop, lval, non_constant_p, + overflow_p); + if (*non_constant_p) + return t; + tree type = TREE_TYPE (t); + + if (VOID_TYPE_P (type)) + return void_node; + + if (TREE_CODE (t) == CONVERT_EXPR && ARITHMETIC_TYPE_P (type) + && INDIRECT_TYPE_P (TREE_TYPE (op)) && ctx->manifestly_const_eval) + { + if (!ctx->quiet) + error_at (loc, + "conversion from pointer type %qT to arithmetic type " + "%qT in a constant expression", + TREE_TYPE (op), type); + *non_constant_p = true; + return t; + } + + if (TYPE_PTROB_P (type) && TYPE_PTR_P (TREE_TYPE (op)) + && VOID_TYPE_P (TREE_TYPE (TREE_TYPE (op)))) + { + /* Likewise, don't error when casting from void* when OP is + &heap uninit and similar. */ + tree sop = tree_strip_nop_conversions (op); + if (TREE_CODE (sop) == ADDR_EXPR && VAR_P (TREE_OPERAND (sop, 0)) + && DECL_ARTIFICIAL (TREE_OPERAND (sop, 0))) + /* OK */; + else + { + if (!ctx->quiet) + error_at (loc, "cast from %qT is not allowed", + TREE_TYPE (op)); + *non_constant_p = true; + return t; + } + } + + if (INDIRECT_TYPE_P (type) && TREE_CODE (op) == INTEGER_CST) + { + if (integer_zerop (op)) + { + if (TYPE_REF_P (type)) + { + if (!ctx->quiet) + error_at (loc, "dereferencing a null pointer"); + *non_constant_p = true; + return t; + } + } + else + { + /* This detects for example: + reinterpret_cast<void*>(sizeof 0) + */ + if (!ctx->quiet) + error_at (loc, + "%<reinterpret_cast<%T>(%E)%> is not " + "a constant expression", + type, op); + *non_constant_p = true; + return t; + } + } + + if (INDIRECT_TYPE_P (type) && TREE_CODE (op) == NOP_EXPR + && TREE_TYPE (op) == ptr_type_node + && TREE_CODE (TREE_OPERAND (op, 0)) == ADDR_EXPR + && VAR_P (TREE_OPERAND (TREE_OPERAND (op, 0), 0)) + && (DECL_NAME (TREE_OPERAND (TREE_OPERAND (op, 0), 0)) + == heap_uninit_identifier + || DECL_NAME (TREE_OPERAND (TREE_OPERAND (op, 0), 0)) + == heap_vec_uninit_identifier)) + { + tree var = TREE_OPERAND (TREE_OPERAND (op, 0), 0); + tree var_size = TYPE_SIZE_UNIT (TREE_TYPE (var)); + tree elt_type = TREE_TYPE (type); + tree cookie_size = NULL_TREE; + if (TREE_CODE (elt_type) == RECORD_TYPE + && TYPE_NAME (elt_type) == heap_identifier) + { + tree fld1 = TYPE_FIELDS (elt_type); + tree fld2 = DECL_CHAIN (fld1); + elt_type = TREE_TYPE (TREE_TYPE (fld2)); + cookie_size = TYPE_SIZE_UNIT (TREE_TYPE (fld1)); + } + DECL_NAME (var) = (DECL_NAME (var) == heap_uninit_identifier + ? heap_identifier + : heap_vec_identifier); + TREE_TYPE (var) + = build_new_constexpr_heap_type (elt_type, cookie_size, var_size); + TREE_TYPE (TREE_OPERAND (op, 0)) + = build_pointer_type (TREE_TYPE (var)); + } + + if (op == oldop) + /* We didn't fold at the top so we could check for ptr-int + conversion. */ + return fold (t); + + tree sop; + + /* Handle an array's bounds having been deduced after we built + the wrapping expression. */ + if (same_type_ignoring_tlq_and_bounds_p (type, TREE_TYPE (op))) + r = op; + else if (sop = tree_strip_nop_conversions (op), + sop != op + && (same_type_ignoring_tlq_and_bounds_p (type, + TREE_TYPE (sop)))) + r = sop; + else + r = fold_build1 (tcode, type, op); + + /* Conversion of an out-of-range value has implementation-defined + behavior; the language considers it different from arithmetic + overflow, which is undefined. */ + if (TREE_OVERFLOW_P (r) && !TREE_OVERFLOW_P (op)) + TREE_OVERFLOW (r) = false; + } + break; + + case PLACEHOLDER_EXPR: + /* Use of the value or address of the current object. */ + if (tree ctor = lookup_placeholder (ctx, lval, TREE_TYPE (t))) + { + if (TREE_CODE (ctor) == CONSTRUCTOR) + return ctor; + else + return eval_constant_expression (ctx, ctor, lval, non_constant_p, + overflow_p); + } + /* A placeholder without a referent. We can get here when + checking whether NSDMIs are noexcept, or in massage_init_elt; + just say it's non-constant for now. */ + gcc_assert (ctx->quiet); + *non_constant_p = true; + break; + + case ANNOTATE_EXPR: + r = eval_constant_expression (ctx, TREE_OPERAND (t, 0), lval, + non_constant_p, overflow_p, jump_target); + break; + + case ASM_EXPR: + if (!ctx->quiet) + inline_asm_in_constexpr_error (loc); + *non_constant_p = true; + return t; + default: break; } @@ -188,9 +2603,44 @@ constexpr_expression (const constexpr_ctx *ctx, tree t) return r; } +/* Complain about a const object OBJ being modified in a constant expression. + EXPR is the MODIFY_EXPR expression performing the modification. */ + +static void +modifying_const_object_error (tree expr, tree obj) +{ + location_t loc = EXPR_LOCATION (expr); + auto_diagnostic_group d; + error_at (loc, + "modifying a const object %qE is not allowed in " + "a constant expression", + TREE_OPERAND (expr, 0)); + inform (location_of (obj), "originally declared %<const%> here"); +} + +/* Return true iff DECL is an empty field, either for an empty base or a + [[no_unique_address]] data member. */ + +bool +is_empty_field (tree decl) +{ + if (!decl || TREE_CODE (decl) != FIELD_DECL) + return false; + + bool r = is_empty_class (TREE_TYPE (decl)); + + /* Empty fields should have size zero. */ + gcc_checking_assert (!r || integer_zerop (DECL_SIZE (decl))); + + return r; +} + static tree -eval_store_expression (const constexpr_ctx *ctx, tree t) +eval_store_expression (const constexpr_ctx *ctx, tree t, bool lval, + bool *non_constant_p, bool *overflow_p) { + constexpr_ctx new_ctx = *ctx; + tree init = TREE_OPERAND (t, 1); if (TREE_CLOBBER_P (init)) /* Just ignore clobbers. */ @@ -205,41 +2655,374 @@ eval_store_expression (const constexpr_ctx *ctx, tree t) { /* Evaluate the value to be stored without knowing what object it will be stored in, so that any side-effects happen first. */ - init = fold_expr (init); + if (!SCALAR_TYPE_P (type)) + new_ctx.ctor = new_ctx.object = NULL_TREE; + init = eval_constant_expression (&new_ctx, init, false, non_constant_p, + overflow_p); + if (*non_constant_p) + return t; } bool evaluated = false; + if (lval) + { + /* If we want to return a reference to the target, we need to evaluate it + as a whole; otherwise, only evaluate the innermost piece to avoid + building up unnecessary *_REFs. */ + target = eval_constant_expression (ctx, target, true, non_constant_p, + overflow_p); + evaluated = true; + if (*non_constant_p) + return t; + } + + /* Find the underlying variable. */ + releasing_vec refs; tree object = NULL_TREE; + /* If we're modifying a const object, save it. */ + tree const_object_being_modified = NULL_TREE; + // bool mutable_p = false; for (tree probe = target; object == NULL_TREE;) { switch (TREE_CODE (probe)) { + case BIT_FIELD_REF: + case COMPONENT_REF: + case ARRAY_REF: { + tree ob = TREE_OPERAND (probe, 0); + tree elt = TREE_OPERAND (probe, 1); + if (TREE_CODE (elt) == FIELD_DECL /*&& DECL_MUTABLE_P (elt)*/) + { + // mutable_p = true; + } + if (TREE_CODE (probe) == ARRAY_REF) + { + // TODO + gcc_unreachable (); + // elt = eval_and_check_array_index (ctx, probe, false, + // non_constant_p, overflow_p); + if (*non_constant_p) + return t; + } + /* We don't check modifying_const_object_p for ARRAY_REFs. Given + "int a[10]", an ARRAY_REF "a[2]" can be "const int", even though + the array isn't const. Instead, check "a" in the next iteration; + that will detect modifying "const int a[10]". */ + // else if (evaluated + // && modifying_const_object_p (TREE_CODE (t), probe, + // mutable_p) + // && const_object_being_modified == NULL_TREE) + // const_object_being_modified = probe; + vec_safe_push (refs, elt); + vec_safe_push (refs, TREE_TYPE (probe)); + probe = ob; + } + break; + default: if (evaluated) object = probe; else { - probe = constexpr_expression (ctx, probe); + probe = eval_constant_expression (ctx, probe, true, + non_constant_p, overflow_p); evaluated = true; + if (*non_constant_p) + return t; } break; } } - return init; + // if (modifying_const_object_p (TREE_CODE (t), object, mutable_p) + // && const_object_being_modified == NULL_TREE) + // const_object_being_modified = object; + + /* And then find/build up our initializer for the path to the subobject + we're initializing. */ + tree *valp; + if (DECL_P (object)) + valp = ctx->global->values.get (object); + else + valp = NULL; + if (!valp) + { + /* A constant-expression cannot modify objects from outside the + constant-expression. */ + if (!ctx->quiet) + error ("modification of %qE is not a constant expression", object); + *non_constant_p = true; + return t; + } + type = TREE_TYPE (object); + bool no_zero_init = true; + + releasing_vec ctors, indexes; + auto_vec<int> index_pos_hints; + bool activated_union_member_p = false; + while (!refs->is_empty ()) + { + if (*valp == NULL_TREE) + { + *valp = build_constructor (type, NULL); + CONSTRUCTOR_NO_CLEARING (*valp) = no_zero_init; + } + else if (TREE_CODE (*valp) == STRING_CST) + { + /* An array was initialized with a string constant, and now + we're writing into one of its elements. Explode the + single initialization into a set of element + initializations. */ + gcc_assert (TREE_CODE (type) == ARRAY_TYPE); + + tree string = *valp; + tree elt_type = TREE_TYPE (type); + unsigned chars_per_elt + = (TYPE_PRECISION (elt_type) / TYPE_PRECISION (char_type_node)); + unsigned num_elts = TREE_STRING_LENGTH (string) / chars_per_elt; + tree ary_ctor = build_constructor (type, NULL); + + vec_safe_reserve (CONSTRUCTOR_ELTS (ary_ctor), num_elts); + for (unsigned ix = 0; ix != num_elts; ix++) + { + constructor_elt elt + = {build_int_cst (size_type_node, ix), + extract_string_elt (string, chars_per_elt, ix)}; + CONSTRUCTOR_ELTS (ary_ctor)->quick_push (elt); + } + + *valp = ary_ctor; + } + + /* If the value of object is already zero-initialized, any new ctors for + subobjects will also be zero-initialized. */ + no_zero_init = CONSTRUCTOR_NO_CLEARING (*valp); + + enum tree_code code = TREE_CODE (type); + type = refs->pop (); + tree index = refs->pop (); + + if (code == RECORD_TYPE && is_empty_field (index)) + /* Don't build a sub-CONSTRUCTOR for an empty base or field, as they + have no data and might have an offset lower than previously declared + fields, which confuses the middle-end. The code below will notice + that we don't have a CONSTRUCTOR for our inner target and just + return init. */ + break; + + if (code == UNION_TYPE && CONSTRUCTOR_NELTS (*valp) + && CONSTRUCTOR_ELT (*valp, 0)->index != index) + { + if (TREE_CODE (t) == MODIFY_EXPR && CONSTRUCTOR_NO_CLEARING (*valp)) + { + /* Diagnose changing the active union member while the union + is in the process of being initialized. */ + if (!ctx->quiet) + error_at (EXPR_LOCATION (t), + "change of the active member of a union " + "from %qD to %qD during initialization", + CONSTRUCTOR_ELT (*valp, 0)->index, index); + *non_constant_p = true; + } + no_zero_init = true; + } + + vec_safe_push (ctors, *valp); + vec_safe_push (indexes, index); + + constructor_elt *cep = get_or_insert_ctor_field (*valp, index); + index_pos_hints.safe_push (cep - CONSTRUCTOR_ELTS (*valp)->begin ()); + + if (code == UNION_TYPE) + activated_union_member_p = true; + + valp = &cep->value; + } + + /* Detect modifying a constant object in constexpr evaluation. + We have found a const object that is being modified. Figure out + if we need to issue an error. Consider + + struct A { + int n; + constexpr A() : n(1) { n = 2; } // #1 + }; + struct B { + const A a; + constexpr B() { a.n = 3; } // #2 + }; + constexpr B b{}; + + #1 is OK, since we're modifying an object under construction, but + #2 is wrong, since "a" is const and has been fully constructed. + To track it, we use the TREE_READONLY bit in the object's CONSTRUCTOR + which means that the object is read-only. For the example above, the + *ctors stack at the point of #2 will look like: + + ctors[0] = {.a={.n=2}} TREE_READONLY = 0 + ctors[1] = {.n=2} TREE_READONLY = 1 + + and we're modifying "b.a", so we search the stack and see if the + constructor for "b.a" has already run. */ + if (const_object_being_modified) + { + bool fail = false; + tree const_objtype + = strip_array_types (TREE_TYPE (const_object_being_modified)); + if (!CLASS_TYPE_P (const_objtype)) + fail = true; + else + { + /* [class.ctor]p5 "A constructor can be invoked for a const, + volatile, or const volatile object. const and volatile + semantics are not applied on an object under construction. + They come into effect when the constructor for the most + derived object ends." */ + for (tree elt : *ctors) + if (same_type_ignoring_top_level_qualifiers_p ( + TREE_TYPE (const_object_being_modified), TREE_TYPE (elt))) + { + fail = TREE_READONLY (elt); + break; + } + } + if (fail) + { + if (!ctx->quiet) + modifying_const_object_error (t, const_object_being_modified); + *non_constant_p = true; + return t; + } + } + + if (!preeval) + { + /* We're handling an INIT_EXPR of class type, so the value of the + initializer can depend on the object it's initializing. */ + + /* Create a new CONSTRUCTOR in case evaluation of the initializer + wants to modify it. */ + if (*valp == NULL_TREE) + { + *valp = build_constructor (type, NULL); + CONSTRUCTOR_NO_CLEARING (*valp) = no_zero_init; + } + new_ctx.ctor = *valp; + new_ctx.object = target; + /* Avoid temporary materialization when initializing from a TARGET_EXPR. + We don't need to mess with AGGR_EXPR_SLOT/VEC_INIT_EXPR_SLOT because + expansion of those trees uses ctx instead. */ + if (TREE_CODE (init) == TARGET_EXPR) + if (tree tinit = TARGET_EXPR_INITIAL (init)) + init = tinit; + init = eval_constant_expression (&new_ctx, init, false, non_constant_p, + overflow_p); + /* The hash table might have moved since the get earlier, and the + initializer might have mutated the underlying CONSTRUCTORs, so we must + recompute VALP. */ + valp = ctx->global->values.get (object); + for (unsigned i = 0; i < vec_safe_length (indexes); i++) + { + constructor_elt *cep + = get_or_insert_ctor_field (*valp, indexes[i], index_pos_hints[i]); + valp = &cep->value; + } + } + + /* Don't share a CONSTRUCTOR that might be changed later. */ + init = unshare_constructor (init); + + if (*valp && TREE_CODE (*valp) == CONSTRUCTOR + && TREE_CODE (init) == CONSTRUCTOR) + { + /* An outer ctx->ctor might be pointing to *valp, so replace + its contents. */ + if (!same_type_ignoring_top_level_qualifiers_p (TREE_TYPE (init), + TREE_TYPE (*valp))) + { + /* For initialization of an empty base, the original target will be + *(base*)this, evaluation of which resolves to the object + argument, which has the derived type rather than the base type. In + this situation, just evaluate the initializer and return, since + there's no actual data to store. */ + gcc_assert (is_empty_class (TREE_TYPE (init))); + return lval ? target : init; + } + CONSTRUCTOR_ELTS (*valp) = CONSTRUCTOR_ELTS (init); + TREE_CONSTANT (*valp) = TREE_CONSTANT (init); + TREE_SIDE_EFFECTS (*valp) = TREE_SIDE_EFFECTS (init); + CONSTRUCTOR_NO_CLEARING (*valp) = CONSTRUCTOR_NO_CLEARING (init); + } + else if (TREE_CODE (init) == CONSTRUCTOR + && !same_type_ignoring_top_level_qualifiers_p (TREE_TYPE (init), + type)) + { + /* See above on initialization of empty bases. */ + gcc_assert (is_empty_class (TREE_TYPE (init)) && !lval); + return init; + } + else + *valp = init; + + /* After initialization, 'const' semantics apply to the value of the + object. Make a note of this fact by marking the CONSTRUCTOR + TREE_READONLY. */ + if (TREE_CODE (t) == INIT_EXPR && TREE_CODE (*valp) == CONSTRUCTOR + && TYPE_READONLY (type)) + { + // this vs self? can rust's self be anything other than self or &self in + // constexpr mode? if (INDIRECT_REF_P (target) + // && (is_this_parameter ( + // tree_strip_nop_conversions (TREE_OPERAND (target, 0))))) + /* We've just initialized '*this' (perhaps via the target + constructor of a delegating constructor). Leave it up to the + caller that set 'this' to set TREE_READONLY appropriately. */ + // gcc_checking_assert ( + // same_type_ignoring_top_level_qualifiers_p (TREE_TYPE (target), + // type)); + // else + // TREE_READONLY (*valp) = true; + } + + /* Update TREE_CONSTANT and TREE_SIDE_EFFECTS on enclosing + CONSTRUCTORs, if any. */ + bool c = TREE_CONSTANT (init); + bool s = TREE_SIDE_EFFECTS (init); + if (!c || s || activated_union_member_p) + for (tree elt : *ctors) + { + if (!c) + TREE_CONSTANT (elt) = false; + if (s) + TREE_SIDE_EFFECTS (elt) = true; + /* Clear CONSTRUCTOR_NO_CLEARING since we've activated a member of + this union. */ + if (TREE_CODE (TREE_TYPE (elt)) == UNION_TYPE) + CONSTRUCTOR_NO_CLEARING (elt) = false; + } + + if (*non_constant_p) + return t; + else if (lval) + return target; + else + return init; } /* Subroutine of cxx_eval_constant_expression. Like cxx_eval_unary_expression, except for binary expressions. */ static tree -eval_binary_expression (const constexpr_ctx *ctx, tree t) +eval_binary_expression (const constexpr_ctx *ctx, tree t, bool lval, + bool *non_constant_p, bool *overflow_p) { tree orig_lhs = TREE_OPERAND (t, 0); tree orig_rhs = TREE_OPERAND (t, 1); tree lhs, rhs; - lhs = constexpr_expression (ctx, orig_lhs); - rhs = constexpr_expression (ctx, orig_rhs); + lhs = eval_constant_expression (ctx, orig_lhs, lval, non_constant_p, + overflow_p); + rhs = eval_constant_expression (ctx, orig_rhs, lval, non_constant_p, + overflow_p); location_t loc = EXPR_LOCATION (t); enum tree_code code = TREE_CODE (t); @@ -248,16 +3031,902 @@ eval_binary_expression (const constexpr_ctx *ctx, tree t) return fold_binary_loc (loc, code, type, lhs, rhs); } +/* Helper function of cxx_bind_parameters_in_call. Return non-NULL + if *TP is address of a static variable (or part of it) currently being + constructed or of a heap artificial variable. */ + +static tree +addr_of_non_const_var (tree *tp, int *walk_subtrees, void *data) +{ + if (TREE_CODE (*tp) == ADDR_EXPR) + if (tree var = get_base_address (TREE_OPERAND (*tp, 0))) + if (VAR_P (var) && TREE_STATIC (var)) + { + if (DECL_NAME (var) == heap_uninit_identifier + || DECL_NAME (var) == heap_identifier + || DECL_NAME (var) == heap_vec_uninit_identifier + || DECL_NAME (var) == heap_vec_identifier) + return var; + + constexpr_global_ctx *global = (constexpr_global_ctx *) data; + if (global->values.get (var)) + return var; + } + if (TYPE_P (*tp)) + *walk_subtrees = false; + return NULL_TREE; +} + +/* Subroutine of cxx_eval_call_expression. + We are processing a call expression (either CALL_EXPR or + AGGR_INIT_EXPR) in the context of CTX. Evaluate + all arguments and bind their values to correspondings + parameters, making up the NEW_CALL context. */ + +static tree +rs_bind_parameters_in_call (const constexpr_ctx *ctx, tree t, tree fun, + bool *non_constant_p, bool *overflow_p, + bool *non_constant_args) +{ + const int nargs = call_expr_nargs (t); + tree parms = DECL_ARGUMENTS (fun); + int i; + /* We don't record ellipsis args below. */ + int nparms = list_length (parms); + int nbinds = nargs < nparms ? nargs : nparms; + tree binds = make_tree_vec (nbinds); + for (i = 0; i < nargs; ++i) + { + tree x, arg; + tree type = parms ? TREE_TYPE (parms) : void_type_node; + if (parms && DECL_BY_REFERENCE (parms)) + type = TREE_TYPE (type); + x = get_nth_callarg (t, i); + + if (TREE_ADDRESSABLE (type)) + /* Undo convert_for_arg_passing work here. */ + x = convert_from_reference (x); + /* Normally we would strip a TARGET_EXPR in an initialization context + such as this, but here we do the elision differently: we keep the + TARGET_EXPR, and use its CONSTRUCTOR as the value of the parm. */ + arg = eval_constant_expression (ctx, x, /*lval=*/false, non_constant_p, + overflow_p); + /* Don't VERIFY_CONSTANT here. */ + if (*non_constant_p && ctx->quiet) + break; + /* Just discard ellipsis args after checking their constantitude. */ + if (!parms) + continue; + + if (!*non_constant_p) + { + /* Make sure the binding has the same type as the parm. But + only for constant args. */ + if (!TYPE_REF_P (type)) + arg = adjust_temp_type (type, arg); + if (!TREE_CONSTANT (arg)) + *non_constant_args = true; + else if (TYPE_HAS_NONTRIVIAL_DESTRUCTOR (type)) + /* The destructor needs to see any modifications the callee makes + to the argument. */ + *non_constant_args = true; + /* If arg is or contains address of a heap artificial variable or + of a static variable being constructed, avoid caching the + function call, as those variables might be modified by the + function, or might be modified by the callers in between + the cached function and just read by the function. */ + else if (!*non_constant_args + && rs_walk_tree (&arg, addr_of_non_const_var, ctx->global, + NULL)) + *non_constant_args = true; + + // /* For virtual calls, adjust the this argument, so that it is + // the object on which the method is called, rather than + // one of its bases. */ + // if (i == 0 && DECL_VIRTUAL_P (fun)) + // { + // tree addr = arg; + // STRIP_NOPS (addr); + // if (TREE_CODE (addr) == ADDR_EXPR) + // { + // tree obj = TREE_OPERAND (addr, 0); + // while (TREE_CODE (obj) == COMPONENT_REF + // && DECL_FIELD_IS_BASE (TREE_OPERAND (obj, 1)) + // && !same_type_ignoring_top_level_qualifiers_p ( + // TREE_TYPE (obj), DECL_CONTEXT (fun))) + // obj = TREE_OPERAND (obj, 0); + // if (obj != TREE_OPERAND (addr, 0)) + // arg = build_fold_addr_expr_with_type (obj, TREE_TYPE + // (arg)); + // } + // } + TREE_VEC_ELT (binds, i) = arg; + } + parms = TREE_CHAIN (parms); + } + + return binds; +} + +// forked from gcc/cp/constexpr.cc cxx_eval_builtin_function_call + +/* Attempt to evaluate T which represents a call to a builtin function. + We assume here that all builtin functions evaluate to scalar types + represented by _CST nodes. */ + +static tree +eval_builtin_function_call (const constexpr_ctx *ctx, tree t, tree fun, + bool lval, bool *non_constant_p, bool *overflow_p) +{ + const int nargs = call_expr_nargs (t); + tree *args = (tree *) alloca (nargs * sizeof (tree)); + tree new_call; + int i; + + /* Don't fold __builtin_constant_p within a constexpr function. */ + bool bi_const_p = DECL_IS_BUILTIN_CONSTANT_P (fun); + + /* If we aren't requiring a constant expression, defer __builtin_constant_p + in a constexpr function until we have values for the parameters. */ + if (bi_const_p && !ctx->manifestly_const_eval && current_function_decl + && DECL_DECLARED_CONSTEXPR_P (current_function_decl)) + { + *non_constant_p = true; + return t; + } + + /* For __builtin_is_constant_evaluated, defer it if not + ctx->manifestly_const_eval (as sometimes we try to constant evaluate + without manifestly_const_eval even expressions or parts thereof which + will later be manifestly const_eval evaluated), otherwise fold it to + true. */ + if (fndecl_built_in_p (fun, CP_BUILT_IN_IS_CONSTANT_EVALUATED, + BUILT_IN_FRONTEND)) + { + if (!ctx->manifestly_const_eval) + { + *non_constant_p = true; + return t; + } + return boolean_true_node; + } + + if (fndecl_built_in_p (fun, CP_BUILT_IN_SOURCE_LOCATION, BUILT_IN_FRONTEND)) + { + temp_override<tree> ovr (current_function_decl); + if (ctx->call && ctx->call->fundef) + current_function_decl = ctx->call->fundef->decl; + return fold_builtin_source_location (EXPR_LOCATION (t)); + } + + int strops = 0; + int strret = 0; + if (fndecl_built_in_p (fun, BUILT_IN_NORMAL)) + switch (DECL_FUNCTION_CODE (fun)) + { + case BUILT_IN_STRLEN: + case BUILT_IN_STRNLEN: + strops = 1; + break; + case BUILT_IN_MEMCHR: + case BUILT_IN_STRCHR: + case BUILT_IN_STRRCHR: + strops = 1; + strret = 1; + break; + case BUILT_IN_MEMCMP: + case BUILT_IN_STRCMP: + strops = 2; + break; + case BUILT_IN_STRSTR: + strops = 2; + strret = 1; + break; + case BUILT_IN_ASAN_POINTER_COMPARE: + case BUILT_IN_ASAN_POINTER_SUBTRACT: + /* These builtins shall be ignored during constant expression + evaluation. */ + return void_node; + default: + break; + } + + /* Be permissive for arguments to built-ins; __builtin_constant_p should + return constant false for a non-constant argument. */ + constexpr_ctx new_ctx = *ctx; + new_ctx.quiet = true; + for (i = 0; i < nargs; ++i) + { + tree arg = CALL_EXPR_ARG (t, i); + tree oarg = arg; + + /* To handle string built-ins we need to pass ADDR_EXPR<STRING_CST> since + expand_builtin doesn't know how to look in the values table. */ + bool strop = i < strops; + if (strop) + { + STRIP_NOPS (arg); + if (TREE_CODE (arg) == ADDR_EXPR) + arg = TREE_OPERAND (arg, 0); + else + strop = false; + } + + /* If builtin_valid_in_constant_expr_p is true, + potential_constant_expression_1 has not recursed into the arguments + of the builtin, verify it here. */ + if (!builtin_valid_in_constant_expr_p (fun) + || potential_constant_expression (arg)) + { + bool dummy1 = false, dummy2 = false; + arg + = eval_constant_expression (&new_ctx, arg, false, &dummy1, &dummy2); + } + + if (bi_const_p) + /* For __builtin_constant_p, fold all expressions with constant values + even if they aren't C++ constant-expressions. */ + arg = cp_fold_rvalue (arg); + else if (strop) + { + if (TREE_CODE (arg) == CONSTRUCTOR) + arg = braced_lists_to_strings (TREE_TYPE (arg), arg); + if (TREE_CODE (arg) == STRING_CST) + arg = build_address (arg); + else + arg = oarg; + } + + args[i] = arg; + } + + bool save_ffbcp = force_folding_builtin_constant_p; + force_folding_builtin_constant_p |= ctx->manifestly_const_eval; + tree save_cur_fn = current_function_decl; + /* Return name of ctx->call->fundef->decl for __builtin_FUNCTION (). */ + if (fndecl_built_in_p (fun, BUILT_IN_FUNCTION) && ctx->call + && ctx->call->fundef) + current_function_decl = ctx->call->fundef->decl; + if (fndecl_built_in_p (fun, + CP_BUILT_IN_IS_POINTER_INTERCONVERTIBLE_WITH_CLASS, + BUILT_IN_FRONTEND)) + { + location_t loc = EXPR_LOCATION (t); + if (nargs >= 1) + VERIFY_CONSTANT (args[0]); + new_call + = fold_builtin_is_pointer_inverconvertible_with_class (loc, nargs, + args); + } + else if (fndecl_built_in_p (fun, CP_BUILT_IN_IS_CORRESPONDING_MEMBER, + BUILT_IN_FRONTEND)) + { + location_t loc = EXPR_LOCATION (t); + if (nargs >= 2) + { + VERIFY_CONSTANT (args[0]); + VERIFY_CONSTANT (args[1]); + } + new_call = fold_builtin_is_corresponding_member (loc, nargs, args); + } + else + new_call = fold_builtin_call_array (EXPR_LOCATION (t), TREE_TYPE (t), + CALL_EXPR_FN (t), nargs, args); + current_function_decl = save_cur_fn; + force_folding_builtin_constant_p = save_ffbcp; + if (new_call == NULL) + { + if (!*non_constant_p && !ctx->quiet) + { + /* Do not allow__builtin_unreachable in constexpr function. + The __builtin_unreachable call with BUILTINS_LOCATION + comes from cp_maybe_instrument_return. */ + if (fndecl_built_in_p (fun, BUILT_IN_UNREACHABLE) + && EXPR_LOCATION (t) == BUILTINS_LOCATION) + error ("%<constexpr%> call flows off the end of the function"); + else + { + new_call = build_call_array_loc (EXPR_LOCATION (t), TREE_TYPE (t), + CALL_EXPR_FN (t), nargs, args); + error ("%q+E is not a constant expression", new_call); + } + } + *non_constant_p = true; + return t; + } + + if (!potential_constant_expression (new_call)) + { + if (!*non_constant_p && !ctx->quiet) + error ("%q+E is not a constant expression", new_call); + *non_constant_p = true; + return t; + } + + if (strret) + { + /* memchr returns a pointer into the first argument, but we replaced the + argument above with a STRING_CST; put it back it now. */ + tree op = CALL_EXPR_ARG (t, strret - 1); + STRIP_NOPS (new_call); + if (TREE_CODE (new_call) == POINTER_PLUS_EXPR) + TREE_OPERAND (new_call, 0) = op; + else if (TREE_CODE (new_call) == ADDR_EXPR) + new_call = op; + } + + return eval_constant_expression (&new_ctx, new_call, lval, non_constant_p, + overflow_p); +} + // Subroutine of cxx_eval_constant_expression. // Evaluate the call expression tree T in the context of OLD_CALL expression // evaluation. static tree -eval_call_expression (const constexpr_ctx *ctx, tree t) +eval_call_expression (const constexpr_ctx *ctx, tree t, bool lval, + bool *non_constant_p, bool *overflow_p) { + location_t loc = EXPR_LOCATION (t); tree fun = get_function_named_in_call (t); - return constexpr_fn_retval (ctx, DECL_SAVED_TREE (fun)); + constexpr_call new_call = {NULL, NULL, NULL, 0, ctx->manifestly_const_eval}; + int depth_ok; + + if (fun == NULL_TREE) + { + // return cxx_eval_internal_function (ctx, t, lval, + // non_constant_p, overflow_p); + gcc_unreachable (); + return error_mark_node; + } + + if (TREE_CODE (fun) != FUNCTION_DECL) + { + if (!ctx->quiet && !*non_constant_p) + error_at (loc, + "expression %qE does not designate a %<constexpr%> " + "function", + fun); + *non_constant_p = true; + return t; + } + + if (fndecl_built_in_p (fun)) + return eval_builtin_function_call (ctx, t, fun, lval, non_constant_p, + overflow_p); + + bool non_constant_args = false; + new_call.bindings + = rs_bind_parameters_in_call (ctx, t, fun, non_constant_p, overflow_p, + &non_constant_args); + + /* We build up the bindings list before we know whether we already have this + call cached. If we don't end up saving these bindings, ggc_free them when + this function exits. */ + class free_bindings + { + tree *bindings; + + public: + free_bindings (tree &b) : bindings (&b) {} + ~free_bindings () + { + if (bindings) + ggc_free (*bindings); + } + void preserve () { bindings = NULL; } + } fb (new_call.bindings); + + if (*non_constant_p) + return t; + + /* If in direct recursive call, optimize definition search. */ + if (ctx && ctx->call && ctx->call->fundef && ctx->call->fundef->decl == fun) + new_call.fundef = ctx->call->fundef; + else + { + new_call.fundef = retrieve_constexpr_fundef (fun); + if (new_call.fundef == NULL || new_call.fundef->body == NULL + || new_call.fundef->result == error_mark_node + || fun == current_function_decl) + { + if (!ctx->quiet) + { + /* We need to check for current_function_decl here in case we're + being called during cp_fold_function, because at that point + DECL_INITIAL is set properly and we have a fundef but we + haven't lowered invisirefs yet (c++/70344). */ + if (DECL_INITIAL (fun) == error_mark_node + || fun == current_function_decl) + error_at (loc, + "%qD called in a constant expression before its " + "definition is complete", + fun); + else if (DECL_INITIAL (fun)) + { + // /* The definition of fun was somehow unsuitable. But + // pretend + // that lambda static thunks don't exist. */ + // if (!lambda_static_thunk_p (fun)) + // error_at (loc, "%qD called in a constant expression", + // fun); + explain_invalid_constexpr_fn (fun); + } + else + error_at (loc, "%qD used before its definition", fun); + } + *non_constant_p = true; + return t; + } + } + + depth_ok = push_cx_call_context (t); + + tree result = NULL_TREE; + constexpr_call *entry = NULL; + if (depth_ok && !non_constant_args && ctx->strict) + { + new_call.hash = constexpr_fundef_hasher::hash (new_call.fundef); + new_call.hash = iterative_hash_object (new_call.bindings, new_call.hash); + new_call.hash + = iterative_hash_object (ctx->manifestly_const_eval, new_call.hash); + + /* If we have seen this call before, we are done. */ + maybe_initialize_constexpr_call_table (); + constexpr_call **slot + = constexpr_call_table->find_slot (&new_call, INSERT); + entry = *slot; + if (entry == NULL) + { + /* Only cache up to constexpr_cache_depth to limit memory use. */ + if (depth_ok < constexpr_cache_depth) + { + /* We need to keep a pointer to the entry, not just the slot, as + the slot can move during evaluation of the body. */ + *slot = entry = ggc_alloc<constexpr_call> (); + *entry = new_call; + fb.preserve (); + } + } + /* Calls that are in progress have their result set to NULL, so that we + can detect circular dependencies. Now that we only cache up to + constexpr_cache_depth this won't catch circular dependencies that + start deeper, but they'll hit the recursion or ops limit. */ + else if (entry->result == NULL) + { + if (!ctx->quiet) + error ("call has circular dependency"); + *non_constant_p = true; + entry->result = result = error_mark_node; + } + else + result = entry->result; + } + + if (!depth_ok) + { + if (!ctx->quiet) + error ("%<constexpr%> evaluation depth exceeds maximum of %d (use " + "%<-fconstexpr-depth=%> to increase the maximum)", + max_constexpr_depth); + *non_constant_p = true; + result = error_mark_node; + } + else + { + bool cacheable = true; + if (result && result != error_mark_node) + /* OK */; + else if (!DECL_SAVED_TREE (fun)) + { + /* When at_eof >= 2, cgraph has started throwing away + DECL_SAVED_TREE, so fail quietly. FIXME we get here because of + late code generation for VEC_INIT_EXPR, which needs to be + completely reconsidered. */ + // gcc_assert (at_eof >= 2 && ctx->quiet); + *non_constant_p = true; + } + else if (tree copy = get_fundef_copy (new_call.fundef)) + { + tree body, parms, res; + releasing_vec ctors; + + /* Reuse or create a new unshared copy of this function's body. */ + body = TREE_PURPOSE (copy); + parms = TREE_VALUE (copy); + res = TREE_TYPE (copy); + + /* Associate the bindings with the remapped parms. */ + tree bound = new_call.bindings; + tree remapped = parms; + for (int i = 0; i < TREE_VEC_LENGTH (bound); ++i) + { + tree arg = TREE_VEC_ELT (bound, i); + if (entry) + { + /* Unshare args going into the hash table to separate them + from the caller's context, for better GC and to avoid + problems with verify_gimple. */ + arg = unshare_expr_without_location (arg); + TREE_VEC_ELT (bound, i) = arg; + + /* And then unshare again so the callee doesn't change the + argument values in the hash table. XXX Could we unshare + lazily in cxx_eval_store_expression? */ + arg = unshare_constructor (arg); + if (TREE_CODE (arg) == CONSTRUCTOR) + vec_safe_push (ctors, arg); + } + + ctx->global->values.put (remapped, arg); + remapped = DECL_CHAIN (remapped); + } + /* Add the RESULT_DECL to the values map, too. */ + gcc_assert (!DECL_BY_REFERENCE (res)); + ctx->global->values.put (res, NULL_TREE); + + /* Track the callee's evaluated SAVE_EXPRs and TARGET_EXPRs so that + we can forget their values after the call. */ + constexpr_ctx ctx_with_save_exprs = *ctx; + auto_vec<tree, 10> save_exprs; + ctx_with_save_exprs.save_exprs = &save_exprs; + ctx_with_save_exprs.call = &new_call; + unsigned save_heap_alloc_count = ctx->global->heap_vars.length (); + unsigned save_heap_dealloc_count = ctx->global->heap_dealloc_count; + + tree jump_target = NULL_TREE; + eval_constant_expression (&ctx_with_save_exprs, body, lval, + non_constant_p, overflow_p, &jump_target); + + if (VOID_TYPE_P (TREE_TYPE (res))) + result = void_node; + else + { + result = *ctx->global->values.get (res); + if (result == NULL_TREE && !*non_constant_p) + { + if (!ctx->quiet) + error ("%<constexpr%> call flows off the end " + "of the function"); + *non_constant_p = true; + } + } + + /* Forget the saved values of the callee's SAVE_EXPRs and + TARGET_EXPRs. */ + for (tree save_expr : save_exprs) + ctx->global->values.remove (save_expr); + + /* Remove the parms/result from the values map. Is it worth + bothering to do this when the map itself is only live for + one constexpr evaluation? If so, maybe also clear out + other vars from call, maybe in BIND_EXPR handling? */ + ctx->global->values.remove (res); + for (tree parm = parms; parm; parm = TREE_CHAIN (parm)) + ctx->global->values.remove (parm); + + /* Make the unshared function copy we used available for re-use. */ + save_fundef_copy (fun, copy); + + /* If the call allocated some heap object that hasn't been + deallocated during the call, or if it deallocated some heap + object it has not allocated, the call isn't really stateless + for the constexpr evaluation and should not be cached. + It is fine if the call allocates something and deallocates it + too. */ + if (entry + && (save_heap_alloc_count != ctx->global->heap_vars.length () + || (save_heap_dealloc_count + != ctx->global->heap_dealloc_count))) + { + tree heap_var; + unsigned int i; + if ((ctx->global->heap_vars.length () + - ctx->global->heap_dealloc_count) + != save_heap_alloc_count - save_heap_dealloc_count) + cacheable = false; + else + FOR_EACH_VEC_ELT_FROM (ctx->global->heap_vars, i, heap_var, + save_heap_alloc_count) + if (DECL_NAME (heap_var) != heap_deleted_identifier) + { + cacheable = false; + break; + } + } + } + else + /* Couldn't get a function copy to evaluate. */ + *non_constant_p = true; + + if (result == error_mark_node) + *non_constant_p = true; + if (*non_constant_p || *overflow_p) + result = error_mark_node; + else if (!result) + result = void_node; + if (entry) + entry->result = cacheable ? result : error_mark_node; + } + + pop_cx_call_context (); + return result; } +/* Subroutine of build_data_member_initialization. MEMBER is a COMPONENT_REF + for a member of an anonymous aggregate, INIT is the initializer for that + member, and VEC_OUTER is the vector of constructor elements for the class + whose constructor we are processing. Add the initializer to the vector + and return true to indicate success. */ + +static bool +build_anon_member_initialization (tree member, tree init, + vec<constructor_elt, va_gc> **vec_outer) +{ + /* MEMBER presents the relevant fields from the inside out, but we need + to build up the initializer from the outside in so that we can reuse + previously built CONSTRUCTORs if this is, say, the second field in an + anonymous struct. So we use a vec as a stack. */ + auto_vec<tree, 2> fields; + do + { + fields.safe_push (TREE_OPERAND (member, 1)); + member = TREE_OPERAND (member, 0); + } + while (ANON_AGGR_TYPE_P (TREE_TYPE (member)) + && TREE_CODE (member) == COMPONENT_REF); + + /* VEC has the constructor elements vector for the context of FIELD. + If FIELD is an anonymous aggregate, we will push inside it. */ + vec<constructor_elt, va_gc> **vec = vec_outer; + tree field; + while (field = fields.pop (), ANON_AGGR_TYPE_P (TREE_TYPE (field))) + { + tree ctor; + /* If there is already an outer constructor entry for the anonymous + aggregate FIELD, use it; otherwise, insert one. */ + if (vec_safe_is_empty (*vec) || (*vec)->last ().index != field) + { + ctor = build_constructor (TREE_TYPE (field), NULL); + CONSTRUCTOR_APPEND_ELT (*vec, field, ctor); + } + else + ctor = (*vec)->last ().value; + vec = &CONSTRUCTOR_ELTS (ctor); + } + + /* Now we're at the innermost field, the one that isn't an anonymous + aggregate. Add its initializer to the CONSTRUCTOR and we're done. */ + gcc_assert (fields.is_empty ()); + CONSTRUCTOR_APPEND_ELT (*vec, field, init); + + return true; +} + +///* V is a vector of constructor elements built up for the base and member +// initializers of a constructor for TYPE. They need to be in increasing +// offset order, which they might not be yet if TYPE has a primary base +// which is not first in the base-clause or a vptr and at least one base +// all of which are non-primary. */ +// +// static vec<constructor_elt, va_gc> * +// sort_constexpr_mem_initializers (tree type, vec<constructor_elt, va_gc> *v) +//{ +// tree pri = CLASSTYPE_PRIMARY_BINFO (type); +// tree field_type; +// unsigned i; +// constructor_elt *ce; +// +// if (pri) +// field_type = BINFO_TYPE (pri); +// else if (TYPE_CONTAINS_VPTR_P (type)) +// field_type = vtbl_ptr_type_node; +// else +// return v; +// +// /* Find the element for the primary base or vptr and move it to the +// beginning of the vec. */ +// for (i = 0; vec_safe_iterate (v, i, &ce); ++i) +// if (TREE_TYPE (ce->index) == field_type) +// break; +// +// if (i > 0 && i < vec_safe_length (v)) +// { +// vec<constructor_elt, va_gc> &vref = *v; +// constructor_elt elt = vref[i]; +// for (; i > 0; --i) +// vref[i] = vref[i - 1]; +// vref[0] = elt; +// } +// +// return v; +//} + +/* Subroutine of build_constexpr_constructor_member_initializers. + The expression tree T represents a data member initialization + in a (constexpr) constructor definition. Build a pairing of + the data member with its initializer, and prepend that pair + to the existing initialization pair INITS. */ + +static bool +build_data_member_initialization (tree t, vec<constructor_elt, va_gc> **vec) +{ + tree member, init; + if (TREE_CODE (t) == CLEANUP_POINT_EXPR) + t = TREE_OPERAND (t, 0); + if (TREE_CODE (t) == EXPR_STMT) + t = TREE_OPERAND (t, 0); + if (t == error_mark_node) + return false; + if (TREE_CODE (t) == STATEMENT_LIST) + { + for (tree stmt : tsi_range (t)) + if (!build_data_member_initialization (stmt, vec)) + return false; + return true; + } + if (TREE_CODE (t) == CONVERT_EXPR) + t = TREE_OPERAND (t, 0); + if (TREE_CODE (t) == INIT_EXPR + /* vptr initialization shows up as a MODIFY_EXPR. In C++14 we only + use what this function builds for cx_check_missing_mem_inits, and + assignment in the ctor body doesn't count. */ + || (TREE_CODE (t) == MODIFY_EXPR)) + { + member = TREE_OPERAND (t, 0); + // Faisal: not sure if we need to port over break_out_target_exprs + // if not, then not sure how to handle init in this case + // init = break_out_target_exprs (TREE_OPERAND (t, 1)); + } + else if (TREE_CODE (t) == CALL_EXPR) + { + tree fn = get_callee_fndecl (t); + if (!fn || !DECL_CONSTRUCTOR_P (fn)) + /* We're only interested in calls to subobject constructors. */ + return true; + member = CALL_EXPR_ARG (t, 0); + /* We don't use build_cplus_new here because it complains about + abstract bases. Leaving the call unwrapped means that it has the + wrong type, but cxx_eval_constant_expression doesn't care. */ + // Faisal: not sure if we need to port over break_out_target_exprs + // if not, then not sure how to handle init in this case + // init = break_out_target_exprs (t); + } + else if (TREE_CODE (t) == BIND_EXPR) + return build_data_member_initialization (BIND_EXPR_BODY (t), vec); + else + /* Don't add anything else to the CONSTRUCTOR. */ + return true; + if (INDIRECT_REF_P (member)) + member = TREE_OPERAND (member, 0); + if (TREE_CODE (member) == NOP_EXPR) + { + tree op = member; + STRIP_NOPS (op); + if (TREE_CODE (op) == ADDR_EXPR) + { + gcc_assert (same_type_ignoring_top_level_qualifiers_p ( + TREE_TYPE (TREE_TYPE (op)), TREE_TYPE (TREE_TYPE (member)))); + /* Initializing a cv-qualified member; we need to look through + the const_cast. */ + member = op; + } + else if (op == current_class_ptr + && (same_type_ignoring_top_level_qualifiers_p ( + TREE_TYPE (TREE_TYPE (member)), current_class_type))) + /* Delegating constructor. */ + member = op; + else + { + /* This is an initializer for an empty base; keep it for now so + we can check it in cxx_eval_bare_aggregate. */ + gcc_assert (is_empty_class (TREE_TYPE (TREE_TYPE (member)))); + } + } + if (TREE_CODE (member) == ADDR_EXPR) + member = TREE_OPERAND (member, 0); + if (TREE_CODE (member) == COMPONENT_REF) + { + tree aggr = TREE_OPERAND (member, 0); + if (TREE_CODE (aggr) == VAR_DECL) + /* Initializing a local variable, don't add anything. */ + return true; + if (TREE_CODE (aggr) != COMPONENT_REF) + /* Normal member initialization. */ + member = TREE_OPERAND (member, 1); + else if (ANON_AGGR_TYPE_P (TREE_TYPE (aggr))) + /* Initializing a member of an anonymous union. */ + return build_anon_member_initialization (member, init, vec); + else + /* We're initializing a vtable pointer in a base. Leave it as + COMPONENT_REF so we remember the path to get to the vfield. */ + gcc_assert (TREE_TYPE (member) == vtbl_ptr_type_node); + } + + /* Value-initialization can produce multiple initializers for the + same field; use the last one. */ + if (!vec_safe_is_empty (*vec) && (*vec)->last ().index == member) + (*vec)->last ().value = init; + else + CONSTRUCTOR_APPEND_ELT (*vec, member, init); + return true; +} + +///* Build compile-time evalable representations of member-initializer list +// for a constexpr constructor. */ +// +// static tree +// build_constexpr_constructor_member_initializers (tree type, tree body) +//{ +// vec<constructor_elt, va_gc> *vec = NULL; +// bool ok = true; +// while (true) +// switch (TREE_CODE (body)) +// { +// case STATEMENT_LIST: +// for (tree stmt : tsi_range (body)) +// { +// body = stmt; +// if (TREE_CODE (body) == BIND_EXPR) +// break; +// } +// break; +// +// case BIND_EXPR: +// body = BIND_EXPR_BODY (body); +// goto found; +// +// default: +// gcc_unreachable (); +// } +// found: +// +// if (TREE_CODE (body) == CLEANUP_POINT_EXPR) +// { +// body = TREE_OPERAND (body, 0); +// if (TREE_CODE (body) == EXPR_STMT) +// body = TREE_OPERAND (body, 0); +// if (TREE_CODE (body) == INIT_EXPR +// && (same_type_ignoring_top_level_qualifiers_p ( +// TREE_TYPE (TREE_OPERAND (body, 0)), current_class_type))) +// { +// /* Trivial copy. */ +// return TREE_OPERAND (body, 1); +// } +// ok = build_data_member_initialization (body, &vec); +// } +// else if (TREE_CODE (body) == STATEMENT_LIST) +// { +// for (tree stmt : tsi_range (body)) +// { +// ok = build_data_member_initialization (stmt, &vec); +// if (!ok) +// break; +// } +// } +// else if (EXPR_P (body)) +// ok = build_data_member_initialization (body, &vec); +// else +// gcc_assert (errorcount > 0); +// if (ok) +// { +// if (vec_safe_length (vec) > 0) +// { +// /* In a delegating constructor, return the target. */ +// constructor_elt *ce = &(*vec)[0]; +// if (ce->index == current_class_ptr) +// { +// body = ce->value; +// vec_free (vec); +// return body; +// } +// } +// vec = sort_constexpr_mem_initializers (type, vec); +// return build_constructor (type, vec); +// } +// else +// return error_mark_node; +//} + // Subroutine of check_constexpr_fundef. BODY is the body of a function // declared to be constexpr, or a sub-statement thereof. Returns the // return value if suitable, error_mark_node for a statement not allowed in @@ -285,9 +3954,12 @@ constexpr_fn_retval (const constexpr_ctx *ctx, tree body) return expr; } - case RETURN_EXPR: - return constexpr_expression (ctx, body); - + case RETURN_EXPR: { + bool non_constant_p = false; + bool overflow_p = false; + return eval_constant_expression (ctx, body, false, &non_constant_p, + &overflow_p); + } case DECL_EXPR: { tree decl = DECL_EXPR_DECL (body); if (TREE_CODE (decl) == USING_DECL @@ -437,5 +4109,2393 @@ var_in_maybe_constexpr_fn (tree t) return (DECL_FUNCTION_SCOPE_P (t) && maybe_constexpr_fn (DECL_CONTEXT (t))); } +/* P0859: A function is needed for constant evaluation if it is a constexpr + function that is named by an expression ([basic.def.odr]) that is + potentially constant evaluated. + + So we need to instantiate any constexpr functions mentioned by the + expression even if the definition isn't needed for evaluating the + expression. */ + +static tree +instantiate_cx_fn_r (tree *tp, int *walk_subtrees, void * /*data*/) +{ + if (TREE_CODE (*tp) == CALL_EXPR) + { + if (EXPR_HAS_LOCATION (*tp)) + input_location = EXPR_LOCATION (*tp); + } + + if (!EXPR_P (*tp)) + *walk_subtrees = 0; + + return NULL_TREE; +} + +static void +instantiate_constexpr_fns (tree t) +{ + location_t loc = input_location; + rs_walk_tree_without_duplicates (&t, instantiate_cx_fn_r, NULL); + input_location = loc; +} + +/* Returns less than, equal to, or greater than zero if KEY is found to be + less than, to match, or to be greater than the constructor_elt's INDEX. */ + +static int +array_index_cmp (tree key, tree index) +{ + gcc_assert (TREE_CODE (key) == INTEGER_CST); + + switch (TREE_CODE (index)) + { + case INTEGER_CST: + return tree_int_cst_compare (key, index); + case RANGE_EXPR: { + tree lo = TREE_OPERAND (index, 0); + tree hi = TREE_OPERAND (index, 1); + if (tree_int_cst_lt (key, lo)) + return -1; + else if (tree_int_cst_lt (hi, key)) + return 1; + else + return 0; + } + default: + gcc_unreachable (); + } +} + +/* If T is a CONSTRUCTOR, return an unshared copy of T and any + sub-CONSTRUCTORs. Otherwise return T. + + We use this whenever we initialize an object as a whole, whether it's a + parameter, a local variable, or a subobject, so that subsequent + modifications don't affect other places where it was used. */ + +tree +unshare_constructor (tree t MEM_STAT_DECL) +{ + if (!t || TREE_CODE (t) != CONSTRUCTOR) + return t; + auto_vec<tree *, 4> ptrs; + ptrs.safe_push (&t); + while (!ptrs.is_empty ()) + { + tree *p = ptrs.pop (); + tree n = copy_node (*p PASS_MEM_STAT); + CONSTRUCTOR_ELTS (n) + = vec_safe_copy (CONSTRUCTOR_ELTS (*p) PASS_MEM_STAT); + *p = n; + vec<constructor_elt, va_gc> *v = CONSTRUCTOR_ELTS (n); + constructor_elt *ce; + for (HOST_WIDE_INT i = 0; vec_safe_iterate (v, i, &ce); ++i) + if (ce->value && TREE_CODE (ce->value) == CONSTRUCTOR) + ptrs.safe_push (&ce->value); + } + return t; +} + +/* Returns the index of the constructor_elt of ARY which matches DINDEX, or -1 + if none. If INSERT is true, insert a matching element rather than fail. */ + +static HOST_WIDE_INT +find_array_ctor_elt (tree ary, tree dindex, bool insert) +{ + if (tree_int_cst_sgn (dindex) < 0) + return -1; + + unsigned HOST_WIDE_INT i = tree_to_uhwi (dindex); + vec<constructor_elt, va_gc> *elts = CONSTRUCTOR_ELTS (ary); + unsigned HOST_WIDE_INT len = vec_safe_length (elts); + + unsigned HOST_WIDE_INT end = len; + unsigned HOST_WIDE_INT begin = 0; + + /* If the last element of the CONSTRUCTOR has its own index, we can assume + that the same is true of the other elements and index directly. */ + if (end > 0) + { + tree cindex = (*elts)[end - 1].index; + if (cindex == NULL_TREE) + { + /* Verify that if the last index is missing, all indexes + are missing. */ + if (flag_checking) + for (unsigned int j = 0; j < len - 1; ++j) + gcc_assert ((*elts)[j].index == NULL_TREE); + if (i < end) + return i; + else + { + begin = end; + if (i == end) + /* If the element is to be added right at the end, + make sure it is added with cleared index too. */ + dindex = NULL_TREE; + else if (insert) + /* Otherwise, in order not to break the assumption + that CONSTRUCTOR either has all indexes or none, + we need to add indexes to all elements. */ + for (unsigned int j = 0; j < len; ++j) + (*elts)[j].index = build_int_cst (TREE_TYPE (dindex), j); + } + } + else if (TREE_CODE (cindex) == INTEGER_CST + && compare_tree_int (cindex, end - 1) == 0) + { + if (i < end) + return i; + else + begin = end; + } + } + + /* Otherwise, find a matching index by means of a binary search. */ + while (begin != end) + { + unsigned HOST_WIDE_INT middle = (begin + end) / 2; + constructor_elt &elt = (*elts)[middle]; + tree idx = elt.index; + + int cmp = array_index_cmp (dindex, idx); + if (cmp < 0) + end = middle; + else if (cmp > 0) + begin = middle + 1; + else + { + if (insert && TREE_CODE (idx) == RANGE_EXPR) + { + /* We need to split the range. */ + constructor_elt e; + tree lo = TREE_OPERAND (idx, 0); + tree hi = TREE_OPERAND (idx, 1); + tree value = elt.value; + dindex = fold_convert (sizetype, dindex); + if (tree_int_cst_lt (lo, dindex)) + { + /* There are still some lower elts; shorten the range. */ + tree new_hi + = int_const_binop (MINUS_EXPR, dindex, size_one_node); + if (tree_int_cst_equal (lo, new_hi)) + /* Only one element left, no longer a range. */ + elt.index = lo; + else + TREE_OPERAND (idx, 1) = new_hi; + /* Append the element we want to insert. */ + ++middle; + e.index = dindex; + e.value = unshare_constructor (value); + vec_safe_insert (CONSTRUCTOR_ELTS (ary), middle, e); + } + else + /* No lower elts, the range elt is now ours. */ + elt.index = dindex; + + if (tree_int_cst_lt (dindex, hi)) + { + /* There are still some higher elts; append a range. */ + tree new_lo + = int_const_binop (PLUS_EXPR, dindex, size_one_node); + if (tree_int_cst_equal (new_lo, hi)) + e.index = hi; + else + e.index = build2 (RANGE_EXPR, sizetype, new_lo, hi); + e.value = unshare_constructor (value); + vec_safe_insert (CONSTRUCTOR_ELTS (ary), middle + 1, e); + } + } + return middle; + } + } + + if (insert) + { + constructor_elt e = {dindex, NULL_TREE}; + vec_safe_insert (CONSTRUCTOR_ELTS (ary), end, e); + return end; + } + + return -1; +} + +/* Some expressions may have constant operands but are not constant + themselves, such as 1/0. Call this function to check for that + condition. + + We only call this in places that require an arithmetic constant, not in + places where we might have a non-constant expression that can be a + component of a constant expression, such as the address of a constexpr + variable that might be dereferenced later. */ + +static bool +verify_constant (tree t, bool allow_non_constant, bool *non_constant_p, + bool *overflow_p) +{ + if (!*non_constant_p && !reduced_constant_expression_p (t) && t != void_node) + { + if (!allow_non_constant) + error ("%q+E is not a constant expression", t); + *non_constant_p = true; + } + if (TREE_OVERFLOW_P (t)) + { + if (!allow_non_constant) + { + permerror (input_location, "overflow in constant expression"); + /* If we're being permissive (and are in an enforcing + context), ignore the overflow. */ + if (flag_permissive) + return *non_constant_p; + } + *overflow_p = true; + } + return *non_constant_p; +} + +// forked from gcc/cp/constexpr.cc find_heap_var_refs + +/* Look for heap variables in the expression *TP. */ + +static tree +find_heap_var_refs (tree *tp, int *walk_subtrees, void * /*data*/) +{ + if (VAR_P (*tp) + && (DECL_NAME (*tp) == heap_uninit_identifier + || DECL_NAME (*tp) == heap_identifier + || DECL_NAME (*tp) == heap_vec_uninit_identifier + || DECL_NAME (*tp) == heap_vec_identifier + || DECL_NAME (*tp) == heap_deleted_identifier)) + return *tp; + + if (TYPE_P (*tp)) + *walk_subtrees = 0; + return NULL_TREE; +} + +// forked from gcc/cp/constexpr.cc find_immediate_fndecl + +/* Find immediate function decls in *TP if any. */ + +static tree +find_immediate_fndecl (tree *tp, int * /*walk_subtrees*/, void * /*data*/) +{ + if (TREE_CODE (*tp) == FUNCTION_DECL && DECL_IMMEDIATE_FUNCTION_P (*tp)) + return *tp; + if (TREE_CODE (*tp) == PTRMEM_CST + && TREE_CODE (PTRMEM_CST_MEMBER (*tp)) == FUNCTION_DECL + && DECL_IMMEDIATE_FUNCTION_P (PTRMEM_CST_MEMBER (*tp))) + return PTRMEM_CST_MEMBER (*tp); + return NULL_TREE; +} + +// forked in gcc/cp/constexpr.cc diag_array_subscript + +/* Under the control of CTX, issue a detailed diagnostic for + an out-of-bounds subscript INDEX into the expression ARRAY. */ + +static void +diag_array_subscript (location_t loc, const constexpr_ctx *ctx, tree array, + tree index) +{ + if (!ctx->quiet) + { + tree arraytype = TREE_TYPE (array); + + /* Convert the unsigned array subscript to a signed integer to avoid + printing huge numbers for small negative values. */ + tree sidx = fold_convert (ssizetype, index); + STRIP_ANY_LOCATION_WRAPPER (array); + if (DECL_P (array)) + { + if (TYPE_DOMAIN (arraytype)) + error_at (loc, + "array subscript value %qE is outside the bounds " + "of array %qD of type %qT", + sidx, array, arraytype); + else + error_at (loc, + "nonzero array subscript %qE is used with array %qD of " + "type %qT with unknown bounds", + sidx, array, arraytype); + inform (DECL_SOURCE_LOCATION (array), "declared here"); + } + else if (TYPE_DOMAIN (arraytype)) + error_at (loc, + "array subscript value %qE is outside the bounds " + "of array type %qT", + sidx, arraytype); + else + error_at (loc, + "nonzero array subscript %qE is used with array of type %qT " + "with unknown bounds", + sidx, arraytype); + } +} + +// forked from gcc/cp/constexpr.cc get_array_or_vector_nelts + +/* Return the number of elements for TYPE (which is an ARRAY_TYPE or + a VECTOR_TYPE). */ + +static tree +get_array_or_vector_nelts (const constexpr_ctx *ctx, tree type, + bool *non_constant_p, bool *overflow_p) +{ + tree nelts; + if (TREE_CODE (type) == ARRAY_TYPE) + { + if (TYPE_DOMAIN (type)) + nelts = array_type_nelts_top (type); + else + nelts = size_zero_node; + } + else if (VECTOR_TYPE_P (type)) + nelts = size_int (TYPE_VECTOR_SUBPARTS (type)); + else + gcc_unreachable (); + + /* For VLAs, the number of elements won't be an integer constant. */ + nelts + = eval_constant_expression (ctx, nelts, false, non_constant_p, overflow_p); + return nelts; +} + +// forked from gcc/cp/constexpr.cc eval_and_check_array_index + +/* Subroutine of cxx_eval_array_reference. T is an ARRAY_REF; evaluate the + subscript, diagnose any problems with it, and return the result. */ + +static tree +eval_and_check_array_index (const constexpr_ctx *ctx, tree t, + bool allow_one_past, bool *non_constant_p, + bool *overflow_p) +{ + location_t loc = rs_expr_loc_or_input_loc (t); + tree ary = TREE_OPERAND (t, 0); + t = TREE_OPERAND (t, 1); + tree index = eval_constant_expression (ctx, t, allow_one_past, non_constant_p, + overflow_p); + VERIFY_CONSTANT (index); + + if (!tree_fits_shwi_p (index) || tree_int_cst_sgn (index) < 0) + { + diag_array_subscript (loc, ctx, ary, index); + *non_constant_p = true; + return t; + } + + tree nelts = get_array_or_vector_nelts (ctx, TREE_TYPE (ary), non_constant_p, + overflow_p); + VERIFY_CONSTANT (nelts); + if (allow_one_past ? !tree_int_cst_le (index, nelts) + : !tree_int_cst_lt (index, nelts)) + { + diag_array_subscript (loc, ctx, ary, index); + *non_constant_p = true; + return t; + } + + return index; +} + +// forked from gcc/cp/constexpr.cc extract_string_elt + +/* Extract element INDEX consisting of CHARS_PER_ELT chars from + STRING_CST STRING. */ + +static tree +extract_string_elt (tree string, unsigned chars_per_elt, unsigned index) +{ + tree type = cv_unqualified (TREE_TYPE (TREE_TYPE (string))); + tree r; + + if (chars_per_elt == 1) + r = build_int_cst (type, TREE_STRING_POINTER (string)[index]); + else + { + const unsigned char *ptr + = ((const unsigned char *) TREE_STRING_POINTER (string) + + index * chars_per_elt); + r = native_interpret_expr (type, ptr, chars_per_elt); + } + return r; +} + +/* Check whether the parameter and return types of FUN are valid for a + constexpr function, and complain if COMPLAIN. */ + +bool +is_valid_constexpr_fn (tree fun, bool complain) +{ + bool ret = true; + + for (tree parm = FUNCTION_FIRST_USER_PARM (fun); parm != NULL_TREE; + parm = TREE_CHAIN (parm)) + if (!literal_type_p (TREE_TYPE (parm))) + { + ret = false; + if (complain) + { + // auto_diagnostic_group d; + // error ("invalid type for parameter %d of %<constexpr%> " + // "function %q+#D", + // DECL_PARM_INDEX (parm), fun); + Location locus = Location (DECL_SOURCE_LOCATION (fun)); + rust_error_at ( + locus, "invalid type for parameter %d of %<constexpr%> function", + DECL_PARM_INDEX (parm)); + } + } + + return ret; +} + +void +explain_invalid_constexpr_fn (tree fun) +{ + static hash_set<tree> *diagnosed; + // tree body; + + if (diagnosed == NULL) + diagnosed = new hash_set<tree>; + if (diagnosed->add (fun)) + /* Already explained. */ + return; + + iloc_sentinel ils = input_location; + // if (!lambda_static_thunk_p (fun)) + // { + // /* Diagnostics should completely ignore the static thunk, so leave + // input_location set to our caller's location. */ + // input_location = DECL_SOURCE_LOCATION (fun); + // inform (input_location, + // "%qD is not usable as a %<constexpr%> function because:", + // fun); + // } + + /* First check the declaration. */ + if (is_valid_constexpr_fn (fun, true)) + { + // /* Then if it's OK, the body. */ + // if (!DECL_DECLARED_CONSTEXPR_P (fun)) + // explain_implicit_non_constexpr (fun); + // else + // { + // if (constexpr_fundef *fd = retrieve_constexpr_fundef (fun)) + // body = fd->body; + // else + // body = DECL_SAVED_TREE (fun); + // body = massage_constexpr_body (fun, body); + // require_potential_rvalue_constant_expression (body); + // } + } +} + +/* BODY is a validated and massaged definition of a constexpr + function. Register it in the hash table. */ + +void +register_constexpr_fundef (const constexpr_fundef &value) +{ + /* Create the constexpr function table if necessary. */ + if (constexpr_fundef_table == NULL) + constexpr_fundef_table + = hash_table<constexpr_fundef_hasher>::create_ggc (101); + + constexpr_fundef **slot = constexpr_fundef_table->find_slot ( + const_cast<constexpr_fundef *> (&value), INSERT); + + gcc_assert (*slot == NULL); + *slot = ggc_alloc<constexpr_fundef> (); + **slot = value; +} + +/* We are processing the definition of the constexpr function FUN. + Check that its body fulfills the apropriate requirements and + enter it in the constexpr function definition table. */ + +void +maybe_save_constexpr_fundef (tree fun) +{ + // FIXME + + constexpr_fundef entry = {fun, NULL_TREE, NULL_TREE, NULL_TREE}; + bool clear_ctx = false; + if (DECL_RESULT (fun) && DECL_CONTEXT (DECL_RESULT (fun)) == NULL_TREE) + { + clear_ctx = true; + DECL_CONTEXT (DECL_RESULT (fun)) = fun; + } + tree saved_fn = current_function_decl; + current_function_decl = fun; + entry.body = copy_fn (entry.decl, entry.parms, entry.result); + current_function_decl = saved_fn; + if (clear_ctx) + DECL_CONTEXT (DECL_RESULT (entry.decl)) = NULL_TREE; + + register_constexpr_fundef (entry); +} + +/* Evaluate a STATEMENT_LIST for side-effects. Handles various jump + semantics, for switch, break, continue, and return. */ + +static tree +eval_statement_list (const constexpr_ctx *ctx, tree t, bool *non_constant_p, + bool *overflow_p, tree *jump_target) +{ + tree local_target; + /* In a statement-expression we want to return the last value. + For empty statement expression return void_node. */ + tree r = void_node; + if (!jump_target) + { + local_target = NULL_TREE; + jump_target = &local_target; + } + for (tree stmt : tsi_range (t)) + { + /* We've found a continue, so skip everything until we reach + the label its jumping to. */ + if (continues (jump_target)) + { + if (label_matches (ctx, jump_target, stmt)) + /* Found it. */ + *jump_target = NULL_TREE; + else + continue; + } + if (TREE_CODE (stmt) == DEBUG_BEGIN_STMT) + continue; + r = eval_constant_expression (ctx, stmt, false, non_constant_p, + overflow_p, jump_target); + if (*non_constant_p) + break; + if (returns (jump_target) || breaks (jump_target)) + break; + } + if (*jump_target && jump_target == &local_target) + { + /* We aren't communicating the jump to our caller, so give up. We don't + need to support evaluation of jumps out of statement-exprs. */ + if (!ctx->quiet) + error_at (EXPR_LOCATION (r), "statement is not a constant expression"); + *non_constant_p = true; + } + return r; +} + +// forked from gcc/cp/constexpr.cc cxx_eval_conditional_expression + +/* Subroutine of cxx_eval_constant_expression. + Attempt to evaluate condition expressions. Dead branches are not + looked into. */ + +static tree +eval_conditional_expression (const constexpr_ctx *ctx, tree t, bool lval, + bool *non_constant_p, bool *overflow_p, + tree *jump_target) +{ + tree val + = eval_constant_expression (ctx, TREE_OPERAND (t, 0), + /*lval*/ false, non_constant_p, overflow_p); + VERIFY_CONSTANT (val); + if (TREE_CODE (t) == IF_STMT && IF_STMT_CONSTEVAL_P (t)) + { + /* Evaluate the condition as if it was + if (__builtin_is_constant_evaluated ()), i.e. defer it if not + ctx->manifestly_const_eval (as sometimes we try to constant evaluate + without manifestly_const_eval even expressions or parts thereof which + will later be manifestly const_eval evaluated), otherwise fold it to + true. */ + if (ctx->manifestly_const_eval) + val = boolean_true_node; + else + { + *non_constant_p = true; + return t; + } + } + /* Don't VERIFY_CONSTANT the other operands. */ + if (integer_zerop (val)) + val = TREE_OPERAND (t, 2); + else + val = TREE_OPERAND (t, 1); + if (/*TREE_CODE (t) == IF_STMT && */ !val) + val = void_node; + return eval_constant_expression (ctx, val, lval, non_constant_p, overflow_p, + jump_target); +} + +// forked from gcc/cp/constexpr.cc cxx_eval_bit_field_ref + +/* Subroutine of cxx_eval_constant_expression. + Attempt to reduce a field access of a value of class type that is + expressed as a BIT_FIELD_REF. */ + +static tree +eval_bit_field_ref (const constexpr_ctx *ctx, tree t, bool lval, + bool *non_constant_p, bool *overflow_p) +{ + tree orig_whole = TREE_OPERAND (t, 0); + tree retval, fldval, utype, mask; + bool fld_seen = false; + HOST_WIDE_INT istart, isize; + tree whole = eval_constant_expression (ctx, orig_whole, lval, non_constant_p, + overflow_p); + tree start, field, value; + unsigned HOST_WIDE_INT i; + + if (whole == orig_whole) + return t; + /* Don't VERIFY_CONSTANT here; we only want to check that we got a + CONSTRUCTOR. */ + if (!*non_constant_p && TREE_CODE (whole) != VECTOR_CST + && TREE_CODE (whole) != CONSTRUCTOR) + { + if (!ctx->quiet) + error ("%qE is not a constant expression", orig_whole); + *non_constant_p = true; + } + if (*non_constant_p) + return t; + + if (TREE_CODE (whole) == VECTOR_CST) + return fold_ternary (BIT_FIELD_REF, TREE_TYPE (t), whole, + TREE_OPERAND (t, 1), TREE_OPERAND (t, 2)); + + start = TREE_OPERAND (t, 2); + istart = tree_to_shwi (start); + isize = tree_to_shwi (TREE_OPERAND (t, 1)); + utype = TREE_TYPE (t); + if (!TYPE_UNSIGNED (utype)) + utype = build_nonstandard_integer_type (TYPE_PRECISION (utype), 1); + retval = build_int_cst (utype, 0); + FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (whole), i, field, value) + { + tree bitpos = bit_position (field); + STRIP_ANY_LOCATION_WRAPPER (value); + if (bitpos == start && DECL_SIZE (field) == TREE_OPERAND (t, 1)) + return value; + if (TREE_CODE (TREE_TYPE (field)) == INTEGER_TYPE + && TREE_CODE (value) == INTEGER_CST && tree_fits_shwi_p (bitpos) + && tree_fits_shwi_p (DECL_SIZE (field))) + { + HOST_WIDE_INT bit = tree_to_shwi (bitpos); + HOST_WIDE_INT sz = tree_to_shwi (DECL_SIZE (field)); + HOST_WIDE_INT shift; + if (bit >= istart && bit + sz <= istart + isize) + { + fldval = fold_convert (utype, value); + mask = build_int_cst_type (utype, -1); + mask = fold_build2 (LSHIFT_EXPR, utype, mask, + size_int (TYPE_PRECISION (utype) - sz)); + mask = fold_build2 (RSHIFT_EXPR, utype, mask, + size_int (TYPE_PRECISION (utype) - sz)); + fldval = fold_build2 (BIT_AND_EXPR, utype, fldval, mask); + shift = bit - istart; + if (BYTES_BIG_ENDIAN) + shift = TYPE_PRECISION (utype) - shift - sz; + fldval + = fold_build2 (LSHIFT_EXPR, utype, fldval, size_int (shift)); + retval = fold_build2 (BIT_IOR_EXPR, utype, retval, fldval); + fld_seen = true; + } + } + } + if (fld_seen) + return fold_convert (TREE_TYPE (t), retval); + gcc_unreachable (); + return error_mark_node; +} + +// forked from gcc/cp/constexpr.cc returns + +/* Predicates for the meaning of *jump_target. */ + +static bool +returns (tree *jump_target) +{ + return *jump_target + && (TREE_CODE (*jump_target) == RETURN_EXPR + || (TREE_CODE (*jump_target) == LABEL_DECL + && LABEL_DECL_CDTOR (*jump_target))); +} + +// forked from gcc/cp/constexpr.cc breaks + +static bool +breaks (tree *jump_target) +{ + return *jump_target + && ((TREE_CODE (*jump_target) == LABEL_DECL + && LABEL_DECL_BREAK (*jump_target)) + || TREE_CODE (*jump_target) == BREAK_STMT + || TREE_CODE (*jump_target) == EXIT_EXPR); +} + +// forked from gcc/cp/constexpr.cc continues + +static bool +continues (tree *jump_target) +{ + return *jump_target + && ((TREE_CODE (*jump_target) == LABEL_DECL + && LABEL_DECL_CONTINUE (*jump_target)) + || TREE_CODE (*jump_target) == CONTINUE_STMT); +} + +// forked from gcc/cp/constexpr.cc switches + +static bool +switches (tree *jump_target) +{ + return *jump_target && TREE_CODE (*jump_target) == INTEGER_CST; +} + +// forked from gcc/cp/constexpr.cc cxx_eval_loop_expr + +/* Evaluate a LOOP_EXPR for side-effects. Handles break and return + semantics; continue semantics are covered by cxx_eval_statement_list. */ + +static tree +eval_loop_expr (const constexpr_ctx *ctx, tree t, bool *non_constant_p, + bool *overflow_p, tree *jump_target) +{ + constexpr_ctx new_ctx = *ctx; + tree local_target; + if (!jump_target) + { + local_target = NULL_TREE; + jump_target = &local_target; + } + + tree body, cond = NULL_TREE, expr = NULL_TREE; + int count = 0; + switch (TREE_CODE (t)) + { + case LOOP_EXPR: + body = LOOP_EXPR_BODY (t); + break; + case WHILE_STMT: + body = WHILE_BODY (t); + cond = WHILE_COND (t); + count = -1; + break; + case FOR_STMT: + if (FOR_INIT_STMT (t)) + eval_constant_expression (ctx, FOR_INIT_STMT (t), /*lval*/ false, + non_constant_p, overflow_p, jump_target); + if (*non_constant_p) + return NULL_TREE; + body = FOR_BODY (t); + cond = FOR_COND (t); + expr = FOR_EXPR (t); + count = -1; + break; + default: + gcc_unreachable (); + } + auto_vec<tree, 10> save_exprs; + new_ctx.save_exprs = &save_exprs; + do + { + if (count != -1) + { + if (body) + eval_constant_expression (&new_ctx, body, /*lval*/ false, + non_constant_p, overflow_p, jump_target); + if (breaks (jump_target)) + { + *jump_target = NULL_TREE; + break; + } + + if (TREE_CODE (t) != LOOP_EXPR && continues (jump_target)) + *jump_target = NULL_TREE; + + if (expr) + eval_constant_expression (&new_ctx, expr, /*lval*/ false, + non_constant_p, overflow_p, jump_target); + } + + if (cond) + { + tree res = eval_constant_expression (&new_ctx, cond, /*lval*/ false, + non_constant_p, overflow_p, + jump_target); + if (res) + { + if (verify_constant (res, ctx->quiet, non_constant_p, overflow_p)) + break; + if (integer_zerop (res)) + break; + } + else + gcc_assert (*jump_target); + } + + /* Forget saved values of SAVE_EXPRs and TARGET_EXPRs. */ + for (tree save_expr : save_exprs) + ctx->global->values.remove (save_expr); + save_exprs.truncate (0); + + if (++count >= constexpr_loop_limit) + { + if (!ctx->quiet) + error_at (rs_expr_loc_or_input_loc (t), + "%<constexpr%> loop iteration count exceeds limit of %d " + "(use %<-fconstexpr-loop-limit=%> to increase the limit)", + constexpr_loop_limit); + *non_constant_p = true; + break; + } + } + while (!returns (jump_target) && !breaks (jump_target) + && !continues (jump_target) && (!switches (jump_target) || count == 0) + && !*non_constant_p); + + /* Forget saved values of SAVE_EXPRs and TARGET_EXPRs. */ + for (tree save_expr : save_exprs) + ctx->global->values.remove (save_expr); + + return NULL_TREE; +} + +// forked from gcc/cp/constexpr.cc cxx_eval_switch_expr + +/* Evaluate a SWITCH_EXPR for side-effects. Handles switch and break jump + semantics. */ + +static tree +eval_switch_expr (const constexpr_ctx *ctx, tree t, bool *non_constant_p, + bool *overflow_p, tree *jump_target) +{ + tree cond + = TREE_CODE (t) == SWITCH_STMT ? SWITCH_STMT_COND (t) : SWITCH_COND (t); + cond + = eval_constant_expression (ctx, cond, false, non_constant_p, overflow_p); + VERIFY_CONSTANT (cond); + *jump_target = cond; + + tree body + = TREE_CODE (t) == SWITCH_STMT ? SWITCH_STMT_BODY (t) : SWITCH_BODY (t); + constexpr_ctx new_ctx = *ctx; + constexpr_switch_state css = css_default_not_seen; + new_ctx.css_state = &css; + eval_constant_expression (&new_ctx, body, false, non_constant_p, overflow_p, + jump_target); + if (switches (jump_target) && css == css_default_seen) + { + /* If the SWITCH_EXPR body has default: label, process it once again, + this time instructing label_matches to return true for default: + label on switches (jump_target). */ + css = css_default_processing; + eval_constant_expression (&new_ctx, body, false, non_constant_p, + overflow_p, jump_target); + } + if (breaks (jump_target) || switches (jump_target)) + *jump_target = NULL_TREE; + return NULL_TREE; +} + +// forked from gcc/cp/constexpr.cc eval_unary_expression + +/* Subroutine of cxx_eval_constant_expression. + Attempt to reduce the unary expression tree T to a compile time value. + If successful, return the value. Otherwise issue a diagnostic + and return error_mark_node. */ + +static tree +eval_unary_expression (const constexpr_ctx *ctx, tree t, bool /*lval*/, + bool *non_constant_p, bool *overflow_p) +{ + tree r; + tree orig_arg = TREE_OPERAND (t, 0); + tree arg = eval_constant_expression (ctx, orig_arg, /*lval*/ false, + non_constant_p, overflow_p); + VERIFY_CONSTANT (arg); + location_t loc = EXPR_LOCATION (t); + enum tree_code code = TREE_CODE (t); + tree type = TREE_TYPE (t); + r = fold_unary_loc (loc, code, type, arg); + if (r == NULL_TREE) + { + if (arg == orig_arg) + r = t; + else + r = build1_loc (loc, code, type, arg); + } + VERIFY_CONSTANT (r); + return r; +} + +// forked from gcc/cp/constexpr.cc cxx_eval_outermost_constant_expr + +/* ALLOW_NON_CONSTANT is false if T is required to be a constant expression. + STRICT has the same sense as for constant_value_1: true if we only allow + conforming C++ constant expressions, or false if we want a constant value + even if it doesn't conform. + MANIFESTLY_CONST_EVAL is true if T is manifestly const-evaluated as + per P0595 even when ALLOW_NON_CONSTANT is true. + CONSTEXPR_DTOR is true when evaluating the dtor of a constexpr variable. + OBJECT must be non-NULL in that case. */ + +static tree +cxx_eval_outermost_constant_expr (tree t, bool allow_non_constant, + bool strict = true, + bool manifestly_const_eval = false, + bool constexpr_dtor = false, + tree object = NULL_TREE) +{ + auto_timevar time (TV_CONSTEXPR); + + bool non_constant_p = false; + bool overflow_p = false; + + if (BRACE_ENCLOSED_INITIALIZER_P (t)) + { + gcc_checking_assert (allow_non_constant); + return t; + } + + constexpr_global_ctx global_ctx; + constexpr_ctx ctx + = {&global_ctx, NULL, + NULL, NULL, + NULL, NULL, + NULL, allow_non_constant, + strict, manifestly_const_eval || !allow_non_constant}; + + /* Turn off -frounding-math for manifestly constant evaluation. */ + warning_sentinel rm (flag_rounding_math, ctx.manifestly_const_eval); + tree type = initialized_type (t); + tree r = t; + bool is_consteval = false; + if (VOID_TYPE_P (type)) + { + if (constexpr_dtor) + /* Used for destructors of array elements. */ + type = TREE_TYPE (object); + else + { + if (TREE_CODE (t) != CALL_EXPR) + return t; + /* Calls to immediate functions returning void need to be + evaluated. */ + tree fndecl = rs_get_callee_fndecl_nofold (t); + if (fndecl == NULL_TREE || !DECL_IMMEDIATE_FUNCTION_P (fndecl)) + return t; + else + is_consteval = true; + } + } + else if ((TREE_CODE (t) == CALL_EXPR || TREE_CODE (t) == TARGET_EXPR)) + { + /* For non-concept checks, determine if it is consteval. */ + tree x = t; + if (TREE_CODE (x) == TARGET_EXPR) + x = TARGET_EXPR_INITIAL (x); + tree fndecl = rs_get_callee_fndecl_nofold (x); + if (fndecl && DECL_IMMEDIATE_FUNCTION_P (fndecl)) + is_consteval = true; + } + if (AGGREGATE_TYPE_P (type) || VECTOR_TYPE_P (type)) + { + /* In C++14 an NSDMI can participate in aggregate initialization, + and can refer to the address of the object being initialized, so + we need to pass in the relevant VAR_DECL if we want to do the + evaluation in a single pass. The evaluation will dynamically + update ctx.values for the VAR_DECL. We use the same strategy + for C++11 constexpr constructors that refer to the object being + initialized. */ + if (constexpr_dtor) + { + gcc_assert (object && VAR_P (object)); + gcc_assert (DECL_DECLARED_CONSTEXPR_P (object)); + gcc_assert (DECL_INITIALIZED_BY_CONSTANT_EXPRESSION_P (object)); + if (error_operand_p (DECL_INITIAL (object))) + return t; + ctx.ctor = unshare_expr (DECL_INITIAL (object)); + TREE_READONLY (ctx.ctor) = false; + /* Temporarily force decl_really_constant_value to return false + for it, we want to use ctx.ctor for the current value instead. */ + DECL_INITIALIZED_BY_CONSTANT_EXPRESSION_P (object) = false; + } + else + { + ctx.ctor = build_constructor (type, NULL); + CONSTRUCTOR_NO_CLEARING (ctx.ctor) = true; + } + if (!object) + { + if (TREE_CODE (t) == TARGET_EXPR) + object = TARGET_EXPR_SLOT (t); + } + ctx.object = object; + if (object) + gcc_assert ( + same_type_ignoring_top_level_qualifiers_p (type, TREE_TYPE (object))); + if (object && DECL_P (object)) + global_ctx.values.put (object, ctx.ctor); + if (TREE_CODE (r) == TARGET_EXPR) + /* Avoid creating another CONSTRUCTOR when we expand the + TARGET_EXPR. */ + r = TARGET_EXPR_INITIAL (r); + } + + auto_vec<tree, 16> cleanups; + global_ctx.cleanups = &cleanups; + + if (manifestly_const_eval) + instantiate_constexpr_fns (r); + r = eval_constant_expression (&ctx, r, false, &non_constant_p, &overflow_p); + + if (!constexpr_dtor) + verify_constant (r, allow_non_constant, &non_constant_p, &overflow_p); + else + DECL_INITIALIZED_BY_CONSTANT_EXPRESSION_P (object) = true; + + unsigned int i; + tree cleanup; + /* Evaluate the cleanups. */ + FOR_EACH_VEC_ELT_REVERSE (cleanups, i, cleanup) + eval_constant_expression (&ctx, cleanup, false, &non_constant_p, + &overflow_p); + + /* Mutable logic is a bit tricky: we want to allow initialization of + constexpr variables with mutable members, but we can't copy those + members to another constexpr variable. */ + if (TREE_CODE (r) == CONSTRUCTOR && CONSTRUCTOR_MUTABLE_POISON (r)) + { + if (!allow_non_constant) + error ("%qE is not a constant expression because it refers to " + "mutable subobjects of %qT", + t, type); + non_constant_p = true; + } + + if (TREE_CODE (r) == CONSTRUCTOR && CONSTRUCTOR_NO_CLEARING (r)) + { + if (!allow_non_constant) + error ("%qE is not a constant expression because it refers to " + "an incompletely initialized variable", + t); + TREE_CONSTANT (r) = false; + non_constant_p = true; + } + + if (!global_ctx.heap_vars.is_empty ()) + { + tree heap_var + = rs_walk_tree_without_duplicates (&r, find_heap_var_refs, NULL); + unsigned int i; + if (heap_var) + { + if (!allow_non_constant && !non_constant_p) + error_at (DECL_SOURCE_LOCATION (heap_var), + "%qE is not a constant expression because it refers to " + "a result of %<operator new%>", + t); + r = t; + non_constant_p = true; + } + FOR_EACH_VEC_ELT (global_ctx.heap_vars, i, heap_var) + { + if (DECL_NAME (heap_var) != heap_deleted_identifier) + { + if (!allow_non_constant && !non_constant_p) + error_at (DECL_SOURCE_LOCATION (heap_var), + "%qE is not a constant expression because allocated " + "storage has not been deallocated", + t); + r = t; + non_constant_p = true; + } + varpool_node::get (heap_var)->remove (); + } + } + + /* Check that immediate invocation does not return an expression referencing + any immediate function decls. */ + if (is_consteval || in_immediate_context ()) + if (tree immediate_fndecl + = rs_walk_tree_without_duplicates (&r, find_immediate_fndecl, NULL)) + { + if (!allow_non_constant && !non_constant_p) + error_at (rs_expr_loc_or_input_loc (t), + "immediate evaluation returns address of immediate " + "function %qD", + immediate_fndecl); + r = t; + non_constant_p = true; + } + + if (non_constant_p) + /* If we saw something bad, go back to our argument. The wrapping below is + only for the cases of TREE_CONSTANT argument or overflow. */ + r = t; + + if (!non_constant_p && overflow_p) + non_constant_p = true; + + /* Unshare the result. */ + bool should_unshare = true; + if (r == t || (TREE_CODE (t) == TARGET_EXPR && TARGET_EXPR_INITIAL (t) == r)) + should_unshare = false; + + if (non_constant_p && !allow_non_constant) + return error_mark_node; + else if (constexpr_dtor) + return r; + else if (non_constant_p && TREE_CONSTANT (r)) + { + /* This isn't actually constant, so unset TREE_CONSTANT. + Don't clear TREE_CONSTANT on ADDR_EXPR, as the middle-end requires + it to be set if it is invariant address, even when it is not + a valid C++ constant expression. Wrap it with a NOP_EXPR + instead. */ + if (EXPR_P (r) && TREE_CODE (r) != ADDR_EXPR) + r = copy_node (r); + else if (TREE_CODE (r) == CONSTRUCTOR) + r = build1 (VIEW_CONVERT_EXPR, TREE_TYPE (r), r); + else + r = build_nop (TREE_TYPE (r), r); + TREE_CONSTANT (r) = false; + } + else if (non_constant_p) + return t; + + if (should_unshare) + r = unshare_expr (r); + + if (TREE_CODE (r) == CONSTRUCTOR && CLASS_TYPE_P (TREE_TYPE (r))) + { + r = adjust_temp_type (type, r); + if (TREE_CODE (t) == TARGET_EXPR && TARGET_EXPR_INITIAL (t) == r) + return t; + } + + /* Remember the original location if that wouldn't need a wrapper. */ + if (location_t loc = EXPR_LOCATION (t)) + protected_set_expr_location (r, loc); + + return r; +} + +/* Like is_constant_expression, but allow const variables that are not allowed + under constexpr rules. */ + +bool +is_static_init_expression (tree t) +{ + return potential_constant_expression_1 (t, false, false, true, tf_none); +} + +/* Like potential_constant_expression, but don't consider possible constexpr + substitution of the current function. That is, PARM_DECL qualifies under + potential_constant_expression, but not here. + + This is basically what you can check when any actual constant values might + be value-dependent. */ + +bool +is_constant_expression (tree t) +{ + return potential_constant_expression_1 (t, false, true, true, tf_none); +} + +/* Returns true if T is a potential static initializer expression that is not + instantiation-dependent. */ + +bool +is_nondependent_static_init_expression (tree t) +{ + return (!type_unknown_p (t) && is_static_init_expression (t)); +} + +/* Like maybe_constant_value, but returns a CONSTRUCTOR directly, rather + than wrapped in a TARGET_EXPR. + ALLOW_NON_CONSTANT is false if T is required to be a constant expression. + MANIFESTLY_CONST_EVAL is true if T is manifestly const-evaluated as + per P0595 even when ALLOW_NON_CONSTANT is true. */ + +static tree +maybe_constant_init_1 (tree t, tree decl, bool allow_non_constant, + bool manifestly_const_eval) +{ + if (!t) + return t; + if (TREE_CODE (t) == EXPR_STMT) + t = TREE_OPERAND (t, 0); + if (TREE_CODE (t) == CONVERT_EXPR && VOID_TYPE_P (TREE_TYPE (t))) + t = TREE_OPERAND (t, 0); + if (TREE_CODE (t) == INIT_EXPR) + t = TREE_OPERAND (t, 1); + if (TREE_CODE (t) == TARGET_EXPR) + t = TARGET_EXPR_INITIAL (t); + if (!is_nondependent_static_init_expression (t)) + /* Don't try to evaluate it. */; + else if (CONSTANT_CLASS_P (t) && allow_non_constant) + /* No evaluation needed. */; + else + t = cxx_eval_outermost_constant_expr (t, allow_non_constant, + /*strict*/ false, + manifestly_const_eval, false, decl); + if (TREE_CODE (t) == TARGET_EXPR) + { + tree init = TARGET_EXPR_INITIAL (t); + if (TREE_CODE (init) == CONSTRUCTOR) + t = init; + } + return t; +} + +/* Wrapper for maybe_constant_init_1 which permits non constants. */ + +tree +maybe_constant_init (tree t, tree decl, bool manifestly_const_eval) +{ + return maybe_constant_init_1 (t, decl, true, manifestly_const_eval); +} + +/* Returns true if T is a potential constant expression that is not + instantiation-dependent, and therefore a candidate for constant folding even + in a template. */ + +bool +is_nondependent_constant_expression (tree t) +{ + return (!type_unknown_p (t) && is_constant_expression (t) + && !instantiation_dependent_expression_p (t)); +} + +// forked from gcc/cp/parser.cc cp_unevaluated_operand + +/* Nonzero if we are parsing an unevaluated operand: an operand to + sizeof, typeof, or alignof. */ +int cp_unevaluated_operand; + +// forked from gcc/cp/constexpr.cc cv_cache + +/* If T is a constant expression, returns its reduced value. + Otherwise, if T does not have TREE_CONSTANT set, returns T. + Otherwise, returns a version of T without TREE_CONSTANT. + MANIFESTLY_CONST_EVAL is true if T is manifestly const-evaluated + as per P0595. */ + +static GTY ((deletable)) hash_map<tree, tree> *cv_cache; + +// forked from gcc/cp/constexpr.cc maybe_constant_value + +tree +maybe_constant_value (tree t, tree decl, bool manifestly_const_eval) +{ + tree r; + + if (!is_nondependent_constant_expression (t)) + { + if (TREE_OVERFLOW_P (t)) + { + t = build_nop (TREE_TYPE (t), t); + TREE_CONSTANT (t) = false; + } + return t; + } + else if (CONSTANT_CLASS_P (t)) + /* No caching or evaluation needed. */ + return t; + + if (manifestly_const_eval) + return cxx_eval_outermost_constant_expr (t, true, true, true, false, decl); + + if (cv_cache == NULL) + cv_cache = hash_map<tree, tree>::create_ggc (101); + if (tree *cached = cv_cache->get (t)) + { + r = *cached; + if (r != t) + { + // Faisal: commenting this out as not sure if it's needed and it's + // huge r = break_out_target_exprs (r, /*clear_loc*/true); + protected_set_expr_location (r, EXPR_LOCATION (t)); + } + return r; + } + + /* Don't evaluate an unevaluated operand. */ + if (cp_unevaluated_operand) + return t; + + uid_sensitive_constexpr_evaluation_checker c; + r = cxx_eval_outermost_constant_expr (t, true, true, false, false, decl); + gcc_checking_assert ( + r == t || CONVERT_EXPR_P (t) || TREE_CODE (t) == VIEW_CONVERT_EXPR + || (TREE_CONSTANT (t) && !TREE_CONSTANT (r)) || !rs_tree_equal (r, t)); + if (!c.evaluation_restricted_p ()) + cv_cache->put (t, r); + return r; +} + +// forked from gcc/cp/constexpr.cc + +bool +potential_constant_expression (tree t) +{ + return potential_constant_expression_1 (t, false, true, false, tf_none); +} + +/* Data structure for passing data from potential_constant_expression_1 + to check_for_return_continue via cp_walk_tree. */ +struct check_for_return_continue_data +{ + hash_set<tree> *pset; + tree continue_stmt; + tree break_stmt; +}; + +/* Helper function for potential_constant_expression_1 SWITCH_STMT handling, + called through cp_walk_tree. Return the first RETURN_EXPR found, or note + the first CONTINUE_STMT and/or BREAK_STMT if RETURN_EXPR is not found. */ +static tree +check_for_return_continue (tree *tp, int *walk_subtrees, void *data) +{ + tree t = *tp, s, b; + check_for_return_continue_data *d = (check_for_return_continue_data *) data; + switch (TREE_CODE (t)) + { + case RETURN_EXPR: + return t; + + case CONTINUE_STMT: + if (d->continue_stmt == NULL_TREE) + d->continue_stmt = t; + break; + + case BREAK_STMT: + if (d->break_stmt == NULL_TREE) + d->break_stmt = t; + break; + +#define RECUR(x) \ + if (tree r = rs_walk_tree (&x, check_for_return_continue, data, d->pset)) \ + return r + + /* For loops, walk subtrees manually, so that continue stmts found + inside of the bodies of the loops are ignored. */ + + case WHILE_STMT: + *walk_subtrees = 0; + RECUR (WHILE_COND (t)); + s = d->continue_stmt; + b = d->break_stmt; + RECUR (WHILE_BODY (t)); + d->continue_stmt = s; + d->break_stmt = b; + break; + + case FOR_STMT: + *walk_subtrees = 0; + RECUR (FOR_INIT_STMT (t)); + RECUR (FOR_COND (t)); + RECUR (FOR_EXPR (t)); + s = d->continue_stmt; + b = d->break_stmt; + RECUR (FOR_BODY (t)); + d->continue_stmt = s; + d->break_stmt = b; + break; + + case RANGE_FOR_STMT: + *walk_subtrees = 0; + RECUR (RANGE_FOR_EXPR (t)); + s = d->continue_stmt; + b = d->break_stmt; + RECUR (RANGE_FOR_BODY (t)); + d->continue_stmt = s; + d->break_stmt = b; + break; + + case SWITCH_STMT: + *walk_subtrees = 0; + RECUR (SWITCH_STMT_COND (t)); + b = d->break_stmt; + RECUR (SWITCH_STMT_BODY (t)); + d->break_stmt = b; + break; +#undef RECUR + + case STATEMENT_LIST: + case CONSTRUCTOR: + break; + + default: + if (!EXPR_P (t)) + *walk_subtrees = 0; + break; + } + + return NULL_TREE; +} + +/* Returns the namespace that contains DECL, whether directly or + indirectly. */ + +tree +decl_namespace_context (tree decl) +{ + while (1) + { + if (TREE_CODE (decl) == NAMESPACE_DECL) + return decl; + else if (TYPE_P (decl)) + decl = CP_DECL_CONTEXT (TYPE_MAIN_DECL (decl)); + else + decl = CP_DECL_CONTEXT (decl); + } +} + +/* Returns true if DECL is in the std namespace. */ + +bool +decl_in_std_namespace_p (tree decl) +{ + while (decl) + { + decl = decl_namespace_context (decl); + if (DECL_NAMESPACE_STD_P (decl)) + return true; + /* Allow inline namespaces inside of std namespace, e.g. with + --enable-symvers=gnu-versioned-namespace std::forward would be + actually std::_8::forward. */ + if (!DECL_NAMESPACE_INLINE_P (decl)) + return false; + decl = CP_DECL_CONTEXT (decl); + } + return false; +} + +/* Return true if FNDECL is std::construct_at. */ + +static inline bool +is_std_construct_at (tree fndecl) +{ + if (!decl_in_std_namespace_p (fndecl)) + return false; + + tree name = DECL_NAME (fndecl); + return name && id_equal (name, "construct_at"); +} + +/* Return true if FNDECL is __dynamic_cast. */ + +static inline bool +cxx_dynamic_cast_fn_p (tree fndecl) +{ + return (id_equal (DECL_NAME (fndecl), "__dynamic_cast") + && CP_DECL_CONTEXT (fndecl) == global_namespace); +} + +/* Return true if FNDECL is std::allocator<T>::{,de}allocate. */ + +static inline bool +is_std_allocator_allocate (tree fndecl) +{ + tree name = DECL_NAME (fndecl); + if (name == NULL_TREE + || !(id_equal (name, "allocate") || id_equal (name, "deallocate"))) + return false; + + tree ctx = DECL_CONTEXT (fndecl); + if (ctx == NULL_TREE || !CLASS_TYPE_P (ctx) || !TYPE_MAIN_DECL (ctx)) + return false; + + tree decl = TYPE_MAIN_DECL (ctx); + name = DECL_NAME (decl); + if (name == NULL_TREE || !id_equal (name, "allocator")) + return false; + + return decl_in_std_namespace_p (decl); +} + +/* Overload for the above taking constexpr_call*. */ + +static inline bool +is_std_allocator_allocate (const constexpr_call *call) +{ + return (call && call->fundef + && is_std_allocator_allocate (call->fundef->decl)); +} + +/* Return true if T denotes a potentially constant expression. Issue + diagnostic as appropriate under control of FLAGS. If WANT_RVAL is true, + an lvalue-rvalue conversion is implied. If NOW is true, we want to + consider the expression in the current context, independent of constexpr + substitution. + + C++0x [expr.const] used to say + + 6 An expression is a potential constant expression if it is + a constant expression where all occurrences of function + parameters are replaced by arbitrary constant expressions + of the appropriate type. + + 2 A conditional expression is a constant expression unless it + involves one of the following as a potentially evaluated + subexpression (3.2), but subexpressions of logical AND (5.14), + logical OR (5.15), and conditional (5.16) operations that are + not evaluated are not considered. */ + +static bool +potential_constant_expression_1 (tree t, bool want_rval, bool strict, bool now, + tsubst_flags_t flags, tree *jump_target) +{ +#define RECUR(T, RV) \ + potential_constant_expression_1 ((T), (RV), strict, now, flags, jump_target) + + enum + { + any = false, + rval = true + }; + int i; + tree tmp; + + if (t == error_mark_node) + return false; + if (t == NULL_TREE) + return true; + location_t loc = rs_expr_loc_or_input_loc (t); + + if (*jump_target) + /* If we are jumping, ignore everything. This is simpler than the + cxx_eval_constant_expression handling because we only need to be + conservatively correct, and we don't necessarily have a constant value + available, so we don't bother with switch tracking. */ + return true; + + if (TREE_THIS_VOLATILE (t) && want_rval) + { + if (flags & tf_error) + error_at (loc, + "lvalue-to-rvalue conversion of a volatile lvalue " + "%qE with type %qT", + t, TREE_TYPE (t)); + return false; + } + if (CONSTANT_CLASS_P (t)) + return true; + if (CODE_CONTAINS_STRUCT (TREE_CODE (t), TS_TYPED) + && TREE_TYPE (t) == error_mark_node) + return false; + + switch (TREE_CODE (t)) + { + case FUNCTION_DECL: + case OVERLOAD: + case LABEL_DECL: + case CASE_LABEL_EXPR: + case PREDICT_EXPR: + case CONST_DECL: + case IDENTIFIER_NODE: + /* We can see a FIELD_DECL in a pointer-to-member expression. */ + case FIELD_DECL: + case RESULT_DECL: + case PLACEHOLDER_EXPR: + case STATIC_ASSERT: + return true; + + case RETURN_EXPR: + if (!RECUR (TREE_OPERAND (t, 0), any)) + return false; + /* FALLTHROUGH */ + + case BREAK_STMT: + case CONTINUE_STMT: + *jump_target = t; + return true; + + case PARM_DECL: + if (now && want_rval) + { + tree type = TREE_TYPE (t); + if (is_really_empty_class (type, /*ignore_vptr*/ false)) + /* An empty class has no data to read. */ + return true; + if (flags & tf_error) + error ("%qE is not a constant expression", t); + return false; + } + return true; + + case CALL_EXPR: + /* -- an invocation of a function other than a constexpr function + or a constexpr constructor. */ + { + tree fun = get_function_named_in_call (t); + const int nargs = call_expr_nargs (t); + i = 0; + + if (fun == NULL_TREE) + { + /* Reset to allow the function to continue past the end + of the block below. Otherwise return early. */ + bool bail = true; + + if (TREE_CODE (t) == CALL_EXPR && CALL_EXPR_FN (t) == NULL_TREE) + switch (CALL_EXPR_IFN (t)) + { + /* These should be ignored, they are optimized away from + constexpr functions. */ + case IFN_UBSAN_NULL: + case IFN_UBSAN_BOUNDS: + case IFN_UBSAN_VPTR: + case IFN_FALLTHROUGH: + return true; + + case IFN_ADD_OVERFLOW: + case IFN_SUB_OVERFLOW: + case IFN_MUL_OVERFLOW: + case IFN_LAUNDER: + case IFN_VEC_CONVERT: + bail = false; + break; + + default: + break; + } + + if (bail) + { + /* fold_call_expr can't do anything with IFN calls. */ + if (flags & tf_error) + error_at (loc, "call to internal function %qE", t); + return false; + } + } + + if (fun && is_overloaded_fn (fun)) + { + if (TREE_CODE (fun) == FUNCTION_DECL) + { + if (builtin_valid_in_constant_expr_p (fun)) + return true; + if (!maybe_constexpr_fn (fun) + /* Allow any built-in function; if the expansion + isn't constant, we'll deal with that then. */ + && !fndecl_built_in_p (fun) + /* In C++20, replaceable global allocation functions + are constant expressions. */ + && (/* !cxx_replaceable_global_alloc_fn (fun) + ||*/ TREE_CODE (t) != CALL_EXPR + || (!CALL_FROM_NEW_OR_DELETE_P (t) + && (current_function_decl == NULL_TREE + /*|| !is_std_allocator_allocate(current_function_decl)*/))) + /* Allow placement new in std::construct_at. */ + && (/*!cxx_placement_new_fn (fun) + ||*/ TREE_CODE (t) != CALL_EXPR + || current_function_decl == NULL_TREE + /*|| !is_std_construct_at (current_function_decl)*/) + /* && !cxx_dynamic_cast_fn_p (fun)*/) + { + if (flags & tf_error) + { + error_at (loc, "call to non-%<constexpr%> function %qD", + fun); + explain_invalid_constexpr_fn (fun); + } + return false; + } + /* A call to a non-static member function takes the address + of the object as the first argument. But in a constant + expression the address will be folded away, so look + through it now. */ + if (DECL_NONSTATIC_MEMBER_FUNCTION_P (fun) + && !DECL_CONSTRUCTOR_P (fun)) + { + tree x = get_nth_callarg (t, 0); + + /* Don't require an immediately constant value, as + constexpr substitution might not use the value. */ + bool sub_now = false; + if (!potential_constant_expression_1 (x, rval, strict, + sub_now, flags, + jump_target)) + return false; + i = 1; + } + } + else + { + if (!RECUR (fun, true)) + return false; + fun = get_first_fn (fun); + } + fun = DECL_ORIGIN (fun); + } + else if (fun) + { + if (RECUR (fun, rval)) + /* Might end up being a constant function pointer. */; + else + return false; + } + for (; i < nargs; ++i) + { + tree x = get_nth_callarg (t, i); + /* In a template, reference arguments haven't been converted to + REFERENCE_TYPE and we might not even know if the parameter + is a reference, so accept lvalue constants too. */ + bool rv = rval; + /* Don't require an immediately constant value, as constexpr + substitution might not use the value of the argument. */ + bool sub_now = false; + if (!potential_constant_expression_1 (x, rv, strict, sub_now, flags, + jump_target)) + return false; + } + return true; + } + + case NON_LVALUE_EXPR: + /* -- an lvalue-to-rvalue conversion (4.1) unless it is applied to + -- an lvalue of integral type that refers to a non-volatile + const variable or static data member initialized with + constant expressions, or + + -- an lvalue of literal type that refers to non-volatile + object defined with constexpr, or that refers to a + sub-object of such an object; */ + return RECUR (TREE_OPERAND (t, 0), rval); + + case VAR_DECL: + if (DECL_HAS_VALUE_EXPR_P (t)) + { + return RECUR (DECL_VALUE_EXPR (t), rval); + } + if (want_rval && !var_in_maybe_constexpr_fn (t) + && !decl_maybe_constant_var_p (t) + && (strict || !RS_TYPE_CONST_NON_VOLATILE_P (TREE_TYPE (t)) + || (DECL_INITIAL (t) + && !DECL_INITIALIZED_BY_CONSTANT_EXPRESSION_P (t))) + && COMPLETE_TYPE_P (TREE_TYPE (t)) + && !is_really_empty_class (TREE_TYPE (t), /*ignore_vptr*/ false)) + { + if (flags & tf_error) + non_const_var_error (loc, t); + return false; + } + return true; + + /* FALLTHRU */ + case NOP_EXPR: + case CONVERT_EXPR: + case VIEW_CONVERT_EXPR: + /* -- a reinterpret_cast. FIXME not implemented, and this rule + may change to something more specific to type-punning (DR 1312). */ + { + tree from = TREE_OPERAND (t, 0); + if (location_wrapper_p (t)) + return (RECUR (from, want_rval)); + if (INDIRECT_TYPE_P (TREE_TYPE (t))) + { + STRIP_ANY_LOCATION_WRAPPER (from); + if (TREE_CODE (from) == INTEGER_CST && !integer_zerop (from)) + { + if (flags & tf_error) + error_at (loc, + "%<reinterpret_cast%> from integer to pointer"); + return false; + } + } + return (RECUR (from, TREE_CODE (t) != VIEW_CONVERT_EXPR)); + } + + case ADDR_EXPR: + /* -- a unary operator & that is applied to an lvalue that + designates an object with thread or automatic storage + duration; */ + t = TREE_OPERAND (t, 0); + + if (TREE_CODE (t) == OFFSET_REF && PTRMEM_OK_P (t)) + /* A pointer-to-member constant. */ + return true; + + // handle_addr_expr: +#if 0 + /* FIXME adjust when issue 1197 is fully resolved. For now don't do + any checking here, as we might dereference the pointer later. If + we remove this code, also remove check_automatic_or_tls. */ + i = check_automatic_or_tls (t); + if (i == ck_ok) + return true; + if (i == ck_bad) + { + if (flags & tf_error) + error ("address-of an object %qE with thread local or " + "automatic storage is not a constant expression", t); + return false; + } +#endif + return RECUR (t, any); + + case COMPONENT_REF: + /* -- a class member access unless its postfix-expression is + of literal type or of pointer to literal type. */ + /* This test would be redundant, as it follows from the + postfix-expression being a potential constant expression. */ + if (type_unknown_p (t)) + return true; + if (is_overloaded_fn (t)) + /* In a template, a COMPONENT_REF of a function expresses ob.fn(), + which uses ob as an lvalue. */ + want_rval = false; + gcc_fallthrough (); + + case REALPART_EXPR: + case IMAGPART_EXPR: + case BIT_FIELD_REF: + return RECUR (TREE_OPERAND (t, 0), want_rval); + + case INDIRECT_REF: { + tree x = TREE_OPERAND (t, 0); + STRIP_NOPS (x); + return RECUR (x, rval); + } + + case STATEMENT_LIST: + for (tree stmt : tsi_range (t)) + if (!RECUR (stmt, any)) + return false; + return true; + + case MODIFY_EXPR: + if (!RECUR (TREE_OPERAND (t, 0), any)) + return false; + /* Just ignore clobbers. */ + if (TREE_CLOBBER_P (TREE_OPERAND (t, 1))) + return true; + if (!RECUR (TREE_OPERAND (t, 1), rval)) + return false; + return true; + + case FOR_STMT: + if (!RECUR (FOR_INIT_STMT (t), any)) + return false; + tmp = FOR_COND (t); + if (!RECUR (tmp, rval)) + return false; + if (tmp) + { + tmp = cxx_eval_outermost_constant_expr (tmp, true); + /* If we couldn't evaluate the condition, it might not ever be + true. */ + if (!integer_onep (tmp)) + { + /* Before returning true, check if the for body can contain + a return. */ + hash_set<tree> pset; + check_for_return_continue_data data + = {&pset, NULL_TREE, NULL_TREE}; + if (tree ret_expr + = rs_walk_tree (&FOR_BODY (t), check_for_return_continue, + &data, &pset)) + *jump_target = ret_expr; + return true; + } + } + if (!RECUR (FOR_EXPR (t), any)) + return false; + if (!RECUR (FOR_BODY (t), any)) + return false; + if (breaks (jump_target) || continues (jump_target)) + *jump_target = NULL_TREE; + return true; + + case WHILE_STMT: + tmp = WHILE_COND (t); + if (!RECUR (tmp, rval)) + return false; + + tmp = cxx_eval_outermost_constant_expr (tmp, true); + /* If we couldn't evaluate the condition, it might not ever be true. */ + if (!integer_onep (tmp)) + { + /* Before returning true, check if the while body can contain + a return. */ + hash_set<tree> pset; + check_for_return_continue_data data = {&pset, NULL_TREE, NULL_TREE}; + if (tree ret_expr + = rs_walk_tree (&WHILE_BODY (t), check_for_return_continue, &data, + &pset)) + *jump_target = ret_expr; + return true; + } + if (!RECUR (WHILE_BODY (t), any)) + return false; + if (breaks (jump_target) || continues (jump_target)) + *jump_target = NULL_TREE; + return true; + + case SWITCH_STMT: + if (!RECUR (SWITCH_STMT_COND (t), rval)) + return false; + /* FIXME we don't check SWITCH_STMT_BODY currently, because even + unreachable labels would be checked and it is enough if there is + a single switch cond value for which it is a valid constant + expression. We need to check if there are any RETURN_EXPRs + or CONTINUE_STMTs inside of the body though, as in that case + we need to set *jump_target. */ + else + { + hash_set<tree> pset; + check_for_return_continue_data data = {&pset, NULL_TREE, NULL_TREE}; + if (tree ret_expr + = rs_walk_tree (&SWITCH_STMT_BODY (t), check_for_return_continue, + &data, &pset)) + /* The switch might return. */ + *jump_target = ret_expr; + else if (data.continue_stmt) + /* The switch can't return, but might continue. */ + *jump_target = data.continue_stmt; + } + return true; + + case DYNAMIC_CAST_EXPR: + case PSEUDO_DTOR_EXPR: + case NEW_EXPR: + case VEC_NEW_EXPR: + case DELETE_EXPR: + case VEC_DELETE_EXPR: + case THROW_EXPR: + case OMP_PARALLEL: + case OMP_TASK: + case OMP_FOR: + case OMP_SIMD: + case OMP_DISTRIBUTE: + case OMP_TASKLOOP: + case OMP_LOOP: + case OMP_TEAMS: + case OMP_TARGET_DATA: + case OMP_TARGET: + case OMP_SECTIONS: + case OMP_ORDERED: + case OMP_CRITICAL: + case OMP_SINGLE: + case OMP_SECTION: + case OMP_MASTER: + case OMP_MASKED: + case OMP_TASKGROUP: + case OMP_TARGET_UPDATE: + case OMP_TARGET_ENTER_DATA: + case OMP_TARGET_EXIT_DATA: + case OMP_ATOMIC: + case OMP_ATOMIC_READ: + case OMP_ATOMIC_CAPTURE_OLD: + case OMP_ATOMIC_CAPTURE_NEW: + case OMP_DEPOBJ: + case OACC_PARALLEL: + case OACC_KERNELS: + case OACC_SERIAL: + case OACC_DATA: + case OACC_HOST_DATA: + case OACC_LOOP: + case OACC_CACHE: + case OACC_DECLARE: + case OACC_ENTER_DATA: + case OACC_EXIT_DATA: + case OACC_UPDATE: + /* GCC internal stuff. */ + case VA_ARG_EXPR: + case TRANSACTION_EXPR: + case AT_ENCODE_EXPR: + + if (flags & tf_error) + error_at (loc, "expression %qE is not a constant expression", t); + return false; + + case ASM_EXPR: + if (flags & tf_error) + inline_asm_in_constexpr_error (loc); + return false; + + case OBJ_TYPE_REF: + return true; + + case POINTER_DIFF_EXPR: + case MINUS_EXPR: + want_rval = true; + goto binary; + + case LT_EXPR: + case LE_EXPR: + case GT_EXPR: + case GE_EXPR: + case EQ_EXPR: + case NE_EXPR: + case SPACESHIP_EXPR: + want_rval = true; + goto binary; + + case PREINCREMENT_EXPR: + case POSTINCREMENT_EXPR: + case PREDECREMENT_EXPR: + case POSTDECREMENT_EXPR: + goto unary; + + case BIT_NOT_EXPR: + /* A destructor. */ + if (TYPE_P (TREE_OPERAND (t, 0))) + return true; + /* fall through. */ + + case CONJ_EXPR: + case SAVE_EXPR: + case FIX_TRUNC_EXPR: + case FLOAT_EXPR: + case NEGATE_EXPR: + case ABS_EXPR: + case ABSU_EXPR: + case TRUTH_NOT_EXPR: + case FIXED_CONVERT_EXPR: + case UNARY_PLUS_EXPR: + case UNARY_LEFT_FOLD_EXPR: + case UNARY_RIGHT_FOLD_EXPR: + unary: + return RECUR (TREE_OPERAND (t, 0), rval); + + case BIND_EXPR: + return RECUR (BIND_EXPR_BODY (t), want_rval); + + case CLEANUP_POINT_EXPR: + case EXPR_STMT: + case PAREN_EXPR: + case NON_DEPENDENT_EXPR: + /* For convenience. */ + case LOOP_EXPR: + case EXIT_EXPR: + return RECUR (TREE_OPERAND (t, 0), want_rval); + + case DECL_EXPR: + tmp = DECL_EXPR_DECL (t); + if (VAR_P (tmp) && !DECL_ARTIFICIAL (tmp)) + { + if (RS_DECL_THREAD_LOCAL_P (tmp)) + { + if (flags & tf_error) + error_at (DECL_SOURCE_LOCATION (tmp), + "%qD declared " + "%<thread_local%> in %<constexpr%> context", + tmp); + return false; + } + else if (TREE_STATIC (tmp)) + { + if (flags & tf_error) + error_at (DECL_SOURCE_LOCATION (tmp), + "%qD declared " + "%<static%> in %<constexpr%> context", + tmp); + return false; + } + else if (!check_for_uninitialized_const_var ( + tmp, /*constexpr_context_p=*/true, flags)) + return false; + } + return RECUR (tmp, want_rval); + + case TRY_FINALLY_EXPR: + return (RECUR (TREE_OPERAND (t, 0), want_rval) + && RECUR (TREE_OPERAND (t, 1), any)); + + case SCOPE_REF: + return RECUR (TREE_OPERAND (t, 1), want_rval); + + case TARGET_EXPR: + if (!TARGET_EXPR_DIRECT_INIT_P (t) && !literal_type_p (TREE_TYPE (t))) + { + if (flags & tf_error) + { + auto_diagnostic_group d; + error_at (loc, + "temporary of non-literal type %qT in a " + "constant expression", + TREE_TYPE (t)); + explain_non_literal_class (TREE_TYPE (t)); + } + return false; + } + /* FALLTHRU */ + case INIT_EXPR: + return RECUR (TREE_OPERAND (t, 1), rval); + + case CONSTRUCTOR: { + vec<constructor_elt, va_gc> *v = CONSTRUCTOR_ELTS (t); + constructor_elt *ce; + for (i = 0; vec_safe_iterate (v, i, &ce); ++i) + if (!RECUR (ce->value, want_rval)) + return false; + return true; + } + + case TREE_LIST: { + gcc_assert (TREE_PURPOSE (t) == NULL_TREE || DECL_P (TREE_PURPOSE (t))); + if (!RECUR (TREE_VALUE (t), want_rval)) + return false; + if (TREE_CHAIN (t) == NULL_TREE) + return true; + return RECUR (TREE_CHAIN (t), want_rval); + } + + case TRUNC_DIV_EXPR: + case CEIL_DIV_EXPR: + case FLOOR_DIV_EXPR: + case ROUND_DIV_EXPR: + case TRUNC_MOD_EXPR: + case CEIL_MOD_EXPR: + case ROUND_MOD_EXPR: { + tree denom = TREE_OPERAND (t, 1); + if (!RECUR (denom, rval)) + return false; + /* We can't call cxx_eval_outermost_constant_expr on an expression + that hasn't been through instantiate_non_dependent_expr yet. */ + denom = cxx_eval_outermost_constant_expr (denom, true); + if (integer_zerop (denom)) + { + if (flags & tf_error) + error ("division by zero is not a constant expression"); + return false; + } + else + { + want_rval = true; + return RECUR (TREE_OPERAND (t, 0), want_rval); + } + } + + case COMPOUND_EXPR: { + /* check_return_expr sometimes wraps a TARGET_EXPR in a + COMPOUND_EXPR; don't get confused. */ + tree op0 = TREE_OPERAND (t, 0); + tree op1 = TREE_OPERAND (t, 1); + STRIP_NOPS (op1); + if (TREE_CODE (op0) == TARGET_EXPR && op1 == TARGET_EXPR_SLOT (op0)) + return RECUR (op0, want_rval); + else + goto binary; + } + + /* If the first operand is the non-short-circuit constant, look at + the second operand; otherwise we only care about the first one for + potentiality. */ + case TRUTH_AND_EXPR: + case TRUTH_ANDIF_EXPR: + tmp = boolean_true_node; + goto truth; + case TRUTH_OR_EXPR: + case TRUTH_ORIF_EXPR: + tmp = boolean_false_node; + truth : { + tree op0 = TREE_OPERAND (t, 0); + tree op1 = TREE_OPERAND (t, 1); + if (!RECUR (op0, rval)) + return false; + if (!(flags & tf_error) && RECUR (op1, rval)) + /* When quiet, try to avoid expensive trial evaluation by first + checking potentiality of the second operand. */ + return true; + op0 = cxx_eval_outermost_constant_expr (op0, true); + if (tree_int_cst_equal (op0, tmp)) + return (flags & tf_error) ? RECUR (op1, rval) : false; + else + return true; + } + + case PLUS_EXPR: + case MULT_EXPR: + case POINTER_PLUS_EXPR: + case RDIV_EXPR: + case EXACT_DIV_EXPR: + case MIN_EXPR: + case MAX_EXPR: + case LSHIFT_EXPR: + case RSHIFT_EXPR: + case LROTATE_EXPR: + case RROTATE_EXPR: + case BIT_IOR_EXPR: + case BIT_XOR_EXPR: + case BIT_AND_EXPR: + case TRUTH_XOR_EXPR: + case UNORDERED_EXPR: + case ORDERED_EXPR: + case UNLT_EXPR: + case UNLE_EXPR: + case UNGT_EXPR: + case UNGE_EXPR: + case UNEQ_EXPR: + case LTGT_EXPR: + case RANGE_EXPR: + case COMPLEX_EXPR: + want_rval = true; + /* Fall through. */ + case ARRAY_REF: + case ARRAY_RANGE_REF: + case MEMBER_REF: + case DOTSTAR_EXPR: + case MEM_REF: + case BINARY_LEFT_FOLD_EXPR: + case BINARY_RIGHT_FOLD_EXPR: + binary: + for (i = 0; i < 2; ++i) + if (!RECUR (TREE_OPERAND (t, i), want_rval)) + return false; + return true; + + case VEC_PERM_EXPR: + for (i = 0; i < 3; ++i) + if (!RECUR (TREE_OPERAND (t, i), true)) + return false; + return true; + + case COND_EXPR: + if (COND_EXPR_IS_VEC_DELETE (t)) + { + if (flags & tf_error) + error_at (loc, "%<delete[]%> is not a constant expression"); + return false; + } + /* Fall through. */ + case IF_STMT: + case VEC_COND_EXPR: + /* If the condition is a known constant, we know which of the legs we + care about; otherwise we only require that the condition and + either of the legs be potentially constant. */ + tmp = TREE_OPERAND (t, 0); + if (!RECUR (tmp, rval)) + return false; + + tmp = cxx_eval_outermost_constant_expr (tmp, true); + /* potential_constant_expression* isn't told if it is called for + manifestly_const_eval or not, so for consteval if always + process both branches as if the condition is not a known + constant. */ + if (TREE_CODE (t) != IF_STMT || !IF_STMT_CONSTEVAL_P (t)) + { + if (integer_zerop (tmp)) + return RECUR (TREE_OPERAND (t, 2), want_rval); + else if (TREE_CODE (tmp) == INTEGER_CST) + return RECUR (TREE_OPERAND (t, 1), want_rval); + } + tmp = *jump_target; + for (i = 1; i < 3; ++i) + { + tree this_jump_target = tmp; + if (potential_constant_expression_1 (TREE_OPERAND (t, i), want_rval, + strict, now, tf_none, + &this_jump_target)) + { + if (returns (&this_jump_target)) + *jump_target = this_jump_target; + else if (!returns (jump_target)) + { + if (breaks (&this_jump_target) + || continues (&this_jump_target)) + *jump_target = this_jump_target; + if (i == 1) + { + /* If the then branch is potentially constant, but + does not return, check if the else branch + couldn't return, break or continue. */ + hash_set<tree> pset; + check_for_return_continue_data data + = {&pset, NULL_TREE, NULL_TREE}; + if (tree ret_expr + = rs_walk_tree (&TREE_OPERAND (t, 2), + check_for_return_continue, &data, + &pset)) + *jump_target = ret_expr; + else if (*jump_target == NULL_TREE) + { + if (data.continue_stmt) + *jump_target = data.continue_stmt; + else if (data.break_stmt) + *jump_target = data.break_stmt; + } + } + } + return true; + } + } + if (flags & tf_error) + error_at (loc, "expression %qE is not a constant expression", t); + return false; + + case TYPE_DECL: + /* We can see these in statement-expressions. */ + return true; + + case LABEL_EXPR: + t = LABEL_EXPR_LABEL (t); + if (DECL_ARTIFICIAL (t)) + return true; + else if (flags & tf_error) + error_at (loc, "label definition in %<constexpr%> function only " + "available with %<-std=c++2b%> or %<-std=gnu++2b%>"); + return false; + + case ANNOTATE_EXPR: + return RECUR (TREE_OPERAND (t, 0), rval); + + case BIT_CAST_EXPR: + return RECUR (TREE_OPERAND (t, 0), rval); + + default: + sorry ("unexpected AST of kind %s", get_tree_code_name (TREE_CODE (t))); + gcc_unreachable (); + return false; + } +#undef RECUR +} + +bool +potential_constant_expression_1 (tree t, bool want_rval, bool strict, bool now, + tsubst_flags_t flags) +{ + if (flags & tf_error) + { + /* Check potentiality quietly first, as that could be performed more + efficiently in some cases (currently only for TRUTH_*_EXPR). If + that fails, replay the check noisily to give errors. */ + flags &= ~tf_error; + if (potential_constant_expression_1 (t, want_rval, strict, now, flags)) + return true; + flags |= tf_error; + } + + tree target = NULL_TREE; + return potential_constant_expression_1 (t, want_rval, strict, now, flags, + &target); +} + +// forked from gcc/cp/constexpr.cc fold_non_dependent_init + +/* Like maybe_constant_init but first fully instantiate the argument. */ + +tree +fold_non_dependent_init (tree t, + tsubst_flags_t complain /*=tf_warning_or_error*/, + bool manifestly_const_eval /*=false*/, + tree object /* = NULL_TREE */) +{ + if (t == NULL_TREE) + return NULL_TREE; + + return maybe_constant_init (t, object, manifestly_const_eval); +} + +// #include "gt-rust-rust-constexpr.h" + } // namespace Compile } // namespace Rust |