diff options
Diffstat (limited to 'gcc/rust/backend/rust-constexpr.cc')
| -rw-r--r-- | gcc/rust/backend/rust-constexpr.cc | 154 |
1 files changed, 154 insertions, 0 deletions
diff --git a/gcc/rust/backend/rust-constexpr.cc b/gcc/rust/backend/rust-constexpr.cc index 9449d59..cac28d6 100644 --- a/gcc/rust/backend/rust-constexpr.cc +++ b/gcc/rust/backend/rust-constexpr.cc @@ -493,6 +493,10 @@ 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); + /* Variables and functions to manage constexpr call expansion context. These do not need to be marked for PCH or GC. */ @@ -731,6 +735,12 @@ eval_constant_expression (const constexpr_ctx *ctx, tree t, bool lval, } break; + case LOOP_EXPR: + case WHILE_STMT: + case FOR_STMT: + eval_loop_expr (ctx, t, non_constant_p, overflow_p, jump_target); + break; + case BIT_FIELD_REF: r = eval_bit_field_ref (ctx, t, lval, non_constant_p, overflow_p); break; @@ -774,6 +784,7 @@ eval_constant_expression (const constexpr_ctx *ctx, tree t, bool lval, r = eval_conditional_expression (ctx, t, lval, non_constant_p, overflow_p, jump_target); break; + default: break; } @@ -2760,6 +2771,149 @@ eval_bit_field_ref (const constexpr_ctx *ctx, tree t, bool lval, return error_mark_node; } +/* 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))); +} + +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); +} + +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); +} + +static bool +switches (tree *jump_target) +{ + return *jump_target && TREE_CODE (*jump_target) == INTEGER_CST; +} + +/* 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; +} + // #include "gt-rust-rust-constexpr.h" } // namespace Compile |