From 54bdeca3c6214485d15454df30183a56ad3e473b Mon Sep 17 00:00:00 2001 From: Richard Biener Date: Tue, 28 Jan 2025 16:20:30 +0100 Subject: middle-end/118684 - wrongly aligned stack local during expansion The following fixes a not properly aligned stack temporary created during RTL expansion of a MEM_REF that we handle as a BIT_FIELD_REF whose base was allocated to a register but which was originally aligned to allow a larger load not trapping. While probably UB in C the vectorizer creates aligned accesses that might overread a (static) allocation because it is then known not to trap. PR middle-end/118684 * expr.cc (expand_expr_real_1): When expanding a reference based on a register and we end up needing a MEM make sure that's aligned as the original reference required. * gcc.dg/pr118684.c: New testcase. --- gcc/expr.cc | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'gcc/expr.cc') diff --git a/gcc/expr.cc b/gcc/expr.cc index a06411e..95f41f6 100644 --- a/gcc/expr.cc +++ b/gcc/expr.cc @@ -12148,7 +12148,11 @@ expand_expr_real_1 (tree exp, rtx target, machine_mode tmode, and need be, put it there. */ else if (CONSTANT_P (op0) || (!MEM_P (op0) && must_force_mem)) { - memloc = assign_temp (TREE_TYPE (tem), 1, 1); + poly_int64 size; + if (!poly_int_tree_p (TYPE_SIZE_UNIT (TREE_TYPE (tem)), &size)) + size = max_int_size_in_bytes (TREE_TYPE (tem)); + memloc = assign_stack_local (TYPE_MODE (TREE_TYPE (tem)), size, + get_object_alignment (tem)); emit_move_insn (memloc, op0); op0 = memloc; clear_mem_expr = true; -- cgit v1.1