From 6318fe77395fc0dd59419bc4d69cd06ac0158e54 Mon Sep 17 00:00:00 2001 From: Marek Polacek Date: Wed, 29 Apr 2020 15:36:35 -0400 Subject: tree: Don't reuse types if TYPE_USER_ALIGN differ [PR94775] Here we trip on the TYPE_USER_ALIGN (t) assert in strip_typedefs: it gets "const d[0]" with TYPE_USER_ALIGN=0 but the result built by build_cplus_array_type is "const char[0]" with TYPE_USER_ALIGN=1. When we strip_typedefs the element of the array "const d", we see it's a typedef_variant_p, so we look at its DECL_ORIGINAL_TYPE, which is char, but we need to add the const qualifier, so we call cp_build_qualified_type -> build_qualified_type where get_qualified_type checks to see if we already have such a type by walking the variants list, which in this case is: char -> c -> const char -> const char -> d -> const d Because check_base_type only checks TYPE_ALIGN and not TYPE_USER_ALIGN, we choose the first const char, which has TYPE_USER_ALIGN set. If the element type of an array has TYPE_USER_ALIGN, the array type gets it too. So we can make check_base_type stricter. I was afraid that it might make us reuse types less often, but measuring showed that we build the same amount of types with and without the patch, while bootstrapping. PR c++/94775 * tree.c (check_base_type): Return true only if TYPE_USER_ALIGN match. (check_aligned_type): Check if TYPE_USER_ALIGN match. * g++.dg/warn/Warray-bounds-10.C: New test. --- gcc/tree.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'gcc/tree.c') diff --git a/gcc/tree.c b/gcc/tree.c index e451401..341766c 100644 --- a/gcc/tree.c +++ b/gcc/tree.c @@ -6493,7 +6493,8 @@ check_base_type (const_tree cand, const_tree base) TYPE_ATTRIBUTES (base))) return false; /* Check alignment. */ - if (TYPE_ALIGN (cand) == TYPE_ALIGN (base)) + if (TYPE_ALIGN (cand) == TYPE_ALIGN (base) + && TYPE_USER_ALIGN (cand) == TYPE_USER_ALIGN (base)) return true; /* Atomic types increase minimal alignment. We must to do so as well or we get duplicated canonical types. See PR88686. */ @@ -6528,6 +6529,7 @@ check_aligned_type (const_tree cand, const_tree base, unsigned int align) && TYPE_CONTEXT (cand) == TYPE_CONTEXT (base) /* Check alignment. */ && TYPE_ALIGN (cand) == align + && TYPE_USER_ALIGN (cand) == TYPE_USER_ALIGN (base) && attribute_list_equal (TYPE_ATTRIBUTES (cand), TYPE_ATTRIBUTES (base)) && check_lang_type (cand, base)); -- cgit v1.1