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author | Marek Polacek <polacek@redhat.com> | 2020-04-29 15:36:35 -0400 |
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committer | Marek Polacek <polacek@redhat.com> | 2020-04-30 08:34:40 -0400 |
commit | 6318fe77395fc0dd59419bc4d69cd06ac0158e54 (patch) | |
tree | 82957bc288e4f51774a1e62f8d862e33626d74ed /gcc/tree.c | |
parent | cd4b68527988f42c10c0d6c10e812d299887e0c2 (diff) | |
download | gcc-6318fe77395fc0dd59419bc4d69cd06ac0158e54.zip gcc-6318fe77395fc0dd59419bc4d69cd06ac0158e54.tar.gz gcc-6318fe77395fc0dd59419bc4d69cd06ac0158e54.tar.bz2 |
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.
Diffstat (limited to 'gcc/tree.c')
-rw-r--r-- | gcc/tree.c | 4 |
1 files changed, 3 insertions, 1 deletions
@@ -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)); |