From: Jakub Jelinek <jakub@redhat.com>
To: Jason Merrill <jason@redhat.com>
Cc: gcc-patches@gcc.gnu.org
Subject: [PATCH] c++: Treat unnamed bitfields as padding for __has_unique_object_representations [PR109096]
Date: Tue, 14 Mar 2023 08:58:00 +0100 [thread overview]
Message-ID: <ZBApCMbOq6n+IGxA@tucnak> (raw)
Hi!
As reported in the PR, for __has_unique_object_representations we
were treating unnamed bitfields as named ones, which is wrong, they
are actually padding.
THe following patch fixes that. Ok for trunk (and what about release
branches later?)?
2023-03-14 Jakub Jelinek <jakub@redhat.com>
PR c++/109096
* tree.cc (record_has_unique_obj_representations): Ignore unnamed
bitfields.
* g++.dg/cpp1z/has-unique-obj-representations3.C: New test.
--- gcc/cp/tree.cc.jj 2023-03-10 10:06:40.247560614 +0100
+++ gcc/cp/tree.cc 2023-03-13 10:38:03.394836926 +0100
@@ -4851,7 +4851,7 @@ record_has_unique_obj_representations (c
DECL_SIZE (field)))
return false;
}
- else if (DECL_C_BIT_FIELD (field))
+ else if (DECL_C_BIT_FIELD (field) && !DECL_UNNAMED_BIT_FIELD (field))
{
tree btype = DECL_BIT_FIELD_TYPE (field);
if (!type_has_unique_obj_representations (btype))
@@ -4862,7 +4862,7 @@ record_has_unique_obj_representations (c
offset_int cur = 0;
for (tree field = TYPE_FIELDS (t); field; field = DECL_CHAIN (field))
- if (TREE_CODE (field) == FIELD_DECL)
+ if (TREE_CODE (field) == FIELD_DECL && !DECL_UNNAMED_BIT_FIELD (field))
{
offset_int fld = wi::to_offset (DECL_FIELD_OFFSET (field));
offset_int bitpos = wi::to_offset (DECL_FIELD_BIT_OFFSET (field));
--- gcc/testsuite/g++.dg/cpp1z/has-unique-obj-representations3.C.jj 2023-03-13 10:50:21.705127719 +0100
+++ gcc/testsuite/g++.dg/cpp1z/has-unique-obj-representations3.C 2023-03-13 10:50:17.751185067 +0100
@@ -0,0 +1,10 @@
+// PR c++/109096
+// { dg-do compile { target c++11 } }
+
+#define INTB (__SIZEOF_INT__ * __CHAR_BIT__)
+struct U { int i : INTB * 3 / 4; int : INTB / 4; };
+struct V { int : INTB * 3 / 4; int j : INTB / 4; };
+struct W { int i; int : 0; int j; };
+static_assert (__has_unique_object_representations (U) == false, "");
+static_assert (__has_unique_object_representations (V) == false, "");
+static_assert (sizeof (W) != 2 * sizeof (int) || __has_unique_object_representations (W) == true, "");
Jakub
next reply other threads:[~2023-03-14 7:58 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-14 7:58 Jakub Jelinek [this message]
2023-03-14 14:35 ` Jason Merrill
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