On Tue, Apr 24, 2018 at 9:19 AM, Jakub Jelinek <ja...@redhat.com> wrote:
> On Mon, Apr 23, 2018 at 04:49:24PM -0400, Jason Merrill wrote:
>> On Tue, Apr 17, 2018 at 8:50 AM, Joseph Myers <jos...@codesourcery.com>
>> wrote:
>> > On Tue, 10 Apr 2018, Jason Merrill wrote:
>> >
>> >> But really this is beside the point: the x86 ABI says that the
>> >> alignment of double is 4, so alignof(double) should be 4 regardless of
>> >> what GCC wants to do internally. And I think the same is true of
>> >> __alignof__.
>> >
>> > __alignof__ needs to stay reflecting the preferred, standalone alignment
>> > of 8 bytes; changing that is ABI-incompatible; code such as that in
>> > stddef.h uses __attribute__((__aligned__(__alignof__(long long)))) to give
>> > structure members the same alignment those types would have for standalone
>> > objects. (This doesn't affect the alignment of max_align_t *now* on i386,
>> > but only because that now includes __float128 as well.)
>>
>> In that case, here's a patch following the 52023 change to the C front
>> end, to change only "alignof".
>>
>> Tested x86_64-pc-linux-gnu, applying to trunk.
>
> This regressed:
> +FAIL: c-c++-common/attr-aligned-1.c -std=c++11 (test for excess errors)
> +UNRESOLVED: c-c++-common/attr-aligned-1.c -std=c++11 compilation failed to
> produce executable
> +FAIL: c-c++-common/attr-aligned-1.c -std=c++14 (test for excess errors)
> +UNRESOLVED: c-c++-common/attr-aligned-1.c -std=c++14 compilation failed to
> produce executable
> +FAIL: g++.dg/cpp0x/alignas4.C -std=c++11 scan-assembler align 8
> +FAIL: g++.dg/cpp0x/alignas4.C -std=c++14 scan-assembler align 8
> on i686-linux, can be reproduced even with just
> make check-gcc check-g++ RUNTESTFLAGS="--target_board=unix\{-m64,-m32\}
> dg.exp='attr-aligned-1.c alignas4.C'"
> on x86_64-linux.
Thanks. How is your build tree configured so that this finds the
appropriate runtime libraries?
> On alignas4.C, this was changed with r249409, perhaps we can limit
> the target to && { ! ia32 } or similar, or do we want to expect align 4
> for ia32?
>
> attr-aligned-1.c testcase doesn't work if
> __alignof__ (double) != alignof (double). Either we should use __alignof__
> in the static_asserts, or guard the static_asserts for targets known not to
> have different results between the two.
Done, thanks.
commit 006eabc3e6328b219f2eee271439cb90f8890856
Author: Jason Merrill <ja...@redhat.com>
Date: Tue Apr 24 11:50:34 2018 -0400
Testsuite fixes for C++11 alignof change.
gcc/testsuite:
* c-c++-common/attr-aligned-1.c: Use __alignof__ in C++11.
* g++.dg/cpp0x/alignas4.C: Expect 4-byte alignment on x86.
diff --git a/gcc/testsuite/c-c++-common/attr-aligned-1.c b/gcc/testsuite/c-c++-common/attr-aligned-1.c
index 671e86baeb6..26b62393ac0 100644
--- a/gcc/testsuite/c-c++-common/attr-aligned-1.c
+++ b/gcc/testsuite/c-c++-common/attr-aligned-1.c
@@ -17,8 +17,8 @@ main ()
}
#if defined(__cplusplus) && __cplusplus >= 201103L
-static_assert (alignof (S) == 2 * alignof (double), "alignment of S");
-static_assert (alignof (T) == 2 * alignof (double), "alignment of T");
-static_assert (alignof (const S) == 2 * alignof (double), "alignment of const S");
-static_assert (alignof (const T) == 2 * alignof (double), "alignment of const T");
+static_assert (alignof (S) == 2 * __alignof__ (double), "alignment of S");
+static_assert (alignof (T) == 2 * __alignof__ (double), "alignment of T");
+static_assert (alignof (const S) == 2 * __alignof__ (double), "alignment of const S");
+static_assert (alignof (const T) == 2 * __alignof__ (double), "alignment of const T");
#endif
diff --git a/gcc/testsuite/g++.dg/cpp0x/alignas4.C b/gcc/testsuite/g++.dg/cpp0x/alignas4.C
index baa56eb8ac5..b66fa651bc2 100644
--- a/gcc/testsuite/g++.dg/cpp0x/alignas4.C
+++ b/gcc/testsuite/g++.dg/cpp0x/alignas4.C
@@ -1,6 +1,7 @@
// PR c++/59012
// { dg-do compile { target c++11 } }
-// { dg-final { scan-assembler "align 8" { target { { i?86-*-* x86_64-*-* } && { ! *-*-darwin* } } } } }
+// { dg-final { scan-assembler "align 8" { target { { i?86-*-* x86_64-*-* } && { { ! ia32 } && { ! *-*-darwin* } } } } } }
+// { dg-final { scan-assembler "align 4" { target ia32 } } }
template <class... T>
struct A
