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* [Bug c/99049] New: _Alignof ignores requested alignment of bit-field types in ms_struct struct
@ 2021-02-10 1:16 ju.orth at gmail dot com
2021-02-10 7:35 ` [Bug c/99049] " rguenth at gcc dot gnu.org
2021-02-10 13:44 ` ju.orth at gmail dot com
0 siblings, 2 replies; 3+ messages in thread
From: ju.orth at gmail dot com @ 2021-02-10 1:16 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99049
Bug ID: 99049
Summary: _Alignof ignores requested alignment of bit-field
types in ms_struct struct
Product: gcc
Version: 10.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: ju.orth at gmail dot com
Target Milestone: ---
Consider
typedef int Int __attribute__((aligned(128)));
struct __attribute__((ms_struct)) X {
Int i:1;
};
struct Y {
char c;
struct X x;
};
int f(void) {
return _Alignof(struct X);
}
int g(void) {
return __builtin_offsetof(struct Y, x);
}
When compiling this on x86_64-unknown-linux-gnu, f returns 16 but g returns
128. I believe that _Alignof and __builtin_offsetof as above should always
return the same value.
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug c/99049] _Alignof ignores requested alignment of bit-field types in ms_struct struct
2021-02-10 1:16 [Bug c/99049] New: _Alignof ignores requested alignment of bit-field types in ms_struct struct ju.orth at gmail dot com
@ 2021-02-10 7:35 ` rguenth at gcc dot gnu.org
2021-02-10 13:44 ` ju.orth at gmail dot com
1 sibling, 0 replies; 3+ messages in thread
From: rguenth at gcc dot gnu.org @ 2021-02-10 7:35 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99049
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |jsm28 at gcc dot gnu.org
Keywords| |ABI, wrong-code
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
I guess the expectation is reasonable but details on the handling of bitfield
types may escape me.
How does MSVC behave here?
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug c/99049] _Alignof ignores requested alignment of bit-field types in ms_struct struct
2021-02-10 1:16 [Bug c/99049] New: _Alignof ignores requested alignment of bit-field types in ms_struct struct ju.orth at gmail dot com
2021-02-10 7:35 ` [Bug c/99049] " rguenth at gcc dot gnu.org
@ 2021-02-10 13:44 ` ju.orth at gmail dot com
1 sibling, 0 replies; 3+ messages in thread
From: ju.orth at gmail dot com @ 2021-02-10 13:44 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99049
--- Comment #2 from Julian Orth <ju.orth at gmail dot com> ---
MSVC returns 128 for both: https://godbolt.org/z/16Tzh7
^ permalink raw reply [flat|nested] 3+ messages in thread
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2021-02-10 1:16 [Bug c/99049] New: _Alignof ignores requested alignment of bit-field types in ms_struct struct ju.orth at gmail dot com
2021-02-10 7:35 ` [Bug c/99049] " rguenth at gcc dot gnu.org
2021-02-10 13:44 ` ju.orth at gmail dot com
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