Clang header file invpcidintrin.h does not compile with vectorcall ABI

[Quuxplusone]

Bugzilla Link	PR41503
Status	RESOLVED FIXED
Importance	P normal
Reported by	David Parks (code.optimizer@gmail.com)
Reported on	2019-04-15 10:39:59 -0700
Last modified on	2019-12-03 05:23:17 -0800
Version	8.0
Hardware	PC Windows 2000
CC	craig.topper@gmail.com, htmldeveloper@gmail.com, llvm-bugs@lists.llvm.org, llvm-dev@redking.me.uk, neeilans@live.com, richard-llvm@metafoo.co.uk, rnk@google.com
Fixed by commit(s)	rG890c6ef1fb1350dd8e6b7b25da411cffbeaf6553
Attachments
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Blocked by
See also

Given the following trivial example:
Win64$ cat test_imm_vectorcall.c
#include <intrin.h>

int f(int i, int j) { return i+j; }
Win64$

It will not compile with the combination of vectorcall ABI and -march/-mtune =
skylake-avx512:

/c/Users/dparks/LLVM-8.0.0/bin/clang -c -c -mtune=skylake-avx512 -march=skylake-
avx512 -Xclang -fdefault-calling-conv=vectorcall test_imm_vectorcall.c
In file included from test_imm_vectorcall.c:1:
c:\Users\dparks\LLVM-8.0.0\lib\clang\8.0.0\include\intrin.h:181:14: error:
function declared 'cdecl' here was previously declared without calling
convention
void __cdecl _invpcid(unsigned int, void *);
             ^
c:\Users\dparks\LLVM-8.0.0\lib\clang\8.0.0\include\invpcidintrin.h:33:1: note:
previous declaration is here
_invpcid(unsigned int __type, void *__descriptor) {
^
1 error generated.

This problem also occurs with Clang 7.0.1, but does not occur with Clang 6.0.0.

[Quuxplusone]

Problem continues to happen with Windows version of Clang-9.0

[Quuxplusone]

Changing line 17 of ...\lib\clang\9.0.0\include\invpcidintrin.h from
static __inline__ void
to
__cdecl static __inline__ void

Allows programs to compile with the vectorcall ABI avoiding the head file
errors.

[Quuxplusone]

What if we remove the forward declaration from intrin.h?

[Quuxplusone]

Should be fixed by 890c6ef1fb1350dd8e6b7b25da411cffbeaf6553

[Quuxplusone]

Hi Craig,

Thank you for taking care of this issue.

Will the fix be included in the next clang-9.X.Y release or will it only show up in clang-10?

Dave