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[clang] Don't mark _ReadBarrier, _ReadWriteBarrier, _WriteBarrier deprecated 

It's true that docs.microsoft.com says:

"""The _ReadBarrier, _WriteBarrier, and _ReadWriteBarrier compiler
intrinsics and the MemoryBarrier macro are all deprecated and should not
be used. For inter-thread communication, use mechanisms such as
atomic_thread_fence and std::atomic<T>, which are defined in the C++
Standard Library. For hardware access, use the /volatile:iso compiler
option together with the volatile keyword."""

And these attributes have been here since these builtins were added in
r192860.

However:

- cl.exe does not warn on them even with /Wall
- none of the replacements are useful for C code
- we don't add __attribute__((__deprecated__())) to any other
  declarations in intrin.h
- intrin0.h in the MSVC headers declares _ReadWriteBarrier() (but
  without the deprecation attribute), so you get inconsistent
  deprecation warnings depending on if you include intrin.h or intrin0.h

The motivation is that compiling sqlite.h with clang-cl produces a
deprecation warning with clang-cl for _ReadWriteBarrier(), but not with
cl.exe.

Differential Revision: https://reviews.llvm.org/D111232
This commit is contained in:
Nico Weber 2021-10-06 10:30:14 -04:00
parent ff41fc07b1
commit f9457f1f88
1 changed files with 3 additions and 6 deletions
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9
clang/lib/Headers/intrin.h
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@ -150,10 +150,8 @@ long _InterlockedExchangeAdd_HLEAcquire(long volatile *, long);
long _InterlockedExchangeAdd_HLERelease(long volatile *, long);
__int64 _InterlockedExchangeAdd64_HLEAcquire(__int64 volatile *, __int64);
__int64 _InterlockedExchangeAdd64_HLERelease(__int64 volatile *, __int64);
void __attribute__((__deprecated__(
"use other intrinsics or C++11 atomics instead"))) _ReadBarrier(void);
void __attribute__((__deprecated__(
"use other intrinsics or C++11 atomics instead"))) _ReadWriteBarrier(void);
void _ReadBarrier(void);
void _ReadWriteBarrier(void);
unsigned int _rorx_u32(unsigned int, const unsigned int);
int _sarx_i32(int, unsigned int);
#if __STDC_HOSTED__
@ -164,8 +162,7 @@ unsigned int _shrx_u32(unsigned int, unsigned int);
void _Store_HLERelease(long volatile *, long);
void _Store64_HLERelease(__int64 volatile *, __int64);
void _StorePointer_HLERelease(void *volatile *, void *);
void __attribute__((__deprecated__(
"use other intrinsics or C++11 atomics instead"))) _WriteBarrier(void);
void _WriteBarrier(void);
unsigned __int32 xbegin(void);
void _xend(void);