[PATCH] D109139: [AIX][RFC] Undefine __STDC_NO_ATOMICS__ to enable c11 atomics functionality

2021-09-02 Thread David Tenty via Phabricator via cfe-commits 
daltenty added a comment.

For the missing library implementation, we may be able to use the 
implementation in compiler-rt. Seems like some other platforms do so.


Repository:
  rG LLVM Github Monorepo

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[PATCH] D109139: [AIX][RFC] Undefine __STDC_NO_ATOMICS__ to enable c11 atomics functionality

2021-09-02 Thread David Tenty via Phabricator via cfe-commits 
daltenty added a comment.

Hmm, I'm not sure that the limitations you outline in the description are the 
only problems that cause us to define the macro in the first place (though the 
lack of libc implementation was part of it). I'll try to dig up the original 
issues.


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[PATCH] D109139: [AIX][RFC] Undefine __STDC_NO_ATOMICS__ to enable c11 atomics functionality

2021-09-02 Thread Kai Luo via Phabricator via cfe-commits 
lkail created this revision.
lkail added reviewers: PowerPC, hubert.reinterpretcast, jsji, cebowleratibm, 
Jake-Egan.
Herald added subscribers: jfb, kbarton, nemanjai.
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Herald added a project: clang.
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In https://reviews.llvm.org/D103707, `__STDC_NO_ATOMICS__` is predefined to 
indicate clang on AIX doesn't support `_Atomic` and not shipped with 
`stdatomic.h` yet. Actually `_Atomic` is already supported. For `stdatomic.h`, 
clang has implemented one in `clang/lib/Headers/stdatomic.h`. The remaining 
problem is

  void atomic_thread_fence(memory_order);
  void atomic_signal_fence(memory_order);
  _Bool atomic_flag_test_and_set(volatile atomic_flag *);
  _Bool atomic_flag_test_and_set_explicit(volatile atomic_flag *, memory_order);

are defined as macros and don't have external linkage required by C11 standard, 
since current libc of AIX doesn't have them now. So is it worthwhile to violate 
the standard a bit, but make c11's atomics functionality available to users? If 
not, we may have to wait for upgrading of AIX's libc to define above routines.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D109139

Files:
  clang/lib/Basic/Targets/OSTargets.h
  clang/test/Preprocessor/init-ppc.c


Index: clang/test/Preprocessor/init-ppc.c
===
--- clang/test/Preprocessor/init-ppc.c
+++ clang/test/Preprocessor/init-ppc.c
@@ -755,11 +755,9 @@
 // RUN: %clang_cc1 -x c -std=c11 -E -dM -ffreestanding 
-triple=powerpc-ibm-aix7.1.0.0 -fno-signed-char < /dev/null | FileCheck 
-match-full-lines -check-prefix PPC-AIX-STDC %s
 // RUN: %clang_cc1 -x c -std=gnu11 -E -dM -ffreestanding 
-triple=powerpc-ibm-aix7.1.0.0 -fno-signed-char < /dev/null | FileCheck 
-match-full-lines -check-prefix PPC-AIX-STDC %s
 // RUN: %clang_cc1 -x c -std=c17 -E -dM -ffreestanding 
-triple=powerpc-ibm-aix7.1.0.0 -fno-signed-char < /dev/null | FileCheck 
-match-full-lines -check-prefix PPC-AIX-STDC %s
-// PPC-AIX-STDC:#define __STDC_NO_ATOMICS__ 1
 // PPC-AIX-STDC:#define __STDC_NO_THREADS__ 1
 
 // RUN: %clang_cc1 -x c -std=c99 -E -dM -ffreestanding 
-triple=powerpc-ibm-aix7.1.0.0 -fno-signed-char < /dev/null | FileCheck 
-match-full-lines -check-prefix PPC-AIX-STDC-N %s
-// PPC-AIX-STDC-N-NOT:#define __STDC_NO_ATOMICS__ 1
 // PPC-AIX-STDC-N-NOT:#define __STDC_NO_THREADS__ 1
 
 // RUN: %clang_cc1 -E -dM -ffreestanding -triple=powerpc-ibm-aix7.1.0.0 
-mlong-double-64 < /dev/null | FileCheck -match-full-lines -check-prefix 
PPC-AIX-LD64 %s
Index: clang/lib/Basic/Targets/OSTargets.h
===
--- clang/lib/Basic/Targets/OSTargets.h
+++ clang/lib/Basic/Targets/OSTargets.h
@@ -679,10 +679,8 @@
 Builder.defineMacro("__TOS_AIX__");
 Builder.defineMacro("__HOS_AIX__");
 
-if (Opts.C11) {
-  Builder.defineMacro("__STDC_NO_ATOMICS__");
+if (Opts.C11)
   Builder.defineMacro("__STDC_NO_THREADS__");
-}
 
 if (Opts.EnableAIXExtendedAltivecABI)
   Builder.defineMacro("__EXTABI__");


Index: clang/test/Preprocessor/init-ppc.c
===
--- clang/test/Preprocessor/init-ppc.c
+++ clang/test/Preprocessor/init-ppc.c
@@ -755,11 +755,9 @@
 // RUN: %clang_cc1 -x c -std=c11 -E -dM -ffreestanding -triple=powerpc-ibm-aix7.1.0.0 -fno-signed-char < /dev/null | FileCheck -match-full-lines -check-prefix PPC-AIX-STDC %s
 // RUN: %clang_cc1 -x c -std=gnu11 -E -dM -ffreestanding -triple=powerpc-ibm-aix7.1.0.0 -fno-signed-char < /dev/null | FileCheck -match-full-lines -check-prefix PPC-AIX-STDC %s
 // RUN: %clang_cc1 -x c -std=c17 -E -dM -ffreestanding -triple=powerpc-ibm-aix7.1.0.0 -fno-signed-char < /dev/null | FileCheck -match-full-lines -check-prefix PPC-AIX-STDC %s
-// PPC-AIX-STDC:#define __STDC_NO_ATOMICS__ 1
 // PPC-AIX-STDC:#define __STDC_NO_THREADS__ 1
 
 // RUN: %clang_cc1 -x c -std=c99 -E -dM -ffreestanding -triple=powerpc-ibm-aix7.1.0.0 -fno-signed-char < /dev/null | FileCheck -match-full-lines -check-prefix PPC-AIX-STDC-N %s
-// PPC-AIX-STDC-N-NOT:#define __STDC_NO_ATOMICS__ 1
 // PPC-AIX-STDC-N-NOT:#define __STDC_NO_THREADS__ 1
 
 // RUN: %clang_cc1 -E -dM -ffreestanding -triple=powerpc-ibm-aix7.1.0.0 -mlong-double-64 < /dev/null | FileCheck -match-full-lines -check-prefix PPC-AIX-LD64 %s
Index: clang/lib/Basic/Targets/OSTargets.h
===
--- clang/lib/Basic/Targets/OSTargets.h
+++ clang/lib/Basic/Targets/OSTargets.h
@@ -679,10 +679,8 @@
 Builder.defineMacro("__TOS_AIX__");
 Builder.defineMacro("__HOS_AIX__");
 
-if (Opts.C11) {
-  Builder.defineMacro("__STDC_NO_ATOMICS__");
+if (Opts.C11)
   Builder.defineMacro("__STDC_NO_THREADS__");
-}
 
 if (Opts.EnableAIXExtendedAltivecABI)
   Builder.defineMacro("__EXTABI__");
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