[tsan] Do not include <stdatomic.h> from sanitize-thread-disable.c

[glider]

Summary

[tsan] Do not include <stdatomic.h> from sanitize-thread-disable.c

Looks like non-x86 bots are unhappy with inclusion of <stdatomic.h>
e.g.:

clang-armv7-vfpv3-2stage - https://lab.llvm.org/buildbot/#/builders/182/builds/626
clang-ppc64le-linux - https://lab.llvm.org/buildbot/#/builders/76/builds/3619
llvm-clang-win-x-armv7l - https://lab.llvm.org/buildbot/#/builders/60/builds/4514

It seems to be unnecessary, just remove it and replace atomic_load()
calls with dereferences of _Atomic*.

[glider]

Not really sure what's the best solution here, but I think restricting the test to x86 should help.
So far only ARM and PPC bots reported failures.

[melver]

clang/test/CodeGen/sanitize-thread-disable.c

20

I think you do not need to use atomic_load.

You can just deref b, and because it's _Atomic type it *should* just use an atomic seq_cst load implicitly.

[melver]

clang/test/CodeGen/sanitize-thread-disable.c

20

Alternatively, there are the __atomic builtins. You could just use __atomic_load_n() instead (it works with either _Atomic or non-_Atomic type).

[glider]

Removed the header

clang/test/CodeGen/sanitize-thread-disable.c

20

You are right, turns out I didn't need the header at all. Removed it.

[melver]

LGTM, thanks!

Patch title ("...an X86-only test..") also needs adjustment.

[glider]

In D108555#2960034, @melver wrote:

LGTM, thanks!

Patch title ("...an X86-only test..") also needs adjustment.

It's strange that Phab doesn't automatically update the title when I update the commit message.

[melver]

In D108555#2960037, @glider wrote:

In D108555#2960034, @melver wrote:

LGTM, thanks!

Patch title ("...an X86-only test..") also needs adjustment.

It's strange that Phab doesn't automatically update the title when I update the commit message.

Hmm, yeah I remember this was broken before. I guess as long as the committed version is right it's fine. I think it's also possible to edit on web interface (not so nice..) and use arc amend or something.

clang/test/CodeGen/sanitize-thread-disable.c

 // RUN: %clang -target x86_64-linux-gnu -S -emit-llvm -o - %s | FileCheck -check-prefixes CHECK,WITHOUT %s
 // RUN: %clang -target x86_64-linux-gnu -S -emit-llvm -o - %s -fsanitize=thread | FileCheck -check-prefixes CHECK,TSAN %s
 
-#include <stdatomic.h>
-
 // Instrumented function.
 // TSan inserts calls to __tsan_func_entry() and __tsan_func_exit() to prologue/epilogue.
 // Non-atomic loads are instrumented with __tsan_readXXX(), atomic loads - with
 // __tsan_atomicXXX_load().
 //
 // CHECK-LABEL: @instrumented1
 // TSAN: call void @__tsan_func_entry
 // WITHOUT-NOT: call void @__tsan_func_entry
 // TSAN: call void @__tsan_read4
 // WITHOUT-NOT: call void @__tsan_read4
 // TSAN: call i32 @__tsan_atomic32_load
 // WITHOUT-NOT: call i32 @__tsan_atomic32_load
 // TSAN: call void @__tsan_func_exit
 // WITHOUT-NOT: call void @__tsan_func_exit
 // CHECK: ret i32
 int instrumented1(int *a, _Atomic int *b) {
-  return *a + atomic_load(b);
+  return *a + *b;
 }
 
 // Function with no_sanitize("thread").
 // TSan only inserts instrumentation necessary to prevent false positives: calls are inserted for
 // function entry/exit and atomics, but not plain memory accesses.
 //
 // CHECK-LABEL: @no_false_positives1
 // TSAN: call void @__tsan_func_entry
 // WITHOUT-NOT: call void @__tsan_func_entry
 // TSAN-NOT: call void @__tsan_read4
 // WITHOUT-NOT: call void @__tsan_read4
 // TSAN: call i32 @__tsan_atomic32_load
 // WITHOUT-NOT: call i32 @__tsan_atomic32_load
 // TSAN: call void @__tsan_func_exit
 // WITHOUT-NOT: call void @__tsan_func_exit
 // CHECK: ret i32
 __attribute__((no_sanitize("thread"))) int no_false_positives1(int *a, _Atomic int *b) {
-  return *a + atomic_load(b);
+  return *a + *b;
 }
 
 // Function with disable_sanitizer_instrumentation: no instrumentation at all.
 //
 // CHECK-LABEL: @no_instrumentation1
 // TSAN-NOT: call void @__tsan_func_entry
 // WITHOUT-NOT: call void @__tsan_func_entry
 // TSAN-NOT: call void @__tsan_read4
 // WITHOUT-NOT: call void @__tsan_read4
 // TSAN-NOT: call i32 @__tsan_atomic32_load
 // WITHOUT-NOT: call i32 @__tsan_atomic32_load
 // TSAN-NOT: call void @__tsan_func_exit
 // WITHOUT-NOT: call void @__tsan_func_exit
 // CHECK: ret i32
 __attribute__((disable_sanitizer_instrumentation)) int no_instrumentation1(int *a, _Atomic int *b) {
-  return *a + atomic_load(b);
+  return *a + *b;
 }