[compiler-rt] a756239 - Fix COMPILER_RT_DEBUG build for targets that don't support thread local storage.

[Dan Liew via llvm-commits]

Author: Dan Liew
Date: 2021-08-05T10:07:25-07:00
New Revision: a756239e727842f2c274208acd8fb93fa745d04a

URL: https://github.com/llvm/llvm-project/commit/a756239e727842f2c274208acd8fb93fa745d04a
DIFF: https://github.com/llvm/llvm-project/commit/a756239e727842f2c274208acd8fb93fa745d04a.diff

LOG: Fix COMPILER_RT_DEBUG build for targets that don't support thread local storage.

022439931f5be77efaf80b44d587666b0c9b13b5 added code that is only enabled
when COMPILER_RT_DEBUG is enabled. This code doesn't build on targets
that don't support thread local storage because the code added uses the
THREADLOCAL macro. Consequently the COMPILER_RT_DEBUG build broke for
some Apple targets (e.g. 32-bit iOS simulators).

```
/Volumes/user_data/dev/llvm/llvm.org/main/src/llvm-project/compiler-rt/lib/sanitizer_common/sanitizer_mutex.cpp:216:8: error: thread-local storage is not supported for the current target
static THREADLOCAL InternalDeadlockDetector deadlock_detector;
       ^
/Volumes/user_data/dev/llvm/llvm.org/main/src/llvm-project/compiler-rt/lib/sanitizer_common/sanitizer_internal_defs.h:227:24: note: expanded from macro 'THREADLOCAL'
 # define THREADLOCAL   __thread
                        ^
1 error generated.
```

To fix this, this patch introduces a `SANITIZER_SUPPORTS_THREADLOCAL`
macro that is `1` iff thread local storage is supported by the current
target. That condition is then added to `SANITIZER_CHECK_DEADLOCKS` to
ensure the code is only enabled when thread local storage is available.

The implementation of `SANITIZER_SUPPORTS_THREADLOCAL` currently assumes
Clang. See `llvm-project/clang/include/clang/Basic/Features.def` for the
definition of the `tls` feature.

rdar://81543007

Differential Revision: https://reviews.llvm.org/D107524

Added: 
    

Modified: 
    compiler-rt/lib/sanitizer_common/sanitizer_mutex.h
    compiler-rt/lib/sanitizer_common/sanitizer_platform.h

Removed: 
    


################################################################################
diff  --git a/compiler-rt/lib/sanitizer_common/sanitizer_mutex.h b/compiler-rt/lib/sanitizer_common/sanitizer_mutex.h
index 3fc2d337a7d93..709ea1c921b5f 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_mutex.h
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_mutex.h
@@ -95,7 +95,8 @@ enum {
 
 // Go linker does not support THREADLOCAL variables,
 // so we can't use per-thread state.
-#define SANITIZER_CHECK_DEADLOCKS (SANITIZER_DEBUG && !SANITIZER_GO)
+#define SANITIZER_CHECK_DEADLOCKS \
+  (SANITIZER_DEBUG && !SANITIZER_GO && SANITIZER_SUPPORTS_THREADLOCAL)
 
 #if SANITIZER_CHECK_DEADLOCKS
 struct MutexMeta {

diff  --git a/compiler-rt/lib/sanitizer_common/sanitizer_platform.h b/compiler-rt/lib/sanitizer_common/sanitizer_platform.h
index 4d3c08893c11c..9b4a0f06237c9 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_platform.h
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_platform.h
@@ -377,4 +377,18 @@
 #define SANITIZER_SUPPORTS_INIT_FOR_DLOPEN 0
 #endif
 
+// SANITIZER_SUPPORTS_THREADLOCAL
+// 1 - THREADLOCAL macro is supported by target
+// 0 - THREADLOCAL macro is not supported by target
+#ifndef __has_feature
+// TODO: Support other compilers here
+#  define SANITIZER_SUPPORTS_THREADLOCAL 1
+#else
+#  if __has_feature(tls)
+#    define SANITIZER_SUPPORTS_THREADLOCAL 1
+#  else
+#    define SANITIZER_SUPPORTS_THREADLOCAL 0
+#  endif
+#endif
+
 #endif // SANITIZER_PLATFORM_H