[PATCH] D56000: [compiler-rt] [xray] Disable alignas() for thread_local objects on NetBSD

[Michał Górny via Phabricator via llvm-commits]

mgorny updated this revision to Diff 179297.

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D56000/new/

https://reviews.llvm.org/D56000

Files:
  lib/xray/xray_basic_logging.cc
  lib/xray/xray_defs.h
  lib/xray/xray_fdr_logging.cc


Index: lib/xray/xray_fdr_logging.cc
===================================================================
--- lib/xray/xray_fdr_logging.cc
+++ lib/xray/xray_fdr_logging.cc
@@ -51,7 +51,7 @@
 // call so that it can be initialized on first use instead of as a global. We
 // force the alignment to 64-bytes for x86 cache line alignment, as this
 // structure is used in the hot path of implementation.
-struct alignas(64) ThreadLocalData {
+struct XRAY_TLS_ALIGNAS(64) ThreadLocalData {
   BufferQueue::Buffer Buffer{};
   BufferQueue *BQ = nullptr;
 
@@ -124,8 +124,10 @@
 // critical section, calling a function that might be XRay instrumented (and
 // thus in turn calling into malloc by virtue of registration of the
 // thread_local's destructor).
+#if XRAY_HAS_TLS_ALIGNAS
 static_assert(alignof(ThreadLocalData) >= 64,
               "ThreadLocalData must be cache line aligned.");
+#endif
 static ThreadLocalData &getThreadLocalData() {
   thread_local typename std::aligned_storage<
       sizeof(ThreadLocalData), alignof(ThreadLocalData)>::type TLDStorage{};
Index: lib/xray/xray_defs.h
===================================================================
--- lib/xray/xray_defs.h
+++ lib/xray/xray_defs.h
@@ -19,4 +19,14 @@
 #define XRAY_NEVER_INSTRUMENT
 #endif
 
+#if !SANITIZER_NETBSD
+#define XRAY_TLS_ALIGNAS(x) alignas(x)
+#define XRAY_HAS_TLS_ALIGNAS 1
+#else
+// NetBSD: thread_local is not aligned properly, and the code relying
+// on it segfaults
+#define XRAY_TLS_ALIGNAS(x)
+#define XRAY_HAS_TLS_ALIGNAS 0
+#endif
+
 #endif  // XRAY_XRAY_DEFS_H
Index: lib/xray/xray_basic_logging.cc
===================================================================
--- lib/xray/xray_basic_logging.cc
+++ lib/xray/xray_basic_logging.cc
@@ -55,7 +55,7 @@
 
 static_assert(sizeof(StackEntry) == 16, "Wrong size for StackEntry");
 
-struct alignas(64) ThreadLocalData {
+struct XRAY_TLS_ALIGNAS(64) ThreadLocalData {
   void *InMemoryBuffer = nullptr;
   size_t BufferSize = 0;
   size_t BufferOffset = 0;


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