[compiler-rt] 103c1bd - Revert "tsan: fix and test detection of TLS races"

[Amy Kwan via llvm-commits]

Author: Amy Kwan
Date: 2021-10-01T16:42:31-05:00
New Revision: 103c1bd118926afe20d7c944d9190e99d811b516

URL: https://github.com/llvm/llvm-project/commit/103c1bd118926afe20d7c944d9190e99d811b516
DIFF: https://github.com/llvm/llvm-project/commit/103c1bd118926afe20d7c944d9190e99d811b516.diff

LOG: Revert "tsan: fix and test detection of TLS races"

This reverts commit b4c1e5cb73bd26e5853af77c2a235ca9f35e2577.

Reverting this as it contains a test that is currently failing on the PPC BE bots.

Added: 
    

Modified: 
    compiler-rt/lib/tsan/rtl/tsan_platform_linux.cpp
    compiler-rt/lib/tsan/rtl/tsan_rtl_thread.cpp

Removed: 
    compiler-rt/test/tsan/tls_race3.cpp


################################################################################
diff  --git a/compiler-rt/lib/tsan/rtl/tsan_platform_linux.cpp b/compiler-rt/lib/tsan/rtl/tsan_platform_linux.cpp
index 2fb753dd080c8..63c751af4a85f 100644
--- a/compiler-rt/lib/tsan/rtl/tsan_platform_linux.cpp
+++ b/compiler-rt/lib/tsan/rtl/tsan_platform_linux.cpp
@@ -453,8 +453,6 @@ static void InitializeLongjmpXorKey() {
 }
 #endif
 
-extern "C" void __tsan_tls_initialization() {}
-
 void ImitateTlsWrite(ThreadState *thr, uptr tls_addr, uptr tls_size) {
   // Check that the thr object is in tls;
   const uptr thr_beg = (uptr)thr;
@@ -464,10 +462,9 @@ void ImitateTlsWrite(ThreadState *thr, uptr tls_addr, uptr tls_size) {
   CHECK_GE(thr_end, tls_addr);
   CHECK_LE(thr_end, tls_addr + tls_size);
   // Since the thr object is huge, skip it.
-  const uptr pc = StackTrace::GetNextInstructionPc(
-      reinterpret_cast<uptr>(__tsan_tls_initialization));
-  MemoryRangeImitateWrite(thr, pc, tls_addr, thr_beg - tls_addr);
-  MemoryRangeImitateWrite(thr, pc, thr_end, tls_addr + tls_size - thr_end);
+  MemoryRangeImitateWrite(thr, /*pc=*/2, tls_addr, thr_beg - tls_addr);
+  MemoryRangeImitateWrite(thr, /*pc=*/2, thr_end,
+                          tls_addr + tls_size - thr_end);
 }
 
 // Note: this function runs with async signals enabled,

diff  --git a/compiler-rt/lib/tsan/rtl/tsan_rtl_thread.cpp b/compiler-rt/lib/tsan/rtl/tsan_rtl_thread.cpp
index 67b12c804fb25..89178a1699ba0 100644
--- a/compiler-rt/lib/tsan/rtl/tsan_rtl_thread.cpp
+++ b/compiler-rt/lib/tsan/rtl/tsan_rtl_thread.cpp
@@ -156,6 +156,13 @@ void ThreadStart(ThreadState *thr, Tid tid, tid_t os_id,
   if (thread_type != ThreadType::Fiber)
     GetThreadStackAndTls(tid == kMainTid, &stk_addr, &stk_size, &tls_addr,
                          &tls_size);
+
+  if (tid != kMainTid) {
+    if (stk_addr && stk_size)
+      MemoryRangeImitateWrite(thr, /*pc=*/ 1, stk_addr, stk_size);
+
+    if (tls_addr && tls_size) ImitateTlsWrite(thr, tls_addr, tls_size);
+  }
 #endif
 
   ThreadRegistry *tr = &ctx->thread_registry;
@@ -171,16 +178,6 @@ void ThreadStart(ThreadState *thr, Tid tid, tid_t os_id,
     ThreadIgnoreSyncBegin(thr, 0);
   }
 #endif
-
-#if !SANITIZER_GO
-  if (tid != kMainTid) {
-    if (stk_addr && stk_size)
-      MemoryRangeImitateWrite(thr, /*pc=*/1, stk_addr, stk_size);
-
-    if (tls_addr && tls_size)
-      ImitateTlsWrite(thr, tls_addr, tls_size);
-  }
-#endif
 }
 
 void ThreadContext::OnStarted(void *arg) {

diff  --git a/compiler-rt/test/tsan/tls_race3.cpp b/compiler-rt/test/tsan/tls_race3.cpp
deleted file mode 100644
index 63eee39408206..0000000000000
--- a/compiler-rt/test/tsan/tls_race3.cpp
+++ /dev/null
@@ -1,35 +0,0 @@
-// RUN: %clangxx_tsan %darwin_min_target_with_tls_support -O1 %s -o %t && \
-// RUN:   %deflake %run %t | FileCheck %s
-
-// Race with initial TLS initialization:
-// there is no explicit second write,
-// but the TLS variable is published unsafely.
-#include "test.h"
-
-__thread long X;
-long *P;
-
-void *Thread(void *a) {
-  __atomic_store_n(&P, &X, __ATOMIC_RELAXED);
-  barrier_wait(&barrier);
-  barrier_wait(&barrier);
-  return 0;
-}
-
-int main() {
-  barrier_init(&barrier, 2);
-  pthread_t t;
-  pthread_create(&t, NULL, Thread, NULL);
-  barrier_wait(&barrier);
-  long *p = __atomic_load_n(&P, __ATOMIC_RELAXED);
-  *p = 42;
-  barrier_wait(&barrier);
-  pthread_join(t, 0);
-}
-
-// CHECK: WARNING: ThreadSanitizer: data race
-// CHECK:   Write of size 8 at {{.*}} by main thread:
-// CHECK:     #0 main
-// CHECK:   Previous write of size 8 at {{.*}} by thread T1:
-// CHECK:     #0 __tsan_tls_initialization
-// CHECK:   Location is TLS of thread T1.