[vm, compiler] Don't do safepoint transitions in generated code under TSAN.

Go to the runtime so TSAN sees the instrumented access to Thread::safepoint_state_, avoiding false data race reports.

TEST=tsan
Bug: #52024
Change-Id: Ic686bac2221d8ac6b9865ce9c82a4c36711037a7
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/295740
Reviewed-by: Alexander Aprelev <[email protected]>
Commit-Queue: Ryan Macnak <[email protected]>

Author: rmacnak-google

runtime/platform/thread_sanitizer.h

@@ -17,8 +17,10 @@
 #define NO_SANITIZE_THREAD __attribute__((no_sanitize("thread")))
 extern "C" void __tsan_acquire(void* addr);
 extern "C" void __tsan_release(void* addr);
+constexpr bool kUsingThreadSanitizer = true;
 #else
 #define NO_SANITIZE_THREAD
+constexpr bool kUsingThreadSanitizer = false;
 #endif
 
 #if defined(USING_THREAD_SANITIZER)

runtime/vm/compiler/assembler/assembler_arm64.cc

@@ -1643,12 +1643,14 @@ void Assembler::LeaveDartFrame() {
 void Assembler::EnterFullSafepoint(Register state) {
   // We generate the same number of instructions whether or not the slow-path is
   // forced. This simplifies GenerateJitCallbackTrampolines.
+  // For TSAN, we always go to the runtime so TSAN is aware of the release
+  // semantics of entering the safepoint.
 
   Register addr = TMP2;
   ASSERT(addr != state);
 
   Label slow_path, done, retry;
-  if (FLAG_use_slow_path) {
+  if (FLAG_use_slow_path || kUsingThreadSanitizer) {
     b(&slow_path);
   }
 
@@ -1663,7 +1665,7 @@ void Assembler::EnterFullSafepoint(Register state) {
   stxr(TMP, state, addr);
   cbz(&done, TMP);  // 0 means stxr was successful.
 
-  if (!FLAG_use_slow_path) {
+  if (!FLAG_use_slow_path && !kUsingThreadSanitizer) {
     b(&retry);
   }
 
@@ -1701,11 +1703,13 @@ void Assembler::ExitFullSafepoint(Register state,
                                   bool ignore_unwind_in_progress) {
   // We generate the same number of instructions whether or not the slow-path is
   // forced, for consistency with EnterFullSafepoint.
+  // For TSAN, we always go to the runtime so TSAN is aware of the acquire
+  // semantics of leaving the safepoint.
   Register addr = TMP2;
   ASSERT(addr != state);
 
   Label slow_path, done, retry;
-  if (FLAG_use_slow_path) {
+  if (FLAG_use_slow_path || kUsingThreadSanitizer) {
     b(&slow_path);
   }
 
@@ -1720,7 +1724,7 @@ void Assembler::ExitFullSafepoint(Register state,
   stxr(TMP, state, addr);
   cbz(&done, TMP);  // 0 means stxr was successful.
 
-  if (!FLAG_use_slow_path) {
+  if (!FLAG_use_slow_path && !kUsingThreadSanitizer) {
     b(&retry);
   }
 

runtime/vm/compiler/assembler/assembler_riscv.cc

@@ -3863,12 +3863,14 @@ void Assembler::TransitionNativeToGenerated(Register state,
 void Assembler::EnterFullSafepoint(Register state) {
   // We generate the same number of instructions whether or not the slow-path is
   // forced. This simplifies GenerateJitCallbackTrampolines.
+  // For TSAN, we always go to the runtime so TSAN is aware of the release
+  // semantics of entering the safepoint.
 
   Register addr = RA;
   ASSERT(addr != state);
 
   Label slow_path, done, retry;
-  if (FLAG_use_slow_path) {
+  if (FLAG_use_slow_path || kUsingThreadSanitizer) {
     j(&slow_path, Assembler::kNearJump);
   }
 
@@ -3882,7 +3884,7 @@ void Assembler::EnterFullSafepoint(Register state) {
   sc(state, state, Address(addr, 0));
   beqz(state, &done, Assembler::kNearJump);  // 0 means sc was successful.
 
-  if (!FLAG_use_slow_path) {
+  if (!FLAG_use_slow_path && !kUsingThreadSanitizer) {
     j(&retry, Assembler::kNearJump);
   }
 
@@ -3898,11 +3900,13 @@ void Assembler::ExitFullSafepoint(Register state,
                                   bool ignore_unwind_in_progress) {
   // We generate the same number of instructions whether or not the slow-path is
   // forced, for consistency with EnterFullSafepoint.
+  // For TSAN, we always go to the runtime so TSAN is aware of the acquire
+  // semantics of leaving the safepoint.
   Register addr = RA;
   ASSERT(addr != state);
 
   Label slow_path, done, retry;
-  if (FLAG_use_slow_path) {
+  if (FLAG_use_slow_path || kUsingThreadSanitizer) {
     j(&slow_path, Assembler::kNearJump);
   }
 
@@ -3916,7 +3920,7 @@ void Assembler::ExitFullSafepoint(Register state,
   sc(state, state, Address(addr, 0));
   beqz(state, &done, Assembler::kNearJump);  // 0 means sc was successful.
 
-  if (!FLAG_use_slow_path) {
+  if (!FLAG_use_slow_path && !kUsingThreadSanitizer) {
     j(&retry, Assembler::kNearJump);
   }
 

runtime/vm/compiler/assembler/assembler_x64.cc

@@ -129,8 +129,10 @@ void Assembler::setcc(Condition condition, ByteRegister dst) {
 void Assembler::EnterFullSafepoint() {
   // We generate the same number of instructions whether or not the slow-path is
   // forced, to simplify GenerateJitCallbackTrampolines.
+  // For TSAN, we always go to the runtime so TSAN is aware of the release
+  // semantics of entering the safepoint.
   Label done, slow_path;
-  if (FLAG_use_slow_path) {
+  if (FLAG_use_slow_path || kUsingThreadSanitizer) {
     jmp(&slow_path);
   }
 
@@ -144,7 +146,7 @@ void Assembler::EnterFullSafepoint() {
   popq(RAX);
   cmpq(TMP, Immediate(target::Thread::full_safepoint_state_unacquired()));
 
-  if (!FLAG_use_slow_path) {
+  if (!FLAG_use_slow_path && !kUsingThreadSanitizer) {
     j(EQUAL, &done);
   }
 
@@ -184,8 +186,10 @@ void Assembler::TransitionGeneratedToNative(Register destination_address,
 void Assembler::ExitFullSafepoint(bool ignore_unwind_in_progress) {
   // We generate the same number of instructions whether or not the slow-path is
   // forced, for consistency with EnterFullSafepoint.
+  // For TSAN, we always go to the runtime so TSAN is aware of the acquire
+  // semantics of leaving the safepoint.
   Label done, slow_path;
-  if (FLAG_use_slow_path) {
+  if (FLAG_use_slow_path || kUsingThreadSanitizer) {
     jmp(&slow_path);
   }
 
@@ -201,7 +205,7 @@ void Assembler::ExitFullSafepoint(bool ignore_unwind_in_progress) {
   popq(RAX);
   cmpq(TMP, Immediate(target::Thread::full_safepoint_state_acquired()));
 
-  if (!FLAG_use_slow_path) {
+  if (!FLAG_use_slow_path && !kUsingThreadSanitizer) {
     j(EQUAL, &done);
   }