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tsan: more precise handling of atomic stores 

Atomic stores terminate release sequences on the atomic variable,
and must use ReleaseStore primitive instead of Release.
This was broken in r192355 during a refactoring.
Restore correct behavior and add a test.

llvm-svn: 286211
This commit is contained in:
Dmitry Vyukov 2016-11-08 05:34:50 +00:00
parent 5ca4d5f5fe
commit 62f99cc486
2 changed files with 50 additions and 1 deletions
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2
compiler-rt/lib/tsan/rtl/tsan_interface_atomic.cc
View File

@ -267,7 +267,7 @@ static void AtomicStore(ThreadState *thr, uptr pc, volatile T *a, T v,
thr->fast_state.IncrementEpoch();
// Can't increment epoch w/o writing to the trace as well.
TraceAddEvent(thr, thr->fast_state, EventTypeMop, 0);
ReleaseImpl(thr, pc, &s->clock);
ReleaseStoreImpl(thr, pc, &s->clock);
NoTsanAtomicStore(a, v, mo);
s->mtx.Unlock();
}

49
compiler-rt/test/tsan/atomic_store.cc Normal file
View File

@ -0,0 +1,49 @@
// RUN: %clangxx_tsan -O1 %s -o %t && %deflake %run %t 2>&1 | FileCheck %s
#include "test.h"
long long Data;
long long Sync;
void *Thread1(void *x) {
Data++;
__atomic_store_n(&Sync, 1, __ATOMIC_RELEASE);
barrier_wait(&barrier);
barrier_wait(&barrier);
return NULL;
}
void *Thread2(void *x) {
barrier_wait(&barrier);
if (__atomic_load_n(&Sync, __ATOMIC_RELAXED) != 1)
exit(0);
// This store must terminate release sequence of the store in Thread1,
// thus tsan must detect race between Thread1 and main on Data.
__atomic_store_n(&Sync, 2, __ATOMIC_RELEASE);
barrier_wait(&barrier);
return NULL;
}
int main() {
barrier_init(&barrier, 3);
pthread_t t[2];
pthread_create(&t[0], NULL, Thread1, NULL);
pthread_create(&t[1], NULL, Thread2, NULL);
barrier_wait(&barrier);
barrier_wait(&barrier);
if (__atomic_load_n(&Sync, __ATOMIC_ACQUIRE) != 2)
exit(0);
if (Data != 1)
exit(0);
pthread_join(t[0], NULL);
pthread_join(t[1], NULL);
fprintf(stderr, "DONE\n");
return 0;
}
// CHECK: WARNING: ThreadSanitizer: data race
// CHECK: Read
// CHECK: #0 main
// CHECK: Previous write
// CHECK: #0 Thread1
// CHECK: Location is global 'Data'
// CHECK: DONE