[compiler-rt] r174168 - tsan: say that the memory access is atomic in reports

Matt Beaumont-Gay matthewbg at google.com
Tue Feb 5 10:17:39 PST 2013


On Fri, Feb 1, 2013 at 3:10 AM, Dmitry Vyukov <dvyukov at google.com> wrote:
> Author: dvyukov
> Date: Fri Feb  1 05:10:53 2013
> New Revision: 174168
>
> URL: http://llvm.org/viewvc/llvm-project?rev=174168&view=rev
> Log:
> tsan: say that the memory access is atomic in reports
>
> Added:
>     compiler-rt/trunk/lib/tsan/lit_tests/atomic_stack.cc
> Modified:
>     compiler-rt/trunk/lib/tsan/lit_tests/race_on_mutex.c
>     compiler-rt/trunk/lib/tsan/rtl/tsan_interface_atomic.cc
>     compiler-rt/trunk/lib/tsan/rtl/tsan_report.cc
>     compiler-rt/trunk/lib/tsan/rtl/tsan_report.h
>     compiler-rt/trunk/lib/tsan/rtl/tsan_rtl_report.cc
>
> Added: compiler-rt/trunk/lib/tsan/lit_tests/atomic_stack.cc
> URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/tsan/lit_tests/atomic_stack.cc?rev=174168&view=auto
> ==============================================================================
> --- compiler-rt/trunk/lib/tsan/lit_tests/atomic_stack.cc (added)
> +++ compiler-rt/trunk/lib/tsan/lit_tests/atomic_stack.cc Fri Feb  1 05:10:53 2013
> @@ -0,0 +1,29 @@
> +// RUN: %clangxx_tsan -O1 %s -o %t && %t 2>&1 | FileCheck %s
> +#include <pthread.h>
> +#include <unistd.h>
> +
> +int Global;
> +
> +void *Thread1(void *x) {
> +  sleep(1);
> +  __atomic_fetch_add(&Global, 1, __ATOMIC_RELAXED);
> +  return NULL;
> +}
> +
> +void *Thread2(void *x) {
> +  Global++;
> +  return NULL;
> +}
> +
> +int main() {
> +  pthread_t t[2];
> +  pthread_create(&t[0], NULL, Thread1, NULL);
> +  pthread_create(&t[1], NULL, Thread2, NULL);
> +  pthread_join(t[0], NULL);
> +  pthread_join(t[1], NULL);
> +}
> +
> +// CHECK: WARNING: ThreadSanitizer: data race
> +// CHECK:   Atomic write of size 4
> +// CHECK:     #0 __tsan_atomic32_fetch_add
> +// CHECK:     #1 Thread1
>
> Modified: compiler-rt/trunk/lib/tsan/lit_tests/race_on_mutex.c
> URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/tsan/lit_tests/race_on_mutex.c?rev=174168&r1=174167&r2=174168&view=diff
> ==============================================================================
> --- compiler-rt/trunk/lib/tsan/lit_tests/race_on_mutex.c (original)
> +++ compiler-rt/trunk/lib/tsan/lit_tests/race_on_mutex.c Fri Feb  1 05:10:53 2013
> @@ -34,7 +34,7 @@ int main() {
>  }
>
>  // CHECK:      WARNING: ThreadSanitizer: data race
> -// CHECK-NEXT:   Read of size 1 at {{.*}} by thread T2:
> +// CHECK-NEXT:   Atomic read of size 1 at {{.*}} by thread T2:
>  // CHECK-NEXT:     #0 pthread_mutex_lock
>  // CHECK-NEXT:     #1 Thread2{{.*}} {{.*}}race_on_mutex.c:20{{(:3)?}} ({{.*}})
>  // CHECK:        Previous write of size 1 at {{.*}} by thread T1:
>
> Modified: compiler-rt/trunk/lib/tsan/rtl/tsan_interface_atomic.cc
> URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/tsan/rtl/tsan_interface_atomic.cc?rev=174168&r1=174167&r2=174168&view=diff
> ==============================================================================
> --- compiler-rt/trunk/lib/tsan/rtl/tsan_interface_atomic.cc (original)
> +++ compiler-rt/trunk/lib/tsan/rtl/tsan_interface_atomic.cc Fri Feb  1 05:10:53 2013
> @@ -29,7 +29,8 @@ using namespace __tsan;  // NOLINT
>
>  #define SCOPED_ATOMIC(func, ...) \
>      const uptr callpc = (uptr)__builtin_return_address(0); \
> -    const uptr pc = __sanitizer::StackTrace::GetCurrentPc(); \
> +    uptr pc = __sanitizer::StackTrace::GetCurrentPc(); \
> +    pc = __sanitizer::StackTrace::GetPreviousInstructionPc(pc); \
>      mo = ConvertOrder(mo); \
>      mo = flags()->force_seq_cst_atomics ? (morder)mo_seq_cst : mo; \
>      ThreadState *const thr = cur_thread(); \
>
> Modified: compiler-rt/trunk/lib/tsan/rtl/tsan_report.cc
> URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/tsan/rtl/tsan_report.cc?rev=174168&r1=174167&r2=174168&view=diff
> ==============================================================================
> --- compiler-rt/trunk/lib/tsan/rtl/tsan_report.cc (original)
> +++ compiler-rt/trunk/lib/tsan/rtl/tsan_report.cc Fri Feb  1 05:10:53 2013
> @@ -89,11 +89,17 @@ static void PrintMutexSet(Vector<ReportM
>    }
>  }
>
> +static const char *MopDesc(bool first, bool write, bool atomic) {
> +  return atomic ? (first ? (write ? "Atomic write" : "Atomic read")
> +                : (write ? "Previous atomic write" : "Previous atomic read"))
> +                : (first ? (write ? "Write" : "Read")
> +                : (write ? "Previous write" : "Previous read"));

IMHO, this would be more readable as 'if' statements rather than
triple-nested conditional expressions.

> +}
> +
>  static void PrintMop(const ReportMop *mop, bool first) {
>    char thrbuf[kThreadBufSize];
>    Printf("  %s of size %d at %p by %s",
> -      (first ? (mop->write ? "Write" : "Read")
> -             : (mop->write ? "Previous write" : "Previous read")),
> +      MopDesc(first, mop->write, mop->atomic),
>        mop->size, (void*)mop->addr,
>        thread_name(thrbuf, mop->tid));
>    PrintMutexSet(mop->mset);
>
> Modified: compiler-rt/trunk/lib/tsan/rtl/tsan_report.h
> URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/tsan/rtl/tsan_report.h?rev=174168&r1=174167&r2=174168&view=diff
> ==============================================================================
> --- compiler-rt/trunk/lib/tsan/rtl/tsan_report.h (original)
> +++ compiler-rt/trunk/lib/tsan/rtl/tsan_report.h Fri Feb  1 05:10:53 2013
> @@ -48,6 +48,7 @@ struct ReportMop {
>    uptr addr;
>    int size;
>    bool write;
> +  bool atomic;
>    Vector<ReportMopMutex> mset;
>    ReportStack *stack;
>
>
> Modified: compiler-rt/trunk/lib/tsan/rtl/tsan_rtl_report.cc
> URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/tsan/rtl/tsan_rtl_report.cc?rev=174168&r1=174167&r2=174168&view=diff
> ==============================================================================
> --- compiler-rt/trunk/lib/tsan/rtl/tsan_rtl_report.cc (original)
> +++ compiler-rt/trunk/lib/tsan/rtl/tsan_rtl_report.cc Fri Feb  1 05:10:53 2013
> @@ -151,6 +151,7 @@ void ScopedReport::AddMemoryAccess(uptr
>    mop->addr = addr + s.addr0();
>    mop->size = s.size();
>    mop->write = s.IsWrite();
> +  mop->atomic = s.IsAtomic();
>    mop->stack = SymbolizeStack(*stack);
>    for (uptr i = 0; i < mset->Size(); i++) {
>      MutexSet::Desc d = mset->Get(i);
>
>
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