3ab6b2347e
Even sleep(1) lead to episodical flakes on some machines. Use an invisible by tsan barrier to enforce required execution order instead. This makes the tests deterministic and faster. llvm-svn: 226659
66 lines
1.8 KiB
C++
66 lines
1.8 KiB
C++
// RUN: %clang_tsan -O1 %s -o %t && %run %t 2>&1 | FileCheck %s
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#include "test.h"
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// Test case https://code.google.com/p/thread-sanitizer/issues/detail?id=87
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// Tsan sees false HB edge on address pointed to by syncp variable.
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// It is false because when acquire is done syncp points to a var in one frame,
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// and during release it points to a var in a different frame.
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// The code is somewhat tricky because it prevents compiler from optimizing
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// our accesses away, structured to not introduce other data races and
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// not introduce other synchronization, and to arrange the vars in different
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// frames to occupy the same address.
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// The data race CHECK-NOT below actually must be CHECK, because the program
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// does contain the data race on global.
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// CHECK-NOT: WARNING: ThreadSanitizer: data race
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// CHECK: DONE
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long global;
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long *syncp;
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long *addr;
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long sink;
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void *Thread(void *x) {
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while (__atomic_load_n(&syncp, __ATOMIC_ACQUIRE) == 0)
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usleep(1000); // spin wait
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global = 42;
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__atomic_store_n(syncp, 1, __ATOMIC_RELEASE);
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__atomic_store_n(&syncp, 0, __ATOMIC_RELAXED);
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return NULL;
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}
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void __attribute__((noinline)) foobar() {
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long s;
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addr = &s;
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__atomic_store_n(&s, 0, __ATOMIC_RELAXED);
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__atomic_store_n(&syncp, &s, __ATOMIC_RELEASE);
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while (__atomic_load_n(&syncp, __ATOMIC_RELAXED) != 0)
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usleep(1000); // spin wait
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}
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void __attribute__((noinline)) barfoo() {
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long s;
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if (addr != &s) {
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printf("address mismatch addr=%p &s=%p\n", addr, &s);
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exit(1);
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}
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__atomic_store_n(&addr, &s, __ATOMIC_RELAXED);
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__atomic_store_n(&s, 0, __ATOMIC_RELAXED);
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sink = __atomic_load_n(&s, __ATOMIC_ACQUIRE);
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global = 43;
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}
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int main() {
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pthread_t t;
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pthread_create(&t, 0, Thread, 0);
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foobar();
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barfoo();
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pthread_join(t, 0);
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if (sink != 0)
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exit(1);
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fprintf(stderr, "DONE\n");
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return 0;
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}
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