5624e86ae0
Certain instrumentations set the !nosanitize metadata for inserted
instructions, which are generally not interested for sanitizers. Skip
tsan instrumentation like we do for asan (D126294)/msan/hwasan.
-fprofile-arcs instrumentation has data race unless
-fprofile-update=atomic is specified. Let's remove the the `__llvm_gcov`
special case from commit 0222adbcd25779a156399bcc16fde9f6d083a809 (2016)
as the racy instructions have the !nosanitize metadata.
(-fprofile-arcs instrumentation does not use `__llvm_gcda` as global variables.)
```
std::atomic<int> c;
void foo() { c++; }
int main() {
std::thread th(foo);
c++;
th.join();
}
```
Tested that `clang++ --coverage -fsanitize=thread a.cc && ./a.out` does
not report spurious tsan errors.
Also remove the default CC1 option -fprofile-update=atomic for
-fsanitize=thread to make options more orthogonal.
Reviewed By: Enna1
Differential Revision: https://reviews.llvm.org/D158385
12 lines
512 B
C
12 lines
512 B
C
/// -fprofile-update=atomic requires the (potentially concurrent) counter updates to be atomic.
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// RUN: %clang_cc1 %s -triple x86_64 -emit-llvm -fprofile-update=atomic \
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// RUN: -coverage-notes-file=/dev/null -coverage-data-file=/dev/null -o - | FileCheck %s
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// CHECK-LABEL: void @foo()
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/// Two counters are incremented by __tsan_atomic64_fetch_add.
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// CHECK: atomicrmw add ptr @__llvm_gcov_ctr{{.*}} monotonic, align 8
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// CHECK-NEXT: atomicrmw sub ptr
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_Atomic(int) cnt;
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void foo(void) { cnt--; }
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