https://llvm.org/bugs/show_bug.cgi?id=31620
Bug ID: 31620
Summary: undefined reference to
'__sync_val_compare_and_swap_16'
Product: libc++
Version: unspecified
Hardware: PC
OS: Linux
Status: NEW
Severity: normal
Priority: P
Component: All Bugs
Assignee: unassignedclangb...@nondot.org
Reporter: dvyu...@google.com
CC: llvm-bugs@lists.llvm.org, mclow.li...@gmail.com
Classification: Unclassified
I am on r291667. Linux/x86_64. libcxx and libcxxabi are checked out into
projects.
The program is:
#include <atomic>
int main()
{
struct X { int a, b, c, d; };
std::atomic<X> x;
X b, c;
x.compare_exchange_strong(b, c);
}
$ clang++ test.cc -std=c++11 -stdlib=libc++
/tmp/test-7383d8.o: In function `main':
/tmp/test.cc:(.text+0xd): undefined reference to
`__sync_val_compare_and_swap_16'
clang-4.0: error: linker command failed with exit code 1 (use -v to see
invocation)
Adding -latomic does not help, libatomic does not provide such function.
A new tsan test fails with a more elaborate error pointing to exact location,
for some reason it's generated for load function:
/tmp/lit_tmp_3Uws7l/atomic_test-af5f74.o: In function `load':
/llvm4/build/projects/compiler-rt/lib/tsan/libcxx_tsan_x86_64/include/c++/v1/atomic:893:
undefined reference to `__sync_val_compare_and_swap_16'
/tmp/lit_tmp_3Uws7l/atomic_test-af5f74.o:/llvm4/build/projects/compiler-rt/lib/tsan/libcxx_tsan_x86_64/include/c++/v1/atomic:893:
more undefined references to `__sync_val_compare_and_swap_16' follow
clang-3.9: error: linker command failed with exit code 1 (use -v to see
invocation)
What am I doing wrong?
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