[libcxx-commits] [libcxx] [libcxx][test] Prevent compiler optimising out uses of 64-bit atomics (PR #172517)

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https://github.com/huixie90 requested changes to this pull request.

Hmm. I am not sure if this is the right approach.  

I assume you have turned the optimisation through

```
--param optimization=speed
```

Basically the way this has-64-bit-atomic "feature" work is that it tries to compile a simple test program with the current testing configuration environment and the flags.

https://github.com/llvm/llvm-project/blob/abe0d62161bbbd9f8093ba07fd602fa5581744d3/libcxx/utils/libcxx/test/features/misc.py#L95


If you invoke lit with this way, the feature test program should be compiled with the optimisation flag -O3 and hopefully that should also compile to nothing and the feature has-64-bit-atomics should return `True` and it won't make the test XFAIL

Could it be that the test program fail to compile due to other reasons?

https://github.com/llvm/llvm-project/pull/172517