[llvm] [NVPTX] Set default value of nvptx-allow-ftz-atomics to true (PR #206154)

[Reid Kleckner via llvm-commits]

https://github.com/rnk approved this pull request.

I talked to some folks here at NVIDIA, and I think I agree with Art. I can't make hard commitments about product release dates and which fixes will be in them, but let's revisit this in the fall, and see if there are new ptxas features that allow us to fix this in a way that gives users the best possible behavior with the least disruption.

I'll go look for this in the issue tracker and write that down as the next step.

https://github.com/llvm/llvm-project/pull/206154