[clang] [llvm] [X86] EmitX86BuiltinExpr - attempt to convert SSE41/AVX1 roundps/d/ss/sd builtins to regular rounding modes (PR #171227)

[Simon Pilgrim via cfe-commits]

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

Yes please - this close to the next release branch I'd prefer to play it safe, and we can more easily relax this in the future than partially revert it.

For this patch please can you require that the _MM_FROUND_NO_EXC bit is set, otherwise keep the x86 round builtin call - this will affect quite a few of the tests and might need alternative test coverage.

https://github.com/llvm/llvm-project/pull/171227