[clang] [llvm] [HLSL][DXIL][SPIRV] Implementation of an abstraction for intrinsic selection of HLSL backends (PR #87171)

[Justin Bogner via cfe-commits]

bogner wrote:

The `GENERATE_HLSL_INTRINSIC_FUNCTION` abstraction parts of this look fairly reasonable, but do we really want/need dx and spirv intrinsics for the "all" function? This is trivial to generate pretty generic IR for and I don't really see the value of maintaining that the user wrote "all(x)" in source - this doesn't even lower to a DXIL operation in the end. Won't simply expanding this out to checks on each of the elements be likely to give us better optimization opportunities?

https://github.com/llvm/llvm-project/pull/87171