[PATCH] D31182: [InstCombine] fadd double (sitofp x), y check that the promotion is valid

[Matt Arsenault via Phabricator via llvm-commits]

arsenm added a comment.

In https://reviews.llvm.org/D31182#706365, @spatel wrote:

> Before getting to any details about the patch, we need to address the question raised in PR27036: why are we doing this transform in InstCombine at all? The assumption is that an integer add is more canonical and/or cheaper than an FP add. Is that universally true?


I would say no. For example on AMDGPU a f32 add is exactly as fast as an i32 add, but the i32 add has an additional carry output constraint to deal with


https://reviews.llvm.org/D31182