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

Matt Arsenault via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Tue Mar 21 08:04:40 PDT 2017

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


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