[PATCH] D43079: [TTI CostModel] change default cost of FP ops to 1 (PR36280)

[Sanjay Patel via Phabricator via llvm-commits]

spatel added a comment.

In https://reviews.llvm.org/D43079#1003118, @RKSimon wrote:

> Wouldn't we be better off avoiding affecting generic targets and just adding tuned FADD/FSUB/FMUL costs to getArithmeticInstrCost in X86TargetTransformInfo.cpp?


I'm not opposed to making that change (and it seems clear that we need to make other x86 cost model changes), but I think this one is independent of that. This is just supposed to make the default cost less necessary to require an override.

The fact that it helps the motivating (PR36280) case that led me here appears to be coincidence. I'm not understanding something fundamental about how SLP uses this cost to decide profitability, but I'll try to sort that out in https://reviews.llvm.org/D42981 or later.


https://reviews.llvm.org/D43079