[PATCH] D73588: AMDGPU: Enhancement on FDIV lowering in AMDGPUCodeGenPrepare

[Matt Arsenault via Phabricator via llvm-commits]

arsenm added inline comments.


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Comment at: llvm/lib/Target/AMDGPU/AMDGPUCodeGenPrepare.cpp:714
   const bool UseFDivFast = Ty->isFloatTy() && !NeedHighAccuracy &&
-                           !FastUnsafeRcpLegal;
+                           !CanReassociateFDiv;
 
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cfang wrote:
> arsenm wrote:
> > fdiv.fast doesn't' care about the reassociation
> You are right. This is just the optimization priority issue.
> 
> If we can reassociate fdiv, x/y -> x * rcp(y) is faster than fdiv.fast so we don't do fdiv.fast.
The comment and variable name are misleading, as no reassociate is going on here. This needs an explanation here


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D73588/new/

https://reviews.llvm.org/D73588