[PATCH] D120150: Constant folding of llvm.amdgcn.trig.preop

[Matt Arsenault via Phabricator via llvm-commits]

arsenm added inline comments.


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Comment at: llvm/lib/Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp:1013
+        Scale += 128;
+      Res = ldexp(Res, Scale);
+      return IC.replaceInstUsesWith(II, ConstantFP::get(Src->getType(), Res));
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Ravi wrote:
> arsenm wrote:
> > You can use scalbn for APFloat instead of relying on host ldexp
> Yes..will try it out and check for any precision difference. Should be good as long as the internal implementation of APFloat is within 0.5 ULP.
Actually we should be constant folding the ldexp intrinsic too. I thought I did that before, but in the code above I don't see it handling arbitrary constants


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  https://reviews.llvm.org/D120150/new/

https://reviews.llvm.org/D120150