[PATCH] D25805: [AMDGPU] Perform uchar to float combine for ISD::SINT_TO_FP

[Matt Arsenault via llvm-commits]

arsenm added inline comments.


================
Comment at: lib/Target/AMDGPU/SIISelLowering.cpp:3560
   }
-
+  case ISD::SINT_TO_FP:
   case ISD::UINT_TO_FP: {
----------------
tstellarAMD wrote:
> tstellarAMD wrote:
> > I don't think this is correct, because it's replacing SINT_TO_FP with CVT_F32_UBYTE0, which is an unsigned conversion.
> Nevermind, I see that this transform is correct, because performUCharToFloatCombine() is checking that the high bits are all zero.
That checks if the high 24 bits are zero. For the signed case it needs to check if 25 bits are 0 so it is still incorrect


Repository:
  rL LLVM

https://reviews.llvm.org/D25805