[AMDGPU] It's not profitable to narrow to i1

Author: justinfargnoli

llvm/lib/Target/AMDGPU/AMDGPUISelLowering.cpp

@@ -1040,6 +1040,8 @@ bool AMDGPUTargetLowering::isNarrowingProfitable(SDNode *N, EVT SrcVT,
   case ISD::MUL:
   case ISD::SETCC:
   case ISD::SELECT:
+    if (DestVT.getScalarSizeInBits() == 1)
+      return false;
     if (Subtarget->has16BitInsts() &&
         (!DestVT.isVector() || !Subtarget->hasVOP3PInsts())) {
       // Don't narrow back down to i16 if promoted to i32 already.