Common loweri64tof16ITOFP

Author: davemgreen

llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp

@@ -7609,6 +7609,22 @@ LegalizerHelper::lowerU64ToF64BitFloatOps(MachineInstr &MI) {
   return Legalized;
 }
 
+/// i64->fp16 itofp can be lowered to i64->f64,f64->f32,f32->f16. We cannot
+/// convert fpround f64->f16 without double-rounding, so we manually perform the
+/// lowering here where we know it is valid.
+static LegalizerHelper::LegalizeResult
+loweri64tof16ITOFP(MachineInstr &MI, Register Dst, LLT DstTy, Register Src,
+                   LLT SrcTy, MachineIRBuilder &MIRBuilder) {
+  auto M1 = MI.getOpcode() == TargetOpcode::G_UITOFP
+                ? MIRBuilder.buildUITOFP(SrcTy, Src)
+                : MIRBuilder.buildSITOFP(SrcTy, Src);
+  LLT S32Ty = SrcTy.changeElementSize(32);
+  auto M2 = MIRBuilder.buildFPTrunc(S32Ty, M1);
+  MIRBuilder.buildFPTrunc(Dst, M2);
+  MI.eraseFromParent();
+  return LegalizerHelper::Legalized;
+}
+
 LegalizerHelper::LegalizeResult LegalizerHelper::lowerUITOFP(MachineInstr &MI) {
   auto [Dst, DstTy, Src, SrcTy] = MI.getFirst2RegLLTs();
 
@@ -7620,17 +7636,8 @@ LegalizerHelper::LegalizeResult LegalizerHelper::lowerUITOFP(MachineInstr &MI) {
     return Legalized;
   }
 
-  // i64->fp16 itofp can be lowered to i64->f64,f64->f32,f32->f16. We cannot
-  // just convert fpround f64->f16 without double-rounding, so we manually
-  // perform the lowering here where we know it is valid.
-  if (DstTy.getScalarSizeInBits() == 16 && SrcTy.getScalarSizeInBits() == 64) {
-    auto M1 = MIRBuilder.buildUITOFP(SrcTy, Src);
-    LLT S32Ty = SrcTy.changeElementSize(32);
-    auto M2 = MIRBuilder.buildFPTrunc(S32Ty, M1);
-    MIRBuilder.buildFPTrunc(Dst, M2);
-    MI.eraseFromParent();
-    return Legalized;
-  }
+  if (DstTy.getScalarSizeInBits() == 16 && SrcTy.getScalarSizeInBits() == 64)
+    return loweri64tof16ITOFP(MI, Dst, DstTy, Src, SrcTy, MIRBuilder);
 
   if (SrcTy != LLT::scalar(64))
     return UnableToLegalize;
@@ -7663,17 +7670,8 @@ LegalizerHelper::LegalizeResult LegalizerHelper::lowerSITOFP(MachineInstr &MI) {
     return Legalized;
   }
 
-  // i64->fp16 itofp can be lowered to i64->f64,f64->f32,f32->f16. We cannot
-  // just convert fpround f64->f16 without double-rounding, so we manually
-  // perform the lowering here where we know it is valid.
-  if (DstTy.getScalarSizeInBits() == 16 && SrcTy.getScalarSizeInBits() == 64) {
-    auto M1 = MIRBuilder.buildSITOFP(SrcTy, Src);
-    LLT S32Ty = SrcTy.changeElementSize(32);
-    auto M2 = MIRBuilder.buildFPTrunc(S32Ty, M1);
-    MIRBuilder.buildFPTrunc(Dst, M2);
-    MI.eraseFromParent();
-    return Legalized;
-  }
+  if (DstTy.getScalarSizeInBits() == 16 && SrcTy.getScalarSizeInBits() == 64)
+    return loweri64tof16ITOFP(MI, Dst, DstTy, Src, SrcTy, MIRBuilder);
 
   if (SrcTy != S64)
     return UnableToLegalize;