vendor/llvm-project/llvmorg-15-init-17485-ga3e38b4a206b

1 files changed, 7 insertions, 23 deletions

diff --git a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
index fb046d519ac8..52ee13757f27 100644
--- a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
@@ -2393,30 +2393,14 @@ LegalizerHelper::widenScalar(MachineInstr &MI, unsigned TypeIdx, LLT WideTy) {
     return Legalized;
   }
   case TargetOpcode::G_FCONSTANT: {
+    // To avoid changing the bits of the constant due to extension to a larger
+    // type and then using G_FPTRUNC, we simply convert to a G_CONSTANT.
     MachineOperand &SrcMO = MI.getOperand(1);
-    LLVMContext &Ctx = MIRBuilder.getMF().getFunction().getContext();
-    APFloat Val = SrcMO.getFPImm()->getValueAPF();
-    bool LosesInfo;
-    switch (WideTy.getSizeInBits()) {
-    case 32:
-      Val.convert(APFloat::IEEEsingle(), APFloat::rmNearestTiesToEven,
-                  &LosesInfo);
-      break;
-    case 64:
-      Val.convert(APFloat::IEEEdouble(), APFloat::rmNearestTiesToEven,
-                  &LosesInfo);
-      break;
-    default:
-      return UnableToLegalize;
-    }
-
-    assert(!LosesInfo && "extend should always be lossless");
-
-    Observer.changingInstr(MI);
-    SrcMO.setFPImm(ConstantFP::get(Ctx, Val));
-
-    widenScalarDst(MI, WideTy, 0, TargetOpcode::G_FPTRUNC);
-    Observer.changedInstr(MI);
+    APInt Val = SrcMO.getFPImm()->getValueAPF().bitcastToAPInt();
+    MIRBuilder.setInstrAndDebugLoc(MI);
+    auto IntCst = MIRBuilder.buildConstant(MI.getOperand(0).getReg(), Val);
+    widenScalarDst(*IntCst, WideTy, 0, TargetOpcode::G_TRUNC);
+    MI.eraseFromParent();
     return Legalized;
   }
   case TargetOpcode::G_IMPLICIT_DEF: {