AMDGPU/GlobalISel: Don't use pointless getConstantVRegVal

This is always a G_CONSTANT already

diff --git a/llvm/lib/Target/AMDGPU/AMDGPUInstructionSelector.cpp b/llvm/lib/Target/AMDGPU/AMDGPUInstructionSelector.cpp
index 4596889..90136f5 100644 (file)
--- a/llvm/lib/Target/AMDGPU/AMDGPUInstructionSelector.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPUInstructionSelector.cpp
@@ -2727,9 +2727,7 @@ void AMDGPUInstructionSelector::renderTruncImm32(MachineInstrBuilder &MIB,
                                                  int OpIdx) const {
   assert(MI.getOpcode() == TargetOpcode::G_CONSTANT && OpIdx == -1 &&
          "Expected G_CONSTANT");
-  Optional<int64_t> CstVal = getConstantVRegVal(MI.getOperand(0).getReg(), *MRI);
-  assert(CstVal && "Expected constant value");
-  MIB.addImm(CstVal.getValue());
+  MIB.addImm(MI.getOperand(1).getCImm()->getSExtValue());
 }
 
 void AMDGPUInstructionSelector::renderNegateImm(MachineInstrBuilder &MIB,