[NFC] Check operand type instead of opcode (#168641)

A folow-up of #168458.

Author: shiltian

llvm/lib/Target/AMDGPU/GCNSubtarget.h

@@ -1423,7 +1423,7 @@ class GCNSubtarget final : public AMDGPUGenSubtargetInfo,
   /// \returns true if the target has packed f32 instructions that only read 32
   /// bits from a scalar operand (SGPR or literal) and replicates the bits to
   /// both channels.
-  bool hasPKF32InstsReplicatingLow32BitsOfScalarInput() const {
+  bool hasPKF32InstsReplicatingLower32BitsOfScalarInput() const {
     return getGeneration() == GFX12 && GFX1250Insts;
   }
 

llvm/lib/Target/AMDGPU/SIFoldOperands.cpp

@@ -766,29 +766,21 @@ static void appendFoldCandidate(SmallVectorImpl<FoldCandidate> &FoldList,
                       FoldCandidate(MI, OpNo, FoldOp, Commuted, ShrinkOp));
 }
 
-// Returns true if the instruction is a packed f32 instruction that only reads
-// 32 bits from a scalar operand (SGPR or literal) and replicates the bits to
-// both channels.
-static bool
-isPKF32InstrReplicatingLow32BitsOfScalarInput(const GCNSubtarget *ST,
-                                              MachineInstr *MI) {
-  if (!ST->hasPKF32InstsReplicatingLow32BitsOfScalarInput())
+// Returns true if the instruction is a packed F32 instruction and the
+// corresponding scalar operand reads 32 bits and replicates the bits to both
+// channels.
+static bool isPKF32InstrReplicatesLower32BitsOfScalarOperand(
+    const GCNSubtarget *ST, MachineInstr *MI, unsigned OpNo) {
+  if (!ST->hasPKF32InstsReplicatingLower32BitsOfScalarInput())
     return false;
-  switch (MI->getOpcode()) {
-  case AMDGPU::V_PK_ADD_F32:
-  case AMDGPU::V_PK_MUL_F32:
-  case AMDGPU::V_PK_FMA_F32:
-    return true;
-  default:
-    return false;
-  }
-  llvm_unreachable("unknown instruction");
+  const MCOperandInfo &OpDesc = MI->getDesc().operands()[OpNo];
+  return OpDesc.OperandType == AMDGPU::OPERAND_REG_IMM_V2FP32;
 }
 
 // Packed FP32 instructions only read 32 bits from a scalar operand (SGPR or
 // literal) and replicates the bits to both channels. Therefore, if the hi and
 // lo are not same, we can't fold it.
-static bool checkImmOpForPKF32InstrReplicatingLow32BitsOfScalarInput(
+static bool checkImmOpForPKF32InstrReplicatesLower32BitsOfScalarOperand(
     const FoldableDef &OpToFold) {
   assert(OpToFold.isImm() && "Expected immediate operand");
   uint64_t ImmVal = OpToFold.getEffectiveImmVal().value();
@@ -953,8 +945,8 @@ bool SIFoldOperandsImpl::tryAddToFoldList(
   // Special case for PK_F32 instructions if we are trying to fold an imm to
   // src0 or src1.
   if (OpToFold.isImm() &&
-      isPKF32InstrReplicatingLow32BitsOfScalarInput(ST, MI) &&
-      !checkImmOpForPKF32InstrReplicatingLow32BitsOfScalarInput(OpToFold))
+      isPKF32InstrReplicatesLower32BitsOfScalarOperand(ST, MI, OpNo) &&
+      !checkImmOpForPKF32InstrReplicatesLower32BitsOfScalarOperand(OpToFold))
     return false;
 
   appendFoldCandidate(FoldList, MI, OpNo, OpToFold);
@@ -1172,8 +1164,8 @@ bool SIFoldOperandsImpl::tryToFoldACImm(
     return false;
 
   if (OpToFold.isImm() && OpToFold.isOperandLegal(*TII, *UseMI, UseOpIdx)) {
-    if (isPKF32InstrReplicatingLow32BitsOfScalarInput(ST, UseMI) &&
-        !checkImmOpForPKF32InstrReplicatingLow32BitsOfScalarInput(OpToFold))
+    if (isPKF32InstrReplicatesLower32BitsOfScalarOperand(ST, UseMI, UseOpIdx) &&
+        !checkImmOpForPKF32InstrReplicatesLower32BitsOfScalarOperand(OpToFold))
       return false;
     appendFoldCandidate(FoldList, UseMI, UseOpIdx, OpToFold);
     return true;