Revert "[AMDGPU] SIPeepholeSDWA: Handle V_CNDMASK_B32_e64 (llvm#137930)"

This reverts commit 721cba4.

Signed-off-by: Ian Wood <ianwood2024@u.northwestern.edu>

Author: IanWood1

llvm/lib/Target/AMDGPU/SIPeepholeSDWA.cpp

@@ -62,7 +62,6 @@ class SIPeepholeSDWA {
   std::unique_ptr<SDWAOperand> matchSDWAOperand(MachineInstr &MI);
   void pseudoOpConvertToVOP2(MachineInstr &MI,
                              const GCNSubtarget &ST) const;
-  void convertVcndmaskToVOP2(MachineInstr &MI, const GCNSubtarget &ST) const;
   MachineInstr *createSDWAVersion(MachineInstr &MI);
   bool convertToSDWA(MachineInstr &MI, const SDWAOperandsVector &SDWAOperands);
   void legalizeScalarOperands(MachineInstr &MI, const GCNSubtarget &ST) const;
@@ -1038,8 +1037,7 @@ void SIPeepholeSDWA::pseudoOpConvertToVOP2(MachineInstr &MI,
     return;
   // Make sure VCC or its subregs are dead before MI.
   MachineBasicBlock &MBB = *MI.getParent();
-  MachineBasicBlock::LivenessQueryResult Liveness =
-      MBB.computeRegisterLiveness(TRI, AMDGPU::VCC, MI, 25);
+  auto Liveness = MBB.computeRegisterLiveness(TRI, AMDGPU::VCC, MI, 25);
   if (Liveness != MachineBasicBlock::LQR_Dead)
     return;
   // Check if VCC is referenced in range of (MI,MISucc].
@@ -1063,53 +1061,6 @@ void SIPeepholeSDWA::pseudoOpConvertToVOP2(MachineInstr &MI,
   MISucc.substituteRegister(CarryIn->getReg(), TRI->getVCC(), 0, *TRI);
 }
 
-/// Try to convert an \p MI in VOP3 which takes an src2 carry-in
-/// operand into the corresponding VOP2 form which expects the
-/// argument in VCC. To this end, add an copy from the carry-in to
-/// VCC.  The conversion will only be applied if \p MI can be shrunk
-/// to VOP2 and if VCC can be proven to be dead before \p MI.
-void SIPeepholeSDWA::convertVcndmaskToVOP2(MachineInstr &MI,
-                                           const GCNSubtarget &ST) const {
-  assert(MI.getOpcode() == AMDGPU::V_CNDMASK_B32_e64);
-
-  LLVM_DEBUG(dbgs() << "Attempting VOP2 conversion: " << MI);
-  if (!TII->canShrink(MI, *MRI)) {
-    LLVM_DEBUG(dbgs() << "Cannot shrink instruction\n");
-    return;
-  }
-
-  const MachineOperand &CarryIn =
-      *TII->getNamedOperand(MI, AMDGPU::OpName::src2);
-  Register CarryReg = CarryIn.getReg();
-  MachineInstr *CarryDef = MRI->getVRegDef(CarryReg);
-  if (!CarryDef) {
-    LLVM_DEBUG(dbgs() << "Missing carry-in operand definition\n");
-    return;
-  }
-
-  // Make sure VCC or its subregs are dead before MI.
-  MCRegister Vcc = TRI->getVCC();
-  MachineBasicBlock &MBB = *MI.getParent();
-  MachineBasicBlock::LivenessQueryResult Liveness =
-      MBB.computeRegisterLiveness(TRI, Vcc, MI);
-  if (Liveness != MachineBasicBlock::LQR_Dead) {
-    LLVM_DEBUG(dbgs() << "VCC not known to be dead before instruction\n");
-    return;
-  }
-
-  BuildMI(MBB, MI, MI.getDebugLoc(), TII->get(AMDGPU::COPY), Vcc).add(CarryIn);
-
-  auto Converted = BuildMI(MBB, MI, MI.getDebugLoc(),
-                           TII->get(AMDGPU::getVOPe32(MI.getOpcode())))
-                       .add(*TII->getNamedOperand(MI, AMDGPU::OpName::vdst))
-                       .add(*TII->getNamedOperand(MI, AMDGPU::OpName::src0))
-                       .add(*TII->getNamedOperand(MI, AMDGPU::OpName::src1))
-                       .setMIFlags(MI.getFlags());
-  TII->fixImplicitOperands(*Converted);
-  LLVM_DEBUG(dbgs() << "Converted to VOP2: " << *Converted);
-  MI.eraseFromParent();
-}
-
 namespace {
 bool isConvertibleToSDWA(MachineInstr &MI,
                          const GCNSubtarget &ST,
@@ -1119,11 +1070,6 @@ bool isConvertibleToSDWA(MachineInstr &MI,
   if (TII->isSDWA(Opc))
     return true;
 
-  // Can only be handled after ealier conversion to
-  // AMDGPU::V_CNDMASK_B32_e32 which is not always possible.
-  if (Opc == AMDGPU::V_CNDMASK_B32_e64)
-    return false;
-
   // Check if this instruction has opcode that supports SDWA
   if (AMDGPU::getSDWAOp(Opc) == -1)
     Opc = AMDGPU::getVOPe32(Opc);
@@ -1162,6 +1108,10 @@ bool isConvertibleToSDWA(MachineInstr &MI,
   if (TII->pseudoToMCOpcode(Opc) == -1)
     return false;
 
+  // FIXME: has SDWA but require handling of implicit VCC use
+  if (Opc == AMDGPU::V_CNDMASK_B32_e32)
+    return false;
+
   if (MachineOperand *Src0 = TII->getNamedOperand(MI, AMDGPU::OpName::src0)) {
     if (!Src0->isReg() && !Src0->isImm())
       return false;
@@ -1316,9 +1266,7 @@ MachineInstr *SIPeepholeSDWA::createSDWAVersion(MachineInstr &MI) {
     SDWAInst->tieOperands(PreserveDstIdx, SDWAInst->getNumOperands() - 1);
   }
 
-  MachineInstr *Ret = SDWAInst.getInstr();
-  TII->fixImplicitOperands(*Ret);
-  return Ret;
+  return SDWAInst.getInstr();
 }
 
 bool SIPeepholeSDWA::convertToSDWA(MachineInstr &MI,
@@ -1436,18 +1384,10 @@ bool SIPeepholeSDWA::run(MachineFunction &MF) {
       for (const auto &OperandPair : SDWAOperands) {
         const auto &Operand = OperandPair.second;
         MachineInstr *PotentialMI = Operand->potentialToConvert(TII, ST);
-        if (!PotentialMI)
-          continue;
-
-        switch (PotentialMI->getOpcode()) {
-        case AMDGPU::V_ADD_CO_U32_e64:
-        case AMDGPU::V_SUB_CO_U32_e64:
+        if (PotentialMI &&
+           (PotentialMI->getOpcode() == AMDGPU::V_ADD_CO_U32_e64 ||
+            PotentialMI->getOpcode() == AMDGPU::V_SUB_CO_U32_e64))
           pseudoOpConvertToVOP2(*PotentialMI, ST);
-          break;
-        case AMDGPU::V_CNDMASK_B32_e64:
-          convertVcndmaskToVOP2(*PotentialMI, ST);
-          break;
-        };
       }
       SDWAOperands.clear();