[RISCV] Sources of vmerge shouldn't overlap V0 (#170070)

According to the spec:

> A vector register cannot be used to provide source operands with more
> than one EEW for a single instruction. A mask register source is
> considered to have EEW=1 for this constraint.

There must be a mask `V0` in `vmerge` variants so the sources should
use register classes without `V0`.

This fixes #169905.

Co-authored-by: Luke Lau <[email protected]>

Author: wangpc-pp

llvm/lib/Target/RISCV/RISCVInstrInfoVPseudos.td

@@ -2982,21 +2982,21 @@ multiclass VPseudoVFWALU_WV_WF_RM {
 multiclass VPseudoVMRG_VM_XM_IM {
   foreach m = MxList in {
     defvar mx = m.MX;
-    def "_VVM" # "_" # m.MX:
-      VPseudoTiedBinaryCarryIn<GetVRegNoV0<m.vrclass>.R,
-                               m.vrclass, m.vrclass, m>,
-      SchedBinary<"WriteVIMergeV", "ReadVIMergeV", "ReadVIMergeV", mx,
-                          forcePassthruRead=true>;
-    def "_VXM" # "_" # m.MX:
-      VPseudoTiedBinaryCarryIn<GetVRegNoV0<m.vrclass>.R,
-                               m.vrclass, GPR, m>,
-      SchedBinary<"WriteVIMergeX", "ReadVIMergeV", "ReadVIMergeX", mx,
-                          forcePassthruRead=true>;
-    def "_VIM" # "_" # m.MX:
-      VPseudoTiedBinaryCarryIn<GetVRegNoV0<m.vrclass>.R,
-                               m.vrclass, simm5, m>,
-      SchedUnary<"WriteVIMergeI", "ReadVIMergeV", mx,
-                          forcePassthruRead=true>;
+    def "_VVM"#"_"#m.MX : VPseudoTiedBinaryCarryIn<GetVRegNoV0<m.vrclass>.R,
+                                                   GetVRegNoV0<m.vrclass>.R,
+                                                   GetVRegNoV0<m.vrclass>.R, m>,
+        SchedBinary<"WriteVIMergeV", "ReadVIMergeV", "ReadVIMergeV", mx,
+                    forcePassthruRead = true>;
+    def "_VXM"#"_"#m.MX
+        : VPseudoTiedBinaryCarryIn<GetVRegNoV0<m.vrclass>.R,
+                                   GetVRegNoV0<m.vrclass>.R, GPR, m>,
+        SchedBinary<"WriteVIMergeX", "ReadVIMergeV", "ReadVIMergeX", mx,
+                    forcePassthruRead = true>;
+    def "_VIM"#"_"#m.MX
+        : VPseudoTiedBinaryCarryIn<GetVRegNoV0<m.vrclass>.R,
+                                   GetVRegNoV0<m.vrclass>.R, simm5, m>,
+        SchedUnary<"WriteVIMergeI", "ReadVIMergeV", mx,
+                   forcePassthruRead = true>;
   }
 }
 

llvm/lib/Target/RISCV/RISCVVectorPeephole.cpp

@@ -73,7 +73,7 @@ class RISCVVectorPeephole : public MachineFunctionPass {
   bool isAllOnesMask(const MachineInstr *MaskDef) const;
   std::optional<unsigned> getConstant(const MachineOperand &VL) const;
   bool ensureDominates(const MachineOperand &Use, MachineInstr &Src) const;
-  bool isKnownSameDefs(Register A, Register B) const;
+  Register lookThruCopies(Register Reg) const;
 };
 
 } // namespace
@@ -387,23 +387,18 @@ bool RISCVVectorPeephole::convertAllOnesVMergeToVMv(MachineInstr &MI) const {
   return true;
 }
 
-bool RISCVVectorPeephole::isKnownSameDefs(Register A, Register B) const {
-  if (A.isPhysical() || B.isPhysical())
-    return false;
-
-  auto LookThruVirtRegCopies = [this](Register Reg) {
-    while (MachineInstr *Def = MRI->getUniqueVRegDef(Reg)) {
-      if (!Def->isFullCopy())
-        break;
-      Register Src = Def->getOperand(1).getReg();
-      if (!Src.isVirtual())
-        break;
-      Reg = Src;
-    }
-    return Reg;
-  };
-
-  return LookThruVirtRegCopies(A) == LookThruVirtRegCopies(B);
+// If \p Reg is defined by one or more COPYs of virtual registers, traverses
+// the chain and returns the root non-COPY source.
+Register RISCVVectorPeephole::lookThruCopies(Register Reg) const {
+  while (MachineInstr *Def = MRI->getUniqueVRegDef(Reg)) {
+    if (!Def->isFullCopy())
+      break;
+    Register Src = Def->getOperand(1).getReg();
+    if (!Src.isVirtual())
+      break;
+    Reg = Src;
+  }
+  return Reg;
 }
 
 /// If a PseudoVMERGE_VVM's true operand is a masked pseudo and both have the
@@ -428,10 +423,11 @@ bool RISCVVectorPeephole::convertSameMaskVMergeToVMv(MachineInstr &MI) {
   if (!TrueMaskedInfo || !hasSameEEW(MI, *True))
     return false;
 
-  const MachineOperand &TrueMask =
-      True->getOperand(TrueMaskedInfo->MaskOpIdx + True->getNumExplicitDefs());
-  const MachineOperand &MIMask = MI.getOperand(4);
-  if (!isKnownSameDefs(TrueMask.getReg(), MIMask.getReg()))
+  Register TrueMaskReg = lookThruCopies(
+      True->getOperand(TrueMaskedInfo->MaskOpIdx + True->getNumExplicitDefs())
+          .getReg());
+  Register MIMaskReg = lookThruCopies(MI.getOperand(4).getReg());
+  if (!TrueMaskReg.isVirtual() || TrueMaskReg != MIMaskReg)
     return false;
 
   // Masked off lanes past TrueVL will come from False, and converting to vmv
@@ -717,9 +713,9 @@ bool RISCVVectorPeephole::foldVMergeToMask(MachineInstr &MI) const {
   if (RISCV::getRVVMCOpcode(MI.getOpcode()) != RISCV::VMERGE_VVM)
     return false;
 
-  Register PassthruReg = MI.getOperand(1).getReg();
-  Register FalseReg = MI.getOperand(2).getReg();
-  Register TrueReg = MI.getOperand(3).getReg();
+  Register PassthruReg = lookThruCopies(MI.getOperand(1).getReg());
+  Register FalseReg = lookThruCopies(MI.getOperand(2).getReg());
+  Register TrueReg = lookThruCopies(MI.getOperand(3).getReg());
   if (!TrueReg.isVirtual() || !MRI->hasOneUse(TrueReg))
     return false;
   MachineInstr &True = *MRI->getUniqueVRegDef(TrueReg);
@@ -740,16 +736,17 @@ bool RISCVVectorPeephole::foldVMergeToMask(MachineInstr &MI) const {
 
   // We require that either passthru and false are the same, or that passthru
   // is undefined.
-  if (PassthruReg && !isKnownSameDefs(PassthruReg, FalseReg))
+  if (PassthruReg && !(PassthruReg.isVirtual() && PassthruReg == FalseReg))
     return false;
 
   std::optional<std::pair<unsigned, unsigned>> NeedsCommute;
 
   // If True has a passthru operand then it needs to be the same as vmerge's
   // False, since False will be used for the result's passthru operand.
-  Register TruePassthru = True.getOperand(True.getNumExplicitDefs()).getReg();
+  Register TruePassthru =
+      lookThruCopies(True.getOperand(True.getNumExplicitDefs()).getReg());
   if (RISCVII::isFirstDefTiedToFirstUse(True.getDesc()) && TruePassthru &&
-      !isKnownSameDefs(TruePassthru, FalseReg)) {
+      !(TruePassthru.isVirtual() && TruePassthru == FalseReg)) {
     // If True's passthru != False, check if it uses False in another operand
     // and try to commute it.
     int OtherIdx = True.findRegisterUseOperandIdx(FalseReg, TRI);

llvm/test/CodeGen/RISCV/GlobalISel/instruction-select/rvv/select.mir

@@ -11,15 +11,15 @@ body:             |
   bb.0.entry:
     ; RV32I-LABEL: name: select_nxv1i8
     ; RV32I: [[DEF:%[0-9]+]]:vmv0 = IMPLICIT_DEF
-    ; RV32I-NEXT: [[DEF1:%[0-9]+]]:vr = IMPLICIT_DEF
+    ; RV32I-NEXT: [[DEF1:%[0-9]+]]:vrnov0 = IMPLICIT_DEF
     ; RV32I-NEXT: [[DEF2:%[0-9]+]]:vrnov0 = IMPLICIT_DEF
     ; RV32I-NEXT: [[PseudoVMERGE_VVM_MF4_:%[0-9]+]]:vrnov0 = PseudoVMERGE_VVM_MF4 [[DEF2]], [[DEF1]], [[DEF1]], [[DEF]], -1, 3 /* e8 */
     ; RV32I-NEXT: $v8 = COPY [[PseudoVMERGE_VVM_MF4_]]
     ; RV32I-NEXT: PseudoRET implicit $v8
     ;
     ; RV64I-LABEL: name: select_nxv1i8
     ; RV64I: [[DEF:%[0-9]+]]:vmv0 = IMPLICIT_DEF
-    ; RV64I-NEXT: [[DEF1:%[0-9]+]]:vr = IMPLICIT_DEF
+    ; RV64I-NEXT: [[DEF1:%[0-9]+]]:vrnov0 = IMPLICIT_DEF
     ; RV64I-NEXT: [[DEF2:%[0-9]+]]:vrnov0 = IMPLICIT_DEF
     ; RV64I-NEXT: [[PseudoVMERGE_VVM_MF4_:%[0-9]+]]:vrnov0 = PseudoVMERGE_VVM_MF4 [[DEF2]], [[DEF1]], [[DEF1]], [[DEF]], -1, 3 /* e8 */
     ; RV64I-NEXT: $v8 = COPY [[PseudoVMERGE_VVM_MF4_]]
@@ -40,15 +40,15 @@ body:             |
   bb.0.entry:
     ; RV32I-LABEL: name: select_nxv4i8
     ; RV32I: [[DEF:%[0-9]+]]:vmv0 = IMPLICIT_DEF
-    ; RV32I-NEXT: [[DEF1:%[0-9]+]]:vr = IMPLICIT_DEF
+    ; RV32I-NEXT: [[DEF1:%[0-9]+]]:vrnov0 = IMPLICIT_DEF
     ; RV32I-NEXT: [[DEF2:%[0-9]+]]:vrnov0 = IMPLICIT_DEF
     ; RV32I-NEXT: [[PseudoVMERGE_VVM_M1_:%[0-9]+]]:vrnov0 = PseudoVMERGE_VVM_M1 [[DEF2]], [[DEF1]], [[DEF1]], [[DEF]], -1, 3 /* e8 */
     ; RV32I-NEXT: $v8 = COPY [[PseudoVMERGE_VVM_M1_]]
     ; RV32I-NEXT: PseudoRET implicit $v8
     ;
     ; RV64I-LABEL: name: select_nxv4i8
     ; RV64I: [[DEF:%[0-9]+]]:vmv0 = IMPLICIT_DEF
-    ; RV64I-NEXT: [[DEF1:%[0-9]+]]:vr = IMPLICIT_DEF
+    ; RV64I-NEXT: [[DEF1:%[0-9]+]]:vrnov0 = IMPLICIT_DEF
     ; RV64I-NEXT: [[DEF2:%[0-9]+]]:vrnov0 = IMPLICIT_DEF
     ; RV64I-NEXT: [[PseudoVMERGE_VVM_M1_:%[0-9]+]]:vrnov0 = PseudoVMERGE_VVM_M1 [[DEF2]], [[DEF1]], [[DEF1]], [[DEF]], -1, 3 /* e8 */
     ; RV64I-NEXT: $v8 = COPY [[PseudoVMERGE_VVM_M1_]]
@@ -69,15 +69,15 @@ body:             |
   bb.0.entry:
     ; RV32I-LABEL: name: select_nxv16i8
     ; RV32I: [[DEF:%[0-9]+]]:vmv0 = IMPLICIT_DEF
-    ; RV32I-NEXT: [[DEF1:%[0-9]+]]:vrm4 = IMPLICIT_DEF
+    ; RV32I-NEXT: [[DEF1:%[0-9]+]]:vrm4nov0 = IMPLICIT_DEF
     ; RV32I-NEXT: [[DEF2:%[0-9]+]]:vrm4nov0 = IMPLICIT_DEF
     ; RV32I-NEXT: [[PseudoVMERGE_VVM_M4_:%[0-9]+]]:vrm4nov0 = PseudoVMERGE_VVM_M4 [[DEF2]], [[DEF1]], [[DEF1]], [[DEF]], -1, 3 /* e8 */
     ; RV32I-NEXT: $v8m4 = COPY [[PseudoVMERGE_VVM_M4_]]
     ; RV32I-NEXT: PseudoRET implicit $v8m4
     ;
     ; RV64I-LABEL: name: select_nxv16i8
     ; RV64I: [[DEF:%[0-9]+]]:vmv0 = IMPLICIT_DEF
-    ; RV64I-NEXT: [[DEF1:%[0-9]+]]:vrm4 = IMPLICIT_DEF
+    ; RV64I-NEXT: [[DEF1:%[0-9]+]]:vrm4nov0 = IMPLICIT_DEF
     ; RV64I-NEXT: [[DEF2:%[0-9]+]]:vrm4nov0 = IMPLICIT_DEF
     ; RV64I-NEXT: [[PseudoVMERGE_VVM_M4_:%[0-9]+]]:vrm4nov0 = PseudoVMERGE_VVM_M4 [[DEF2]], [[DEF1]], [[DEF1]], [[DEF]], -1, 3 /* e8 */
     ; RV64I-NEXT: $v8m4 = COPY [[PseudoVMERGE_VVM_M4_]]
@@ -98,15 +98,15 @@ body:             |
   bb.0.entry:
     ; RV32I-LABEL: name: select_nxv64i8
     ; RV32I: [[DEF:%[0-9]+]]:vmv0 = IMPLICIT_DEF
-    ; RV32I-NEXT: [[DEF1:%[0-9]+]]:vr = IMPLICIT_DEF
+    ; RV32I-NEXT: [[DEF1:%[0-9]+]]:vrnov0 = IMPLICIT_DEF
     ; RV32I-NEXT: [[DEF2:%[0-9]+]]:vrnov0 = IMPLICIT_DEF
     ; RV32I-NEXT: [[PseudoVMERGE_VVM_MF4_:%[0-9]+]]:vrnov0 = PseudoVMERGE_VVM_MF4 [[DEF2]], [[DEF1]], [[DEF1]], [[DEF]], -1, 4 /* e16 */
     ; RV32I-NEXT: $v8 = COPY [[PseudoVMERGE_VVM_MF4_]]
     ; RV32I-NEXT: PseudoRET implicit $v8
     ;
     ; RV64I-LABEL: name: select_nxv64i8
     ; RV64I: [[DEF:%[0-9]+]]:vmv0 = IMPLICIT_DEF
-    ; RV64I-NEXT: [[DEF1:%[0-9]+]]:vr = IMPLICIT_DEF
+    ; RV64I-NEXT: [[DEF1:%[0-9]+]]:vrnov0 = IMPLICIT_DEF
     ; RV64I-NEXT: [[DEF2:%[0-9]+]]:vrnov0 = IMPLICIT_DEF
     ; RV64I-NEXT: [[PseudoVMERGE_VVM_MF4_:%[0-9]+]]:vrnov0 = PseudoVMERGE_VVM_MF4 [[DEF2]], [[DEF1]], [[DEF1]], [[DEF]], -1, 4 /* e16 */
     ; RV64I-NEXT: $v8 = COPY [[PseudoVMERGE_VVM_MF4_]]
@@ -127,15 +127,15 @@ body:             |
   bb.0.entry:
     ; RV32I-LABEL: name: select_nxv2i16
     ; RV32I: [[DEF:%[0-9]+]]:vmv0 = IMPLICIT_DEF
-    ; RV32I-NEXT: [[DEF1:%[0-9]+]]:vr = IMPLICIT_DEF
+    ; RV32I-NEXT: [[DEF1:%[0-9]+]]:vrnov0 = IMPLICIT_DEF
     ; RV32I-NEXT: [[DEF2:%[0-9]+]]:vrnov0 = IMPLICIT_DEF
     ; RV32I-NEXT: [[PseudoVMERGE_VVM_M1_:%[0-9]+]]:vrnov0 = PseudoVMERGE_VVM_M1 [[DEF2]], [[DEF1]], [[DEF1]], [[DEF]], -1, 4 /* e16 */
     ; RV32I-NEXT: $v8 = COPY [[PseudoVMERGE_VVM_M1_]]
     ; RV32I-NEXT: PseudoRET implicit $v8
     ;
     ; RV64I-LABEL: name: select_nxv2i16
     ; RV64I: [[DEF:%[0-9]+]]:vmv0 = IMPLICIT_DEF
-    ; RV64I-NEXT: [[DEF1:%[0-9]+]]:vr = IMPLICIT_DEF
+    ; RV64I-NEXT: [[DEF1:%[0-9]+]]:vrnov0 = IMPLICIT_DEF
     ; RV64I-NEXT: [[DEF2:%[0-9]+]]:vrnov0 = IMPLICIT_DEF
     ; RV64I-NEXT: [[PseudoVMERGE_VVM_M1_:%[0-9]+]]:vrnov0 = PseudoVMERGE_VVM_M1 [[DEF2]], [[DEF1]], [[DEF1]], [[DEF]], -1, 4 /* e16 */
     ; RV64I-NEXT: $v8 = COPY [[PseudoVMERGE_VVM_M1_]]
@@ -156,15 +156,15 @@ body:             |
   bb.0.entry:
     ; RV32I-LABEL: name: select_nxv8i16
     ; RV32I: [[DEF:%[0-9]+]]:vmv0 = IMPLICIT_DEF
-    ; RV32I-NEXT: [[DEF1:%[0-9]+]]:vrm4 = IMPLICIT_DEF
+    ; RV32I-NEXT: [[DEF1:%[0-9]+]]:vrm4nov0 = IMPLICIT_DEF
     ; RV32I-NEXT: [[DEF2:%[0-9]+]]:vrm4nov0 = IMPLICIT_DEF
     ; RV32I-NEXT: [[PseudoVMERGE_VVM_M4_:%[0-9]+]]:vrm4nov0 = PseudoVMERGE_VVM_M4 [[DEF2]], [[DEF1]], [[DEF1]], [[DEF]], -1, 4 /* e16 */
     ; RV32I-NEXT: $v8m4 = COPY [[PseudoVMERGE_VVM_M4_]]
     ; RV32I-NEXT: PseudoRET implicit $v8m4
     ;
     ; RV64I-LABEL: name: select_nxv8i16
     ; RV64I: [[DEF:%[0-9]+]]:vmv0 = IMPLICIT_DEF
-    ; RV64I-NEXT: [[DEF1:%[0-9]+]]:vrm4 = IMPLICIT_DEF
+    ; RV64I-NEXT: [[DEF1:%[0-9]+]]:vrm4nov0 = IMPLICIT_DEF
     ; RV64I-NEXT: [[DEF2:%[0-9]+]]:vrm4nov0 = IMPLICIT_DEF
     ; RV64I-NEXT: [[PseudoVMERGE_VVM_M4_:%[0-9]+]]:vrm4nov0 = PseudoVMERGE_VVM_M4 [[DEF2]], [[DEF1]], [[DEF1]], [[DEF]], -1, 4 /* e16 */
     ; RV64I-NEXT: $v8m4 = COPY [[PseudoVMERGE_VVM_M4_]]
@@ -185,15 +185,15 @@ body:             |
   bb.0.entry:
     ; RV32I-LABEL: name: select_nxv32i16
     ; RV32I: [[DEF:%[0-9]+]]:vmv0 = IMPLICIT_DEF
-    ; RV32I-NEXT: [[DEF1:%[0-9]+]]:vr = IMPLICIT_DEF
+    ; RV32I-NEXT: [[DEF1:%[0-9]+]]:vrnov0 = IMPLICIT_DEF
     ; RV32I-NEXT: [[DEF2:%[0-9]+]]:vrnov0 = IMPLICIT_DEF
     ; RV32I-NEXT: [[PseudoVMERGE_VVM_MF2_:%[0-9]+]]:vrnov0 = PseudoVMERGE_VVM_MF2 [[DEF2]], [[DEF1]], [[DEF1]], [[DEF]], -1, 5 /* e32 */
     ; RV32I-NEXT: $v8 = COPY [[PseudoVMERGE_VVM_MF2_]]
     ; RV32I-NEXT: PseudoRET implicit $v8
     ;
     ; RV64I-LABEL: name: select_nxv32i16
     ; RV64I: [[DEF:%[0-9]+]]:vmv0 = IMPLICIT_DEF
-    ; RV64I-NEXT: [[DEF1:%[0-9]+]]:vr = IMPLICIT_DEF
+    ; RV64I-NEXT: [[DEF1:%[0-9]+]]:vrnov0 = IMPLICIT_DEF
     ; RV64I-NEXT: [[DEF2:%[0-9]+]]:vrnov0 = IMPLICIT_DEF
     ; RV64I-NEXT: [[PseudoVMERGE_VVM_MF2_:%[0-9]+]]:vrnov0 = PseudoVMERGE_VVM_MF2 [[DEF2]], [[DEF1]], [[DEF1]], [[DEF]], -1, 5 /* e32 */
     ; RV64I-NEXT: $v8 = COPY [[PseudoVMERGE_VVM_MF2_]]
@@ -214,15 +214,15 @@ body:             |
   bb.0.entry:
     ; RV32I-LABEL: name: select_nxv2i32
     ; RV32I: [[DEF:%[0-9]+]]:vmv0 = IMPLICIT_DEF
-    ; RV32I-NEXT: [[DEF1:%[0-9]+]]:vrm2 = IMPLICIT_DEF
+    ; RV32I-NEXT: [[DEF1:%[0-9]+]]:vrm2nov0 = IMPLICIT_DEF
     ; RV32I-NEXT: [[DEF2:%[0-9]+]]:vrm2nov0 = IMPLICIT_DEF
     ; RV32I-NEXT: [[PseudoVMERGE_VVM_M2_:%[0-9]+]]:vrm2nov0 = PseudoVMERGE_VVM_M2 [[DEF2]], [[DEF1]], [[DEF1]], [[DEF]], -1, 5 /* e32 */
     ; RV32I-NEXT: $v8m2 = COPY [[PseudoVMERGE_VVM_M2_]]
     ; RV32I-NEXT: PseudoRET implicit $v8m2
     ;
     ; RV64I-LABEL: name: select_nxv2i32
     ; RV64I: [[DEF:%[0-9]+]]:vmv0 = IMPLICIT_DEF
-    ; RV64I-NEXT: [[DEF1:%[0-9]+]]:vrm2 = IMPLICIT_DEF
+    ; RV64I-NEXT: [[DEF1:%[0-9]+]]:vrm2nov0 = IMPLICIT_DEF
     ; RV64I-NEXT: [[DEF2:%[0-9]+]]:vrm2nov0 = IMPLICIT_DEF
     ; RV64I-NEXT: [[PseudoVMERGE_VVM_M2_:%[0-9]+]]:vrm2nov0 = PseudoVMERGE_VVM_M2 [[DEF2]], [[DEF1]], [[DEF1]], [[DEF]], -1, 5 /* e32 */
     ; RV64I-NEXT: $v8m2 = COPY [[PseudoVMERGE_VVM_M2_]]
@@ -243,15 +243,15 @@ body:             |
   bb.0.entry:
     ; RV32I-LABEL: name: select_nxv8i32
     ; RV32I: [[DEF:%[0-9]+]]:vmv0 = IMPLICIT_DEF
-    ; RV32I-NEXT: [[DEF1:%[0-9]+]]:vrm8 = IMPLICIT_DEF
+    ; RV32I-NEXT: [[DEF1:%[0-9]+]]:vrm8nov0 = IMPLICIT_DEF
     ; RV32I-NEXT: [[DEF2:%[0-9]+]]:vrm8nov0 = IMPLICIT_DEF
     ; RV32I-NEXT: [[PseudoVMERGE_VVM_M8_:%[0-9]+]]:vrm8nov0 = PseudoVMERGE_VVM_M8 [[DEF2]], [[DEF1]], [[DEF1]], [[DEF]], -1, 5 /* e32 */
     ; RV32I-NEXT: $v8m8 = COPY [[PseudoVMERGE_VVM_M8_]]
     ; RV32I-NEXT: PseudoRET implicit $v8m8
     ;
     ; RV64I-LABEL: name: select_nxv8i32
     ; RV64I: [[DEF:%[0-9]+]]:vmv0 = IMPLICIT_DEF
-    ; RV64I-NEXT: [[DEF1:%[0-9]+]]:vrm8 = IMPLICIT_DEF
+    ; RV64I-NEXT: [[DEF1:%[0-9]+]]:vrm8nov0 = IMPLICIT_DEF
     ; RV64I-NEXT: [[DEF2:%[0-9]+]]:vrm8nov0 = IMPLICIT_DEF
     ; RV64I-NEXT: [[PseudoVMERGE_VVM_M8_:%[0-9]+]]:vrm8nov0 = PseudoVMERGE_VVM_M8 [[DEF2]], [[DEF1]], [[DEF1]], [[DEF]], -1, 5 /* e32 */
     ; RV64I-NEXT: $v8m8 = COPY [[PseudoVMERGE_VVM_M8_]]
@@ -272,15 +272,15 @@ body:             |
   bb.0.entry:
     ; RV32I-LABEL: name: select_nxv1i64
     ; RV32I: [[DEF:%[0-9]+]]:vmv0 = IMPLICIT_DEF
-    ; RV32I-NEXT: [[DEF1:%[0-9]+]]:vrm2 = IMPLICIT_DEF
+    ; RV32I-NEXT: [[DEF1:%[0-9]+]]:vrm2nov0 = IMPLICIT_DEF
     ; RV32I-NEXT: [[DEF2:%[0-9]+]]:vrm2nov0 = IMPLICIT_DEF
     ; RV32I-NEXT: [[PseudoVMERGE_VVM_M2_:%[0-9]+]]:vrm2nov0 = PseudoVMERGE_VVM_M2 [[DEF2]], [[DEF1]], [[DEF1]], [[DEF]], -1, 6 /* e64 */
     ; RV32I-NEXT: $v8m2 = COPY [[PseudoVMERGE_VVM_M2_]]
     ; RV32I-NEXT: PseudoRET implicit $v8m2
     ;
     ; RV64I-LABEL: name: select_nxv1i64
     ; RV64I: [[DEF:%[0-9]+]]:vmv0 = IMPLICIT_DEF
-    ; RV64I-NEXT: [[DEF1:%[0-9]+]]:vrm2 = IMPLICIT_DEF
+    ; RV64I-NEXT: [[DEF1:%[0-9]+]]:vrm2nov0 = IMPLICIT_DEF
     ; RV64I-NEXT: [[DEF2:%[0-9]+]]:vrm2nov0 = IMPLICIT_DEF
     ; RV64I-NEXT: [[PseudoVMERGE_VVM_M2_:%[0-9]+]]:vrm2nov0 = PseudoVMERGE_VVM_M2 [[DEF2]], [[DEF1]], [[DEF1]], [[DEF]], -1, 6 /* e64 */
     ; RV64I-NEXT: $v8m2 = COPY [[PseudoVMERGE_VVM_M2_]]
@@ -301,15 +301,15 @@ body:             |
   bb.0.entry:
     ; RV32I-LABEL: name: select_nxv4i64
     ; RV32I: [[DEF:%[0-9]+]]:vmv0 = IMPLICIT_DEF
-    ; RV32I-NEXT: [[DEF1:%[0-9]+]]:vrm8 = IMPLICIT_DEF
+    ; RV32I-NEXT: [[DEF1:%[0-9]+]]:vrm8nov0 = IMPLICIT_DEF
     ; RV32I-NEXT: [[DEF2:%[0-9]+]]:vrm8nov0 = IMPLICIT_DEF
     ; RV32I-NEXT: [[PseudoVMERGE_VVM_M8_:%[0-9]+]]:vrm8nov0 = PseudoVMERGE_VVM_M8 [[DEF2]], [[DEF1]], [[DEF1]], [[DEF]], -1, 6 /* e64 */
     ; RV32I-NEXT: $v8m8 = COPY [[PseudoVMERGE_VVM_M8_]]
     ; RV32I-NEXT: PseudoRET implicit $v8m8
     ;
     ; RV64I-LABEL: name: select_nxv4i64
     ; RV64I: [[DEF:%[0-9]+]]:vmv0 = IMPLICIT_DEF
-    ; RV64I-NEXT: [[DEF1:%[0-9]+]]:vrm8 = IMPLICIT_DEF
+    ; RV64I-NEXT: [[DEF1:%[0-9]+]]:vrm8nov0 = IMPLICIT_DEF
     ; RV64I-NEXT: [[DEF2:%[0-9]+]]:vrm8nov0 = IMPLICIT_DEF
     ; RV64I-NEXT: [[PseudoVMERGE_VVM_M8_:%[0-9]+]]:vrm8nov0 = PseudoVMERGE_VVM_M8 [[DEF2]], [[DEF1]], [[DEF1]], [[DEF]], -1, 6 /* e64 */
     ; RV64I-NEXT: $v8m8 = COPY [[PseudoVMERGE_VVM_M8_]]

llvm/test/CodeGen/RISCV/rvv/combine-reduce-add-to-vcpop.ll

@@ -311,10 +311,10 @@ define i32 @test_nxv128i1(<vscale x 128 x i1> %x) {
 ; CHECK-NEXT:    vmerge.vim v16, v16, 1, v0
 ; CHECK-NEXT:    vsetvli a2, zero, e8, mf2, ta, ma
 ; CHECK-NEXT:    vslidedown.vx v0, v6, a0
+; CHECK-NEXT:    vsetvli a2, zero, e32, m8, ta, ma
+; CHECK-NEXT:    vmerge.vim v8, v8, 1, v0
 ; CHECK-NEXT:    vsetvli a2, zero, e8, m1, ta, ma
 ; CHECK-NEXT:    vslidedown.vx v6, v7, a1
-; CHECK-NEXT:    vsetvli a1, zero, e32, m8, ta, ma
-; CHECK-NEXT:    vmerge.vim v8, v8, 1, v0
 ; CHECK-NEXT:    vsetvli a1, zero, e8, mf2, ta, ma
 ; CHECK-NEXT:    vslidedown.vx v0, v7, a0
 ; CHECK-NEXT:    vslidedown.vx v5, v6, a0

llvm/test/CodeGen/RISCV/rvv/copyprop.mir

@@ -43,7 +43,7 @@ body:             |
     %2:gpr = COPY $x11
     %1:gpr = COPY $x10
     %3:vr = COPY $v8
-    %17:vr = PseudoVSLL_VI_M1 undef $noreg, %3, 5, 1, 6 /* e64 */, 0
+    %17:vrnov0 = PseudoVSLL_VI_M1 undef $noreg, %3, 5, 1, 6 /* e64 */, 0
     %22:vr = PseudoVMSNE_VI_M1 %3, 0, 1, 6 /* e64 */
     %23:vmv0 = COPY %22
     %25:vrnov0 = PseudoVMERGE_VIM_M1 undef $noreg, %17, -1, %23, 1, 6 /* e64 */