[SDAG] Allow scalable vectors in ComputeNumSignBits

[reames]

Summary

This is a continuation of the series of patches adding lane wise support for scalable vectors in various knownbit-esq routines.

The basic idea here is that we track a single lane for scalable vectors which corresponds to an unknown number of lanes at runtime. This is enough for us to perform lane wise reasoning on many arithmetic operations.

[reames]

rebase and ping

[craig.topper]

LGTM

[reames]

Realized I hadn't included a bailout before ComputeNumSignBitsForTargetNode in this patch. This was unintentional, but there are few enough implementations of this that a quick audit was easy. I didn't see anything concerning. So I'm going to leave this as is instead of inserting the bailout and then removing it again. :)

[paulwalker-arm]

llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp

4385–4386

This can never be true can it?

More relevant to the other exit paths but is return 1; what we want here rather than break;? I asked because the existing scalable vector early exits do the latter (e.g. a couple of lines down) and so I'm wondering if we're loosing information or if the other exit paths are wrong.

[reames]

llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp

4385–4386

I think this one is dead. Extract_vector_elt should always be returning a vector. We have extract_subvector for vector extract from vector.

As for the 1 vs break thing, both are correct, but 1 is possible non-optimal. The code below the switch uses compute known bits, so if our compute known bits handles one of these and the sign bits are known, then 1 is unnecessarily conservative.

I'll fix both in a follow up commit.

[reames]

llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp

4385–4386

Addressed in 3fb08d1

[reames]

I reverted this on Friday due to a reported problem with an earlier dependent change. Reopening so that I remember to reland once the underlying issue is resolved. No action needed from reviewers.

Note: When I reland, I will fold in the post-commit review comment and fixes that originally landed separately.

llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp

bool SelectionDAG::isKnownToBeAPowerOfTwo(SDValue Val) const {
   // Fall back to computeKnownBits to catch other known cases.
   KnownBits Known = computeKnownBits(Val);
   return (Known.countMaxPopulation() == 1) && (Known.countMinPopulation() == 1);
 }
 
 unsigned SelectionDAG::ComputeNumSignBits(SDValue Op, unsigned Depth) const {
   EVT VT = Op.getValueType();
 
-  // TODO: Assume we don't know anything for now.
-  if (VT.isScalableVector())
-    return 1;
-
-  APInt DemandedElts = VT.isVector()
+  // Since the number of lanes in a scalable vector is unknown at compile time,
+  // we track one bit which is implicitly broadcast to all lanes.  This means
+  // that all lanes in a scalable vector are considered demanded.
+  APInt DemandedElts = VT.isFixedLengthVector()
                            ? APInt::getAllOnes(VT.getVectorNumElements())
                            : APInt(1, 1);
   return ComputeNumSignBits(Op, DemandedElts, Depth);
 }
 
 unsigned SelectionDAG::ComputeNumSignBits(SDValue Op, const APInt &DemandedElts,
                                           unsigned Depth) const {
   EVT VT = Op.getValueType();
   assert((VT.isInteger() || VT.isFloatingPoint()) && "Invalid VT!");
   unsigned VTBits = VT.getScalarSizeInBits();
   unsigned NumElts = DemandedElts.getBitWidth();
   unsigned Tmp, Tmp2;
   unsigned FirstAnswer = 1;
 
   if (auto *C = dyn_cast<ConstantSDNode>(Op)) {
     const APInt &Val = C->getAPIntValue();
     return Val.getNumSignBits();
   }
 
   if (Depth >= MaxRecursionDepth)
     return 1;  // Limit search depth.
 
-  if (!DemandedElts || VT.isScalableVector())
+  if (!DemandedElts)
     return 1;  // No demanded elts, better to assume we don't know anything.
 
   unsigned Opcode = Op.getOpcode();
   switch (Opcode) {
   default: break;
   case ISD::AssertSext:
     Tmp = cast<VTSDNode>(Op.getOperand(1))->getVT().getSizeInBits();
     return VTBits-Tmp+1;
   case ISD::AssertZext:
     Tmp = cast<VTSDNode>(Op.getOperand(1))->getVT().getSizeInBits();
     return VTBits-Tmp;
   case ISD::MERGE_VALUES:
     return ComputeNumSignBits(Op.getOperand(Op.getResNo()), DemandedElts,
                               Depth + 1);
+  case ISD::SPLAT_VECTOR: {
+    // Check if the sign bits of source go down as far as the truncated value.
+    unsigned NumSrcBits = Op.getOperand(0).getValueSizeInBits();
+    unsigned NumSrcSignBits = ComputeNumSignBits(Op.getOperand(0), Depth + 1);
+    if (NumSrcSignBits > (NumSrcBits - VTBits))
+      return NumSrcSignBits - (NumSrcBits - VTBits);
+    break;
+  }
   case ISD::BUILD_VECTOR:
+    assert(!VT.isScalableVector());
     Tmp = VTBits;
     for (unsigned i = 0, e = Op.getNumOperands(); (i < e) && (Tmp > 1); ++i) {
       if (!DemandedElts[i])
         continue;
 
       SDValue SrcOp = Op.getOperand(i);
       Tmp2 = ComputeNumSignBits(SrcOp, Depth + 1);
 
case ISD::VECTOR_SHUFFLE: {
     // If we don't know anything, early out and try computeKnownBits fall-back.
     if (Tmp == 1)
       break;
     assert(Tmp <= VTBits && "Failed to determine minimum sign bits");
     return Tmp;
   }
 
   case ISD::BITCAST: {
+    if (VT.isScalableVector())
+      return 1;
     SDValue N0 = Op.getOperand(0);
     EVT SrcVT = N0.getValueType();
     unsigned SrcBits = SrcVT.getScalarSizeInBits();
 
     // Ignore bitcasts from unsupported types..
     if (!(SrcVT.isInteger() || SrcVT.isFloatingPoint()))
       break;
 
case ISD::SIGN_EXTEND:
     return ComputeNumSignBits(Op.getOperand(0), DemandedElts, Depth+1) + Tmp;
   case ISD::SIGN_EXTEND_INREG:
     // Max of the input and what this extends.
     Tmp = cast<VTSDNode>(Op.getOperand(1))->getVT().getScalarSizeInBits();
     Tmp = VTBits-Tmp+1;
     Tmp2 = ComputeNumSignBits(Op.getOperand(0), DemandedElts, Depth+1);
     return std::max(Tmp, Tmp2);
   case ISD::SIGN_EXTEND_VECTOR_INREG: {
+    if (VT.isScalableVector())
+      return 1;
     SDValue Src = Op.getOperand(0);
     EVT SrcVT = Src.getValueType();
     APInt DemandedSrcElts = DemandedElts.zext(SrcVT.getVectorNumElements());
     Tmp = VTBits - SrcVT.getScalarSizeInBits();
     return ComputeNumSignBits(Src, DemandedSrcElts, Depth+1) + Tmp;
   }
   case ISD::SRA:
     Tmp = ComputeNumSignBits(Op.getOperand(0), DemandedElts, Depth + 1);
case ISD::TRUNCATE: {
     // Check if the sign bits of source go down as far as the truncated value.
     unsigned NumSrcBits = Op.getOperand(0).getScalarValueSizeInBits();
     unsigned NumSrcSignBits = ComputeNumSignBits(Op.getOperand(0), Depth + 1);
     if (NumSrcSignBits > (NumSrcBits - VTBits))
       return NumSrcSignBits - (NumSrcBits - VTBits);
     break;
   }
   case ISD::EXTRACT_ELEMENT: {
+    if (VT.isScalableVector())
+      return 1;
     const int KnownSign = ComputeNumSignBits(Op.getOperand(0), Depth+1);
     const int BitWidth = Op.getValueSizeInBits();
     const int Items = Op.getOperand(0).getValueSizeInBits() / BitWidth;
 
     // Get reverse index (starting from 1), Op1 value indexes elements from
     // little end. Sign starts at big end.
     const int rIndex = Items - 1 - Op.getConstantOperandVal(1);
 
     // If the sign portion ends in our element the subtraction gives correct
     // result. Otherwise it gives either negative or > bitwidth result
     return std::clamp(KnownSign - rIndex * BitWidth, 0, BitWidth);
   }
   case ISD::INSERT_VECTOR_ELT: {
+    if (VT.isScalableVector())
+      return 1;
     // If we know the element index, split the demand between the
     // source vector and the inserted element, otherwise assume we need
     // the original demanded vector elements and the value.
     SDValue InVec = Op.getOperand(0);
     SDValue InVal = Op.getOperand(1);
     SDValue EltNo = Op.getOperand(2);
     bool DemandedVal = true;
     APInt DemandedVecElts = DemandedElts;
case ISD::INSERT_VECTOR_ELT: {
     if (!!DemandedVecElts) {
       Tmp2 = ComputeNumSignBits(InVec, DemandedVecElts, Depth + 1);
       Tmp = std::min(Tmp, Tmp2);
     }
     assert(Tmp <= VTBits && "Failed to determine minimum sign bits");
     return Tmp;
   }
   case ISD::EXTRACT_VECTOR_ELT: {
+    if (VT.isScalableVector())
+      return 1;
     SDValue InVec = Op.getOperand(0);
     SDValue EltNo = Op.getOperand(1);
     EVT VecVT = InVec.getValueType();
     // ComputeNumSignBits not yet implemented for scalable vectors.
     if (VecVT.isScalableVector())
       break;
     const unsigned BitWidth = Op.getValueSizeInBits();
     const unsigned EltBitWidth = Op.getOperand(0).getScalarValueSizeInBits();
case ISD::EXTRACT_SUBVECTOR: {
     if (Src.getValueType().isScalableVector())
       break;
     uint64_t Idx = Op.getConstantOperandVal(1);
     unsigned NumSrcElts = Src.getValueType().getVectorNumElements();
     APInt DemandedSrcElts = DemandedElts.zext(NumSrcElts).shl(Idx);
     return ComputeNumSignBits(Src, DemandedSrcElts, Depth + 1);
   }
   case ISD::CONCAT_VECTORS: {
+    if (VT.isScalableVector())
+      return 1;
     // Determine the minimum number of sign bits across all demanded
     // elts of the input vectors. Early out if the result is already 1.
     Tmp = std::numeric_limits<unsigned>::max();
     EVT SubVectorVT = Op.getOperand(0).getValueType();
     unsigned NumSubVectorElts = SubVectorVT.getVectorNumElements();
     unsigned NumSubVectors = Op.getNumOperands();
     for (unsigned i = 0; (i < NumSubVectors) && (Tmp > 1); ++i) {
       APInt DemandedSub =
           DemandedElts.extractBits(NumSubVectorElts, i * NumSubVectorElts);
       if (!DemandedSub)
         continue;
       Tmp2 = ComputeNumSignBits(Op.getOperand(i), DemandedSub, Depth + 1);
       Tmp = std::min(Tmp, Tmp2);
     }
     assert(Tmp <= VTBits && "Failed to determine minimum sign bits");
     return Tmp;
   }
   case ISD::INSERT_SUBVECTOR: {
+    if (VT.isScalableVector())
+      return 1;
     // Demand any elements from the subvector and the remainder from the src its
     // inserted into.
     SDValue Src = Op.getOperand(0);
     SDValue Sub = Op.getOperand(1);
     uint64_t Idx = Op.getConstantOperandVal(2);
     unsigned NumSubElts = Sub.getValueType().getVectorNumElements();
     APInt DemandedSubElts = DemandedElts.extractBits(NumSubElts, Idx);
     APInt DemandedSrcElts = DemandedElts;
if (LoadSDNode *LD = dyn_cast<LoadSDNode>(Op)) {
       case ISD::ZEXTLOAD: // e.g. i16->i32 = '16' bits known.
         Tmp = LD->getMemoryVT().getScalarSizeInBits();
         return VTBits - Tmp;
       case ISD::NON_EXTLOAD:
         if (const Constant *Cst = TLI->getTargetConstantFromLoad(LD)) {
           // We only need to handle vectors - computeKnownBits should handle
           // scalar cases.
           Type *CstTy = Cst->getType();
-          if (CstTy->isVectorTy() &&
+          if (CstTy->isVectorTy() && !VT.isScalableVector() &&
               (NumElts * VTBits) == CstTy->getPrimitiveSizeInBits() &&
               VTBits == CstTy->getScalarSizeInBits()) {
             Tmp = VTBits;
             for (unsigned i = 0; i != NumElts; ++i) {
               if (!DemandedElts[i])
                 continue;
               if (Constant *Elt = Cst->getAggregateElement(i)) {
                 if (auto *CInt = dyn_cast<ConstantInt>(Elt)) {
if (Op.getResNo() == 0) {
     }
   }
 
   // Allow the target to implement this method for its nodes.
   if (Opcode >= ISD::BUILTIN_OP_END ||
       Opcode == ISD::INTRINSIC_WO_CHAIN ||
       Opcode == ISD::INTRINSIC_W_CHAIN ||
       Opcode == ISD::INTRINSIC_VOID) {
+    // TODO: This can probably be removed once target code is audited.  This
+    // is here purely to reduce patch size and review complexity.
+    if (VT.isScalableVector())
+      return 1;
     unsigned NumBits =
         TLI->ComputeNumSignBitsForTargetNode(Op, DemandedElts, *this, Depth);
     if (NumBits > 1)
       FirstAnswer = std::max(FirstAnswer, NumBits);
   }
 
   // Finally, if we can prove that the top bits of the result are 0's or 1's,
   // use this information.

llvm/test/CodeGen/AArch64/sve-masked-gather-legalize.ll

; CHECK-NEXT:    ret
   ret <vscale x 4 x half> %data
 }
 
 define <vscale x 2 x float> @masked_gather_nxv2f32(float* %base, <vscale x 2 x i16> %indices, <vscale x 2 x i1> %mask) #0 {
 ; CHECK-LABEL: masked_gather_nxv2f32:
 ; CHECK:       // %bb.0:
 ; CHECK-NEXT:    ptrue p1.d
 ; CHECK-NEXT:    sxth z0.d, p1/m, z0.d
-; CHECK-NEXT:    ld1w { z0.d }, p0/z, [x0, z0.d, sxtw #2]
+; CHECK-NEXT:    ld1w { z0.d }, p0/z, [x0, z0.d, lsl #2]
 ; CHECK-NEXT:    ret
   %ptrs = getelementptr float, float* %base, <vscale x 2 x i16> %indices
   %data = call <vscale x 2 x float> @llvm.masked.gather.nxv2f32(<vscale x 2 x float*> %ptrs, i32 1, <vscale x 2 x i1> %mask, <vscale x 2 x float> undef)
   ret <vscale x 2 x float> %data
 }
 
 define <vscale x 8 x half> @masked_gather_nxv8f16(<vscale x 8 x half*> %ptrs, <vscale x 8 x i1> %mask) #0 {
 ; CHECK-LABEL: masked_gather_nxv8f16:

llvm/test/CodeGen/AArch64/sve-smulo-sdnode.ll

 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
 ; RUN: llc -mtriple=aarch64-linux-gnu -mattr=+sve -verify-machineinstrs < %s | FileCheck %s
 
 declare { <vscale x 2 x i8>, <vscale x 2 x i1> } @llvm.smul.with.overflow.nxv2i8(<vscale x 2 x i8>, <vscale x 2 x i8>)
 
 define <vscale x 2 x i8> @smulo_nxv2i8(<vscale x 2 x i8> %x, <vscale x 2 x i8> %y) {
 ; CHECK-LABEL: smulo_nxv2i8:
 ; CHECK:       // %bb.0:
 ; CHECK-NEXT:    ptrue p0.d
 ; CHECK-NEXT:    sxtb z1.d, p0/m, z1.d
 ; CHECK-NEXT:    sxtb z0.d, p0/m, z0.d
-; CHECK-NEXT:    movprfx z2, z0
-; CHECK-NEXT:    smulh z2.d, p0/m, z2.d, z1.d
 ; CHECK-NEXT:    mul z0.d, p0/m, z0.d, z1.d
-; CHECK-NEXT:    asr z1.d, z0.d, #63
-; CHECK-NEXT:    movprfx z3, z0
-; CHECK-NEXT:    sxtb z3.d, p0/m, z0.d
-; CHECK-NEXT:    cmpne p1.d, p0/z, z2.d, z1.d
-; CHECK-NEXT:    cmpne p0.d, p0/z, z3.d, z0.d
-; CHECK-NEXT:    sel p0.b, p0, p0.b, p1.b
+; CHECK-NEXT:    movprfx z1, z0
+; CHECK-NEXT:    sxtb z1.d, p0/m, z0.d
+; CHECK-NEXT:    cmpne p0.d, p0/z, z1.d, z0.d
 ; CHECK-NEXT:    mov z0.d, p0/m, #0 // =0x0
 ; CHECK-NEXT:    ret
   %a = call { <vscale x 2 x i8>, <vscale x 2 x i1> } @llvm.smul.with.overflow.nxv2i8(<vscale x 2 x i8> %x, <vscale x 2 x i8> %y)
   %b = extractvalue { <vscale x 2 x i8>, <vscale x 2 x i1> } %a, 0
   %c = extractvalue { <vscale x 2 x i8>, <vscale x 2 x i1> } %a, 1
   %d = select <vscale x 2 x i1> %c, <vscale x 2 x i8> zeroinitializer, <vscale x 2 x i8> %b
   ret <vscale x 2 x i8> %d
 }
 
 declare { <vscale x 4 x i8>, <vscale x 4 x i1> } @llvm.smul.with.overflow.nxv4i8(<vscale x 4 x i8>, <vscale x 4 x i8>)
 
 define <vscale x 4 x i8> @smulo_nxv4i8(<vscale x 4 x i8> %x, <vscale x 4 x i8> %y) {
 ; CHECK-LABEL: smulo_nxv4i8:
 ; CHECK:       // %bb.0:
 ; CHECK-NEXT:    ptrue p0.s
 ; CHECK-NEXT:    sxtb z1.s, p0/m, z1.s
 ; CHECK-NEXT:    sxtb z0.s, p0/m, z0.s
-; CHECK-NEXT:    movprfx z2, z0
-; CHECK-NEXT:    smulh z2.s, p0/m, z2.s, z1.s
 ; CHECK-NEXT:    mul z0.s, p0/m, z0.s, z1.s
-; CHECK-NEXT:    asr z1.s, z0.s, #31
-; CHECK-NEXT:    movprfx z3, z0
-; CHECK-NEXT:    sxtb z3.s, p0/m, z0.s
-; CHECK-NEXT:    cmpne p1.s, p0/z, z2.s, z1.s
-; CHECK-NEXT:    cmpne p0.s, p0/z, z3.s, z0.s
-; CHECK-NEXT:    sel p0.b, p0, p0.b, p1.b
+; CHECK-NEXT:    movprfx z1, z0
+; CHECK-NEXT:    sxtb z1.s, p0/m, z0.s
+; CHECK-NEXT:    cmpne p0.s, p0/z, z1.s, z0.s
 ; CHECK-NEXT:    mov z0.s, p0/m, #0 // =0x0
 ; CHECK-NEXT:    ret
   %a = call { <vscale x 4 x i8>, <vscale x 4 x i1> } @llvm.smul.with.overflow.nxv4i8(<vscale x 4 x i8> %x, <vscale x 4 x i8> %y)
   %b = extractvalue { <vscale x 4 x i8>, <vscale x 4 x i1> } %a, 0
   %c = extractvalue { <vscale x 4 x i8>, <vscale x 4 x i1> } %a, 1
   %d = select <vscale x 4 x i1> %c, <vscale x 4 x i8> zeroinitializer, <vscale x 4 x i8> %b
   ret <vscale x 4 x i8> %d
 }
 
 declare { <vscale x 8 x i8>, <vscale x 8 x i1> } @llvm.smul.with.overflow.nxv8i8(<vscale x 8 x i8>, <vscale x 8 x i8>)
 
 define <vscale x 8 x i8> @smulo_nxv8i8(<vscale x 8 x i8> %x, <vscale x 8 x i8> %y) {
 ; CHECK-LABEL: smulo_nxv8i8:
 ; CHECK:       // %bb.0:
 ; CHECK-NEXT:    ptrue p0.h
 ; CHECK-NEXT:    sxtb z1.h, p0/m, z1.h
 ; CHECK-NEXT:    sxtb z0.h, p0/m, z0.h
-; CHECK-NEXT:    movprfx z2, z0
-; CHECK-NEXT:    smulh z2.h, p0/m, z2.h, z1.h
 ; CHECK-NEXT:    mul z0.h, p0/m, z0.h, z1.h
-; CHECK-NEXT:    asr z1.h, z0.h, #15
-; CHECK-NEXT:    movprfx z3, z0
-; CHECK-NEXT:    sxtb z3.h, p0/m, z0.h
-; CHECK-NEXT:    cmpne p1.h, p0/z, z2.h, z1.h
-; CHECK-NEXT:    cmpne p0.h, p0/z, z3.h, z0.h
-; CHECK-NEXT:    sel p0.b, p0, p0.b, p1.b
+; CHECK-NEXT:    movprfx z1, z0
+; CHECK-NEXT:    sxtb z1.h, p0/m, z0.h
+; CHECK-NEXT:    cmpne p0.h, p0/z, z1.h, z0.h
 ; CHECK-NEXT:    mov z0.h, p0/m, #0 // =0x0
 ; CHECK-NEXT:    ret
   %a = call { <vscale x 8 x i8>, <vscale x 8 x i1> } @llvm.smul.with.overflow.nxv8i8(<vscale x 8 x i8> %x, <vscale x 8 x i8> %y)
   %b = extractvalue { <vscale x 8 x i8>, <vscale x 8 x i1> } %a, 0
   %c = extractvalue { <vscale x 8 x i8>, <vscale x 8 x i1> } %a, 1
   %d = select <vscale x 8 x i1> %c, <vscale x 8 x i8> zeroinitializer, <vscale x 8 x i8> %b
   ret <vscale x 8 x i8> %d
 }

 declare { <vscale x 2 x i16>, <vscale x 2 x i1> } @llvm.smul.with.overflow.nxv2i16(<vscale x 2 x i16>, <vscale x 2 x i16>)
 
 define <vscale x 2 x i16> @smulo_nxv2i16(<vscale x 2 x i16> %x, <vscale x 2 x i16> %y) {
 ; CHECK-LABEL: smulo_nxv2i16:
 ; CHECK:       // %bb.0:
 ; CHECK-NEXT:    ptrue p0.d
 ; CHECK-NEXT:    sxth z1.d, p0/m, z1.d
 ; CHECK-NEXT:    sxth z0.d, p0/m, z0.d
-; CHECK-NEXT:    movprfx z2, z0
-; CHECK-NEXT:    smulh z2.d, p0/m, z2.d, z1.d
 ; CHECK-NEXT:    mul z0.d, p0/m, z0.d, z1.d
-; CHECK-NEXT:    asr z1.d, z0.d, #63
-; CHECK-NEXT:    movprfx z3, z0
-; CHECK-NEXT:    sxth z3.d, p0/m, z0.d
-; CHECK-NEXT:    cmpne p1.d, p0/z, z2.d, z1.d
-; CHECK-NEXT:    cmpne p0.d, p0/z, z3.d, z0.d
-; CHECK-NEXT:    sel p0.b, p0, p0.b, p1.b
+; CHECK-NEXT:    movprfx z1, z0
+; CHECK-NEXT:    sxth z1.d, p0/m, z0.d
+; CHECK-NEXT:    cmpne p0.d, p0/z, z1.d, z0.d
 ; CHECK-NEXT:    mov z0.d, p0/m, #0 // =0x0
 ; CHECK-NEXT:    ret
   %a = call { <vscale x 2 x i16>, <vscale x 2 x i1> } @llvm.smul.with.overflow.nxv2i16(<vscale x 2 x i16> %x, <vscale x 2 x i16> %y)
   %b = extractvalue { <vscale x 2 x i16>, <vscale x 2 x i1> } %a, 0
   %c = extractvalue { <vscale x 2 x i16>, <vscale x 2 x i1> } %a, 1
   %d = select <vscale x 2 x i1> %c, <vscale x 2 x i16> zeroinitializer, <vscale x 2 x i16> %b
   ret <vscale x 2 x i16> %d
 }
 
 declare { <vscale x 4 x i16>, <vscale x 4 x i1> } @llvm.smul.with.overflow.nxv4i16(<vscale x 4 x i16>, <vscale x 4 x i16>)
 
 define <vscale x 4 x i16> @smulo_nxv4i16(<vscale x 4 x i16> %x, <vscale x 4 x i16> %y) {
 ; CHECK-LABEL: smulo_nxv4i16:
 ; CHECK:       // %bb.0:
 ; CHECK-NEXT:    ptrue p0.s
 ; CHECK-NEXT:    sxth z1.s, p0/m, z1.s
 ; CHECK-NEXT:    sxth z0.s, p0/m, z0.s
-; CHECK-NEXT:    movprfx z2, z0
-; CHECK-NEXT:    smulh z2.s, p0/m, z2.s, z1.s
 ; CHECK-NEXT:    mul z0.s, p0/m, z0.s, z1.s
-; CHECK-NEXT:    asr z1.s, z0.s, #31
-; CHECK-NEXT:    movprfx z3, z0
-; CHECK-NEXT:    sxth z3.s, p0/m, z0.s
-; CHECK-NEXT:    cmpne p1.s, p0/z, z2.s, z1.s
-; CHECK-NEXT:    cmpne p0.s, p0/z, z3.s, z0.s
-; CHECK-NEXT:    sel p0.b, p0, p0.b, p1.b
+; CHECK-NEXT:    movprfx z1, z0
+; CHECK-NEXT:    sxth z1.s, p0/m, z0.s
+; CHECK-NEXT:    cmpne p0.s, p0/z, z1.s, z0.s
 ; CHECK-NEXT:    mov z0.s, p0/m, #0 // =0x0
 ; CHECK-NEXT:    ret
   %a = call { <vscale x 4 x i16>, <vscale x 4 x i1> } @llvm.smul.with.overflow.nxv4i16(<vscale x 4 x i16> %x, <vscale x 4 x i16> %y)
   %b = extractvalue { <vscale x 4 x i16>, <vscale x 4 x i1> } %a, 0
   %c = extractvalue { <vscale x 4 x i16>, <vscale x 4 x i1> } %a, 1
   %d = select <vscale x 4 x i1> %c, <vscale x 4 x i16> zeroinitializer, <vscale x 4 x i16> %b
   ret <vscale x 4 x i16> %d
 }

 declare { <vscale x 2 x i32>, <vscale x 2 x i1> } @llvm.smul.with.overflow.nxv2i32(<vscale x 2 x i32>, <vscale x 2 x i32>)
 
 define <vscale x 2 x i32> @smulo_nxv2i32(<vscale x 2 x i32> %x, <vscale x 2 x i32> %y) {
 ; CHECK-LABEL: smulo_nxv2i32:
 ; CHECK:       // %bb.0:
 ; CHECK-NEXT:    ptrue p0.d
 ; CHECK-NEXT:    sxtw z1.d, p0/m, z1.d
 ; CHECK-NEXT:    sxtw z0.d, p0/m, z0.d
-; CHECK-NEXT:    movprfx z2, z0
-; CHECK-NEXT:    smulh z2.d, p0/m, z2.d, z1.d
 ; CHECK-NEXT:    mul z0.d, p0/m, z0.d, z1.d
-; CHECK-NEXT:    asr z1.d, z0.d, #63
-; CHECK-NEXT:    movprfx z3, z0
-; CHECK-NEXT:    sxtw z3.d, p0/m, z0.d
-; CHECK-NEXT:    cmpne p1.d, p0/z, z2.d, z1.d
-; CHECK-NEXT:    cmpne p0.d, p0/z, z3.d, z0.d
-; CHECK-NEXT:    sel p0.b, p0, p0.b, p1.b
+; CHECK-NEXT:    movprfx z1, z0
+; CHECK-NEXT:    sxtw z1.d, p0/m, z0.d
+; CHECK-NEXT:    cmpne p0.d, p0/z, z1.d, z0.d
 ; CHECK-NEXT:    mov z0.d, p0/m, #0 // =0x0
 ; CHECK-NEXT:    ret
   %a = call { <vscale x 2 x i32>, <vscale x 2 x i1> } @llvm.smul.with.overflow.nxv2i32(<vscale x 2 x i32> %x, <vscale x 2 x i32> %y)
   %b = extractvalue { <vscale x 2 x i32>, <vscale x 2 x i1> } %a, 0
   %c = extractvalue { <vscale x 2 x i32>, <vscale x 2 x i1> } %a, 1
   %d = select <vscale x 2 x i1> %c, <vscale x 2 x i32> zeroinitializer, <vscale x 2 x i32> %b
   ret <vscale x 2 x i32> %d
 }

llvm/test/CodeGen/RISCV/rvv/vdiv-vp.ll

 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
 ; RUN: llc -mtriple=riscv32 -mattr=+v -verify-machineinstrs < %s \
 ; RUN:   | FileCheck %s --check-prefixes=CHECK,RV32
 ; RUN: llc -mtriple=riscv64 -mattr=+v -verify-machineinstrs < %s \
 ; RUN:   | FileCheck %s --check-prefixes=CHECK,RV64
 
 declare <vscale x 8 x i7> @llvm.vp.sdiv.nxv8i7(<vscale x 8 x i7>, <vscale x 8 x i7>, <vscale x 8 x i1>, i32)
 
 define <vscale x 8 x i7> @vdiv_vx_nxv8i7(<vscale x 8 x i7> %a, i7 signext %b, <vscale x 8 x i1> %mask, i32 zeroext %evl) {
 ; CHECK-LABEL: vdiv_vx_nxv8i7:
 ; CHECK:       # %bb.0:
 ; CHECK-NEXT:    vsetvli a2, zero, e8, m1, ta, ma
 ; CHECK-NEXT:    vadd.vv v8, v8, v8
 ; CHECK-NEXT:    vsra.vi v8, v8, 1
-; CHECK-NEXT:    vmv.v.x v9, a0
-; CHECK-NEXT:    vadd.vv v9, v9, v9
-; CHECK-NEXT:    vsra.vi v9, v9, 1
 ; CHECK-NEXT:    vsetvli zero, a1, e8, m1, ta, ma
-; CHECK-NEXT:    vdiv.vv v8, v8, v9, v0.t
+; CHECK-NEXT:    vdiv.vx v8, v8, a0, v0.t
 ; CHECK-NEXT:    ret
   %elt.head = insertelement <vscale x 8 x i7> poison, i7 %b, i32 0
   %vb = shufflevector <vscale x 8 x i7> %elt.head, <vscale x 8 x i7> poison, <vscale x 8 x i32> zeroinitializer
   %v = call <vscale x 8 x i7> @llvm.vp.sdiv.nxv8i7(<vscale x 8 x i7> %a, <vscale x 8 x i7> %vb, <vscale x 8 x i1> %mask, i32 %evl)
   ret <vscale x 8 x i7> %v
 }
 
 declare <vscale x 1 x i8> @llvm.vp.sdiv.nxv1i8(<vscale x 1 x i8>, <vscale x 1 x i8>, <vscale x 1 x i1>, i32)

llvm/test/CodeGen/RISCV/rvv/vmax-vp.ll

 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
 ; RUN: llc -mtriple=riscv32 -mattr=+v -verify-machineinstrs < %s \
 ; RUN:   | FileCheck %s --check-prefixes=CHECK,RV32
 ; RUN: llc -mtriple=riscv64 -mattr=+v -verify-machineinstrs < %s \
 ; RUN:   | FileCheck %s --check-prefixes=CHECK,RV64
 
 declare <vscale x 8 x i7> @llvm.vp.smax.nxv8i7(<vscale x 8 x i7>, <vscale x 8 x i7>, <vscale x 8 x i1>, i32)
 
 define <vscale x 8 x i7> @vmax_vx_nxv8i7(<vscale x 8 x i7> %a, i7 signext %b, <vscale x 8 x i1> %mask, i32 zeroext %evl) {
 ; CHECK-LABEL: vmax_vx_nxv8i7:
 ; CHECK:       # %bb.0:
 ; CHECK-NEXT:    vsetvli a2, zero, e8, m1, ta, ma
 ; CHECK-NEXT:    vadd.vv v8, v8, v8
 ; CHECK-NEXT:    vsra.vi v8, v8, 1
-; CHECK-NEXT:    vmv.v.x v9, a0
-; CHECK-NEXT:    vadd.vv v9, v9, v9
-; CHECK-NEXT:    vsra.vi v9, v9, 1
 ; CHECK-NEXT:    vsetvli zero, a1, e8, m1, ta, ma
-; CHECK-NEXT:    vmax.vv v8, v8, v9, v0.t
+; CHECK-NEXT:    vmax.vx v8, v8, a0, v0.t
 ; CHECK-NEXT:    ret
   %elt.head = insertelement <vscale x 8 x i7> poison, i7 %b, i32 0
   %vb = shufflevector <vscale x 8 x i7> %elt.head, <vscale x 8 x i7> poison, <vscale x 8 x i32> zeroinitializer
   %v = call <vscale x 8 x i7> @llvm.vp.smax.nxv8i7(<vscale x 8 x i7> %a, <vscale x 8 x i7> %vb, <vscale x 8 x i1> %mask, i32 %evl)
   ret <vscale x 8 x i7> %v
 }
 
 declare <vscale x 1 x i8> @llvm.vp.smax.nxv1i8(<vscale x 1 x i8>, <vscale x 1 x i8>, <vscale x 1 x i1>, i32)

llvm/test/CodeGen/RISCV/rvv/vmin-vp.ll

 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
 ; RUN: llc -mtriple=riscv32 -mattr=+v -verify-machineinstrs < %s \
 ; RUN:   | FileCheck %s --check-prefixes=CHECK,RV32
 ; RUN: llc -mtriple=riscv64 -mattr=+v -verify-machineinstrs < %s \
 ; RUN:   | FileCheck %s --check-prefixes=CHECK,RV64
 
 declare <vscale x 8 x i7> @llvm.vp.smin.nxv8i7(<vscale x 8 x i7>, <vscale x 8 x i7>, <vscale x 8 x i1>, i32)
 
 define <vscale x 8 x i7> @vmin_vx_nxv8i7(<vscale x 8 x i7> %a, i7 signext %b, <vscale x 8 x i1> %mask, i32 zeroext %evl) {
 ; CHECK-LABEL: vmin_vx_nxv8i7:
 ; CHECK:       # %bb.0:
 ; CHECK-NEXT:    vsetvli a2, zero, e8, m1, ta, ma
 ; CHECK-NEXT:    vadd.vv v8, v8, v8
 ; CHECK-NEXT:    vsra.vi v8, v8, 1
-; CHECK-NEXT:    vmv.v.x v9, a0
-; CHECK-NEXT:    vadd.vv v9, v9, v9
-; CHECK-NEXT:    vsra.vi v9, v9, 1
 ; CHECK-NEXT:    vsetvli zero, a1, e8, m1, ta, ma
-; CHECK-NEXT:    vmin.vv v8, v8, v9, v0.t
+; CHECK-NEXT:    vmin.vx v8, v8, a0, v0.t
 ; CHECK-NEXT:    ret
   %elt.head = insertelement <vscale x 8 x i7> poison, i7 %b, i32 0
   %vb = shufflevector <vscale x 8 x i7> %elt.head, <vscale x 8 x i7> poison, <vscale x 8 x i32> zeroinitializer
   %v = call <vscale x 8 x i7> @llvm.vp.smin.nxv8i7(<vscale x 8 x i7> %a, <vscale x 8 x i7> %vb, <vscale x 8 x i1> %mask, i32 %evl)
   ret <vscale x 8 x i7> %v
 }
 
 declare <vscale x 1 x i8> @llvm.vp.smin.nxv1i8(<vscale x 1 x i8>, <vscale x 1 x i8>, <vscale x 1 x i1>, i32)

llvm/test/CodeGen/RISCV/rvv/vrem-vp.ll

 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
 ; RUN: llc -mtriple=riscv32 -mattr=+v -verify-machineinstrs < %s \
 ; RUN:   | FileCheck %s --check-prefixes=CHECK,RV32
 ; RUN: llc -mtriple=riscv64 -mattr=+v -verify-machineinstrs < %s \
 ; RUN:   | FileCheck %s --check-prefixes=CHECK,RV64
 
 declare <vscale x 8 x i7> @llvm.vp.srem.nxv8i7(<vscale x 8 x i7>, <vscale x 8 x i7>, <vscale x 8 x i1>, i32)
 
 define <vscale x 8 x i7> @vrem_vx_nxv8i7(<vscale x 8 x i7> %a, i7 signext %b, <vscale x 8 x i1> %mask, i32 zeroext %evl) {
 ; CHECK-LABEL: vrem_vx_nxv8i7:
 ; CHECK:       # %bb.0:
 ; CHECK-NEXT:    vsetvli a2, zero, e8, m1, ta, ma
 ; CHECK-NEXT:    vadd.vv v8, v8, v8
 ; CHECK-NEXT:    vsra.vi v8, v8, 1
-; CHECK-NEXT:    vmv.v.x v9, a0
-; CHECK-NEXT:    vadd.vv v9, v9, v9
-; CHECK-NEXT:    vsra.vi v9, v9, 1
 ; CHECK-NEXT:    vsetvli zero, a1, e8, m1, ta, ma
-; CHECK-NEXT:    vrem.vv v8, v8, v9, v0.t
+; CHECK-NEXT:    vrem.vx v8, v8, a0, v0.t
 ; CHECK-NEXT:    ret
   %elt.head = insertelement <vscale x 8 x i7> poison, i7 %b, i32 0
   %vb = shufflevector <vscale x 8 x i7> %elt.head, <vscale x 8 x i7> poison, <vscale x 8 x i32> zeroinitializer
   %v = call <vscale x 8 x i7> @llvm.vp.srem.nxv8i7(<vscale x 8 x i7> %a, <vscale x 8 x i7> %vb, <vscale x 8 x i1> %mask, i32 %evl)
   ret <vscale x 8 x i7> %v
 }
 
 declare <vscale x 1 x i8> @llvm.vp.srem.nxv1i8(<vscale x 1 x i8>, <vscale x 1 x i8>, <vscale x 1 x i1>, i32)