[IR] Split vscale_range interface

[c-rhodes]

Summary

Interface is split from:

std::pair<unsigned, unsigned> getVScaleRangeArgs()

into separate functions for min/max:

unsigned getVScaleRangeMin();
Optional<unsigned> getVScaleRangeMax();

[bsmith]

llvm/include/llvm/IR/Attributes.h

224

I'm not sure how I feel about this being an Optional type, all of the code changes below are still having to check max against 0, it seems that having this be Optional is just complicating the code for no gain.

Either this should not be Optional, or a value of 0 should be disallowed for max from this interface.

[paulwalker-arm]

llvm/include/llvm/IR/Attributes.h

224

I agree. I believe the intent is for getVScaleRangeMax to only return a real >0 value or None otherwise.

[c-rhodes]

return None for unbounded in getVScaleRangeMax

[c-rhodes]

llvm/include/llvm/IR/Attributes.h

224

thanks for comments and sorry for only just getting back to you, I've updated the patch so 0 is replaced with None in the interface, hopefully this makes more sense now.

[sdesmalen]

llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp

1609–1610

nit: this is probably a stylistic thing, but I personally find the following a bit nicer to read:

Attribute Attr = CI.getFunction()->getFnAttribute(Attribute::VScaleRange);
if (Optional<unsigned> MaxVScale = Attr.getVScaleRangeMax())
  if (Log2_32(MaxVScale.getValue()) < (SrcBitSize - 1)) {
    ..
  }

(same suggestion for the similar cases)

llvm/lib/Transforms/Vectorize/LoopVectorize.cpp

5654–5657

nit: similar suggestion here:

Attribute Attr = CI.getFunction()->getFnAttribute(Attribute::VScaleRange);
if (Optional<unsigned> Max = Attr.getVScaleRangeMax())
  MaxVScale = Max.getValue();

[c-rhodes]

Address comments

[c-rhodes]

llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp

1609–1610

nit: this is probably a stylistic thing, but I personally find the following a bit nicer to read:

Attribute Attr = CI.getFunction()->getFnAttribute(Attribute::VScaleRange);
if (Optional<unsigned> MaxVScale = Attr.getVScaleRangeMax())
  if (Log2_32(MaxVScale.getValue()) < (SrcBitSize - 1)) {
    ..
  }

(same suggestion for the similar cases)

I agree, done

[sdesmalen]

Thanks, I left two more minor comments that I didn't spot earlier. Otherwise looks good to me.

llvm/include/llvm/IR/Attributes.h

223–224

s/. If omitted, this will be the minimum,//

This probably meant to say "if omitted in the textual representation of the LLVM IR attribute", but I'm not sure how that's relevant for this comment.

1064–1065

Same here, please just omit that part of the comment.

[c-rhodes]

Update interface comment

[sdesmalen]

Thanks @c-rhodes, LGTM

[paulwalker-arm]

llvm/include/llvm/IR/Attributes.h

223–224

Up to you but I think "or None when unknown." is simpler.

1064

As above.

llvm/lib/Transforms/Vectorize/LoopVectorize.cpp

5655–5656

Is this if statement required? MaxVScale is an optional so I think MaxVScale = Attr.getVScaleRangeMax(); just works?

[c-rhodes]

Address comments

[c-rhodes]

llvm/lib/Transforms/Vectorize/LoopVectorize.cpp

5655–5656

Is this if statement required? MaxVScale is an optional so I think MaxVScale = Attr.getVScaleRangeMax(); just works?

I wondered that, you're right it works.

llvm/include/llvm/IR/Attributes.h

public:
   /// Returns the number of dereferenceable_or_null bytes from the
   /// dereferenceable_or_null attribute.
   uint64_t getDereferenceableOrNullBytes() const;
 
   /// Returns the argument numbers for the allocsize attribute (or pair(0, 0)
   /// if not known).
   std::pair<unsigned, Optional<unsigned>> getAllocSizeArgs() const;
 
-  /// Returns the argument numbers for the vscale_range attribute (or pair(1, 0)
-  /// if not known).
-  std::pair<unsigned, unsigned> getVScaleRangeArgs() const;
+  /// Returns the minimum value for the vscale_range attribute.
+  unsigned getVScaleRangeMin() const;
+
+  /// Returns the maximum value for the vscale_range attribute. If omitted,
+  /// this will be the minimum, or None for unbounded (0).
+  Optional<unsigned> getVScaleRangeMax() const;
 
   /// The Attribute is converted to a string of equivalent mnemonic. This
   /// is, presumably, for writing out the mnemonics for the assembly writer.
   std::string getAsString(bool InAttrGrp = false) const;
 
   /// Return true if this attribute belongs to the LLVMContext.
   bool hasParentContext(LLVMContext &C) const;
 
public:
   uint64_t getDereferenceableOrNullBytes() const;
   Type *getByValType() const;
   Type *getStructRetType() const;
   Type *getByRefType() const;
   Type *getPreallocatedType() const;
   Type *getInAllocaType() const;
   Type *getElementType() const;
   std::pair<unsigned, Optional<unsigned>> getAllocSizeArgs() const;
-  std::pair<unsigned, unsigned> getVScaleRangeArgs() const;
+  unsigned getVScaleRangeMin() const;
+  Optional<unsigned> getVScaleRangeMax() const;
   std::string getAsString(bool InAttrGrp = false) const;
 
   /// Return true if this attribute set belongs to the LLVMContext.
   bool hasParentContext(LLVMContext &C) const;
 
   using iterator = const Attribute *;
 
   iterator begin() const;
public:
 
   /// Retrieve the inalloca type.
   Type *getInAllocaType() const { return getTypeAttr(Attribute::InAlloca); }
 
   /// Retrieve the allocsize args, if the allocsize attribute exists.  If it
   /// doesn't exist, pair(0, 0) is returned.
   std::pair<unsigned, Optional<unsigned>> getAllocSizeArgs() const;
 
-  /// Retrieve the vscale_range args, if the vscale_range attribute exists.  If
-  /// it doesn't exist, pair(1, 0) is returned.
-  std::pair<unsigned, unsigned> getVScaleRangeArgs() const;
+  /// Retrieve the minimum value of 'vscale_range'.
+  unsigned getVScaleRangeMin() const;
+
+  /// Retrieve the maximum value of 'vscale_range'. If omitted,
+  /// this will be the minimum, or None for unbounded (0).
+  Optional<unsigned> getVScaleRangeMax() const;
 
   /// Add integer attribute with raw value (packed/encoded if necessary).
   AttrBuilder &addRawIntAttr(Attribute::AttrKind Kind, uint64_t Value);
 
   /// This turns an alignment into the form used internally in Attribute.
   /// This call has no effect if Align is not set.
   AttrBuilder &addAlignmentAttr(MaybeAlign Align);
 
public:
   /// form used internally in Attribute.
   AttrBuilder &addDereferenceableOrNullAttr(uint64_t Bytes);
 
   /// This turns one (or two) ints into the form used internally in Attribute.
   AttrBuilder &addAllocSizeAttr(unsigned ElemSizeArg,
                                 const Optional<unsigned> &NumElemsArg);
 
   /// This turns two ints into the form used internally in Attribute.
-  AttrBuilder &addVScaleRangeAttr(unsigned MinValue, unsigned MaxValue);
+  AttrBuilder &addVScaleRangeAttr(unsigned MinValue,
+                                  Optional<unsigned> MaxValue);
 
   /// Add a type attribute with the given type.
   AttrBuilder &addTypeAttr(Attribute::AttrKind Kind, Type *Ty);
 
   /// This turns a byval type into the form used internally in Attribute.
   AttrBuilder &addByValAttr(Type *Ty);
 
   /// This turns a sret type into the form used internally in Attribute.

llvm/lib/Analysis/InstructionSimplify.cpp

if (!NumOperands) {
     switch (IID) {
     case Intrinsic::vscale: {
       // Call may not be inserted into the IR yet at point of calling simplify.
       if (!Call->getParent() || !Call->getParent()->getParent())
         return nullptr;
       auto Attr = Call->getFunction()->getFnAttribute(Attribute::VScaleRange);
       if (!Attr.isValid())
         return nullptr;
-      unsigned VScaleMin, VScaleMax;
-      std::tie(VScaleMin, VScaleMax) = Attr.getVScaleRangeArgs();
-      if (VScaleMin == VScaleMax && VScaleMax != 0)
+      unsigned VScaleMin = Attr.getVScaleRangeMin();
+      Optional<unsigned> VScaleMax = Attr.getVScaleRangeMax();
+      if (VScaleMax && VScaleMin == VScaleMax)
         return ConstantInt::get(F->getReturnType(), VScaleMin);
       return nullptr;
     }
     default:
       return nullptr;
     }
   }
 

llvm/lib/Analysis/ValueTracking.cpp

if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) {
         if (BitWidth >= 32)
           Known.Zero.setBitsFrom(31);
         break;
       case Intrinsic::vscale: {
         if (!II->getParent() || !II->getFunction() ||
             !II->getFunction()->hasFnAttribute(Attribute::VScaleRange))
           break;
 
-        auto VScaleRange = II->getFunction()
-                               ->getFnAttribute(Attribute::VScaleRange)
-                               .getVScaleRangeArgs();
+        auto Attr = II->getFunction()->getFnAttribute(Attribute::VScaleRange);
+        Optional<unsigned> VScaleMax = Attr.getVScaleRangeMax();
 
-        if (VScaleRange.second == 0)
+        if (!VScaleMax)
           break;
 
+        unsigned VScaleMin = Attr.getVScaleRangeMin();
+
         // If vscale min = max then we know the exact value at compile time
         // and hence we know the exact bits.
-        if (VScaleRange.first == VScaleRange.second) {
-          Known.One = VScaleRange.first;
-          Known.Zero = VScaleRange.first;
+        if (VScaleMin == VScaleMax) {
+          Known.One = VScaleMin;
+          Known.Zero = VScaleMin;
           Known.Zero.flipAllBits();
           break;
         }
 
-        unsigned FirstZeroHighBit = 32 - countLeadingZeros(VScaleRange.second);
+        unsigned FirstZeroHighBit =
+            32 - countLeadingZeros(VScaleMax.getValue());
         if (FirstZeroHighBit < BitWidth)
           Known.Zero.setBitsFrom(FirstZeroHighBit);
 
         break;
       }
       }
     }
     break;

llvm/lib/AsmParser/LLParser.cpp

if (parseAllocSizeArguments(ElemSizeArg, NumElemsArg))
       return true;
     B.addAllocSizeAttr(ElemSizeArg, NumElemsArg);
     return false;
   }
   case Attribute::VScaleRange: {
     unsigned MinValue, MaxValue;
     if (parseVScaleRangeArguments(MinValue, MaxValue))
       return true;
-    B.addVScaleRangeAttr(MinValue, MaxValue);
+    B.addVScaleRangeAttr(MinValue,
+                         MaxValue > 0 ? MaxValue : Optional<unsigned>());
     return false;
   }
   case Attribute::Dereferenceable: {
     uint64_t Bytes;
     if (parseOptionalDerefAttrBytes(lltok::kw_dereferenceable, Bytes))
       return true;
     B.addDereferenceableAttr(Bytes);
     return false;

llvm/lib/IR/AttributeImpl.h

public:
   Attribute getAttribute(Attribute::AttrKind Kind) const;
   Attribute getAttribute(StringRef Kind) const;
 
   MaybeAlign getAlignment() const;
   MaybeAlign getStackAlignment() const;
   uint64_t getDereferenceableBytes() const;
   uint64_t getDereferenceableOrNullBytes() const;
   std::pair<unsigned, Optional<unsigned>> getAllocSizeArgs() const;
-  std::pair<unsigned, unsigned> getVScaleRangeArgs() const;
+  unsigned getVScaleRangeMin() const;
+  Optional<unsigned> getVScaleRangeMax() const;
   std::string getAsString(bool InAttrGrp) const;
   Type *getAttributeType(Attribute::AttrKind Kind) const;
 
   using iterator = const Attribute *;
 
   iterator begin() const { return getTrailingObjects<Attribute>(); }
   iterator end() const { return begin() + NumAttrs; }
 

llvm/lib/IR/Attributes.cpp

unpackAllocSizeArgs(uint64_t Num) {
   unsigned ElemSizeArg = Num >> 32;
 
   Optional<unsigned> NumElemsArg;
   if (NumElems != AllocSizeNumElemsNotPresent)
     NumElemsArg = NumElems;
   return std::make_pair(ElemSizeArg, NumElemsArg);
 }
 
-static uint64_t packVScaleRangeArgs(unsigned MinValue, unsigned MaxValue) {
-  return uint64_t(MinValue) << 32 | MaxValue;
+static uint64_t packVScaleRangeArgs(unsigned MinValue,
+                                    Optional<unsigned> MaxValue) {
+  return uint64_t(MinValue) << 32 | MaxValue.getValueOr(0);
 }
 
-static std::pair<unsigned, unsigned> unpackVScaleRangeArgs(uint64_t Value) {
+static std::pair<unsigned, Optional<unsigned>>
+unpackVScaleRangeArgs(uint64_t Value) {
   unsigned MaxValue = Value & std::numeric_limits<unsigned>::max();
   unsigned MinValue = Value >> 32;
 
-  return std::make_pair(MinValue, MaxValue);
+  return std::make_pair(MinValue,
+                        MaxValue > 0 ? MaxValue : Optional<unsigned>());
 }
 
 Attribute Attribute::get(LLVMContext &Context, Attribute::AttrKind Kind,
                          uint64_t Val) {
   if (Val)
     assert(Attribute::isIntAttrKind(Kind) && "Not an int attribute");
   else
     assert(Attribute::isEnumAttrKind(Kind) && "Not an enum attribute");

 }
 
 std::pair<unsigned, Optional<unsigned>> Attribute::getAllocSizeArgs() const {
   assert(hasAttribute(Attribute::AllocSize) &&
          "Trying to get allocsize args from non-allocsize attribute");
   return unpackAllocSizeArgs(pImpl->getValueAsInt());
 }
 
-std::pair<unsigned, unsigned> Attribute::getVScaleRangeArgs() const {
+unsigned Attribute::getVScaleRangeMin() const {
   assert(hasAttribute(Attribute::VScaleRange) &&
          "Trying to get vscale args from non-vscale attribute");
-  return unpackVScaleRangeArgs(pImpl->getValueAsInt());
+  return unpackVScaleRangeArgs(pImpl->getValueAsInt()).first;
+}
+
+Optional<unsigned> Attribute::getVScaleRangeMax() const {
+  assert(hasAttribute(Attribute::VScaleRange) &&
+         "Trying to get vscale args from non-vscale attribute");
+  return unpackVScaleRangeArgs(pImpl->getValueAsInt()).second;
 }
 
 std::string Attribute::getAsString(bool InAttrGrp) const {
   if (!pImpl) return {};
 
   if (isEnumAttribute())
     return getNameFromAttrKind(getKindAsEnum()).str();
 
if (NumElems.hasValue()) {
       Result += ',';
       Result += utostr(*NumElems);
     }
     Result += ')';
     return Result;
   }
 
   if (hasAttribute(Attribute::VScaleRange)) {
-    unsigned MinValue, MaxValue;
-    std::tie(MinValue, MaxValue) = getVScaleRangeArgs();
+    unsigned MinValue = getVScaleRangeMin();
+    Optional<unsigned> MaxValue = getVScaleRangeMax();
 
     std::string Result = "vscale_range(";
     Result += utostr(MinValue);
     Result += ',';
-    Result += utostr(MaxValue);
+    Result += utostr(MaxValue.getValueOr(0));
     Result += ')';
     return Result;
   }
 
   // Convert target-dependent attributes to strings of the form:
   //
   //   "kind"
   //   "kind" = "value"
Type *AttributeSet::getElementType() const {
   return SetNode ? SetNode->getAttributeType(Attribute::ElementType) : nullptr;
 }
 
 std::pair<unsigned, Optional<unsigned>> AttributeSet::getAllocSizeArgs() const {
   return SetNode ? SetNode->getAllocSizeArgs()
                  : std::pair<unsigned, Optional<unsigned>>(0, 0);
 }
 
-std::pair<unsigned, unsigned> AttributeSet::getVScaleRangeArgs() const {
-  return SetNode ? SetNode->getVScaleRangeArgs()
-                 : std::pair<unsigned, unsigned>(1, 0);
+unsigned AttributeSet::getVScaleRangeMin() const {
+  return SetNode ? SetNode->getVScaleRangeMin() : 1;
+}
+
+Optional<unsigned> AttributeSet::getVScaleRangeMax() const {
+  return SetNode ? SetNode->getVScaleRangeMax() : None;
 }
 
 std::string AttributeSet::getAsString(bool InAttrGrp) const {
   return SetNode ? SetNode->getAsString(InAttrGrp) : "";
 }
 
 bool AttributeSet::hasParentContext(LLVMContext &C) const {
   assert(hasAttributes() && "empty AttributeSet doesn't refer to any context");

 
 std::pair<unsigned, Optional<unsigned>>
 AttributeSetNode::getAllocSizeArgs() const {
   if (auto A = findEnumAttribute(Attribute::AllocSize))
     return A->getAllocSizeArgs();
   return std::make_pair(0, 0);
 }
 
-std::pair<unsigned, unsigned> AttributeSetNode::getVScaleRangeArgs() const {
+unsigned AttributeSetNode::getVScaleRangeMin() const {
   if (auto A = findEnumAttribute(Attribute::VScaleRange))
-    return A->getVScaleRangeArgs();
-  return std::make_pair(1, 0);
+    return A->getVScaleRangeMin();
+  return 1;
+}
+
+Optional<unsigned> AttributeSetNode::getVScaleRangeMax() const {
+  if (auto A = findEnumAttribute(Attribute::VScaleRange))
+    return A->getVScaleRangeMax();
+  return None;
 }
 
 std::string AttributeSetNode::getAsString(bool InAttrGrp) const {
   std::string Str;
   for (iterator I = begin(), E = end(); I != E; ++I) {
     if (I != begin())
       Str += ' ';
     Str += I->getAsString(InAttrGrp);
AttrBuilder &AttrBuilder::addRawIntAttr(Attribute::AttrKind Kind,
   IntAttrs[*IntIndex] = Value;
   return *this;
 }
 
 std::pair<unsigned, Optional<unsigned>> AttrBuilder::getAllocSizeArgs() const {
   return unpackAllocSizeArgs(getRawIntAttr(Attribute::AllocSize));
 }
 
-std::pair<unsigned, unsigned> AttrBuilder::getVScaleRangeArgs() const {
-  return unpackVScaleRangeArgs(getRawIntAttr(Attribute::VScaleRange));
+unsigned AttrBuilder::getVScaleRangeMin() const {
+  return unpackVScaleRangeArgs(getRawIntAttr(Attribute::VScaleRange)).first;
+}
+
+Optional<unsigned> AttrBuilder::getVScaleRangeMax() const {
+  return unpackVScaleRangeArgs(getRawIntAttr(Attribute::VScaleRange)).second;
 }
 
 AttrBuilder &AttrBuilder::addAlignmentAttr(MaybeAlign Align) {
   if (!Align)
     return *this;
 
   assert(*Align <= llvm::Value::MaximumAlignment && "Alignment too large.");
   return addRawIntAttr(Attribute::Alignment, Align->value());

 
 AttrBuilder &AttrBuilder::addAllocSizeAttrFromRawRepr(uint64_t RawArgs) {
   // (0, 0) is our "not present" value, so we need to check for it here.
   assert(RawArgs && "Invalid allocsize arguments -- given allocsize(0, 0)");
   return addRawIntAttr(Attribute::AllocSize, RawArgs);
 }
 
 AttrBuilder &AttrBuilder::addVScaleRangeAttr(unsigned MinValue,
-                                             unsigned MaxValue) {
+                                             Optional<unsigned> MaxValue) {
   return addVScaleRangeAttrFromRawRepr(packVScaleRangeArgs(MinValue, MaxValue));
 }
 
 AttrBuilder &AttrBuilder::addVScaleRangeAttrFromRawRepr(uint64_t RawArgs) {
   // (0, 0) is not present hence ignore this case
   if (RawArgs == 0)
     return *this;
 

llvm/lib/IR/Verifier.cpp

if (Attrs.hasFnAttr(Attribute::AllocSize)) {
     if (!CheckParam("element size", Args.first))
       return;
 
     if (Args.second && !CheckParam("number of elements", *Args.second))
       return;
   }
 
   if (Attrs.hasFnAttr(Attribute::VScaleRange)) {
-    std::pair<unsigned, unsigned> Args =
-        Attrs.getFnAttrs().getVScaleRangeArgs();
-
-    if (Args.first == 0)
+    unsigned VScaleMin = Attrs.getFnAttrs().getVScaleRangeMin();
+    if (VScaleMin == 0)
       CheckFailed("'vscale_range' minimum must be greater than 0", V);
 
-    if (Args.first > Args.second && Args.second != 0)
+    Optional<unsigned> VScaleMax = Attrs.getFnAttrs().getVScaleRangeMax();
+    if (VScaleMax && VScaleMin > VScaleMax)
       CheckFailed("'vscale_range' minimum cannot be greater than maximum", V);
   }
 
   if (Attrs.hasFnAttr("frame-pointer")) {
     StringRef FP = Attrs.getFnAttr("frame-pointer").getValueAsString();
     if (FP != "all" && FP != "non-leaf" && FP != "none")
       CheckFailed("invalid value for 'frame-pointer' attribute: " + FP, V);
   }

llvm/lib/Target/AArch64/AArch64TargetMachine.cpp

std::string FS =
       FSAttr.isValid() ? FSAttr.getValueAsString().str() : TargetFS;
 
   SmallString<512> Key;
 
   unsigned MinSVEVectorSize = 0;
   unsigned MaxSVEVectorSize = 0;
   Attribute VScaleRangeAttr = F.getFnAttribute(Attribute::VScaleRange);
   if (VScaleRangeAttr.isValid()) {
-    std::tie(MinSVEVectorSize, MaxSVEVectorSize) =
-        VScaleRangeAttr.getVScaleRangeArgs();
-    MinSVEVectorSize *= 128;
-    MaxSVEVectorSize *= 128;
+    Optional<unsigned> VScaleMax = VScaleRangeAttr.getVScaleRangeMax();
+    MinSVEVectorSize = VScaleRangeAttr.getVScaleRangeMin() * 128;
+    MaxSVEVectorSize = VScaleMax ? VScaleMax.getValue() * 128 : 0;
   } else {
     MinSVEVectorSize = SVEVectorBitsMinOpt;
     MaxSVEVectorSize = SVEVectorBitsMaxOpt;
   }
 
   assert(MinSVEVectorSize % 128 == 0 &&
          "SVE requires vector length in multiples of 128!");
   assert(MaxSVEVectorSize % 128 == 0 &&

llvm/lib/Target/AArch64/SVEIntrinsicOpts.cpp

 // This is done in SVEIntrinsicOpts rather than InstCombine so that we introduce
 // scalable stores as late as possible
 bool SVEIntrinsicOpts::optimizePredicateStore(Instruction *I) {
   auto *F = I->getFunction();
   auto Attr = F->getFnAttribute(Attribute::VScaleRange);
   if (!Attr.isValid())
     return false;
 
-  unsigned MinVScale, MaxVScale;
-  std::tie(MinVScale, MaxVScale) = Attr.getVScaleRangeArgs();
+  unsigned MinVScale = Attr.getVScaleRangeMin();
+  Optional<unsigned> MaxVScale = Attr.getVScaleRangeMax();
   // The transform needs to know the exact runtime length of scalable vectors
-  if (MinVScale != MaxVScale || MinVScale == 0)
+  if (!MaxVScale || MinVScale != MaxVScale)
     return false;
 
   auto *PredType =
       ScalableVectorType::get(Type::getInt1Ty(I->getContext()), 16);
   auto *FixedPredType =
       FixedVectorType::get(Type::getInt8Ty(I->getContext()), MinVScale * 2);
 
   // If we have a store..

 // This is done in SVEIntrinsicOpts rather than InstCombine so that we introduce
 // scalable loads as late as possible
 bool SVEIntrinsicOpts::optimizePredicateLoad(Instruction *I) {
   auto *F = I->getFunction();
   auto Attr = F->getFnAttribute(Attribute::VScaleRange);
   if (!Attr.isValid())
     return false;
 
-  unsigned MinVScale, MaxVScale;
-  std::tie(MinVScale, MaxVScale) = Attr.getVScaleRangeArgs();
+  unsigned MinVScale = Attr.getVScaleRangeMin();
+  Optional<unsigned> MaxVScale = Attr.getVScaleRangeMax();
   // The transform needs to know the exact runtime length of scalable vectors
-  if (MinVScale != MaxVScale || MinVScale == 0)
+  if (!MaxVScale || MinVScale != MaxVScale)
     return false;
 
   auto *PredType =
       ScalableVectorType::get(Type::getInt1Ty(I->getContext()), 16);
   auto *FixedPredType =
       FixedVectorType::get(Type::getInt8Ty(I->getContext()), MinVScale * 2);
 
   // If we have a bitcast..

llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp

if (AWidth == DestWidth && AWidth > Log2_32(SrcWidth)) {
           Builder.CreateIntrinsic(Intrinsic::ctlz, {Trunc.getType()}, {A, B});
       return BinaryOperator::CreateAdd(NarrowCtlz, WidthDiff);
     }
   }
 
   if (match(Src, m_VScale(DL))) {
     if (Trunc.getFunction() &&
         Trunc.getFunction()->hasFnAttribute(Attribute::VScaleRange)) {
-      unsigned MaxVScale = Trunc.getFunction()
-                               ->getFnAttribute(Attribute::VScaleRange)
-                               .getVScaleRangeArgs()
-                               .second;
-      if (MaxVScale > 0 && Log2_32(MaxVScale) < DestWidth) {
+      Attribute Attr =
+          Trunc.getFunction()->getFnAttribute(Attribute::VScaleRange);
+      if (Optional<unsigned> MaxVScale = Attr.getVScaleRangeMax()) {
+        if (Log2_32(MaxVScale.getValue()) < DestWidth) {
           Value *VScale = Builder.CreateVScale(ConstantInt::get(DestTy, 1));
           return replaceInstUsesWith(Trunc, VScale);
         }
       }
     }
+  }
 
   return nullptr;
 }
 
 Instruction *InstCombinerImpl::transformZExtICmp(ICmpInst *Cmp, ZExtInst &Zext) {
   // If we are just checking for a icmp eq of a single bit and zext'ing it
   // to an integer, then shift the bit to the appropriate place and then
   // cast to integer to avoid the comparison.
if (match(Src, m_OneUse(m_Xor(m_Value(And), m_Constant(C)))) &&
       X->getType() == CI.getType()) {
     Constant *ZC = ConstantExpr::getZExt(C, CI.getType());
     return BinaryOperator::CreateXor(Builder.CreateAnd(X, ZC), ZC);
   }
 
   if (match(Src, m_VScale(DL))) {
     if (CI.getFunction() &&
         CI.getFunction()->hasFnAttribute(Attribute::VScaleRange)) {
-      unsigned MaxVScale = CI.getFunction()
-                               ->getFnAttribute(Attribute::VScaleRange)
-                               .getVScaleRangeArgs()
-                               .second;
+      Attribute Attr = CI.getFunction()->getFnAttribute(Attribute::VScaleRange);
+      if (Optional<unsigned> MaxVScale = Attr.getVScaleRangeMax()) {
         unsigned TypeWidth = Src->getType()->getScalarSizeInBits();
-      if (MaxVScale > 0 && Log2_32(MaxVScale) < TypeWidth) {
+        if (Log2_32(MaxVScale.getValue()) < TypeWidth) {
           Value *VScale = Builder.CreateVScale(ConstantInt::get(DestTy, 1));
           return replaceInstUsesWith(CI, VScale);
         }
       }
     }
+  }
 
   return nullptr;
 }
 
 /// Transform (sext icmp) to bitwise / integer operations to eliminate the icmp.
 Instruction *InstCombinerImpl::transformSExtICmp(ICmpInst *ICI,
                                                  Instruction &CI) {
   Value *Op0 = ICI->getOperand(0), *Op1 = ICI->getOperand(1);
if (match(Src, m_OneUse(m_AShr(m_Trunc(m_Value(X)),
     Constant *ShlAmtC = ConstantInt::get(DestTy, DestBitSize - SrcBitSize);
     Constant *AshrAmtC = ConstantInt::get(DestTy, DestBitSize - 1);
     Value *Shl = Builder.CreateShl(X, ShlAmtC);
     return BinaryOperator::CreateAShr(Shl, AshrAmtC);
   }
 
   if (match(Src, m_VScale(DL))) {
     if (CI.getFunction() &&
         CI.getFunction()->hasFnAttribute(Attribute::VScaleRange)) {
-      unsigned MaxVScale = CI.getFunction()
-                               ->getFnAttribute(Attribute::VScaleRange)
-                               .getVScaleRangeArgs()
-                               .second;
-      if (MaxVScale > 0 && Log2_32(MaxVScale) < (SrcBitSize - 1)) {
+      Attribute Attr = CI.getFunction()->getFnAttribute(Attribute::VScaleRange);
+      if (Optional<unsigned> MaxVScale = Attr.getVScaleRangeMax()) {
+        if (Log2_32(MaxVScale.getValue()) < (SrcBitSize - 1)) {
           Value *VScale = Builder.CreateVScale(ConstantInt::get(DestTy, 1));
           return replaceInstUsesWith(CI, VScale);
         }
       }
     }
+  }
 
   return nullptr;
 }
 
 /// Return a Constant* for the specified floating-point constant if it fits
 /// in the specified FP type without changing its value.
 static bool fitsInFPType(ConstantFP *CFP, const fltSemantics &Sem) {
   bool losesInfo;

llvm/lib/Transforms/Vectorize/LoopVectorize.cpp

LoopVectorizationCostModel::getMaxLegalScalableVF(unsigned MaxSafeElements) {
   }
 
   if (Legal->isSafeForAnyVectorWidth())
     return MaxScalableVF;
 
   // Limit MaxScalableVF by the maximum safe dependence distance.
   Optional<unsigned> MaxVScale = TTI.getMaxVScale();
   if (!MaxVScale && TheFunction->hasFnAttribute(Attribute::VScaleRange)) {
-    unsigned VScaleMax = TheFunction->getFnAttribute(Attribute::VScaleRange)
-                             .getVScaleRangeArgs()
-                             .second;
-    if (VScaleMax > 0)
-      MaxVScale = VScaleMax;
+    Attribute Attr = TheFunction->getFnAttribute(Attribute::VScaleRange);
+    if (Optional<unsigned> VScaleMax = Attr.getVScaleRangeMax())
+      MaxVScale = VScaleMax.getValue();
   }
   MaxScalableVF = ElementCount::getScalable(
       MaxVScale ? (MaxSafeElements / MaxVScale.getValue()) : 0);
   if (!MaxScalableVF)
     reportVectorizationInfo(
         "Max legal vector width too small, scalable vectorization "
         "unfeasible.",
         "ScalableVFUnfeasible", ORE, TheLoop);