[NFC] Reduce copies created of ConstantRange when getting ConstantRangeAttributes (#90335)

Think that it can be good to reduce the number of copies created when
working with ConstantRangeAttributes.

Author: andjo403

llvm/include/llvm/IR/Attributes.h

@@ -224,7 +224,7 @@ class Attribute {
 
   /// Return the attribute's value as a ConstantRange. This requires the
   /// attribute to be a ConstantRange attribute.
-  ConstantRange getValueAsConstantRange() const;
+  const ConstantRange &getValueAsConstantRange() const;
 
   /// Returns the alignment field of an attribute as a byte alignment
   /// value.
@@ -265,7 +265,7 @@ class Attribute {
   FPClassTest getNoFPClass() const;
 
   /// Returns the value of the range attribute.
-  ConstantRange getRange() const;
+  const ConstantRange &getRange() const;
 
   /// The Attribute is converted to a string of equivalent mnemonic. This
   /// is, presumably, for writing out the mnemonics for the assembly writer.

llvm/lib/IR/AttributeImpl.h

@@ -77,7 +77,7 @@ class AttributeImpl : public FoldingSetNode {
 
   Type *getValueAsType() const;
 
-  ConstantRange getValueAsConstantRange() const;
+  const ConstantRange &getValueAsConstantRange() const;
 
   /// Used when sorting the attributes.
   bool operator<(const AttributeImpl &AI) const;
@@ -219,7 +219,7 @@ class ConstantRangeAttributeImpl : public EnumAttributeImpl {
   ConstantRangeAttributeImpl(Attribute::AttrKind Kind, const ConstantRange &CR)
       : EnumAttributeImpl(ConstantRangeAttrEntry, Kind), CR(CR) {}
 
-  ConstantRange getConstantRangeValue() const { return CR; }
+  const ConstantRange &getConstantRangeValue() const { return CR; }
 };
 
 class AttributeBitSet {

llvm/lib/IR/Attributes.cpp

@@ -360,7 +360,7 @@ Type *Attribute::getValueAsType() const {
   return pImpl->getValueAsType();
 }
 
-ConstantRange Attribute::getValueAsConstantRange() const {
+const ConstantRange &Attribute::getValueAsConstantRange() const {
   assert(isConstantRangeAttribute() &&
          "Invalid attribute type to get the value as a ConstantRange!");
   return pImpl->getValueAsConstantRange();
@@ -444,7 +444,7 @@ FPClassTest Attribute::getNoFPClass() const {
   return static_cast<FPClassTest>(pImpl->getValueAsInt());
 }
 
-ConstantRange Attribute::getRange() const {
+const ConstantRange &Attribute::getRange() const {
   assert(hasAttribute(Attribute::Range) &&
          "Trying to get range args from non-range attribute");
   return pImpl->getValueAsConstantRange();
@@ -607,7 +607,7 @@ std::string Attribute::getAsString(bool InAttrGrp) const {
   if (hasAttribute(Attribute::Range)) {
     std::string Result;
     raw_string_ostream OS(Result);
-    ConstantRange CR = getValueAsConstantRange();
+    const ConstantRange &CR = getValueAsConstantRange();
     OS << "range(";
     OS << "i" << CR.getBitWidth() << " ";
     OS << CR.getLower() << ", " << CR.getUpper();
@@ -735,7 +735,7 @@ Type *AttributeImpl::getValueAsType() const {
   return static_cast<const TypeAttributeImpl *>(this)->getTypeValue();
 }
 
-ConstantRange AttributeImpl::getValueAsConstantRange() const {
+const ConstantRange &AttributeImpl::getValueAsConstantRange() const {
   assert(isConstantRangeAttribute());
   return static_cast<const ConstantRangeAttributeImpl *>(this)
       ->getConstantRangeValue();

llvm/lib/IR/Verifier.cpp

@@ -2065,7 +2065,8 @@ void Verifier::verifyParameterAttrs(AttributeSet Attrs, Type *Ty,
           "Invalid value for 'nofpclass' test mask", V);
   }
   if (Attrs.hasAttribute(Attribute::Range)) {
-    auto CR = Attrs.getAttribute(Attribute::Range).getValueAsConstantRange();
+    const ConstantRange &CR =
+        Attrs.getAttribute(Attribute::Range).getValueAsConstantRange();
     Check(Ty->isIntOrIntVectorTy(CR.getBitWidth()),
           "Range bit width must match type bit width!", V);
   }

llvm/lib/Transforms/Utils/FunctionComparator.cpp

@@ -148,8 +148,8 @@ int FunctionComparator::cmpAttrs(const AttributeList L,
         if (LA.getKindAsEnum() != RA.getKindAsEnum())
           return cmpNumbers(LA.getKindAsEnum(), RA.getKindAsEnum());
 
-        ConstantRange LCR = LA.getRange();
-        ConstantRange RCR = RA.getRange();
+        const ConstantRange &LCR = LA.getRange();
+        const ConstantRange &RCR = RA.getRange();
         if (int Res = cmpAPInts(LCR.getLower(), RCR.getLower()))
           return Res;
         if (int Res = cmpAPInts(LCR.getUpper(), RCR.getUpper()))