Remove the need for one const_cast

Author: jayfoad

llvm/include/llvm/IR/DerivedTypes.h

@@ -290,7 +290,7 @@ class StructType : public Type {
   bool isSized(SmallPtrSetImpl<Type *> *Visited = nullptr) const;
 
   /// Returns true if this struct contains a scalable vector.
-  bool isScalableTy(SmallPtrSetImpl<Type *> &Visited) const;
+  bool isScalableTy(SmallPtrSetImpl<const Type *> &Visited) const;
   using Type::isScalableTy;
 
   /// Returns true if this struct contains homogeneous scalable vector types.

llvm/include/llvm/IR/Type.h

@@ -206,7 +206,7 @@ class Type {
   bool isScalableTargetExtTy() const;
 
   /// Return true if this is a type whose size is a known multiple of vscale.
-  bool isScalableTy(SmallPtrSetImpl<Type *> &Visited) const;
+  bool isScalableTy(SmallPtrSetImpl<const Type *> &Visited) const;
   bool isScalableTy() const;
 
   /// Return true if this is a FP type or a vector of FP.

llvm/lib/IR/Type.cpp

@@ -58,7 +58,7 @@ bool Type::isIntegerTy(unsigned Bitwidth) const {
   return isIntegerTy() && cast<IntegerType>(this)->getBitWidth() == Bitwidth;
 }
 
-bool Type::isScalableTy(SmallPtrSetImpl<Type *> &Visited) const {
+bool Type::isScalableTy(SmallPtrSetImpl<const Type *> &Visited) const {
   if (const auto *ATy = dyn_cast<ArrayType>(this))
     return ATy->getElementType()->isScalableTy(Visited);
   if (const auto *STy = dyn_cast<StructType>(this))
@@ -67,7 +67,7 @@ bool Type::isScalableTy(SmallPtrSetImpl<Type *> &Visited) const {
 }
 
 bool Type::isScalableTy() const {
-  SmallPtrSet<Type *, 4> Visited;
+  SmallPtrSet<const Type *, 4> Visited;
   return isScalableTy(Visited);
 }
 
@@ -397,14 +397,14 @@ StructType *StructType::get(LLVMContext &Context, ArrayRef<Type*> ETypes,
   return ST;
 }
 
-bool StructType::isScalableTy(SmallPtrSetImpl<Type *> &Visited) const {
+bool StructType::isScalableTy(SmallPtrSetImpl<const Type *> &Visited) const {
   if ((getSubclassData() & SCDB_ContainsScalableVector) != 0)
     return true;
 
   if ((getSubclassData() & SCDB_NotContainsScalableVector) != 0)
     return false;
 
-  if (!Visited.insert(const_cast<StructType *>(this)).second)
+  if (!Visited.insert(this).second)
     return false;
 
   for (Type *Ty : elements()) {