ConstantFolding: remove function in context of opaque ptrs

The function StripPtrCastKeepAS() no longer makes any sense, as we've
migrated to using opaque pointers throughout the codebase. Hence, remove
it. No changes to tests are required.

Differential Revision: https://reviews.llvm.org/D156555

Author: artagnon

llvm/lib/Analysis/ConstantFolding.cpp

@@ -861,20 +861,6 @@ Constant *CastGEPIndices(Type *SrcElemTy, ArrayRef<Constant *> Ops,
   return ConstantFoldConstant(C, DL, TLI);
 }
 
-/// Strip the pointer casts, but preserve the address space information.
-// TODO: This probably doesn't make sense with opaque pointers.
-static Constant *StripPtrCastKeepAS(Constant *Ptr) {
-  assert(Ptr->getType()->isPointerTy() && "Not a pointer type");
-  auto *OldPtrTy = cast<PointerType>(Ptr->getType());
-  Ptr = cast<Constant>(Ptr->stripPointerCasts());
-  auto *NewPtrTy = cast<PointerType>(Ptr->getType());
-
-  // Preserve the address space number of the pointer.
-  if (NewPtrTy->getAddressSpace() != OldPtrTy->getAddressSpace())
-    Ptr = ConstantExpr::getPointerCast(Ptr, OldPtrTy);
-  return Ptr;
-}
-
 /// If we can symbolically evaluate the GEP constant expression, do so.
 Constant *SymbolicallyEvaluateGEP(const GEPOperator *GEP,
                                   ArrayRef<Constant *> Ops,
@@ -909,7 +895,6 @@ Constant *SymbolicallyEvaluateGEP(const GEPOperator *GEP,
       BitWidth,
       DL.getIndexedOffsetInType(
           SrcElemTy, ArrayRef((Value *const *)Ops.data() + 1, Ops.size() - 1)));
-  Ptr = StripPtrCastKeepAS(Ptr);
 
   // If this is a GEP of a GEP, fold it all into a single GEP.
   while (auto *GEP = dyn_cast<GEPOperator>(Ptr)) {
@@ -931,7 +916,6 @@ Constant *SymbolicallyEvaluateGEP(const GEPOperator *GEP,
     Ptr = cast<Constant>(GEP->getOperand(0));
     SrcElemTy = GEP->getSourceElementType();
     Offset += APInt(BitWidth, DL.getIndexedOffsetInType(SrcElemTy, NestedOps));
-    Ptr = StripPtrCastKeepAS(Ptr);
   }
 
   // If the base value for this address is a literal integer value, fold the