ConstantFolding: remove function in context of opaque ptrs

[artagnon]

Summary

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.

llvm/lib/Analysis/ConstantFolding.cpp

Constant *CastGEPIndices(Type *SrcElemTy, ArrayRef<Constant *> Ops,
   if (!Any)
     return nullptr;
 
   Constant *C = ConstantExpr::getGetElementPtr(
       SrcElemTy, Ops[0], NewIdxs, InBounds, InRangeIndex);
   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,
                                   const DataLayout &DL,
                                   const TargetLibraryInfo *TLI) {
   const GEPOperator *InnermostGEP = GEP;
   bool InBounds = GEP->isInBounds();
 
for (unsigned i = 1, e = Ops.size(); i != e; ++i)
     if (!isa<ConstantInt>(Ops[i]))
       return nullptr;
 
   unsigned BitWidth = DL.getTypeSizeInBits(IntIdxTy);
   APInt Offset = APInt(
       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)) {
     InnermostGEP = GEP;
     InBounds &= GEP->isInBounds();
 
     SmallVector<Value *, 4> NestedOps(llvm::drop_begin(GEP->operands()));
 
     // Do not try the incorporate the sub-GEP if some index is not a number.
     bool AllConstantInt = true;
     for (Value *NestedOp : NestedOps)
       if (!isa<ConstantInt>(NestedOp)) {
         AllConstantInt = false;
         break;
       }
     if (!AllConstantInt)
       break;
 
     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
   // getelementptr to the resulting integer value casted to the pointer type.
   APInt BasePtr(BitWidth, 0);
   if (auto *CE = dyn_cast<ConstantExpr>(Ptr)) {
     if (CE->getOpcode() == Instruction::IntToPtr) {
       if (auto *Base = dyn_cast<ConstantInt>(CE->getOperand(0)))