[llvm] Remove no-op ptr-to-ptr casts (NFC)

Remove calls to CreatePointerCast which are just doing no-op ptr-to-ptr
bitcasts.

Opaque ptr cleanup effort (NFC).

Author: JOE1994

llvm/lib/CodeGen/CodeGenPrepare.cpp

@@ -6188,8 +6188,6 @@ bool CodeGenPrepare::splitLargeGEPOffsets() {
       // Generate a new GEP to replace the current one.
       LLVMContext &Ctx = GEP->getContext();
       Type *PtrIdxTy = DL->getIndexType(GEP->getType());
-      Type *I8PtrTy =
-          PointerType::get(Ctx, GEP->getType()->getPointerAddressSpace());
       Type *I8Ty = Type::getInt8Ty(Ctx);
 
       if (!NewBaseGEP) {
@@ -6200,16 +6198,10 @@ bool CodeGenPrepare::splitLargeGEPOffsets() {
 
       IRBuilder<> Builder(GEP);
       Value *NewGEP = NewBaseGEP;
-      if (Offset == BaseOffset) {
-        if (GEP->getType() != I8PtrTy)
-          NewGEP = Builder.CreatePointerCast(NewGEP, GEP->getType());
-      } else {
+      if (Offset != BaseOffset) {
         // Calculate the new offset for the new GEP.
         Value *Index = ConstantInt::get(PtrIdxTy, Offset - BaseOffset);
         NewGEP = Builder.CreateGEP(I8Ty, NewBaseGEP, Index);
-
-        if (GEP->getType() != I8PtrTy)
-          NewGEP = Builder.CreatePointerCast(NewGEP, GEP->getType());
       }
       replaceAllUsesWith(GEP, NewGEP, FreshBBs, IsHugeFunc);
       LargeOffsetGEPID.erase(GEP);

llvm/lib/Target/AMDGPU/AMDGPULibCalls.cpp

@@ -562,11 +562,10 @@ bool AMDGPULibCalls::fold_read_write_pipe(CallInst *CI, IRBuilder<> &B,
   if (!F)
     return false;
 
-  auto *BCast = B.CreatePointerCast(PtrArg, PtrTy);
   SmallVector<Value *, 6> Args;
   for (unsigned I = 0; I != PtrArgLoc; ++I)
     Args.push_back(CI->getArgOperand(I));
-  Args.push_back(BCast);
+  Args.push_back(PtrArg);
 
   auto *NCI = B.CreateCall(F, Args);
   NCI->setAttributes(CI->getAttributes());

llvm/lib/Target/X86/X86LowerAMXIntrinsics.cpp

@@ -184,9 +184,7 @@ Value *X86LowerAMXIntrinsics::createTileLoadStoreLoops(
   Value *CurrentColZExt = B.CreateZExt(CurrentCol, Stride->getType());
   Value *Offset =
       B.CreateAdd(B.CreateMul(CurrentRowZExt, Stride), CurrentColZExt);
-  unsigned AS = cast<PointerType>(Ptr->getType())->getAddressSpace();
-  Value *EltBasePtr = B.CreatePointerCast(Ptr, PointerType::get(EltTy, AS));
-  Value *EltPtr = B.CreateGEP(EltTy, EltBasePtr, Offset);
+  Value *EltPtr = B.CreateGEP(EltTy, Ptr, Offset);
   Value *Idx = B.CreateAdd(B.CreateMul(CurrentRow, B.getInt16(16)), CurrentCol);
   if (IsTileLoad) {
     // tileload.scalarize.rows.header: