[polly] Avoid llvm::Type::getPointerTo() (NFC) (#112368)

`llvm::Type::getPointerTo()` is to be deprecated & removed soon.

Also, avoid pointercasts that are essentially no-ops.

polly/lib/CodeGen/BlockGenerators.cpp

@@ -786,12 +786,6 @@ void BlockGenerator::generateScalarStores(
                                Builder.GetInsertBlock())) &&
                  "Domination violation");
 
-          // The new Val might have a different type than the old Val due to
-          // ScalarEvolution looking through bitcasts.
-          Address = Builder.CreateBitOrPointerCast(
-              Address, Val->getType()->getPointerTo(
-                           Address->getType()->getPointerAddressSpace()));
-
           Builder.CreateStore(Val, Address);
         });
   }

polly/lib/CodeGen/IslNodeBuilder.cpp

@@ -1050,8 +1050,6 @@ Value *IslNodeBuilder::preloadUnconditionally(__isl_take isl_set *AccessRange,
 
   auto *Ptr = AddressValue;
   auto Name = Ptr->getName();
-  auto AS = Ptr->getType()->getPointerAddressSpace();
-  Ptr = Builder.CreatePointerCast(Ptr, Ty->getPointerTo(AS), Name + ".cast");
   PreloadVal = Builder.CreateLoad(Ty, Ptr, Name + ".load");
   if (LoadInst *PreloadInst = dyn_cast<LoadInst>(PreloadVal))
     PreloadInst->setAlignment(cast<LoadInst>(AccInst)->getAlign());

polly/lib/CodeGen/LoopGeneratorsGOMP.cpp

@@ -183,7 +183,7 @@ Value *ParallelLoopGeneratorGOMP::createCallGetWorkItem(Value *LBPtr,
   // If F is not available, declare it.
   if (!F) {
     GlobalValue::LinkageTypes Linkage = Function::ExternalLinkage;
-    Type *Params[] = {LongType->getPointerTo(), LongType->getPointerTo()};
+    Type *Params[] = {Builder.getPtrTy(0), Builder.getPtrTy(0)};
     FunctionType *Ty = FunctionType::get(Builder.getInt8Ty(), Params, false);
     F = Function::Create(Ty, Linkage, Name, M);
   }