[Continuations] - Add helper for getWithSamePointeeType

PointerType::getWithSamePointeeType was removed in upstream
LLVM, but we rely on it in typed pointer mode.
Add a helper function that calls the LLVM function for old
LLVM, and returns an untyped pointer for new LLVM.

This helper can be removed once typed pointer support is no longer
needed.

shared/continuations/include/continuations/ContinuationsUtil.h

@@ -637,6 +637,11 @@ findIntrImplEntryByIntrinsicCall(CallInst *Call);
 // during DXILContPostProcess, so we cannot remove all unused declarations right
 // at the end of LowerRaytracingPipeline.
 bool removeUnusedFunctionDecls(Module *Mod, bool OnlyIntrinsics = true);
+
+// Replacement for PointerType::getWithSamePointeeType that works with new LLVM.
+// Returns a typed pointer type if the pointer type is typed.
+PointerType *getWithSamePointeeType(PointerType *PtrTy, unsigned AddressSpace);
+
 } // namespace llvm
 
 #endif

shared/continuations/lib/ContinuationsUtil.cpp

@@ -110,3 +110,14 @@ bool llvm::removeUnusedFunctionDecls(Module *Mod, bool OnlyIntrinsics) {
 
   return DidChange;
 }
+
+PointerType *llvm::getWithSamePointeeType(PointerType *PtrTy,
+                                          unsigned AddressSpace) {
+#if LLVM_MAIN_REVISION && LLVM_MAIN_REVISION < 482880
+  return PointerType::getWithSamePointeeType(PtrTy, AddressSpace);
+#else
+  // New version of the code (also handles unknown version, which we treat as
+  // latest)
+  return PointerType::get(PtrTy->getContext(), AddressSpace);
+#endif
+}

shared/continuations/lib/RegisterBuffer.cpp

@@ -194,16 +194,16 @@ Value *RegisterBufferPass::computeMemAddr(IRBuilder<> &Builder,
     Value *MemSrc = computeMemAddr(Builder, Src);
     New = Builder.CreateCast(
         Inst->getOpcode(), MemSrc,
-        PointerType::getWithSamePointeeType(
-            cast<PointerType>(Inst->getDestTy()), Data.Addrspace));
+        getWithSamePointeeType(cast<PointerType>(Inst->getDestTy()),
+                               Data.Addrspace));
   } else if (auto *Inst = dyn_cast<ConstantExpr>(Address)) {
     if (Inst->isCast()) {
       auto *Src = Inst->getOperand(0);
       Value *MemSrc = computeMemAddr(Builder, Src);
       New = Builder.CreateCast(
           static_cast<Instruction::CastOps>(Inst->getOpcode()), MemSrc,
-          PointerType::getWithSamePointeeType(
-              cast<PointerType>(Inst->getType()), Data.Addrspace));
+          getWithSamePointeeType(cast<PointerType>(Inst->getType()),
+                                 Data.Addrspace));
     } else {
       LLVM_DEBUG(Address->dump());
       llvm_unreachable(
@@ -242,8 +242,7 @@ Value *RegisterBufferPass::handleSingleLoadStore(
   // Change load/store to use addrspace(20)
   auto *AddressType = cast<PointerType>(Address->getType());
   Address = Builder.CreateAddrSpaceCast(
-      Address, PointerType::getWithSamePointeeType(AddressType,
-                                                   GlobalRegisterAddrspace));
+      Address, getWithSamePointeeType(AddressType, GlobalRegisterAddrspace));
 
   // If only registers are accessed, emit a simple load/store
   if (TotalElementCount <= Data.RegisterCount)