[Coroutines][NFC] Refactor CoroCloner (#116885)

* Move CoroCloner to its own header. For now, the header is located in llvm/lib/Transforms/Coroutines
* Change private to protected to allow inheritance
* Create CoroSwitchCloner and move some of the switch specific code into this cloner. More code will follow in later commits.

Author: TylerNowicki

llvm/lib/Transforms/Coroutines/CoroCloner.h

@@ -0,0 +1,155 @@
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+// Helper class for splitting a coroutine into separate functions. For example
+// the returned-continuation coroutine is split into separate continuation
+// functions.
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIB_TRANSFORMS_COROUTINES_COROCLONER_H
+#define LLVM_LIB_TRANSFORMS_COROUTINES_COROCLONER_H
+
+#include "llvm/IR/Function.h"
+#include "llvm/IR/IRBuilder.h"
+#include "llvm/Support/TimeProfiler.h"
+#include "llvm/Transforms/Coroutines/ABI.h"
+#include "llvm/Transforms/Coroutines/CoroInstr.h"
+#include "llvm/Transforms/Utils/ValueMapper.h"
+
+namespace llvm {
+
+namespace coro {
+
+enum class CloneKind {
+  /// The shared resume function for a switch lowering.
+  SwitchResume,
+
+  /// The shared unwind function for a switch lowering.
+  SwitchUnwind,
+
+  /// The shared cleanup function for a switch lowering.
+  SwitchCleanup,
+
+  /// An individual continuation function.
+  Continuation,
+
+  /// An async resume function.
+  Async,
+};
+
+class BaseCloner {
+protected:
+  Function &OrigF;
+  const Twine &Suffix;
+  coro::Shape &Shape;
+  CloneKind FKind;
+  IRBuilder<> Builder;
+  TargetTransformInfo &TTI;
+
+  ValueToValueMapTy VMap;
+  Function *NewF = nullptr;
+  Value *NewFramePtr = nullptr;
+
+  /// The active suspend instruction; meaningful only for continuation and async
+  /// ABIs.
+  AnyCoroSuspendInst *ActiveSuspend = nullptr;
+
+  /// Create a cloner for a continuation lowering.
+  BaseCloner(Function &OrigF, const Twine &Suffix, coro::Shape &Shape,
+             Function *NewF, AnyCoroSuspendInst *ActiveSuspend,
+             TargetTransformInfo &TTI)
+      : OrigF(OrigF), Suffix(Suffix), Shape(Shape),
+        FKind(Shape.ABI == ABI::Async ? CloneKind::Async
+                                      : CloneKind::Continuation),
+        Builder(OrigF.getContext()), TTI(TTI), NewF(NewF),
+        ActiveSuspend(ActiveSuspend) {
+    assert(Shape.ABI == ABI::Retcon || Shape.ABI == ABI::RetconOnce ||
+           Shape.ABI == ABI::Async);
+    assert(NewF && "need existing function for continuation");
+    assert(ActiveSuspend && "need active suspend point for continuation");
+  }
+
+public:
+  BaseCloner(Function &OrigF, const Twine &Suffix, coro::Shape &Shape,
+             CloneKind FKind, TargetTransformInfo &TTI)
+      : OrigF(OrigF), Suffix(Suffix), Shape(Shape), FKind(FKind),
+        Builder(OrigF.getContext()), TTI(TTI) {}
+
+  virtual ~BaseCloner() {}
+
+  /// Create a clone for a continuation lowering.
+  static Function *createClone(Function &OrigF, const Twine &Suffix,
+                               coro::Shape &Shape, Function *NewF,
+                               AnyCoroSuspendInst *ActiveSuspend,
+                               TargetTransformInfo &TTI) {
+    assert(Shape.ABI == ABI::Retcon || Shape.ABI == ABI::RetconOnce ||
+           Shape.ABI == ABI::Async);
+    TimeTraceScope FunctionScope("BaseCloner");
+
+    BaseCloner Cloner(OrigF, Suffix, Shape, NewF, ActiveSuspend, TTI);
+    Cloner.create();
+    return Cloner.getFunction();
+  }
+
+  Function *getFunction() const {
+    assert(NewF != nullptr && "declaration not yet set");
+    return NewF;
+  }
+
+  virtual void create();
+
+protected:
+  bool isSwitchDestroyFunction() {
+    switch (FKind) {
+    case CloneKind::Async:
+    case CloneKind::Continuation:
+    case CloneKind::SwitchResume:
+      return false;
+    case CloneKind::SwitchUnwind:
+    case CloneKind::SwitchCleanup:
+      return true;
+    }
+    llvm_unreachable("Unknown ClonerKind enum");
+  }
+
+  void replaceEntryBlock();
+  Value *deriveNewFramePointer();
+  void replaceRetconOrAsyncSuspendUses();
+  void replaceCoroSuspends();
+  void replaceCoroEnds();
+  void replaceSwiftErrorOps();
+  void salvageDebugInfo();
+  void handleFinalSuspend();
+};
+
+class SwitchCloner : public BaseCloner {
+protected:
+  /// Create a cloner for a switch lowering.
+  SwitchCloner(Function &OrigF, const Twine &Suffix, coro::Shape &Shape,
+               CloneKind FKind, TargetTransformInfo &TTI)
+      : BaseCloner(OrigF, Suffix, Shape, FKind, TTI) {}
+
+  void create() override;
+
+public:
+  /// Create a clone for a switch lowering.
+  static Function *createClone(Function &OrigF, const Twine &Suffix,
+                               coro::Shape &Shape, CloneKind FKind,
+                               TargetTransformInfo &TTI) {
+    assert(Shape.ABI == ABI::Switch);
+    TimeTraceScope FunctionScope("SwitchCloner");
+
+    SwitchCloner Cloner(OrigF, Suffix, Shape, FKind, TTI);
+    Cloner.create();
+    return Cloner.getFunction();
+  }
+};
+
+} // end namespace coro
+
+} // end namespace llvm
+
+#endif // LLVM_LIB_TRANSFORMS_COROUTINES_COROCLONER_H

llvm/lib/Transforms/Coroutines/CoroFrame.cpp

@@ -1133,7 +1133,7 @@ static void insertSpills(const FrameDataInfo &FrameData, coro::Shape &Shape) {
           bool AllowUnresolved = false;
           // This dbg.declare is preserved for all coro-split function
           // fragments. It will be unreachable in the main function, and
-          // processed by coro::salvageDebugInfo() by CoroCloner.
+          // processed by coro::salvageDebugInfo() by the Cloner.
           if (UseNewDbgInfoFormat) {
             DbgVariableRecord *NewDVR = new DbgVariableRecord(
                 ValueAsMetadata::get(CurrentReload), DDI->getVariable(),