[Coroutines] Split buildCoroutineFrame into normalization and frame building (#108076)

* Split buildCoroutineFrame into code related to normalization and code
related to actually building the coroutine frame.
* This will enable future specialization of buildCoroutineFrame for
different ABIs while the normalization can be done by splitCoroutine
prior to calling buildCoroutineFrame.

See RFC for more info:
https://discourse.llvm.org/t/rfc-abi-objects-for-coroutines/81057

Author: TylerNowicki

llvm/lib/Transforms/Coroutines/CoroFrame.cpp

@@ -1754,7 +1754,8 @@ static bool willLeaveFunctionImmediatelyAfter(BasicBlock *BB,
   if (depth == 0) return false;
 
   // If this is a suspend block, we're about to exit the resumption function.
-  if (isSuspendBlock(BB)) return true;
+  if (isSuspendBlock(BB))
+    return true;
 
   // Recurse into the successors.
   for (auto *Succ : successors(BB)) {
@@ -2288,9 +2289,8 @@ static void doRematerializations(
   rewriteMaterializableInstructions(AllRemats);
 }
 
-void coro::buildCoroutineFrame(
-    Function &F, Shape &Shape, TargetTransformInfo &TTI,
-    const std::function<bool(Instruction &)> &MaterializableCallback) {
+void coro::normalizeCoroutine(Function &F, coro::Shape &Shape,
+                              TargetTransformInfo &TTI) {
   // Don't eliminate swifterror in async functions that won't be split.
   if (Shape.ABI != coro::ABI::Async || !Shape.CoroSuspends.empty())
     eliminateSwiftError(F, Shape);
@@ -2337,10 +2337,12 @@ void coro::buildCoroutineFrame(
   // Transforms multi-edge PHI Nodes, so that any value feeding into a PHI will
   // never have its definition separated from the PHI by the suspend point.
   rewritePHIs(F);
+}
 
-  // Build suspend crossing info.
+void coro::buildCoroutineFrame(
+    Function &F, Shape &Shape,
+    const std::function<bool(Instruction &)> &MaterializableCallback) {
   SuspendCrossingInfo Checker(F, Shape.CoroSuspends, Shape.CoroEnds);
-
   doRematerializations(F, Checker, MaterializableCallback);
 
   const DominatorTree DT(F);

llvm/lib/Transforms/Coroutines/CoroInternal.h

@@ -281,8 +281,10 @@ struct LLVM_LIBRARY_VISIBILITY Shape {
 };
 
 bool defaultMaterializable(Instruction &V);
+void normalizeCoroutine(Function &F, coro::Shape &Shape,
+                        TargetTransformInfo &TTI);
 void buildCoroutineFrame(
-    Function &F, Shape &Shape, TargetTransformInfo &TTI,
+    Function &F, Shape &Shape,
     const std::function<bool(Instruction &)> &MaterializableCallback);
 CallInst *createMustTailCall(DebugLoc Loc, Function *MustTailCallFn,
                              TargetTransformInfo &TTI,

llvm/lib/Transforms/Coroutines/CoroSplit.cpp

@@ -2030,7 +2030,8 @@ splitCoroutine(Function &F, SmallVectorImpl<Function *> &Clones,
   lowerAwaitSuspends(F, Shape);
 
   simplifySuspendPoints(Shape);
-  buildCoroutineFrame(F, Shape, TTI, MaterializableCallback);
+  normalizeCoroutine(F, Shape, TTI);
+  buildCoroutineFrame(F, Shape, MaterializableCallback);
   replaceFrameSizeAndAlignment(Shape);
   bool isNoSuspendCoroutine = Shape.CoroSuspends.empty();