Revert "[Coroutines] Only do symmetric transfer if optimization is on"

This reverts commit 7782e080e8. According
to the discussion of WG21, symmetric transfer is a desired feature.

llvm/include/llvm/Transforms/Coroutines/CoroSplit.h

@@ -22,14 +22,14 @@
 namespace llvm {
 
 struct CoroSplitPass : PassInfoMixin<CoroSplitPass> {
-  CoroSplitPass(bool Optimizing = false) : Optimizing(Optimizing) {}
+  CoroSplitPass(bool OptimizeFrame = false) : OptimizeFrame(OptimizeFrame) {}
 
   PreservedAnalyses run(LazyCallGraph::SCC &C, CGSCCAnalysisManager &AM,
                         LazyCallGraph &CG, CGSCCUpdateResult &UR);
   static bool isRequired() { return true; }
 
   // Would be true if the Optimization level isn't O0.
-  bool Optimizing;
+  bool OptimizeFrame;
 };
 } // end namespace llvm
 

llvm/lib/Passes/PassBuilder.cpp

@@ -601,7 +601,7 @@ Expected<bool> parseInlinerPassOptions(StringRef Params) {
 }
 
 Expected<bool> parseCoroSplitPassOptions(StringRef Params) {
-  return parseSinglePassOption(Params, "optimizing", "CoroSplitPass");
+  return parseSinglePassOption(Params, "reuse-storage", "CoroSplitPass");
 }
 
 Expected<bool> parseEarlyCSEPassOptions(StringRef Params) {

llvm/lib/Passes/PassRegistry.def

@@ -192,7 +192,7 @@ CGSCC_PASS_WITH_PARAMS("coro-split",
                          return CoroSplitPass(OptimizeFrame);
                        },
                        parseCoroSplitPassOptions,
-                       "optimizing")
+                       "reuse-storage")
 #undef CGSCC_PASS_WITH_PARAMS
 
 #ifndef FUNCTION_ANALYSIS

llvm/lib/Transforms/Coroutines/CoroFrame.cpp

@@ -608,7 +608,7 @@ void FrameTypeBuilder::addFieldForAllocas(const Function &F,
     }
   });
 
-  if (!Shape.Optimizing) {
+  if (!Shape.OptimizeFrame) {
     for (const auto &A : FrameData.Allocas) {
       AllocaInst *Alloca = A.Alloca;
       NonOverlapedAllocas.emplace_back(AllocaSetType(1, Alloca));
@@ -1692,14 +1692,14 @@ static void insertSpills(const FrameDataInfo &FrameData, coro::Shape &Shape) {
                              &*Builder.GetInsertPoint());
           // This dbg.declare is for the main function entry point.  It
           // will be deleted in all coro-split functions.
-          coro::salvageDebugInfo(DbgPtrAllocaCache, DDI, Shape.Optimizing);
+          coro::salvageDebugInfo(DbgPtrAllocaCache, DDI, Shape.OptimizeFrame);
         }
       }
 
       // Salvage debug info on any dbg.addr that we see. We do not insert them
       // into each block where we have a use though.
       if (auto *DI = dyn_cast<DbgAddrIntrinsic>(U)) {
-        coro::salvageDebugInfo(DbgPtrAllocaCache, DI, Shape.Optimizing);
+        coro::salvageDebugInfo(DbgPtrAllocaCache, DI, Shape.OptimizeFrame);
       }
 
       // If we have a single edge PHINode, remove it and replace it with a
@@ -2548,7 +2548,7 @@ static void collectFrameAllocas(Function &F, coro::Shape &Shape,
 
 void coro::salvageDebugInfo(
     SmallDenseMap<llvm::Value *, llvm::AllocaInst *, 4> &DbgPtrAllocaCache,
-    DbgVariableIntrinsic *DVI, bool Optimizing) {
+    DbgVariableIntrinsic *DVI, bool OptimizeFrame) {
   Function *F = DVI->getFunction();
   IRBuilder<> Builder(F->getContext());
   auto InsertPt = F->getEntryBlock().getFirstInsertionPt();
@@ -2601,7 +2601,7 @@ void coro::salvageDebugInfo(
   //
   // Avoid to create the alloca would be eliminated by optimization
   // passes and the corresponding dbg.declares would be invalid.
-  if (!Optimizing)
+  if (!OptimizeFrame)
     if (auto *Arg = dyn_cast<llvm::Argument>(Storage)) {
       auto &Cached = DbgPtrAllocaCache[Storage];
       if (!Cached) {

llvm/lib/Transforms/Coroutines/CoroInternal.h

@@ -31,7 +31,7 @@ void replaceCoroFree(CoroIdInst *CoroId, bool Elide);
 /// holding a pointer to the coroutine frame.
 void salvageDebugInfo(
     SmallDenseMap<llvm::Value *, llvm::AllocaInst *, 4> &DbgPtrAllocaCache,
-    DbgVariableIntrinsic *DVI, bool Optimizing);
+    DbgVariableIntrinsic *DVI, bool OptimizeFrame);
 
 // Keeps data and helper functions for lowering coroutine intrinsics.
 struct LowererBase {
@@ -104,7 +104,7 @@ struct LLVM_LIBRARY_VISIBILITY Shape {
   BasicBlock *AllocaSpillBlock;
 
   /// This would only be true if optimization are enabled.
-  bool Optimizing;
+  bool OptimizeFrame;
 
   struct SwitchLoweringStorage {
     SwitchInst *ResumeSwitch;
@@ -255,8 +255,8 @@ struct LLVM_LIBRARY_VISIBILITY Shape {
   void emitDealloc(IRBuilder<> &Builder, Value *Ptr, CallGraph *CG) const;
 
   Shape() = default;
-  explicit Shape(Function &F, bool Optimizing = false)
-      : Optimizing(Optimizing) {
+  explicit Shape(Function &F, bool OptimizeFrame = false)
+      : OptimizeFrame(OptimizeFrame) {
     buildFrom(F);
   }
   void buildFrom(Function &F);

llvm/lib/Transforms/Coroutines/CoroSplit.cpp

@@ -683,7 +683,7 @@ void CoroCloner::salvageDebugInfo() {
       if (auto *DVI = dyn_cast<DbgVariableIntrinsic>(&I))
         Worklist.push_back(DVI);
   for (DbgVariableIntrinsic *DVI : Worklist)
-    coro::salvageDebugInfo(DbgPtrAllocaCache, DVI, Shape.Optimizing);
+    coro::salvageDebugInfo(DbgPtrAllocaCache, DVI, Shape.OptimizeFrame);
 
   // Remove all salvaged dbg.declare intrinsics that became
   // either unreachable or stale due to the CoroSplit transformation.
@@ -1351,8 +1351,8 @@ static bool shouldBeMustTail(const CallInst &CI, const Function &F) {
 }
 
 // Add musttail to any resume instructions that is immediately followed by a
-// suspend (i.e. ret) to implement symmetric transfer. We wouldn't do this in
-// O0 since symmetric transfer is not part of standard now.
+// suspend (i.e. ret). We do this even in -O0 to support guaranteed tail call
+// for symmetrical coroutine control transfer (C++ Coroutines TS extension).
 // This transformation is done only in the resume part of the coroutine that has
 // identical signature and calling convention as the coro.resume call.
 static void addMustTailToCoroResumes(Function &F) {
@@ -1580,10 +1580,7 @@ static void splitSwitchCoroutine(Function &F, coro::Shape &Shape,
   postSplitCleanup(*DestroyClone);
   postSplitCleanup(*CleanupClone);
 
-  // Prepare to do symmetric transfer. We only do this if optimization is
-  // enabled since the symmetric transfer is not part of the C++ standard now.
-  if (Shape.Optimizing)
-    addMustTailToCoroResumes(*ResumeClone);
+  addMustTailToCoroResumes(*ResumeClone);
 
   // Store addresses resume/destroy/cleanup functions in the coroutine frame.
   updateCoroFrame(Shape, ResumeClone, DestroyClone, CleanupClone);
@@ -1888,14 +1885,14 @@ namespace {
 
 static coro::Shape splitCoroutine(Function &F,
                                   SmallVectorImpl<Function *> &Clones,
-                                  bool Optimizing) {
+                                  bool OptimizeFrame) {
   PrettyStackTraceFunction prettyStackTrace(F);
 
   // The suspend-crossing algorithm in buildCoroutineFrame get tripped
   // up by uses in unreachable blocks, so remove them as a first pass.
   removeUnreachableBlocks(F);
 
-  coro::Shape Shape(F, Optimizing);
+  coro::Shape Shape(F, OptimizeFrame);
   if (!Shape.CoroBegin)
     return Shape;
 
@@ -1944,7 +1941,7 @@ static coro::Shape splitCoroutine(Function &F,
     }
   }
   for (auto *DDI : Worklist)
-    coro::salvageDebugInfo(DbgPtrAllocaCache, DDI, Shape.Optimizing);
+    coro::salvageDebugInfo(DbgPtrAllocaCache, DDI, Shape.OptimizeFrame);
 
   return Shape;
 }
@@ -2087,7 +2084,7 @@ PreservedAnalyses CoroSplitPass::run(LazyCallGraph::SCC &C,
     F.setSplittedCoroutine();
 
     SmallVector<Function *, 4> Clones;
-    const coro::Shape Shape = splitCoroutine(F, Clones, Optimizing);
+    const coro::Shape Shape = splitCoroutine(F, Clones, OptimizeFrame);
     updateCallGraphAfterCoroutineSplit(*N, Shape, Clones, C, CG, AM, UR, FAM);
 
     if (!Shape.CoroSuspends.empty()) {

llvm/test/Transforms/Coroutines/coro-debug-O2.ll

@@ -1,4 +1,4 @@
-; RUN: opt < %s -passes='module(coro-early),cgscc(coro-split<optimizing>),function(sroa)' -S | FileCheck %s
+; RUN: opt < %s -passes='module(coro-early),cgscc(coro-split<reuse-storage>),function(sroa)' -S | FileCheck %s
 
 ; Checks whether the dbg.declare for `__promise` remains valid under O2.
 

llvm/test/Transforms/Coroutines/coro-frame-reuse-alloca-00.ll

@@ -1,5 +1,5 @@
 ; Check that we can handle spills of array allocas
-; RUN: opt < %s -passes='cgscc(coro-split<optimizing>),simplifycfg,early-cse' -S | FileCheck %s
+; RUN: opt < %s -passes='cgscc(coro-split<reuse-storage>),simplifycfg,early-cse' -S | FileCheck %s
 
 %struct.big_structure = type { [500 x i8] }
 declare void @consume(%struct.big_structure*)

llvm/test/Transforms/Coroutines/coro-frame-reuse-alloca-01.ll

@@ -1,6 +1,6 @@
 ; Tests that variables in a Corotuine whose lifetime range is not overlapping each other
 ; re-use the same slot in Coroutine frame.
-; RUN: opt < %s -passes='cgscc(coro-split<optimizing>),simplifycfg,early-cse' -S | FileCheck %s
+; RUN: opt < %s -passes='cgscc(coro-split<reuse-storage>),simplifycfg,early-cse' -S | FileCheck %s
 %"struct.task::promise_type" = type { i8 }
 %struct.awaitable = type { i8 }
 %struct.big_structure = type { [500 x i8] }

llvm/test/Transforms/Coroutines/coro-frame-reuse-alloca-02.ll

@@ -1,6 +1,6 @@
 ; Tests that variables of different type in a Corotuine whose lifetime range is not overlapping each other
 ; re-use the same slot in Coroutine frame.
-; RUN: opt < %s -passes='cgscc(coro-split<optimizing>),simplifycfg,early-cse' -S | FileCheck %s
+; RUN: opt < %s -passes='cgscc(coro-split<reuse-storage>),simplifycfg,early-cse' -S | FileCheck %s
 %"struct.task::promise_type" = type { i8 }
 %struct.awaitable = type { i8 }
 %struct.big_structure = type { [500 x i8] }

llvm/test/Transforms/Coroutines/coro-frame-reuse-alloca-04.ll

@@ -1,6 +1,6 @@
 ; Tests that variables of different type with incompatible alignment in a Corotuine whose lifetime 
 ; range is not overlapping each other should not re-use the same slot in Coroutine frame. 
-; RUN: opt < %s -passes='cgscc(coro-split<optimizing>),simplifycfg,early-cse' -S | FileCheck %s
+; RUN: opt < %s -passes='cgscc(coro-split<reuse-storage>),simplifycfg,early-cse' -S | FileCheck %s
 %"struct.task::promise_type" = type { i8 }
 %struct.awaitable = type { i8 }
 %struct.big_structure = type { [500 x i8] }

llvm/test/Transforms/Coroutines/coro-frame-reuse-alloca-05.ll

@@ -1,6 +1,6 @@
 ; Tests that variables of different type with incompatible alignment in a Corotuine whose 
 ; lifetime range is not overlapping each other re-use the same slot in CorotuineFrame.
-; RUN: opt < %s -passes='cgscc(coro-split<optimizing>),simplifycfg,early-cse' -S | FileCheck %s
+; RUN: opt < %s -passes='cgscc(coro-split<reuse-storage>),simplifycfg,early-cse' -S | FileCheck %s
 %"struct.task::promise_type" = type { i8 }
 %struct.awaitable = type { i8 }
 %struct.big_structure = type { [500 x i8] }

llvm/test/Transforms/Coroutines/coro-split-musttail.ll

@@ -1,6 +1,6 @@
 ; Tests that coro-split will convert coro.resume followed by a suspend to a
 ; musttail call.
-; RUN: opt < %s -passes='cgscc(coro-split<optimizing>),simplifycfg,early-cse' -S | FileCheck %s
+; RUN: opt < %s -passes='cgscc(coro-split),simplifycfg,early-cse' -S | FileCheck %s
 
 define void @f() #0 {
 entry:

llvm/test/Transforms/Coroutines/coro-split-musttail1.ll

@@ -1,6 +1,6 @@
 ; Tests that coro-split will convert coro.resume followed by a suspend to a
 ; musttail call.
-; RUN: opt < %s -passes='cgscc(coro-split<optimizing>),simplifycfg,early-cse' -S | FileCheck %s
+; RUN: opt < %s -passes='cgscc(coro-split),simplifycfg,early-cse' -S | FileCheck %s
 
 define void @f() #0 {
 entry:

llvm/test/Transforms/Coroutines/coro-split-musttail2.ll

@@ -1,6 +1,6 @@
 ; Tests that coro-split will convert coro.resume followed by a suspend to a
 ; musttail call.
-; RUN: opt < %s -passes='cgscc(coro-split<optimizing>),simplifycfg,early-cse' -S | FileCheck %s
+; RUN: opt < %s -passes='cgscc(coro-split),simplifycfg,early-cse' -S | FileCheck %s
 
 define void @fakeresume1(i8*)  {
 entry:

llvm/test/Transforms/Coroutines/coro-split-musttail3.ll

@@ -1,6 +1,6 @@
 ; Tests that coro-split will convert coro.resume followed by a suspend to a
 ; musttail call.
-; RUN: opt < %s -passes='cgscc(coro-split<optimizing>),simplifycfg,early-cse' -S | FileCheck %s
+; RUN: opt < %s -passes='cgscc(coro-split),simplifycfg,early-cse' -S | FileCheck %s
 
 define void @f() #0 {
 entry:

llvm/test/Transforms/Coroutines/coro-split-musttail4.ll

@@ -1,6 +1,6 @@
 ; Tests that coro-split will convert a call before coro.suspend to a musttail call
 ; while the user of the coro.suspend is a icmpinst.
-; RUN: opt < %s -passes='cgscc(coro-split<optimizing>),simplifycfg,early-cse' -S | FileCheck %s
+; RUN: opt < %s -passes='cgscc(coro-split),simplifycfg,early-cse' -S | FileCheck %s
 
 define void @fakeresume1(i8*)  {
 entry:

llvm/test/Transforms/Coroutines/coro-split-musttail5.ll

@@ -1,6 +1,6 @@
 ; Tests that sinked lifetime markers wouldn't provent optimization
 ; to convert a resuming call to a musttail call.
-; RUN: opt < %s -passes='cgscc(coro-split<optimizing>),simplifycfg,early-cse' -S | FileCheck %s
+; RUN: opt < %s -passes='cgscc(coro-split),simplifycfg,early-cse' -S | FileCheck %s
 
 declare void @fakeresume1(i64* align 8)
 

llvm/test/Transforms/Coroutines/coro-split-musttail6.ll

@@ -3,7 +3,7 @@
 ; The difference between this and coro-split-musttail5.ll is that there is
 ; an extra bitcast instruction in the path, which makes it harder to
 ; optimize.
-; RUN: opt < %s -passes='cgscc(coro-split<optimizing>),simplifycfg,early-cse' -S | FileCheck %s
+; RUN: opt < %s -passes='cgscc(coro-split),simplifycfg,early-cse' -S | FileCheck %s
 
 declare void @fakeresume1(i64* align 8)
 

llvm/test/Transforms/Coroutines/coro-split-musttail7.ll

@@ -3,7 +3,7 @@
 ; The difference between this and coro-split-musttail5.ll and coro-split-musttail5.ll
 ; is that this contains dead instruction generated during the transformation,
 ; which makes the optimization harder.
-; RUN: opt < %s -passes='cgscc(coro-split<optimizing>),simplifycfg,early-cse' -S | FileCheck %s
+; RUN: opt < %s -passes='cgscc(coro-split),simplifycfg,early-cse' -S | FileCheck %s
 
 declare void @fakeresume1(i64* align 8)