Import LLVM 10.0.0 release including clang, lld and lldb.

ok hackroom
tested by plenty

1 files changed, 758 insertions, 0 deletions

diff --git a/gnu/llvm/clang/lib/CodeGen/CGCoroutine.cpp b/gnu/llvm/clang/lib/CodeGen/CGCoroutine.cpp
new file mode 100644
index 00000000000..aee5a927a05
--- /dev/null
+++ b/gnu/llvm/clang/lib/CodeGen/CGCoroutine.cpp
@@ -0,0 +1,758 @@
+//===----- CGCoroutine.cpp - Emit LLVM Code for C++ coroutines ------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+// This contains code dealing with C++ code generation of coroutines.
+//
+//===----------------------------------------------------------------------===//
+
+#include "CGCleanup.h"
+#include "CodeGenFunction.h"
+#include "llvm/ADT/ScopeExit.h"
+#include "clang/AST/StmtCXX.h"
+#include "clang/AST/StmtVisitor.h"
+
+using namespace clang;
+using namespace CodeGen;
+
+using llvm::Value;
+using llvm::BasicBlock;
+
+namespace {
+enum class AwaitKind { Init, Normal, Yield, Final };
+static constexpr llvm::StringLiteral AwaitKindStr[] = {"init", "await", "yield",
+                                                       "final"};
+}
+
+struct clang::CodeGen::CGCoroData {
+  // What is the current await expression kind and how many
+  // await/yield expressions were encountered so far.
+  // These are used to generate pretty labels for await expressions in LLVM IR.
+  AwaitKind CurrentAwaitKind = AwaitKind::Init;
+  unsigned AwaitNum = 0;
+  unsigned YieldNum = 0;
+
+  // How many co_return statements are in the coroutine. Used to decide whether
+  // we need to add co_return; equivalent at the end of the user authored body.
+  unsigned CoreturnCount = 0;
+
+  // A branch to this block is emitted when coroutine needs to suspend.
+  llvm::BasicBlock *SuspendBB = nullptr;
+
+  // The promise type's 'unhandled_exception' handler, if it defines one.
+  Stmt *ExceptionHandler = nullptr;
+
+  // A temporary i1 alloca that stores whether 'await_resume' threw an
+  // exception. If it did, 'true' is stored in this variable, and the coroutine
+  // body must be skipped. If the promise type does not define an exception
+  // handler, this is null.
+  llvm::Value *ResumeEHVar = nullptr;
+
+  // Stores the jump destination just before the coroutine memory is freed.
+  // This is the destination that every suspend point jumps to for the cleanup
+  // branch.
+  CodeGenFunction::JumpDest CleanupJD;
+
+  // Stores the jump destination just before the final suspend. The co_return
+  // statements jumps to this point after calling return_xxx promise member.
+  CodeGenFunction::JumpDest FinalJD;
+
+  // Stores the llvm.coro.id emitted in the function so that we can supply it
+  // as the first argument to coro.begin, coro.alloc and coro.free intrinsics.
+  // Note: llvm.coro.id returns a token that cannot be directly expressed in a
+  // builtin.
+  llvm::CallInst *CoroId = nullptr;
+
+  // Stores the llvm.coro.begin emitted in the function so that we can replace
+  // all coro.frame intrinsics with direct SSA value of coro.begin that returns
+  // the address of the coroutine frame of the current coroutine.
+  llvm::CallInst *CoroBegin = nullptr;
+
+  // Stores the last emitted coro.free for the deallocate expressions, we use it
+  // to wrap dealloc code with if(auto mem = coro.free) dealloc(mem).
+  llvm::CallInst *LastCoroFree = nullptr;
+
+  // If coro.id came from the builtin, remember the expression to give better
+  // diagnostic. If CoroIdExpr is nullptr, the coro.id was created by
+  // EmitCoroutineBody.
+  CallExpr const *CoroIdExpr = nullptr;
+};
+
+// Defining these here allows to keep CGCoroData private to this file.
+clang::CodeGen::CodeGenFunction::CGCoroInfo::CGCoroInfo() {}
+CodeGenFunction::CGCoroInfo::~CGCoroInfo() {}
+
+static void createCoroData(CodeGenFunction &CGF,
+                           CodeGenFunction::CGCoroInfo &CurCoro,
+                           llvm::CallInst *CoroId,
+                           CallExpr const *CoroIdExpr = nullptr) {
+  if (CurCoro.Data) {
+    if (CurCoro.Data->CoroIdExpr)
+      CGF.CGM.Error(CoroIdExpr->getBeginLoc(),
+                    "only one __builtin_coro_id can be used in a function");
+    else if (CoroIdExpr)
+      CGF.CGM.Error(CoroIdExpr->getBeginLoc(),
+                    "__builtin_coro_id shall not be used in a C++ coroutine");
+    else
+      llvm_unreachable("EmitCoroutineBodyStatement called twice?");
+
+    return;
+  }
+
+  CurCoro.Data = std::unique_ptr<CGCoroData>(new CGCoroData);
+  CurCoro.Data->CoroId = CoroId;
+  CurCoro.Data->CoroIdExpr = CoroIdExpr;
+}
+
+// Synthesize a pretty name for a suspend point.
+static SmallString<32> buildSuspendPrefixStr(CGCoroData &Coro, AwaitKind Kind) {
+  unsigned No = 0;
+  switch (Kind) {
+  case AwaitKind::Init:
+  case AwaitKind::Final:
+    break;
+  case AwaitKind::Normal:
+    No = ++Coro.AwaitNum;
+    break;
+  case AwaitKind::Yield:
+    No = ++Coro.YieldNum;
+    break;
+  }
+  SmallString<32> Prefix(AwaitKindStr[static_cast<unsigned>(Kind)]);
+  if (No > 1) {
+    Twine(No).toVector(Prefix);
+  }
+  return Prefix;
+}
+
+static bool memberCallExpressionCanThrow(const Expr *E) {
+  if (const auto *CE = dyn_cast<CXXMemberCallExpr>(E))
+    if (const auto *Proto =
+            CE->getMethodDecl()->getType()->getAs<FunctionProtoType>())
+      if (isNoexceptExceptionSpec(Proto->getExceptionSpecType()) &&
+          Proto->canThrow() == CT_Cannot)
+        return false;
+  return true;
+}
+
+// Emit suspend expression which roughly looks like:
+//
+//   auto && x = CommonExpr();
+//   if (!x.await_ready()) {
+//      llvm_coro_save();
+//      x.await_suspend(...);     (*)
+//      llvm_coro_suspend(); (**)
+//   }
+//   x.await_resume();
+//
+// where the result of the entire expression is the result of x.await_resume()
+//
+//   (*) If x.await_suspend return type is bool, it allows to veto a suspend:
+//      if (x.await_suspend(...))
+//        llvm_coro_suspend();
+//
+//  (**) llvm_coro_suspend() encodes three possible continuations as
+//       a switch instruction:
+//
+//  %where-to = call i8 @llvm.coro.suspend(...)
+//  switch i8 %where-to, label %coro.ret [ ; jump to epilogue to suspend
+//    i8 0, label %yield.ready   ; go here when resumed
+//    i8 1, label %yield.cleanup ; go here when destroyed
+//  ]
+//
+//  See llvm's docs/Coroutines.rst for more details.
+//
+namespace {
+  struct LValueOrRValue {
+    LValue LV;
+    RValue RV;
+  };
+}
+static LValueOrRValue emitSuspendExpression(CodeGenFunction &CGF, CGCoroData &Coro,
+                                    CoroutineSuspendExpr const &S,
+                                    AwaitKind Kind, AggValueSlot aggSlot,
+                                    bool ignoreResult, bool forLValue) {
+  auto *E = S.getCommonExpr();
+
+  auto Binder =
+      CodeGenFunction::OpaqueValueMappingData::bind(CGF, S.getOpaqueValue(), E);
+  auto UnbindOnExit = llvm::make_scope_exit([&] { Binder.unbind(CGF); });
+
+  auto Prefix = buildSuspendPrefixStr(Coro, Kind);
+  BasicBlock *ReadyBlock = CGF.createBasicBlock(Prefix + Twine(".ready"));
+  BasicBlock *SuspendBlock = CGF.createBasicBlock(Prefix + Twine(".suspend"));
+  BasicBlock *CleanupBlock = CGF.createBasicBlock(Prefix + Twine(".cleanup"));
+
+  // If expression is ready, no need to suspend.
+  CGF.EmitBranchOnBoolExpr(S.getReadyExpr(), ReadyBlock, SuspendBlock, 0);
+
+  // Otherwise, emit suspend logic.
+  CGF.EmitBlock(SuspendBlock);
+
+  auto &Builder = CGF.Builder;
+  llvm::Function *CoroSave = CGF.CGM.getIntrinsic(llvm::Intrinsic::coro_save);
+  auto *NullPtr = llvm::ConstantPointerNull::get(CGF.CGM.Int8PtrTy);
+  auto *SaveCall = Builder.CreateCall(CoroSave, {NullPtr});
+
+  auto *SuspendRet = CGF.EmitScalarExpr(S.getSuspendExpr());
+  if (SuspendRet != nullptr && SuspendRet->getType()->isIntegerTy(1)) {
+    // Veto suspension if requested by bool returning await_suspend.
+    BasicBlock *RealSuspendBlock =
+        CGF.createBasicBlock(Prefix + Twine(".suspend.bool"));
+    CGF.Builder.CreateCondBr(SuspendRet, RealSuspendBlock, ReadyBlock);
+    CGF.EmitBlock(RealSuspendBlock);
+  }
+
+  // Emit the suspend point.
+  const bool IsFinalSuspend = (Kind == AwaitKind::Final);
+  llvm::Function *CoroSuspend =
+      CGF.CGM.getIntrinsic(llvm::Intrinsic::coro_suspend);
+  auto *SuspendResult = Builder.CreateCall(
+      CoroSuspend, {SaveCall, Builder.getInt1(IsFinalSuspend)});
+
+  // Create a switch capturing three possible continuations.
+  auto *Switch = Builder.CreateSwitch(SuspendResult, Coro.SuspendBB, 2);
+  Switch->addCase(Builder.getInt8(0), ReadyBlock);
+  Switch->addCase(Builder.getInt8(1), CleanupBlock);
+
+  // Emit cleanup for this suspend point.
+  CGF.EmitBlock(CleanupBlock);
+  CGF.EmitBranchThroughCleanup(Coro.CleanupJD);
+
+  // Emit await_resume expression.
+  CGF.EmitBlock(ReadyBlock);
+
+  // Exception handling requires additional IR. If the 'await_resume' function
+  // is marked as 'noexcept', we avoid generating this additional IR.
+  CXXTryStmt *TryStmt = nullptr;
+  if (Coro.ExceptionHandler && Kind == AwaitKind::Init &&
+      memberCallExpressionCanThrow(S.getResumeExpr())) {
+    Coro.ResumeEHVar =
+        CGF.CreateTempAlloca(Builder.getInt1Ty(), Prefix + Twine("resume.eh"));
+    Builder.CreateFlagStore(true, Coro.ResumeEHVar);
+
+    auto Loc = S.getResumeExpr()->getExprLoc();
+    auto *Catch = new (CGF.getContext())
+        CXXCatchStmt(Loc, /*exDecl=*/nullptr, Coro.ExceptionHandler);
+    auto *TryBody =
+        CompoundStmt::Create(CGF.getContext(), S.getResumeExpr(), Loc, Loc);
+    TryStmt = CXXTryStmt::Create(CGF.getContext(), Loc, TryBody, Catch);
+    CGF.EnterCXXTryStmt(*TryStmt);
+  }
+
+  LValueOrRValue Res;
+  if (forLValue)
+    Res.LV = CGF.EmitLValue(S.getResumeExpr());
+  else
+    Res.RV = CGF.EmitAnyExpr(S.getResumeExpr(), aggSlot, ignoreResult);
+
+  if (TryStmt) {
+    Builder.CreateFlagStore(false, Coro.ResumeEHVar);
+    CGF.ExitCXXTryStmt(*TryStmt);
+  }
+
+  return Res;
+}
+
+RValue CodeGenFunction::EmitCoawaitExpr(const CoawaitExpr &E,
+                                        AggValueSlot aggSlot,
+                                        bool ignoreResult) {
+  return emitSuspendExpression(*this, *CurCoro.Data, E,
+                               CurCoro.Data->CurrentAwaitKind, aggSlot,
+                               ignoreResult, /*forLValue*/false).RV;
+}
+RValue CodeGenFunction::EmitCoyieldExpr(const CoyieldExpr &E,
+                                        AggValueSlot aggSlot,
+                                        bool ignoreResult) {
+  return emitSuspendExpression(*this, *CurCoro.Data, E, AwaitKind::Yield,
+                               aggSlot, ignoreResult, /*forLValue*/false).RV;
+}
+
+void CodeGenFunction::EmitCoreturnStmt(CoreturnStmt const &S) {
+  ++CurCoro.Data->CoreturnCount;
+  const Expr *RV = S.getOperand();
+  if (RV && RV->getType()->isVoidType()) {
+    // Make sure to evaluate the expression of a co_return with a void
+    // expression for side effects.
+    RunCleanupsScope cleanupScope(*this);
+    EmitIgnoredExpr(RV);
+  }
+  EmitStmt(S.getPromiseCall());
+  EmitBranchThroughCleanup(CurCoro.Data->FinalJD);
+}
+
+
+#ifndef NDEBUG
+static QualType getCoroutineSuspendExprReturnType(const ASTContext &Ctx,
+  const CoroutineSuspendExpr *E) {
+  const auto *RE = E->getResumeExpr();
+  // Is it possible for RE to be a CXXBindTemporaryExpr wrapping
+  // a MemberCallExpr?
+  assert(isa<CallExpr>(RE) && "unexpected suspend expression type");
+  return cast<CallExpr>(RE)->getCallReturnType(Ctx);
+}
+#endif
+
+LValue
+CodeGenFunction::EmitCoawaitLValue(const CoawaitExpr *E) {
+  assert(getCoroutineSuspendExprReturnType(getContext(), E)->isReferenceType() &&
+         "Can't have a scalar return unless the return type is a "
+         "reference type!");
+  return emitSuspendExpression(*this, *CurCoro.Data, *E,
+                               CurCoro.Data->CurrentAwaitKind, AggValueSlot::ignored(),
+                               /*ignoreResult*/false, /*forLValue*/true).LV;
+}
+
+LValue
+CodeGenFunction::EmitCoyieldLValue(const CoyieldExpr *E) {
+  assert(getCoroutineSuspendExprReturnType(getContext(), E)->isReferenceType() &&
+         "Can't have a scalar return unless the return type is a "
+         "reference type!");
+  return emitSuspendExpression(*this, *CurCoro.Data, *E,
+                               AwaitKind::Yield, AggValueSlot::ignored(),
+                               /*ignoreResult*/false, /*forLValue*/true).LV;
+}
+
+// Hunts for the parameter reference in the parameter copy/move declaration.
+namespace {
+struct GetParamRef : public StmtVisitor<GetParamRef> {
+public:
+  DeclRefExpr *Expr = nullptr;
+  GetParamRef() {}
+  void VisitDeclRefExpr(DeclRefExpr *E) {
+    assert(Expr == nullptr && "multilple declref in param move");
+    Expr = E;
+  }
+  void VisitStmt(Stmt *S) {
+    for (auto *C : S->children()) {
+      if (C)
+        Visit(C);
+    }
+  }
+};
+}
+
+// This class replaces references to parameters to their copies by changing
+// the addresses in CGF.LocalDeclMap and restoring back the original values in
+// its destructor.
+
+namespace {
+  struct ParamReferenceReplacerRAII {
+    CodeGenFunction::DeclMapTy SavedLocals;
+    CodeGenFunction::DeclMapTy& LocalDeclMap;
+
+    ParamReferenceReplacerRAII(CodeGenFunction::DeclMapTy &LocalDeclMap)
+        : LocalDeclMap(LocalDeclMap) {}
+
+    void addCopy(DeclStmt const *PM) {
+      // Figure out what param it refers to.
+
+      assert(PM->isSingleDecl());
+      VarDecl const*VD = static_cast<VarDecl const*>(PM->getSingleDecl());
+      Expr const *InitExpr = VD->getInit();
+      GetParamRef Visitor;
+      Visitor.Visit(const_cast<Expr*>(InitExpr));
+      assert(Visitor.Expr);
+      DeclRefExpr *DREOrig = Visitor.Expr;
+      auto *PD = DREOrig->getDecl();
+
+      auto it = LocalDeclMap.find(PD);
+      assert(it != LocalDeclMap.end() && "parameter is not found");
+      SavedLocals.insert({ PD, it->second });
+
+      auto copyIt = LocalDeclMap.find(VD);
+      assert(copyIt != LocalDeclMap.end() && "parameter copy is not found");
+      it->second = copyIt->getSecond();
+    }
+
+    ~ParamReferenceReplacerRAII() {
+      for (auto&& SavedLocal : SavedLocals) {
+        LocalDeclMap.insert({SavedLocal.first, SavedLocal.second});
+      }
+    }
+  };
+}
+
+// For WinEH exception representation backend needs to know what funclet coro.end
+// belongs to. That information is passed in a funclet bundle.
+static SmallVector<llvm::OperandBundleDef, 1>
+getBundlesForCoroEnd(CodeGenFunction &CGF) {
+  SmallVector<llvm::OperandBundleDef, 1> BundleList;
+
+  if (llvm::Instruction *EHPad = CGF.CurrentFuncletPad)
+    BundleList.emplace_back("funclet", EHPad);
+
+  return BundleList;
+}
+
+namespace {
+// We will insert coro.end to cut any of the destructors for objects that
+// do not need to be destroyed once the coroutine is resumed.
+// See llvm/docs/Coroutines.rst for more details about coro.end.
+struct CallCoroEnd final : public EHScopeStack::Cleanup {
+  void Emit(CodeGenFunction &CGF, Flags flags) override {
+    auto &CGM = CGF.CGM;
+    auto *NullPtr = llvm::ConstantPointerNull::get(CGF.Int8PtrTy);
+    llvm::Function *CoroEndFn = CGM.getIntrinsic(llvm::Intrinsic::coro_end);
+    // See if we have a funclet bundle to associate coro.end with. (WinEH)
+    auto Bundles = getBundlesForCoroEnd(CGF);
+    auto *CoroEnd = CGF.Builder.CreateCall(
+        CoroEndFn, {NullPtr, CGF.Builder.getTrue()}, Bundles);
+    if (Bundles.empty()) {
+      // Otherwise, (landingpad model), create a conditional branch that leads
+      // either to a cleanup block or a block with EH resume instruction.
+      auto *ResumeBB = CGF.getEHResumeBlock(/*isCleanup=*/true);
+      auto *CleanupContBB = CGF.createBasicBlock("cleanup.cont");
+      CGF.Builder.CreateCondBr(CoroEnd, ResumeBB, CleanupContBB);
+      CGF.EmitBlock(CleanupContBB);
+    }
+  }
+};
+}
+
+namespace {
+// Make sure to call coro.delete on scope exit.
+struct CallCoroDelete final : public EHScopeStack::Cleanup {
+  Stmt *Deallocate;
+
+  // Emit "if (coro.free(CoroId, CoroBegin)) Deallocate;"
+
+  // Note: That deallocation will be emitted twice: once for a normal exit and
+  // once for exceptional exit. This usage is safe because Deallocate does not
+  // contain any declarations. The SubStmtBuilder::makeNewAndDeleteExpr()
+  // builds a single call to a deallocation function which is safe to emit
+  // multiple times.
+  void Emit(CodeGenFunction &CGF, Flags) override {
+    // Remember the current point, as we are going to emit deallocation code
+    // first to get to coro.free instruction that is an argument to a delete
+    // call.
+    BasicBlock *SaveInsertBlock = CGF.Builder.GetInsertBlock();
+
+    auto *FreeBB = CGF.createBasicBlock("coro.free");
+    CGF.EmitBlock(FreeBB);
+    CGF.EmitStmt(Deallocate);
+
+    auto *AfterFreeBB = CGF.createBasicBlock("after.coro.free");
+    CGF.EmitBlock(AfterFreeBB);
+
+    // We should have captured coro.free from the emission of deallocate.
+    auto *CoroFree = CGF.CurCoro.Data->LastCoroFree;
+    if (!CoroFree) {
+      CGF.CGM.Error(Deallocate->getBeginLoc(),
+                    "Deallocation expressoin does not refer to coro.free");
+      return;
+    }
+
+    // Get back to the block we were originally and move coro.free there.
+    auto *InsertPt = SaveInsertBlock->getTerminator();
+    CoroFree->moveBefore(InsertPt);
+    CGF.Builder.SetInsertPoint(InsertPt);
+
+    // Add if (auto *mem = coro.free) Deallocate;
+    auto *NullPtr = llvm::ConstantPointerNull::get(CGF.Int8PtrTy);
+    auto *Cond = CGF.Builder.CreateICmpNE(CoroFree, NullPtr);
+    CGF.Builder.CreateCondBr(Cond, FreeBB, AfterFreeBB);
+
+    // No longer need old terminator.
+    InsertPt->eraseFromParent();
+    CGF.Builder.SetInsertPoint(AfterFreeBB);
+  }
+  explicit CallCoroDelete(Stmt *DeallocStmt) : Deallocate(DeallocStmt) {}
+};
+}
+
+namespace {
+struct GetReturnObjectManager {
+  CodeGenFunction &CGF;
+  CGBuilderTy &Builder;
+  const CoroutineBodyStmt &S;
+
+  Address GroActiveFlag;
+  CodeGenFunction::AutoVarEmission GroEmission;
+
+  GetReturnObjectManager(CodeGenFunction &CGF, const CoroutineBodyStmt &S)
+      : CGF(CGF), Builder(CGF.Builder), S(S), GroActiveFlag(Address::invalid()),
+        GroEmission(CodeGenFunction::AutoVarEmission::invalid()) {}
+
+  // The gro variable has to outlive coroutine frame and coroutine promise, but,
+  // it can only be initialized after coroutine promise was created, thus, we
+  // split its emission in two parts. EmitGroAlloca emits an alloca and sets up
+  // cleanups. Later when coroutine promise is available we initialize the gro
+  // and sets the flag that the cleanup is now active.
+
+  void EmitGroAlloca() {
+    auto *GroDeclStmt = dyn_cast<DeclStmt>(S.getResultDecl());
+    if (!GroDeclStmt) {
+      // If get_return_object returns void, no need to do an alloca.
+      return;
+    }
+
+    auto *GroVarDecl = cast<VarDecl>(GroDeclStmt->getSingleDecl());
+
+    // Set GRO flag that it is not initialized yet
+    GroActiveFlag =
+      CGF.CreateTempAlloca(Builder.getInt1Ty(), CharUnits::One(), "gro.active");
+    Builder.CreateStore(Builder.getFalse(), GroActiveFlag);
+
+    GroEmission = CGF.EmitAutoVarAlloca(*GroVarDecl);
+
+    // Remember the top of EHStack before emitting the cleanup.
+    auto old_top = CGF.EHStack.stable_begin();
+    CGF.EmitAutoVarCleanups(GroEmission);
+    auto top = CGF.EHStack.stable_begin();
+
+    // Make the cleanup conditional on gro.active
+    for (auto b = CGF.EHStack.find(top), e = CGF.EHStack.find(old_top);
+      b != e; b++) {
+      if (auto *Cleanup = dyn_cast<EHCleanupScope>(&*b)) {
+        assert(!Cleanup->hasActiveFlag() && "cleanup already has active flag?");
+        Cleanup->setActiveFlag(GroActiveFlag);
+        Cleanup->setTestFlagInEHCleanup();
+        Cleanup->setTestFlagInNormalCleanup();
+      }
+    }
+  }
+
+  void EmitGroInit() {
+    if (!GroActiveFlag.isValid()) {
+      // No Gro variable was allocated. Simply emit the call to
+      // get_return_object.
+      CGF.EmitStmt(S.getResultDecl());
+      return;
+    }
+
+    CGF.EmitAutoVarInit(GroEmission);
+    Builder.CreateStore(Builder.getTrue(), GroActiveFlag);
+  }
+};
+}
+
+static void emitBodyAndFallthrough(CodeGenFunction &CGF,
+                                   const CoroutineBodyStmt &S, Stmt *Body) {
+  CGF.EmitStmt(Body);
+  const bool CanFallthrough = CGF.Builder.GetInsertBlock();
+  if (CanFallthrough)
+    if (Stmt *OnFallthrough = S.getFallthroughHandler())
+      CGF.EmitStmt(OnFallthrough);
+}
+
+void CodeGenFunction::EmitCoroutineBody(const CoroutineBodyStmt &S) {
+  auto *NullPtr = llvm::ConstantPointerNull::get(Builder.getInt8PtrTy());
+  auto &TI = CGM.getContext().getTargetInfo();
+  unsigned NewAlign = TI.getNewAlign() / TI.getCharWidth();
+
+  auto *EntryBB = Builder.GetInsertBlock();
+  auto *AllocBB = createBasicBlock("coro.alloc");
+  auto *InitBB = createBasicBlock("coro.init");
+  auto *FinalBB = createBasicBlock("coro.final");
+  auto *RetBB = createBasicBlock("coro.ret");
+
+  auto *CoroId = Builder.CreateCall(
+      CGM.getIntrinsic(llvm::Intrinsic::coro_id),
+      {Builder.getInt32(NewAlign), NullPtr, NullPtr, NullPtr});
+  createCoroData(*this, CurCoro, CoroId);
+  CurCoro.Data->SuspendBB = RetBB;
+
+  // Backend is allowed to elide memory allocations, to help it, emit
+  // auto mem = coro.alloc() ? 0 : ... allocation code ...;
+  auto *CoroAlloc = Builder.CreateCall(
+      CGM.getIntrinsic(llvm::Intrinsic::coro_alloc), {CoroId});
+
+  Builder.CreateCondBr(CoroAlloc, AllocBB, InitBB);
+
+  EmitBlock(AllocBB);
+  auto *AllocateCall = EmitScalarExpr(S.getAllocate());
+  auto *AllocOrInvokeContBB = Builder.GetInsertBlock();
+
+  // Handle allocation failure if 'ReturnStmtOnAllocFailure' was provided.
+  if (auto *RetOnAllocFailure = S.getReturnStmtOnAllocFailure()) {
+    auto *RetOnFailureBB = createBasicBlock("coro.ret.on.failure");
+
+    // See if allocation was successful.
+    auto *NullPtr = llvm::ConstantPointerNull::get(Int8PtrTy);
+    auto *Cond = Builder.CreateICmpNE(AllocateCall, NullPtr);
+    Builder.CreateCondBr(Cond, InitBB, RetOnFailureBB);
+
+    // If not, return OnAllocFailure object.
+    EmitBlock(RetOnFailureBB);
+    EmitStmt(RetOnAllocFailure);
+  }
+  else {
+    Builder.CreateBr(InitBB);
+  }
+
+  EmitBlock(InitBB);
+
+  // Pass the result of the allocation to coro.begin.
+  auto *Phi = Builder.CreatePHI(VoidPtrTy, 2);
+  Phi->addIncoming(NullPtr, EntryBB);
+  Phi->addIncoming(AllocateCall, AllocOrInvokeContBB);
+  auto *CoroBegin = Builder.CreateCall(
+      CGM.getIntrinsic(llvm::Intrinsic::coro_begin), {CoroId, Phi});
+  CurCoro.Data->CoroBegin = CoroBegin;
+
+  GetReturnObjectManager GroManager(*this, S);
+  GroManager.EmitGroAlloca();
+
+  CurCoro.Data->CleanupJD = getJumpDestInCurrentScope(RetBB);
+  {
+    ParamReferenceReplacerRAII ParamReplacer(LocalDeclMap);
+    CodeGenFunction::RunCleanupsScope ResumeScope(*this);
+    EHStack.pushCleanup<CallCoroDelete>(NormalAndEHCleanup, S.getDeallocate());
+
+    // Create parameter copies. We do it before creating a promise, since an
+    // evolution of coroutine TS may allow promise constructor to observe
+    // parameter copies.
+    for (auto *PM : S.getParamMoves()) {
+      EmitStmt(PM);
+      ParamReplacer.addCopy(cast<DeclStmt>(PM));
+      // TODO: if(CoroParam(...)) need to surround ctor and dtor
+      // for the copy, so that llvm can elide it if the copy is
+      // not needed.
+    }
+
+    EmitStmt(S.getPromiseDeclStmt());
+
+    Address PromiseAddr = GetAddrOfLocalVar(S.getPromiseDecl());
+    auto *PromiseAddrVoidPtr =
+        new llvm::BitCastInst(PromiseAddr.getPointer(), VoidPtrTy, "", CoroId);
+    // Update CoroId to refer to the promise. We could not do it earlier because
+    // promise local variable was not emitted yet.
+    CoroId->setArgOperand(1, PromiseAddrVoidPtr);
+
+    // Now we have the promise, initialize the GRO
+    GroManager.EmitGroInit();
+
+    EHStack.pushCleanup<CallCoroEnd>(EHCleanup);
+
+    CurCoro.Data->CurrentAwaitKind = AwaitKind::Init;
+    CurCoro.Data->ExceptionHandler = S.getExceptionHandler();
+    EmitStmt(S.getInitSuspendStmt());
+    CurCoro.Data->FinalJD = getJumpDestInCurrentScope(FinalBB);
+
+    CurCoro.Data->CurrentAwaitKind = AwaitKind::Normal;
+
+    if (CurCoro.Data->ExceptionHandler) {
+      // If we generated IR to record whether an exception was thrown from
+      // 'await_resume', then use that IR to determine whether the coroutine
+      // body should be skipped.
+      // If we didn't generate the IR (perhaps because 'await_resume' was marked
+      // as 'noexcept'), then we skip this check.
+      BasicBlock *ContBB = nullptr;
+      if (CurCoro.Data->ResumeEHVar) {
+        BasicBlock *BodyBB = createBasicBlock("coro.resumed.body");
+        ContBB = createBasicBlock("coro.resumed.cont");
+        Value *SkipBody = Builder.CreateFlagLoad(CurCoro.Data->ResumeEHVar,
+                                                 "coro.resumed.eh");
+        Builder.CreateCondBr(SkipBody, ContBB, BodyBB);
+        EmitBlock(BodyBB);
+      }
+
+      auto Loc = S.getBeginLoc();
+      CXXCatchStmt Catch(Loc, /*exDecl=*/nullptr,
+                         CurCoro.Data->ExceptionHandler);
+      auto *TryStmt =
+          CXXTryStmt::Create(getContext(), Loc, S.getBody(), &Catch);
+
+      EnterCXXTryStmt(*TryStmt);
+      emitBodyAndFallthrough(*this, S, TryStmt->getTryBlock());
+      ExitCXXTryStmt(*TryStmt);
+
+      if (ContBB)
+        EmitBlock(ContBB);
+    }
+    else {
+      emitBodyAndFallthrough(*this, S, S.getBody());
+    }
+
+    // See if we need to generate final suspend.
+    const bool CanFallthrough = Builder.GetInsertBlock();
+    const bool HasCoreturns = CurCoro.Data->CoreturnCount > 0;
+    if (CanFallthrough || HasCoreturns) {
+      EmitBlock(FinalBB);
+      CurCoro.Data->CurrentAwaitKind = AwaitKind::Final;
+      EmitStmt(S.getFinalSuspendStmt());
+    } else {
+      // We don't need FinalBB. Emit it to make sure the block is deleted.
+      EmitBlock(FinalBB, /*IsFinished=*/true);
+    }
+  }
+
+  EmitBlock(RetBB);
+  // Emit coro.end before getReturnStmt (and parameter destructors), since
+  // resume and destroy parts of the coroutine should not include them.
+  llvm::Function *CoroEnd = CGM.getIntrinsic(llvm::Intrinsic::coro_end);
+  Builder.CreateCall(CoroEnd, {NullPtr, Builder.getFalse()});
+
+  if (Stmt *Ret = S.getReturnStmt())
+    EmitStmt(Ret);
+}
+
+// Emit coroutine intrinsic and patch up arguments of the token type.
+RValue CodeGenFunction::EmitCoroutineIntrinsic(const CallExpr *E,
+                                               unsigned int IID) {
+  SmallVector<llvm::Value *, 8> Args;
+  switch (IID) {
+  default:
+    break;
+  // The coro.frame builtin is replaced with an SSA value of the coro.begin
+  // intrinsic.
+  case llvm::Intrinsic::coro_frame: {
+    if (CurCoro.Data && CurCoro.Data->CoroBegin) {
+      return RValue::get(CurCoro.Data->CoroBegin);
+    }
+    CGM.Error(E->getBeginLoc(), "this builtin expect that __builtin_coro_begin "
+                                "has been used earlier in this function");
+    auto NullPtr = llvm::ConstantPointerNull::get(Builder.getInt8PtrTy());
+    return RValue::get(NullPtr);
+  }
+  // The following three intrinsics take a token parameter referring to a token
+  // returned by earlier call to @llvm.coro.id. Since we cannot represent it in
+  // builtins, we patch it up here.
+  case llvm::Intrinsic::coro_alloc:
+  case llvm::Intrinsic::coro_begin:
+  case llvm::Intrinsic::coro_free: {
+    if (CurCoro.Data && CurCoro.Data->CoroId) {
+      Args.push_back(CurCoro.Data->CoroId);
+      break;
+    }
+    CGM.Error(E->getBeginLoc(), "this builtin expect that __builtin_coro_id has"
+                                " been used earlier in this function");
+    // Fallthrough to the next case to add TokenNone as the first argument.
+    LLVM_FALLTHROUGH;
+  }
+  // @llvm.coro.suspend takes a token parameter. Add token 'none' as the first
+  // argument.
+  case llvm::Intrinsic::coro_suspend:
+    Args.push_back(llvm::ConstantTokenNone::get(getLLVMContext()));
+    break;
+  }
+  for (const Expr *Arg : E->arguments())
+    Args.push_back(EmitScalarExpr(Arg));
+
+  llvm::Function *F = CGM.getIntrinsic(IID);
+  llvm::CallInst *Call = Builder.CreateCall(F, Args);
+
+  // Note: The following code is to enable to emit coro.id and coro.begin by
+  // hand to experiment with coroutines in C.
+  // If we see @llvm.coro.id remember it in the CoroData. We will update
+  // coro.alloc, coro.begin and coro.free intrinsics to refer to it.
+  if (IID == llvm::Intrinsic::coro_id) {
+    createCoroData(*this, CurCoro, Call, E);
+  }
+  else if (IID == llvm::Intrinsic::coro_begin) {
+    if (CurCoro.Data)
+      CurCoro.Data->CoroBegin = Call;
+  }
+  else if (IID == llvm::Intrinsic::coro_free) {
+    // Remember the last coro_free as we need it to build the conditional
+    // deletion of the coroutine frame.
+    if (CurCoro.Data)
+      CurCoro.Data->LastCoroFree = Call;
+  }
+  return RValue::get(Call);
+}