Vendor import of clang trunk r304149:vendor/clang/clang-trunk-r304149

https://llvm.org/svn/llvm-project/cfe/trunk@304149

1 files changed, 298 insertions, 15 deletions

diff --git a/lib/CodeGen/CGCoroutine.cpp b/lib/CodeGen/CGCoroutine.cpp
index 0ef680ef6609..c468c1bb4b5f 100644
--- a/lib/CodeGen/CGCoroutine.cpp
+++ b/lib/CodeGen/CGCoroutine.cpp
@@ -11,9 +11,11 @@
 //
 //===----------------------------------------------------------------------===//
 
+#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;
@@ -57,6 +59,15 @@ struct clang::CodeGen::CGCoroData {
   // 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.
@@ -142,6 +153,20 @@ static RValue emitSuspendExpression(CodeGenFunction &CGF, CGCoroData &Coro,
                                     AwaitKind Kind, AggValueSlot aggSlot,
                                     bool ignoreResult) {
   auto *E = S.getCommonExpr();
+
+  // FIXME: rsmith 5/22/2017. Does it still make sense for us to have a 
+  // UO_Coawait at all? As I recall, the only purpose it ever had was to
+  // represent a dependent co_await expression that couldn't yet be resolved to
+  // a CoawaitExpr. But now we have (and need!) a separate DependentCoawaitExpr
+  // node to store unqualified lookup results, it seems that the UnaryOperator
+  // portion of the representation serves no purpose (and as seen in this patch,
+  // it's getting in the way). Can we remove it?
+
+  // Skip passthrough operator co_await (present when awaiting on an LValue).
+  if (auto *UO = dyn_cast<UnaryOperator>(E))
+    if (UO->getOpcode() == UO_Coawait)
+      E = UO->getSubExpr();
+
   auto Binder =
       CodeGenFunction::OpaqueValueMappingData::bind(CGF, S.getOpaqueValue(), E);
   auto UnbindOnExit = llvm::make_scope_exit([&] { Binder.unbind(CGF); });
@@ -215,7 +240,67 @@ void CodeGenFunction::EmitCoreturnStmt(CoreturnStmt const &S) {
   EmitBranchThroughCleanup(CurCoro.Data->FinalJD);
 }
 
-// For WinEH exception representation backend need to know what funclet coro.end
+// 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);
+      auto *DREOrig = cast<DeclRefExpr>(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) {
@@ -257,24 +342,135 @@ namespace {
 struct CallCoroDelete final : public EHScopeStack::Cleanup {
   Stmt *Deallocate;
 
-  // TODO: Wrap deallocate in if(coro.free(...)) 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 {
-    // 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.
+    // 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->getLocStart(),
+                    "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");
 
@@ -284,12 +480,20 @@ void CodeGenFunction::EmitCoroutineBody(const CoroutineBodyStmt &S) {
   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");
-    auto *InitBB = createBasicBlock("coro.init");
 
     // See if allocation was successful.
     auto *NullPtr = llvm::ConstantPointerNull::get(Int8PtrTy);
@@ -299,40 +503,96 @@ void CodeGenFunction::EmitCoroutineBody(const CoroutineBodyStmt &S) {
     // If not, return OnAllocFailure object.
     EmitBlock(RetOnFailureBB);
     EmitStmt(RetOnAllocFailure);
-
-    EmitBlock(InitBB);
   }
+  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;
+    EmitStmt(S.getInitSuspendStmt());
     CurCoro.Data->FinalJD = getJumpDestInCurrentScope(FinalBB);
 
-    // FIXME: Emit initial suspend and more before the body.
-
     CurCoro.Data->CurrentAwaitKind = AwaitKind::Normal;
-    EmitStmt(S.getBody());
+
+    if (auto *OnException = S.getExceptionHandler()) {
+      auto Loc = S.getLocStart();
+      CXXCatchStmt Catch(Loc, /*exDecl=*/nullptr, OnException);
+      auto *TryStmt = CXXTryStmt::Create(getContext(), Loc, S.getBody(), &Catch);
+
+      EnterCXXTryStmt(*TryStmt);
+      emitBodyAndFallthrough(*this, S, TryStmt->getTryBlock());
+      ExitCXXTryStmt(*TryStmt);
+    }
+    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);
-      // FIXME: Emit final suspend.
+      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()});
 
-  // FIXME: Emit return for the coroutine return object.
+  if (Stmt *Ret = S.getReturnStmt())
+    EmitStmt(Ret);
 }
 
 // Emit coroutine intrinsic and patch up arguments of the token type.
@@ -342,6 +602,17 @@ RValue CodeGenFunction::EmitCoroutineIntrinsic(const CallExpr *E,
   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->getLocStart(), "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.
@@ -368,10 +639,22 @@ RValue CodeGenFunction::EmitCoroutineIntrinsic(const CallExpr *E,
   llvm::Value *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);
 }