[coroutines] Build a CoroutineBodyStmt when finishing parsing a coroutine, and form the initial_suspend, final_suspend, and get_return_object calls.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@253946 91177308-0d34-0410-b5e6-96231b3b80d8

include/clang/AST/StmtCXX.h

@@ -292,14 +292,33 @@ public:
 /// body and holds the additional semantic context required to set up and tear
 /// down the coroutine frame.
 class CoroutineBodyStmt : public Stmt {
-  enum SubStmt { Body, Count };
-  Stmt *SubStmts[SubStmt::Count];
+  enum SubStmt {
+    Body,          ///< The body of the coroutine.
+    Promise,       ///< The promise statement.
+    InitSuspend,   ///< The initial suspend statement, run before the body.
+    FinalSuspend,  ///< The final suspend statement, run after the body.
+    OnException,   ///< Handler for exceptions thrown in the body.
+    OnFallthrough, ///< Handler for control flow falling off the body.
+    ReturnValue,   ///< Return value for thunk function.
+    FirstParamMove ///< First offset for move construction of parameter copies.
+  };
+  Stmt *SubStmts[SubStmt::FirstParamMove];
 
   friend class ASTStmtReader;
 public:
-  CoroutineBodyStmt(Stmt *Body)
+  CoroutineBodyStmt(Stmt *Body, Stmt *Promise, Stmt *InitSuspend,
+                    Stmt *FinalSuspend, Stmt *OnException, Stmt *OnFallthrough,
+                    Expr *ReturnValue, ArrayRef<Expr *> ParamMoves)
       : Stmt(CoroutineBodyStmtClass) {
     SubStmts[CoroutineBodyStmt::Body] = Body;
+    SubStmts[CoroutineBodyStmt::Promise] = Promise;
+    SubStmts[CoroutineBodyStmt::InitSuspend] = InitSuspend;
+    SubStmts[CoroutineBodyStmt::FinalSuspend] = FinalSuspend;
+    SubStmts[CoroutineBodyStmt::OnException] = OnException;
+    SubStmts[CoroutineBodyStmt::OnFallthrough] = OnFallthrough;
+    SubStmts[CoroutineBodyStmt::ReturnValue] = ReturnValue;
+    // FIXME: Tail-allocate space for parameter move expressions and store them.
+    assert(ParamMoves.empty() && "not implemented yet");
   }
 
   /// \brief Retrieve the body of the coroutine as written. This will be either
@@ -308,6 +327,23 @@ public:
     return SubStmts[SubStmt::Body];
   }
 
+  Stmt *getPromiseDeclStmt() const { return SubStmts[SubStmt::Promise]; }
+  VarDecl *getPromiseDecl() const {
+    return cast<VarDecl>(cast<DeclStmt>(getPromiseDeclStmt())->getSingleDecl());
+  }
+
+  Stmt *getInitSuspendStmt() const { return SubStmts[SubStmt::InitSuspend]; }
+  Stmt *getFinalSuspendStmt() const { return SubStmts[SubStmt::FinalSuspend]; }
+
+  Stmt *getExceptionHandler() const { return SubStmts[SubStmt::OnException]; }
+  Stmt *getFallthroughHandler() const {
+    return SubStmts[SubStmt::OnFallthrough];
+  }
+
+  Expr *getReturnValueInit() const {
+    return cast<Expr>(SubStmts[SubStmt::ReturnValue]);
+  }
+
   SourceLocation getLocStart() const LLVM_READONLY {
     return getBody()->getLocStart();
   }
@@ -316,7 +352,7 @@ public:
   }
 
   child_range children() {
-    return child_range(SubStmts, SubStmts + SubStmt::Count);
+    return child_range(SubStmts, SubStmts + SubStmt::FirstParamMove);
   }
 
   static bool classof(const Stmt *T) {

include/clang/Sema/Sema.h

@@ -7738,7 +7738,7 @@ public:
   ExprResult BuildCoyieldExpr(SourceLocation KwLoc, Expr *E);
   StmtResult BuildCoreturnStmt(SourceLocation KwLoc, Expr *E);
 
-  void CheckCompletedCoroutineBody(FunctionDecl *FD, Stmt *Body);
+  void CheckCompletedCoroutineBody(FunctionDecl *FD, Stmt *&Body);
 
   //===--------------------------------------------------------------------===//
   // OpenMP directives and clauses.

lib/Sema/SemaCoroutine.cpp

@@ -16,6 +16,7 @@
 #include "clang/AST/ExprCXX.h"
 #include "clang/AST/StmtCXX.h"
 #include "clang/Lex/Preprocessor.h"
+#include "clang/Sema/Initialization.h"
 #include "clang/Sema/Overload.h"
 using namespace clang;
 using namespace sema;
@@ -108,6 +109,7 @@ checkCoroutineContext(Sema &S, SourceLocation Loc, StringRef Keyword) {
   }
 
   // Any other usage must be within a function.
+  // FIXME: Reject a coroutine with a deduced return type.
   auto *FD = dyn_cast<FunctionDecl>(S.CurContext);
   if (!FD) {
     S.Diag(Loc, isa<ObjCMethodDecl>(S.CurContext)
@@ -338,7 +340,7 @@ StmtResult Sema::BuildCoreturnStmt(SourceLocation Loc, Expr *E) {
   }
 
   // FIXME: If the operand is a reference to a variable that's about to go out
-  // ot scope, we should treat the operand as an xvalue for this overload
+  // of scope, we should treat the operand as an xvalue for this overload
   // resolution.
   ExprResult PC;
   if (E && !E->getType()->isVoidType()) {
@@ -357,7 +359,7 @@ StmtResult Sema::BuildCoreturnStmt(SourceLocation Loc, Expr *E) {
   return Res;
 }
 
-void Sema::CheckCompletedCoroutineBody(FunctionDecl *FD, Stmt *Body) {
+void Sema::CheckCompletedCoroutineBody(FunctionDecl *FD, Stmt *&Body) {
   FunctionScopeInfo *Fn = getCurFunction();
   assert(Fn && !Fn->CoroutineStmts.empty() && "not a coroutine");
 
@@ -382,6 +384,65 @@ void Sema::CheckCompletedCoroutineBody(FunctionDecl *FD, Stmt *Body) {
     Diag(Fn->CoroutineStmts.front()->getLocStart(),
          diag::ext_coroutine_without_co_await_co_yield);
 
-  // FIXME: Perform analysis of initial and final suspend,
-  // and set_exception call.
+  SourceLocation Loc = FD->getLocation();
+
+  // Form a declaration statement for the promise declaration, so that AST
+  // visitors can more easily find it.
+  StmtResult PromiseStmt =
+      ActOnDeclStmt(ConvertDeclToDeclGroup(Fn->CoroutinePromise), Loc, Loc);
+  if (PromiseStmt.isInvalid())
+    return FD->setInvalidDecl();
+
+  // Form and check implicit 'co_await p.initial_suspend();' statement.
+  ExprResult InitialSuspend =
+      buildPromiseCall(*this, Fn, Loc, "initial_suspend", None);
+  // FIXME: Support operator co_await here.
+  if (!InitialSuspend.isInvalid())
+    InitialSuspend = BuildCoawaitExpr(Loc, InitialSuspend.get());
+  InitialSuspend = ActOnFinishFullExpr(InitialSuspend.get());
+  if (InitialSuspend.isInvalid())
+    return FD->setInvalidDecl();
+
+  // Form and check implicit 'co_await p.final_suspend();' statement.
+  ExprResult FinalSuspend =
+      buildPromiseCall(*this, Fn, Loc, "final_suspend", None);
+  // FIXME: Support operator co_await here.
+  if (!FinalSuspend.isInvalid())
+    FinalSuspend = BuildCoawaitExpr(Loc, FinalSuspend.get());
+  FinalSuspend = ActOnFinishFullExpr(FinalSuspend.get());
+  if (FinalSuspend.isInvalid())
+    return FD->setInvalidDecl();
+
+  // FIXME: Perform analysis of set_exception call.
+
+  // FIXME: Try to form 'p.return_void();' expression statement to handle
+  // control flowing off the end of the coroutine.
+
+  // Build implicit 'p.get_return_object()' expression and form initialization
+  // of return type from it.
+  ExprResult ReturnObject =
+    buildPromiseCall(*this, Fn, Loc, "get_return_object", None);
+  if (ReturnObject.isInvalid())
+    return FD->setInvalidDecl();
+  QualType RetType = FD->getReturnType();
+  if (!RetType->isDependentType()) {
+    InitializedEntity Entity =
+        InitializedEntity::InitializeResult(Loc, RetType, false);
+    ReturnObject = PerformMoveOrCopyInitialization(Entity, nullptr, RetType,
+                                                   ReturnObject.get());
+    if (ReturnObject.isInvalid())
+      return FD->setInvalidDecl();
+  }
+  ReturnObject = ActOnFinishFullExpr(ReturnObject.get(), Loc);
+  if (ReturnObject.isInvalid())
+    return FD->setInvalidDecl();
+
+  // FIXME: Perform move-initialization of parameters into frame-local copies.
+  SmallVector<Expr*, 16> ParamMoves;
+
+  // Build body for the coroutine wrapper statement.
+  Body = new (Context) CoroutineBodyStmt(
+      Body, PromiseStmt.get(), InitialSuspend.get(), FinalSuspend.get(),
+      /*SetException*/nullptr, /*Fallthrough*/nullptr,
+      ReturnObject.get(), ParamMoves);
 }

test/SemaCXX/coroutines.cpp

@@ -6,6 +6,18 @@ struct awaitable {
   void await_resume();
 } a;
 
+struct suspend_always {
+  bool await_ready() { return false; }
+  void await_suspend() {}
+  void await_resume() {}
+};
+
+struct suspend_never {
+  bool await_ready() { return true; }
+  void await_suspend() {}
+  void await_resume() {}
+};
+
 void no_coroutine_traits() {
   co_await a; // expected-error {{need to include <coroutine>}}
 }
@@ -14,6 +26,12 @@ namespace std {
   template<typename ...T> struct coroutine_traits; // expected-note {{declared here}}
 };
 
+template<typename Promise> struct coro {};
+template<typename Promise, typename... Ps>
+struct std::coroutine_traits<coro<Promise>, Ps...> {
+  using promise_type = Promise;
+};
+
 void no_specialization() {
   co_await a; // expected-error {{implicit instantiation of undefined template 'std::coroutine_traits<void>'}}
 }
@@ -36,11 +54,13 @@ double bad_promise_type_2(int) {
   co_yield 0; // expected-error {{no member named 'yield_value' in 'std::coroutine_traits<double, int>::promise_type'}}
 }
 
-struct promise; // expected-note {{forward declaration}}
+struct promise; // expected-note 2{{forward declaration}}
 template<typename ...T> struct std::coroutine_traits<void, T...> { using promise_type = promise; };
 
   // FIXME: This diagnostic is terrible.
 void undefined_promise() { // expected-error {{variable has incomplete type 'promise_type'}}
+  // FIXME: This diagnostic doesn't make any sense.
+  // expected-error@-2 {{incomplete definition of type 'promise'}}
   co_await a;
 }
 
@@ -49,6 +69,9 @@ struct yielded_thing { const char *p; short a, b; };
 struct not_awaitable {};
 
 struct promise {
+  void get_return_object();
+  suspend_always initial_suspend();
+  suspend_always final_suspend();
   awaitable yield_value(int); // expected-note 2{{candidate}}
   awaitable yield_value(yielded_thing); // expected-note 2{{candidate}}
   not_awaitable yield_value(void()); // expected-note 2{{candidate}}
@@ -165,6 +188,10 @@ template<> struct std::coroutine_traits<void, yield_fn_tag> {
     // FIXME: add an await_transform overload for functions
     awaitable yield_value(int());
     void return_value(int());
+
+    suspend_never initial_suspend();
+    suspend_never final_suspend();
+    void get_return_object();
   };
 };
 
@@ -193,3 +220,49 @@ namespace placeholder {
     co_return g;
   }
 }
+
+struct bad_promise_1 {
+  suspend_always initial_suspend();
+  suspend_always final_suspend();
+};
+coro<bad_promise_1> missing_get_return_object() { // expected-error {{no member named 'get_return_object' in 'bad_promise_1'}}
+  co_await a;
+}
+
+struct bad_promise_2 {
+  coro<bad_promise_2> get_return_object();
+  // FIXME: We shouldn't offer a typo-correction here!
+  suspend_always final_suspend(); // expected-note {{here}}
+};
+coro<bad_promise_2> missing_initial_suspend() { // expected-error {{no member named 'initial_suspend' in 'bad_promise_2'}}
+  co_await a;
+}
+
+struct bad_promise_3 {
+  coro<bad_promise_3> get_return_object();
+  // FIXME: We shouldn't offer a typo-correction here!
+  suspend_always initial_suspend(); // expected-note {{here}}
+};
+coro<bad_promise_3> missing_final_suspend() { // expected-error {{no member named 'final_suspend' in 'bad_promise_3'}}
+  co_await a;
+}
+
+struct bad_promise_4 {
+  coro<bad_promise_4> get_return_object();
+  not_awaitable initial_suspend();
+  suspend_always final_suspend();
+};
+// FIXME: This diagnostic is terrible.
+coro<bad_promise_4> bad_initial_suspend() { // expected-error {{no member named 'await_ready' in 'not_awaitable'}}
+  co_await a;
+}
+
+struct bad_promise_5 {
+  coro<bad_promise_5> get_return_object();
+  suspend_always initial_suspend();
+  not_awaitable final_suspend();
+};
+// FIXME: This diagnostic is terrible.
+coro<bad_promise_5> bad_final_suspend() { // expected-error {{no member named 'await_ready' in 'not_awaitable'}}
+  co_await a;
+}