[coroutines] Add codegen for await and yield expressions

Details:

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
]

llvm-svn: 298784

1 files changed, 7 insertions, 1 deletions

diff --git a/clang/lib/CodeGen/CodeGenFunction.h b/clang/lib/CodeGen/CodeGenFunction.h
index 7e99bdb73c4..4a7cc0253b4 100644
--- a/clang/lib/CodeGen/CodeGenFunction.h
+++ b/clang/lib/CodeGen/CodeGenFunction.h
@@ -1986,7 +1986,7 @@ public:
   /// pointer to a char.
   Address EmitMSVAListRef(const Expr *E);
 
-  /// EmitAnyExprToTemp - Similary to EmitAnyExpr(), however, the result will
+  /// EmitAnyExprToTemp - Similarly to EmitAnyExpr(), however, the result will
   /// always be accessible even if no aggregate location is provided.
   RValue EmitAnyExprToTemp(const Expr *E);
 
@@ -2528,6 +2528,12 @@ public:
 
   void EmitCoroutineBody(const CoroutineBodyStmt &S);
   void EmitCoreturnStmt(const CoreturnStmt &S);
+  RValue EmitCoawaitExpr(const CoawaitExpr &E,
+                         AggValueSlot aggSlot = AggValueSlot::ignored(),
+                         bool ignoreResult = false);
+  RValue EmitCoyieldExpr(const CoyieldExpr &E,
+                         AggValueSlot aggSlot = AggValueSlot::ignored(),
+                         bool ignoreResult = false);
   RValue EmitCoroutineIntrinsic(const CallExpr *E, unsigned int IID);
 
   void EnterCXXTryStmt(const CXXTryStmt &S, bool IsFnTryBlock = false);