[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, 0 deletions

diff --git a/clang/lib/CodeGen/CGExprAgg.cpp b/clang/lib/CodeGen/CGExprAgg.cpp
index 009244784e5..fdf8e6acae0 100644
--- a/clang/lib/CodeGen/CGExprAgg.cpp
+++ b/clang/lib/CodeGen/CGExprAgg.cpp
@@ -111,6 +111,13 @@ public:
   void VisitGenericSelectionExpr(GenericSelectionExpr *GE) {
     Visit(GE->getResultExpr());
   }
+  void VisitCoawaitExpr(CoawaitExpr *E) {
+    CGF.EmitCoawaitExpr(*E, Dest, IsResultUnused);
+  }
+  void VisitCoyieldExpr(CoyieldExpr *E) {
+    CGF.EmitCoyieldExpr(*E, Dest, IsResultUnused);
+  }
+  void VisitUnaryCoawait(UnaryOperator *E) { Visit(E->getSubExpr()); }
   void VisitUnaryExtension(UnaryOperator *E) { Visit(E->getSubExpr()); }
   void VisitSubstNonTypeTemplateParmExpr(SubstNonTypeTemplateParmExpr *E) {
     return Visit(E->getReplacement());