[coroutines] Wrap the body of the coroutine in try-catch

Summary:
If unhandled_exception member function is present in the coroutine promise,
wrap the body of the coroutine in:

```
try {
  body
} catch(...) { promise.unhandled_exception(); }
```

Reviewers: EricWF, rnk, rsmith

Reviewed By: rsmith

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D31692

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@303583 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 55 insertions, 20 deletions

diff --git a/test/CodeGenCoroutines/coro-cleanup.cpp b/test/CodeGenCoroutines/coro-cleanup.cpp
index 7f6f35cfe2..519282e2b6 100644
--- a/test/CodeGenCoroutines/coro-cleanup.cpp
+++ b/test/CodeGenCoroutines/coro-cleanup.cpp
@@ -6,38 +6,38 @@ template <typename... T> struct coroutine_traits;
 
 template <class Promise = void> struct coroutine_handle {
   coroutine_handle() = default;
-  static coroutine_handle from_address(void *) { return {}; }
+  static coroutine_handle from_address(void *) noexcept;
 };
 template <> struct coroutine_handle<void> {
-  static coroutine_handle from_address(void *) { return {}; }
+  static coroutine_handle from_address(void *) noexcept;
   coroutine_handle() = default;
   template <class PromiseType>
-  coroutine_handle(coroutine_handle<PromiseType>) {}
+  coroutine_handle(coroutine_handle<PromiseType>) noexcept;
 };
 }
 
 struct suspend_always {
-  bool await_ready();
-  void await_suspend(std::experimental::coroutine_handle<>);
-  void await_resume();
+  bool await_ready() noexcept;
+  void await_suspend(std::experimental::coroutine_handle<>) noexcept;
+  void await_resume() noexcept;
 };
 
 template <> struct std::experimental::coroutine_traits<void> {
   struct promise_type {
-    void get_return_object();
-    suspend_always initial_suspend();
-    suspend_always final_suspend();
-    void return_void();
+    void get_return_object() noexcept;
+    suspend_always initial_suspend() noexcept;
+    suspend_always final_suspend() noexcept;
+    void return_void() noexcept;
     promise_type();
     ~promise_type();
-    void unhandled_exception();
+    void unhandled_exception() noexcept;
   };
 };
 
 struct Cleanup { ~Cleanup(); };
 void may_throw();
 
-// CHECK: define void @_Z1fv(
+// CHECK-LABEL: define void @_Z1fv(
 void f() {
   // CHECK: call i8* @_Znwm(i64
 
@@ -52,19 +52,34 @@ void f() {
   // if may_throw throws, check that we destroy the promise and free the memory.
 
   // CHECK: invoke void @_Z9may_throwv(
-  // CHECK-NEXT: to label %{{.+}} unwind label %[[PromDtorPad:.+]]
+  // CHECK-NEXT: to label %{{.+}} unwind label %[[CatchPad:.+]]
 
   // CHECK: [[DeallocPad]]:
   // CHECK-NEXT: landingpad
   // CHECK-NEXT:   cleanup
   // CHECK: br label %[[Dealloc:.+]]
 
-  // CHECK: [[PromDtorPad]]:
-  // CHECK-NEXT: landingpad
-  // CHECK-NEXT:   cleanup
-  // CHECK: call void @_ZN7CleanupD1Ev(%struct.Cleanup*
+  // CHECK: [[CatchPad]]:
+  // CHECK-NEXT:  landingpad
+  // CHECK-NEXT:       catch i8* null
+  // CHECK:  call void @_ZN7CleanupD1Ev(
+  // CHECK:  br label %[[Catch:.+]]
+
+  // CHECK: [[Catch]]:
+  // CHECK:    call i8* @__cxa_begin_catch(
+  // CHECK:    call void @_ZNSt12experimental16coroutine_traitsIJvEE12promise_type19unhandled_exceptionEv(
+  // CHECK:    invoke void @__cxa_end_catch()
+  // CHECK-NEXT:    to label %[[Cont:.+]] unwind
+
+  // CHECK: [[Cont]]:
+  // CHECK-NEXT: br label %[[Cont2:.+]]
+  // CHECK: [[Cont2]]:
+  // CHECK-NEXT: br label %[[Cleanup:.+]]
+
+  // CHECK: [[Cleanup]]:
   // CHECK: call void @_ZNSt12experimental16coroutine_traitsIJvEE12promise_typeD1Ev(
-  // CHECK: br label %[[Dealloc]]
+  // CHECK: %[[Mem0:.+]] = call i8* @llvm.coro.free(
+  // CHECK: call void @_ZdlPv(i8* %[[Mem0]]
 
   // CHECK: [[Dealloc]]:
   // CHECK:   %[[Mem:.+]] = call i8* @llvm.coro.free(
@@ -72,3 +87,11 @@ void f() {
 
   co_return;
 }
+
+// CHECK-LABEL: define void @_Z1gv(
+void g() {
+  for (;;)
+    co_await suspend_always{};
+  // Since this is the endless loop there should be no fallthrough handler (call to 'return_void').
+  // CHECK-NOT: call void @_ZNSt12experimental16coroutine_traitsIJvEE12promise_type11return_voidEv
+}
diff --git a/test/CodeGenCoroutines/coro-eh-cleanup.cpp b/test/CodeGenCoroutines/coro-eh-cleanup.cpp
index 578d57fbab..901ed54923 100644
--- a/test/CodeGenCoroutines/coro-eh-cleanup.cpp
+++ b/test/CodeGenCoroutines/coro-eh-cleanup.cpp
@@ -51,7 +51,13 @@ coro_t f() {
 // CHECK: [[EHCLEANUP]]:
 // CHECK:   %[[INNERPAD:.+]] = cleanuppad within none []
 // CHECK:   call void @"\01??_DCleanup@@QEAAXXZ"(
-// CHECK:   cleanupret from %[[INNERPAD]] unwind label %[[COROENDBB:.+]]
+// CHECK:   cleanupret from %4 unwind label %[[CATCHDISPATCH:.+]]
+
+// CHECK: [[CATCHDISPATCH]]:
+// CHECK:   catchswitch within none [label %[[CATCHPAD:.+]]] unwind label %[[COROENDBB:.+]]
+// CHECK: [[CATCHPAD]]:
+// CHECK:   call void @"\01?unhandled_exception@promise_type@coro_t@@QEAAXXZ"
+
 // CHECK: [[COROENDBB]]:
 // CHECK-NEXT: %[[CLPAD:.+]] = cleanuppad within none
 // CHECK-NEXT: call i1 @llvm.coro.end(i8* null, i1 true) [ "funclet"(token %[[CLPAD]]) ]
@@ -62,8 +68,14 @@ coro_t f() {
 // CHECK-LPAD:       to label %[[CONT:.+]] unwind label %[[EHCLEANUP:.+]]
 // CHECK-LPAD: [[EHCLEANUP]]:
 // CHECK-LPAD:    landingpad { i8*, i32 }
-// CHECK-LPAD:          cleanup
+// CHECK-LPAD:          catch
 // CHECK-LPAD:   call void @_ZN7CleanupD1Ev(
+// CHECK-LPAD:   call i8* @__cxa_begin_catch
+// CHECK-LPAD:   call void @_ZN6coro_t12promise_type19unhandled_exceptionEv
+// CHECK-LPAD:   invoke void @__cxa_end_catch()
+// CHECK-LPAD:             to label %{{.+}} unwind label %[[UNWINDBB:.+]]
+
+// CHECK-LPAD: [[UNWINDBB]]:
 // CHECK-LPAD:   %[[I1RESUME:.+]] = call i1 @llvm.coro.end(i8* null, i1 true)
 // CHECK-LPAD:   br i1  %[[I1RESUME]], label %[[EHRESUME:.+]], label
 // CHECK-LPAD: [[EHRESUME]]: