[PATCH] D36070: [coroutines] Evaluate the operand of void `co_return` expressions.

[Eric Fiselier via Phabricator via cfe-commits]

EricWF created this revision.

Previously Clang incorrectly ignored the expression of a void `co_return`. This 
patch addresses that bug.

I'm not quite sure if I got the code-gen right, but this patch is at least a 
start.


https://reviews.llvm.org/D36070

Files:
  lib/CodeGen/CGCoroutine.cpp
  test/CodeGenCoroutines/coro-ret-void.cpp


Index: test/CodeGenCoroutines/coro-ret-void.cpp
===================================================================
--- test/CodeGenCoroutines/coro-ret-void.cpp
+++ test/CodeGenCoroutines/coro-ret-void.cpp
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -std=c++14 -fcoroutines-ts -triple=x86_64-unknown-linux-gnu 
-emit-llvm %s -o - -disable-llvm-passes | FileCheck %s
+// RUN: %clang_cc1 -std=c++14 -fcoroutines-ts -munwind-tables 
-triple=x86_64-unknown-linux-gnu -emit-llvm %s -o - -disable-llvm-passes | 
FileCheck %s
 
 #include "Inputs/coroutine.h"
 
@@ -21,6 +21,20 @@
 // CHECK: call void 
@_ZNSt12experimental13coroutines_v113suspend_never12await_resumeEv(%"struct.std::experimental::coroutines_v1::suspend_never"*
 // CHECK: call void 
@_ZN5coro112promise_type11return_voidEv(%"struct.coro1::promise_type"* 
%__promise)
 
+struct A {
+  A();
+  ~A();
+};
+
+coro1 f2() {
+  co_return(void) A{};
+}
+
+// CHECK-LABEL: define void @_Z2f2v(
+// CHECK: call void @_ZN1AC1Ev(%struct.A* %[[AVar:.*]])
+// CHECK-NEXT: call void @_ZN1AD1Ev(%struct.A* %[[AVar]])
+// CHECK-NEXT: call void 
@_ZN5coro112promise_type11return_voidEv(%"struct.coro1::promise_type"*
+
 struct coro2 {
   struct promise_type {
     coro2 get_return_object();
Index: lib/CodeGen/CGCoroutine.cpp
===================================================================
--- lib/CodeGen/CGCoroutine.cpp
+++ lib/CodeGen/CGCoroutine.cpp
@@ -234,6 +234,13 @@
 
 void CodeGenFunction::EmitCoreturnStmt(CoreturnStmt const &S) {
   ++CurCoro.Data->CoreturnCount;
+  const Expr *RV = S.getOperand();
+  if (RV && RV->getType()->isVoidType()) {
+    // Make sure to evaluate the expression of a co_return with a void
+    // expression for side effects.
+    RunCleanupsScope cleanupScope(*this);
+    EmitIgnoredExpr(RV);
+  }
   EmitStmt(S.getPromiseCall());
   EmitBranchThroughCleanup(CurCoro.Data->FinalJD);
 }



Index: test/CodeGenCoroutines/coro-ret-void.cpp
===================================================================
--- test/CodeGenCoroutines/coro-ret-void.cpp
+++ test/CodeGenCoroutines/coro-ret-void.cpp
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -std=c++14 -fcoroutines-ts -triple=x86_64-unknown-linux-gnu -emit-llvm %s -o - -disable-llvm-passes | FileCheck %s
+// RUN: %clang_cc1 -std=c++14 -fcoroutines-ts -munwind-tables -triple=x86_64-unknown-linux-gnu -emit-llvm %s -o - -disable-llvm-passes | FileCheck %s
 
 #include "Inputs/coroutine.h"
 
@@ -21,6 +21,20 @@
 // CHECK: call void @_ZNSt12experimental13coroutines_v113suspend_never12await_resumeEv(%"struct.std::experimental::coroutines_v1::suspend_never"*
 // CHECK: call void @_ZN5coro112promise_type11return_voidEv(%"struct.coro1::promise_type"* %__promise)
 
+struct A {
+  A();
+  ~A();
+};
+
+coro1 f2() {
+  co_return(void) A{};
+}
+
+// CHECK-LABEL: define void @_Z2f2v(
+// CHECK: call void @_ZN1AC1Ev(%struct.A* %[[AVar:.*]])
+// CHECK-NEXT: call void @_ZN1AD1Ev(%struct.A* %[[AVar]])
+// CHECK-NEXT: call void @_ZN5coro112promise_type11return_voidEv(%"struct.coro1::promise_type"*
+
 struct coro2 {
   struct promise_type {
     coro2 get_return_object();
Index: lib/CodeGen/CGCoroutine.cpp
===================================================================
--- lib/CodeGen/CGCoroutine.cpp
+++ lib/CodeGen/CGCoroutine.cpp
@@ -234,6 +234,13 @@
 
 void CodeGenFunction::EmitCoreturnStmt(CoreturnStmt const &S) {
   ++CurCoro.Data->CoreturnCount;
+  const Expr *RV = S.getOperand();
+  if (RV && RV->getType()->isVoidType()) {
+    // Make sure to evaluate the expression of a co_return with a void
+    // expression for side effects.
+    RunCleanupsScope cleanupScope(*this);
+    EmitIgnoredExpr(RV);
+  }
   EmitStmt(S.getPromiseCall());
   EmitBranchThroughCleanup(CurCoro.Data->FinalJD);
 }

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