[PATCH] D87470: [Coroutine][Sema] Tighten the lifetime of symmetric transfer returned handle

[Xun Li via Phabricator via cfe-commits]

This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
Closed by commit rGdf477db5f9e0: [Coroutine][Sema] Tighten the lifetime of symmetric transfer returned handle (authored by lxfind).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D87470/new/

https://reviews.llvm.org/D87470

Files:
  clang/lib/Sema/SemaCoroutine.cpp
  clang/test/CodeGenCoroutines/Inputs/coroutine.h
  clang/test/CodeGenCoroutines/coro-semmetric-transfer.cpp


Index: clang/test/CodeGenCoroutines/coro-semmetric-transfer.cpp
===================================================================
--- /dev/null
+++ clang/test/CodeGenCoroutines/coro-semmetric-transfer.cpp
@@ -0,0 +1,53 @@
+// RUN: %clang -std=c++14 -fcoroutines-ts -emit-llvm -S -O1 %s -o -
+
+#include "Inputs/coroutine.h"
+
+namespace coro = std::experimental::coroutines_v1;
+
+struct detached_task {
+  struct promise_type {
+    detached_task get_return_object() noexcept {
+      return detached_task{coro::coroutine_handle<promise_type>::from_promise(*this)};
+    }
+
+    void return_void() noexcept {}
+
+    struct final_awaiter {
+      bool await_ready() noexcept { return false; }
+      coro::coroutine_handle<> await_suspend(coro::coroutine_handle<promise_type> h) noexcept {
+        h.destroy();
+        return {};
+      }
+      void await_resume() noexcept {}
+    };
+
+    void unhandled_exception() noexcept {}
+
+    final_awaiter final_suspend() noexcept { return {}; }
+
+    coro::suspend_always initial_suspend() noexcept { return {}; }
+  };
+
+  ~detached_task() {
+    if (coro_) {
+      coro_.destroy();
+      coro_ = {};
+    }
+  }
+
+  void start() && {
+    auto tmp = coro_;
+    coro_ = {};
+    tmp.resume();
+  }
+
+  coro::coroutine_handle<promise_type> coro_;
+};
+
+detached_task foo() {
+  co_return;
+}
+
+// check that the lifetime of the coroutine handle used to obtain the address ended right away.
+// CHECK:       %{{.*}} = call i8* @{{.*address.*}}(%"struct.std::experimental::coroutines_v1::coroutine_handle.0"* nonnull %{{.*}})
+// CHECK-NEXT:  call void @llvm.lifetime.end.p0i8(i64 8, i8* nonnull %{{.*}})
Index: clang/test/CodeGenCoroutines/Inputs/coroutine.h
===================================================================
--- clang/test/CodeGenCoroutines/Inputs/coroutine.h
+++ clang/test/CodeGenCoroutines/Inputs/coroutine.h
@@ -15,7 +15,7 @@
     return me;
   }
   void operator()() { resume(); }
-  void *address() const { return ptr; }
+  void *address() const noexcept { return ptr; }
   void resume() const { __builtin_coro_resume(ptr); }
   void destroy() const { __builtin_coro_destroy(ptr); }
   bool done() const { return __builtin_coro_done(ptr); }
Index: clang/lib/Sema/SemaCoroutine.cpp
===================================================================
--- clang/lib/Sema/SemaCoroutine.cpp
+++ clang/lib/Sema/SemaCoroutine.cpp
@@ -398,6 +398,10 @@
            diag::warn_coroutine_handle_address_invalid_return_type)
         << JustAddress->getType();
 
+  // The coroutine handle used to obtain the address is no longer needed
+  // at this point, clean it up to avoid unnecessarily long lifetime which
+  // could lead to unnecessary spilling.
+  JustAddress = S.MaybeCreateExprWithCleanups(JustAddress);
   return buildBuiltinCall(S, Loc, Builtin::BI__builtin_coro_resume,
                           JustAddress);
 }


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