[PATCH] D145641: [Coroutines] Implement fix for cwg2563 issue and enable RVO under certain conditions

[Chuanqi Xu via Phabricator via cfe-commits]

ChuanqiXu added inline comments.


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Comment at: clang/lib/CodeGen/CGCoroutine.cpp:475
   const CoroutineBodyStmt &S;
+  bool DirectEmit = false;
 
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nit. Rewords it if you like.


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Comment at: clang/lib/CodeGen/CGCoroutine.cpp:483-499
+    // The call to get_­return_­object is sequenced before the call to
+    // initial_­suspend and is invoked at most once, but there are caveats
+    // regarding on whether the prvalue result object may be initialized
+    // directly/eager or delayed, depending on the types involved.
+    //
+    // The general cases:
+    // 1. Same type of get_return_object and coroutine return type (direct
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I'll feel better if we can attach the conclusion and links from the wg21.


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Comment at: clang/lib/CodeGen/CGCoroutine.cpp:500-508
+    DirectEmit = [&]() {
+      auto *RVI = S.getReturnValueInit();
+      if (!RVI || CGF.FnRetTy->isVoidType())
+        return true;
+      auto GroType = RVI->getType();
+      if (GroType->isVoidType())
+        return true;
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What's the case about returning void and the return_object type is different from the returning type?


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Comment at: clang/lib/Sema/SemaCoroutine.cpp:1733
 
+  bool GroMatchesRetType = GroType == FnRetType;
+
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Let's have some comments here.


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Comment at: clang/test/SemaCXX/coroutine-no-move-ctor.cpp:24-26
 invoker f() {
   co_return;
 }
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How about adding a failing case that the types are not matched?


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D145641/new/

https://reviews.llvm.org/D145641