[libcxx-commits] [clang] [libcxx] Elide suspension points via [[clang::coro_await_suspend_destroy]] (PR #152623)

[via libcxx-commits]

================
@@ -243,95 +321,105 @@ static LValueOrRValue emitSuspendExpression(CodeGenFunction &CGF, CGCoroData &Co
   CGF.EmitBlock(SuspendBlock);
 
   auto &Builder = CGF.Builder;
-  llvm::Function *CoroSave = CGF.CGM.getIntrinsic(llvm::Intrinsic::coro_save);
-  auto *NullPtr = llvm::ConstantPointerNull::get(CGF.CGM.Int8PtrTy);
-  auto *SaveCall = Builder.CreateCall(CoroSave, {NullPtr});
 
   auto SuspendWrapper = CodeGenFunction(CGF.CGM).generateAwaitSuspendWrapper(
       CGF.CurFn->getName(), Prefix, S);
 
-  CGF.CurCoro.InSuspendBlock = true;
-
   assert(CGF.CurCoro.Data && CGF.CurCoro.Data->CoroBegin &&
          "expected to be called in coroutine context");
 
-  SmallVector<llvm::Value *, 3> SuspendIntrinsicCallArgs;
-  SuspendIntrinsicCallArgs.push_back(
-      CGF.getOrCreateOpaqueLValueMapping(S.getOpaqueValue()).getPointer(CGF));
-
-  SuspendIntrinsicCallArgs.push_back(CGF.CurCoro.Data->CoroBegin);
-  SuspendIntrinsicCallArgs.push_back(SuspendWrapper);
-
-  const auto SuspendReturnType = S.getSuspendReturnType();
-  llvm::Intrinsic::ID AwaitSuspendIID;
-
-  switch (SuspendReturnType) {
-  case CoroutineSuspendExpr::SuspendReturnType::SuspendVoid:
-    AwaitSuspendIID = llvm::Intrinsic::coro_await_suspend_void;
-    break;
-  case CoroutineSuspendExpr::SuspendReturnType::SuspendBool:
-    AwaitSuspendIID = llvm::Intrinsic::coro_await_suspend_bool;
-    break;
-  case CoroutineSuspendExpr::SuspendReturnType::SuspendHandle:
-    AwaitSuspendIID = llvm::Intrinsic::coro_await_suspend_handle;
-    break;
-  }
-
-  llvm::Function *AwaitSuspendIntrinsic = CGF.CGM.getIntrinsic(AwaitSuspendIID);
-
   // SuspendHandle might throw since it also resumes the returned handle.
+  const auto SuspendReturnType = S.getSuspendReturnType();
   const bool AwaitSuspendCanThrow =
       SuspendReturnType ==
           CoroutineSuspendExpr::SuspendReturnType::SuspendHandle ||
       StmtCanThrow(S.getSuspendExpr());
 
-  llvm::CallBase *SuspendRet = nullptr;
-  // FIXME: add call attributes?
-  if (AwaitSuspendCanThrow)
-    SuspendRet =
-        CGF.EmitCallOrInvoke(AwaitSuspendIntrinsic, SuspendIntrinsicCallArgs);
-  else
-    SuspendRet = CGF.EmitNounwindRuntimeCall(AwaitSuspendIntrinsic,
-                                             SuspendIntrinsicCallArgs);
+  llvm::Value *Awaiter =
+      CGF.getOrCreateOpaqueLValueMapping(S.getOpaqueValue()).getPointer(CGF);
+  llvm::Value *Frame = CGF.CurCoro.Data->CoroBegin;
 
-  assert(SuspendRet);
-  CGF.CurCoro.InSuspendBlock = false;
+  if (useCoroAwaitSuspendDestroy(S)) { // Call `await_suspend_destroy` & cleanup
+    emitAwaitSuspendDestroy(CGF, Coro, SuspendWrapper, Awaiter, Frame,
+                            AwaitSuspendCanThrow);
+  } else { // Normal suspend path -- can actually suspend, uses intrinsics
----------------
snarkmaster wrote:

Sure, I'll give it a try. If the argument list isn't too gross, I'd also prefer that.

Here, I was trying to change the existing code layout as little as necessary.

https://github.com/llvm/llvm-project/pull/152623