diff --git a/clang/lib/CodeGen/CGStmt.cpp b/clang/lib/CodeGen/CGStmt.cpp index 8898e3f22a7df..cb5a004e4f4a6 100644 --- a/clang/lib/CodeGen/CGStmt.cpp +++ b/clang/lib/CodeGen/CGStmt.cpp @@ -1341,10 +1341,8 @@ struct SaveRetExprRAII { }; } // namespace -/// If we have 'return f(...);', where both caller and callee are SwiftAsync, -/// codegen it as 'tail call ...; ret void;'. -static void makeTailCallIfSwiftAsync(const CallExpr *CE, CGBuilderTy &Builder, - const CGFunctionInfo *CurFnInfo) { +/// Determine if the given call uses the swiftasync calling convention. +static bool isSwiftAsyncCallee(const CallExpr *CE) { auto calleeQualType = CE->getCallee()->getType(); const FunctionType *calleeType = nullptr; if (calleeQualType->isFunctionPointerType() || @@ -1359,18 +1357,12 @@ static void makeTailCallIfSwiftAsync(const CallExpr *CE, CGBuilderTy &Builder, // getMethodDecl() doesn't handle member pointers at the moment. calleeType = methodDecl->getType()->castAs(); } else { - return; + return false; } } else { - return; - } - if (calleeType->getCallConv() == CallingConv::CC_SwiftAsync && - (CurFnInfo->getASTCallingConvention() == CallingConv::CC_SwiftAsync)) { - auto CI = cast(&Builder.GetInsertBlock()->back()); - CI->setTailCallKind(llvm::CallInst::TCK_MustTail); - Builder.CreateRetVoid(); - Builder.ClearInsertionPoint(); + return false; } + return calleeType->getCallConv() == CallingConv::CC_SwiftAsync; } /// EmitReturnStmt - Note that due to GCC extensions, this can have an operand @@ -1410,6 +1402,19 @@ void CodeGenFunction::EmitReturnStmt(const ReturnStmt &S) { RunCleanupsScope cleanupScope(*this); if (const auto *EWC = dyn_cast_or_null(RV)) RV = EWC->getSubExpr(); + + // If we're in a swiftasynccall function, and the return expression is a + // call to a swiftasynccall function, mark the call as the musttail call. + std::optional> SaveMustTail; + if (RV && CurFnInfo && + CurFnInfo->getASTCallingConvention() == CallingConv::CC_SwiftAsync) { + if (auto CE = dyn_cast(RV)) { + if (isSwiftAsyncCallee(CE)) { + SaveMustTail.emplace(MustTailCall, CE); + } + } + } + // FIXME: Clean this up by using an LValue for ReturnTemp, // EmitStoreThroughLValue, and EmitAnyExpr. // Check if the NRVO candidate was not globalized in OpenMP mode. @@ -1432,8 +1437,6 @@ void CodeGenFunction::EmitReturnStmt(const ReturnStmt &S) { // for side effects. if (RV) { EmitAnyExpr(RV); - if (auto *CE = dyn_cast(RV)) - makeTailCallIfSwiftAsync(CE, Builder, CurFnInfo); } } else if (!RV) { // Do nothing (return value is left uninitialized) diff --git a/clang/test/CodeGen/swift-async-call-conv.c b/clang/test/CodeGen/swift-async-call-conv.c index ce32c22fe8098..39511698bbae9 100644 --- a/clang/test/CodeGen/swift-async-call-conv.c +++ b/clang/test/CodeGen/swift-async-call-conv.c @@ -182,3 +182,19 @@ SWIFTASYNCCALL void async_struct_field_and_methods(int i, S &sref, S *sptr) { // CPPONLY-LABEL: define{{.*}} swifttailcc void @{{.*}}async_nonleaf_method2 // CPPONLY: musttail call swifttailcc void @{{.*}}async_leaf_method #endif + +// Passing this as an argument requires a coerce-and-expand operation, +// which requires a temporary. Make sure that cleaning up that temporary +// doesn't mess around with the musttail handling. +struct coerce_and_expand { + char a,b,c,d; +}; +struct coerce_and_expand return_coerced(void); +SWIFTASYNCCALL void take_coerced_async(struct coerce_and_expand); + +// CHECK-LABEL: swifttailcc void @{{.*}}test_coerced +SWIFTASYNCCALL void test_coerced() { + // CHECK: musttail call swifttailcc void @{{.*}}take_coerced_async + // CHECK-NEXT: ret void + return take_coerced_async(return_coerced()); +}