; RUN: llc -relocation-model=static -verify-machineinstrs -O2 < %s | FileCheck %s ; The call to function TestBar should be a tail call, when in C++ the string ; `ret` is RVO returned. ; string TestFoo() { ; string ret = undef; ; TestBar(&ret); // tail call optimized ; return ret; ; } target triple = "aarch64-linux-gnu" %class.basic_string.11.42.73 = type { %"class.__gnu_cxx::__versa_string.10.41.72" } %"class.__gnu_cxx::__versa_string.10.41.72" = type { %"class.__gnu_cxx::__sso_string_base.9.40.71" } %"class.__gnu_cxx::__sso_string_base.9.40.71" = type { %"struct.__gnu_cxx::__vstring_utility<char, std::char_traits<char>, std::allocator<char> >::_Alloc_hider.7.38.69", i64, %union.anon.8.39.70 } %"struct.__gnu_cxx::__vstring_utility<char, std::char_traits<char>, std::allocator<char> >::_Alloc_hider.7.38.69" = type { i8* } %union.anon.8.39.70 = type { i64, [8 x i8] } declare void @TestBaz(%class.basic_string.11.42.73* noalias sret %arg) define void @TestBar(%class.basic_string.11.42.73* noalias sret %arg) { bb: call void @TestBaz(%class.basic_string.11.42.73* noalias sret %arg) ret void } define void @TestFoo(%class.basic_string.11.42.73* noalias sret %arg) { ; CHECK-LABEL: TestFoo: ; CHECK: b TestBar bb: %tmp = getelementptr inbounds %class.basic_string.11.42.73, %class.basic_string.11.42.73* %arg, i64 0, i32 0, i32 0, i32 2 %tmp1 = bitcast %class.basic_string.11.42.73* %arg to %union.anon.8.39.70** store %union.anon.8.39.70* %tmp, %union.anon.8.39.70** %tmp1, align 8 %tmp2 = bitcast %union.anon.8.39.70* %tmp to i8* tail call void @llvm.memcpy.p0i8.p0i8.i64(i8* %tmp2, i8* nonnull undef, i64 13, i1 false) %tmp3 = getelementptr inbounds %class.basic_string.11.42.73, %class.basic_string.11.42.73* %arg, i64 0, i32 0, i32 0, i32 1 store i64 13, i64* %tmp3, align 8 %tmp4 = getelementptr inbounds %class.basic_string.11.42.73, %class.basic_string.11.42.73* %arg, i64 0, i32 0, i32 0, i32 2, i32 1, i64 5 store i8 0, i8* %tmp4, align 1 tail call void @TestBar(%class.basic_string.11.42.73* noalias sret %arg) ret void } ; Function Attrs: argmemonly nounwind declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture, i8* nocapture readonly, i64, i1) #0 attributes #0 = { argmemonly nounwind }