1 /*
2 * Copyright (C) 2019 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include "gtest/gtest.h"
18
19 #include <cinttypes>
20 #include <optional>
21 #include <tuple>
22
23 #include "berberis/base/bit_util.h"
24
25 #pragma clang diagnostic push
26 // Clang does not allow use of C++ types in “extern "C"” functions - but we need to declare one to
27 // test it.
28 #pragma clang diagnostic ignored "-Wreturn-type-c-linkage"
29
30 extern "C" std::tuple<uint64_t> AsmTupleTest(std::tuple<uint64_t>*);
31
32 // This function takes first parameter %rdi and uses it as the address of a tuple.
33 // If tuple is returned on registers it would contain address of a tuple passed via pointer.
34 // If tuple is returned on stack this would be address of the returned tuple (hidden parameter).
35 asm(R"(.p2align 4, 0x90
36 .type AsmTupleTest,@function
37 AsmTupleTest:
38 .cfi_startproc
39 movl $42, (%rdi)
40 movq %rdi, %rax
41 ret
42 .size AsmTupleTest, .-AsmTupleTest
43 .cfi_endproc)");
44
45 #pragma clang diagnostic pop
46
47 namespace berberis {
48
49 namespace {
50
TupleIsReturnedOnRegisters()51 std::optional<bool> TupleIsReturnedOnRegisters() {
52 std::tuple<uint64_t> result_if_on_regs{};
53 std::tuple<uint64_t> result_if_on_stack{};
54 result_if_on_stack = AsmTupleTest(&result_if_on_regs);
55 if (std::get<uint64_t>(result_if_on_regs) == 42 &&
56 std::get<uint64_t>(result_if_on_stack) == bit_cast<uint64_t>(&result_if_on_regs)) {
57 return true;
58 } else if (std::get<uint64_t>(result_if_on_regs) == 0 &&
59 std::get<uint64_t>(result_if_on_stack) == 42) {
60 return false;
61 } else {
62 // Shouldn't happen with proper x86-64 compiler.
63 return {};
64 }
65 }
66
67 // Note: tuple is returned on registers when libc++ is used and on stack if libstdc++ is used.
TEST(LibCxxAbi,Tuple)68 TEST(LibCxxAbi, Tuple) {
69 auto tuple_is_returned_on_registers = TupleIsReturnedOnRegisters();
70 EXPECT_TRUE(tuple_is_returned_on_registers.has_value());
71 #ifdef _LIBCPP_VERSION
72 EXPECT_TRUE(*tuple_is_returned_on_registers);
73 #else
74 EXPECT_FALSE(*tuple_is_returned_on_registers);
75 #endif
76 }
77
78 } // namespace
79
80 } // namespace berberis
81