1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
|
// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
// TODO: Figure out why this fails with Memory Sanitizer.
// XFAIL: msan
// This test fails on older llvm, when built with picolibc.
// XFAIL: clang-16 && LIBCXX-PICOLIBC-FIXME
#undef NDEBUG
#include <assert.h>
#include <stdlib.h>
#include <unwind.h>
#define EXPECTED_NUM_FRAMES 50
#define NUM_FRAMES_UPPER_BOUND 100
__attribute__((noinline)) _Unwind_Reason_Code callback(_Unwind_Context *context,
void *cnt) {
(void)context;
int *i = (int *)cnt;
++*i;
if (*i > NUM_FRAMES_UPPER_BOUND) {
abort();
}
return _URC_NO_REASON;
}
__attribute__((noinline)) void test_backtrace() {
int n = 0;
_Unwind_Backtrace(&callback, &n);
if (n < EXPECTED_NUM_FRAMES) {
abort();
}
}
// These functions are effectively the same, but we have to be careful to avoid
// unwanted optimizations that would mess with the number of frames we expect.
// Surprisingly, slapping `noinline` is not sufficient -- we also have to avoid
// writing the function in a way that the compiler can easily spot tail
// recursion.
__attribute__((noinline)) int test1(int i);
__attribute__((noinline)) int test2(int i);
__attribute__((noinline)) int test1(int i) {
if (i == 0) {
test_backtrace();
return 0;
} else {
return i + test2(i - 1);
}
}
__attribute__((noinline)) int test2(int i) {
if (i == 0) {
test_backtrace();
return 0;
} else {
return i + test1(i - 1);
}
}
int main(int, char**) {
int total = test1(50);
assert(total == 1275);
return 0;
}
|
