OSchip
/
llvm-project
mirror of https://github.com/THU-DSP-LAB/llvm-project.git
13
0
Fork 2
Code Issues Packages Projects Releases Wiki Activity

[libunwind] Ensure test/libunwind_01.pass is not completely inlined 

By adding noinline and calling fprintf before returning we ensure that
every function will have a distinct call frame and that the return address
will always be saved instead of saving the target in main as the result.

Before this change all backtraces were always backtrace -> main -> _start,
i.e. always exactly three entries. This happenend because all calls were
inlined in main() and the test just happenend to pass because there is at
least _start before main.

I found this while fixing some bugs in libunwind for CHERI and noticed that
the test was passing even though the code was completely broken.

Obtained from: https://github.com/CTSRD-CHERI/llvm-project

Reviewed By: #libunwind, ldionne, MaskRay

Differential Revision: https://reviews.llvm.org/D126611
This commit is contained in:
Alex Richardson 2022-06-20 08:57:12 +00:00 committed by Alex Richardson
parent b02d970b43
commit 8df257a6d0
1 changed files with 22 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

29
libunwind/test/libunwind_01.pass.cpp
View File

@ -15,6 +15,7 @@
#include <libunwind.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
void backtrace(int lower_bound) {
@ -24,9 +25,17 @@ void backtrace(int lower_bound) {
unw_cursor_t cursor;
unw_init_local(&cursor, &context);
char buffer[1024];
unw_word_t offset = 0;
int n = 0;
do {
++n;
n++;
if (unw_get_proc_name(&cursor, buffer, sizeof(buffer), &offset) == 0) {
fprintf(stderr, "Frame %d: %s+%p\n", n, buffer, (void*)offset);
} else {
fprintf(stderr, "Frame %d: Could not get name for cursor\n", n);
}
if (n > 100) {
abort();
}
@ -37,18 +46,24 @@ void backtrace(int lower_bound) {
}
}
void test1(int i) {
__attribute__((noinline)) void test1(int i) {
fprintf(stderr, "starting %s\n", __func__);
backtrace(i);
fprintf(stderr, "finished %s\n", __func__); // ensure return address is saved
}
void test2(int i, int j) {
__attribute__((noinline)) void test2(int i, int j) {
fprintf(stderr, "starting %s\n", __func__);
backtrace(i);
test1(j);
fprintf(stderr, "finished %s\n", __func__); // ensure return address is saved
}
void test3(int i, int j, int k) {
__attribute__((noinline)) void test3(int i, int j, int k) {
fprintf(stderr, "starting %s\n", __func__);
backtrace(i);
test2(j, k);
fprintf(stderr, "finished %s\n", __func__); // ensure return address is saved
}
void test_no_info() {
@ -142,9 +157,9 @@ void test_fpreg_get_set() {}
#endif
int main(int, char**) {
test1(1);
test2(1, 2);
test3(1, 2, 3);
test1(3);
test2(3, 4);
test3(3, 4, 5);
test_no_info();
test_reg_names();
test_reg_get_set();