| Issue |
148623
|
| Summary |
[LLVM-COV] wrong coverage for std library function call
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
8ss-boop
|
llvm version:
clang version 21.0.0git (https://github.com/llvm/llvm-project.git 872eac7af0050813062baba9662beb81093b6b55)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /root/software/llvm-releases/llvm-0704/bin
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/11
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/12
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/12
Candidate multilib: .;@m64
Selected multilib: .;@m64
```c
#include <stdatomic.h>
#include <stdio.h>
int main() {
atomic_int ai = 42;
int val = atomic_load(&ai);
int a = val + 10;
int b = (a * 2) / (a != 0 ? a : 1);
for (int i = 0; i < b && i < 50; ++i) {
printf("i=%d\n",i);
if (i % 3 == 0)
atomic_fetch_add(&ai, i);
}
printf("Final atomic value: %d\n", atomic_load(&ai));
return 0;
}
```
for the program above, we got the following coverage report from llvm-cov
```
/*
clang -std=c2x -lm -fcoverage-mapping -fprofile-instr-generate test.c
./a.out
llvm-profdata merge default.profraw -o default.profdata;
llvm-cov show --show-line-counts -instr-profile="" ./a.out > test.c.lcov
*/
1| |#include <stdatomic.h>
2| |#include <stdio.h>
3| 1|int main() {
4| 1| atomic_int ai = 42;
5| 1| int val = atomic_load(&ai);
6| 1| int a = val + 10;
7| 1| int b = (a * 2) / (a != 0 ? a : 1);
8| 3| for (int i = 0; i < b && i < 50; ++i) {
9| 2| printf("i=%d\n",i);
10| 2| if (i % 3 == 0)
11| 2| atomic_fetch_add(&ai, i);
12| 2| }
13| | printf("Final atomic value: %d\n", atomic_load(&ai));
14| 1| return 0;
15| 1|}
```
the output is:
```
i=0
i=1
Final atomic value: 42
```
so the line 11 should be executed only once instead of twice
btw, no coverage count was given for line 13 which is rare for llvm
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