Assembly return instruction incorrectly annotated

[Reeeemi]

I think I found a bug in the assembly coverage annotation. In the example below, the retq instruction is annotated with a "-", indicating it was not executed, while I'm pretty sure it should always be executed. I think it's caused by the jmp instruction to the retq statement.

GNATCoverage output:

Coverage level: branch
f !: 0000000000400530-0000000000400550
0000000000400530 +:  85 ff            test   %edi,%edi
0000000000400532 v:  7e 1a            jle    0x40054e <f+0x1e>
0000000000400534 +:  31 c9            xor    %ecx,%ecx
0000000000400536 +:  31 c0            xor    %eax,%eax
0000000000400538 +:  0f 1f 84 00 00 00 00 00   nopl   0x0(%rax,%rax,1)
0000000000400540 +:  89 ca            mov    %ecx,%edx
0000000000400542 +:  21 fa            and    %edi,%edx
0000000000400544 +:  01 d0            add    %edx,%eax
0000000000400546 +:  ff c1            inc    %ecx
0000000000400548 +:  39 cf            cmp    %ecx,%edi
000000000040054a v:  75 f4            jne    0x400540 <f+0x10>
000000000040054c +:  eb 02            jmp    0x400550 <f+0x20>
000000000040054e -:  31 c0            xor    %eax,%eax
0000000000400550 -:  c3               retq   

This happens when compiling the example below with clang at optimization level -O1 (X86-64).

f.c:

int f(int n) {
    int total = 0;
    for (int i = 0 ; i < n ; i++) {
        total += i & n;
    }
    return total;
}

main.c:

#include<stdio.h>

int f(int n);

int main() {
    printf("%i\n", f(1));
    return 0;
}

Compiling:

clang -c main.c
clang -O1 -c f.c
clang main.o f.o -o main

GNATCoverage:

gnatcov run ./main
gnatcov coverage --level=branch --annotate=asm main.trace --routines=f

I hope I provided all information needed to investigate this.

Regards,

Remi

[pmderodat]

Hello Remi,
Thank you for reporting this issue! We could reproduce on our side and are investigating this.

[pmderodat]

This bug should now be fixed. Thank you again for reporting it!