https://bugs.llvm.org/show_bug.cgi?id=37132
Bug ID: 37132
Summary: [LLVM-COV] Wrong coverage with far jump
Product: Runtime Libraries
Version: trunk
Hardware: PC
OS: All
Status: NEW
Severity: enhancement
Priority: P
Component: libprofile library
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected]
$ clang -v
clang version 7.0.0- (trunk)
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/4.8
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/4.8.5
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/5
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/5.4.1
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/6
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/6.4.0
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/7
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/7.2.0
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/8
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/8.0.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8.5
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5.4.1
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6.4.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7.2.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/8
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/8.0.0
Selected GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/8.0.0
Candidate multilib: .;@m64
Selected multilib: .;@m64
$ cat small.c
#include <setjmp.h>
void quux(jmp_buf buf) { longjmp(buf, 927); }
void baz(jmp_buf buf)
{
jmp_buf local_buf;
if (!setjmp(local_buf))
quux(buf);
else
;
}
int main()
{
jmp_buf buf;
if (!setjmp(buf))
baz(buf);
return 0;
}
$ clang -O0 -g -fcoverage-mapping -fprofile-instr-generate=small.profraw
small.c; ./a.out; llvm-profdata merge small.profraw -o small.profdata; llvm-cov
show a.out -instr-profile=small.profdata small.c > small.gcov; cat small.gcov
1| |#include <setjmp.h>
2| |
3| 1|void quux(jmp_buf buf) { longjmp(buf, 927); }
4| |
5| |void baz(jmp_buf buf)
6| 1|{
7| 1| jmp_buf local_buf;
8| 1|
9| 1| if (!setjmp(local_buf))
10| 1| quux(buf);
11| 0| else
12| 0| ;
13| 1|}
14| |
15| |int main()
16| 1|{
17| 1| jmp_buf buf;
18| 1|
19| 1| if (!setjmp(buf))
20| 1| baz(buf);
21| 1|
22| 1| return 0;
23| 1|}
Line #13 is wrongly marked as executed.
when call the quux function, the function will dirrectly jump to the main
function. Thus, the else block and the rest baz function will not executed.
Therefore, Line #13 should be not marked as executed.
Coverage report from gcov for reference:
-: 1:#include <setjmp.h>
-: 2:
1: 3:void quux(jmp_buf buf) { longjmp(buf, 927); }
-: 4:
1: 5:void baz(jmp_buf buf)
-: 6:{
-: 7: jmp_buf local_buf;
-: 8:
1: 9: if (!setjmp(local_buf))
1: 10: quux(buf);
-: 11: else
-: 12: ;
#####: 13:}
-: 14:
1: 15:int main()
-: 16:{
-: 17: jmp_buf buf;
-: 18:
1: 19: if (!setjmp(buf))
1: 20: baz(buf);
-: 21:
1: 22: return 0;
-: 23:}
In gcov, the 13th line is marked as "#####" not executed.
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