[LLVM-COV] source code inside a label after a loop is wrongly labeled as not executed in llvm-cov

[llvmbot]

Bugzilla Link	35394
Resolution	DUPLICATE
Resolved on	Dec 07, 2017 02:47
Version	trunk
OS	Linux
Reporter	LLVM Bugzilla Contributor
CC	@def-,@vedantk

Extended Description

$ clang -v
clang version 6.0.0-svn318792-1~exp1 (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/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/6.3.0
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/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/6.3.0
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
Selected GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/7.2.0
Candidate multilib: .;@m64
Selected multilib: .;@m64

$ cat small.c
int main()
{
int i=0, k=0;
if (1) {
if (1) {
goto lbl;
}
} else {
lbl:
for (; k < 2; k++)
;

    i = i+1;
}

printf("%d\n", i);
return 0;

}

$ clang -w -O0 -g -fcoverae-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
1

$ cat small.gcov
1| |int main()
2| 1|{
3| 1| int i=0, k=0;
4| 1| if (1) {
5| 1| if (1) {
6| 1| goto lbl;
7| 1| }
8| 0| } else {
9| 1|lbl:
10| 3| for (; k < 2; k++)
11| 2| ;
12| 0|
13| 0| i = i+1;
14| 0| }
15| 1|
16| 1| printf("%d\n", i);
17| 1| return 0;
18| 1|}

Line #​13 is executed but the output showed that this line is not executed in llvm-cov.

[llvmbot]

$ clang -v
clang version 6.0.0-svn318792-1~exp1 (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/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/6.3.0
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/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/6.3.0
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
Selected GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/7.2.0
Candidate multilib: .;@m64
Selected multilib: .;@m64

$ cat small.c
int main()
{
int i=0, k=0;
if (1) {
if (1) {
goto lbl;
}
} else {
lbl:
for (; k < 2; k++)
;

    i = i+1;
}

printf("%d\n", i);
return 0;

}

$ clang -w -O0 -g -fcoverae-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
1

sorry. The "-fcoverae-mapping" should be "-fcoverage-mapping". Thus the correct command should be as follows:
$ clang -w -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| |int main()
2| 1|{
3| 1| int i=0, k=0;
4| 1| if (1) {
5| 1| if (1) {
6| 1| goto lbl;
7| 1| }
8| 0| } else {
9| 1|lbl:
10| 3| for (; k < 2; k++)
11| 2| ;
12| 0|
13| 0| i = i+1;
14| 0| }
15| 1|
16| 1| printf("%d\n", i);
17| 1| return 0;
18| 1|}

Line #​13 is executed but the output showed that this line is not executed in
llvm-cov.

[vedantk]

*** This bug has been marked as a duplicate of bug llvm/llvm-bugzilla-archive#35426 ***

[vedantk]

mentioned in issue llvm/llvm-bugzilla-archive#35426