[llvm-bugs] [Bug 35394] New: source code inside a label after a loop is wrongly labeled as not executed in llvm-cov

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=35394

            Bug ID: 35394
           Summary: source code inside a label after a loop is wrongly
                    labeled as not executed in llvm-cov
           Product: clang
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: -New Bugs
          Assignee: unassignedclangbugs at nondot.org
          Reporter: yangyibiao at nju.edu.cn
                CC: llvm-bugs at lists.llvm.org

$ 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.

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