[llvm-bugs] [Bug 35426] New: [LLVM-COV] A non-executed label was wrongly marked as executed in llvm-cov

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=35426

            Bug ID: 35426
           Summary: [LLVM-COV] A non-executed label was wrongly marked as
                    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=1, j=1, k=1;
    if (i > 0) {
        if (j == 1) {
            if (k == 1)
                return 0;
            else
                goto lbl;
        } else {
            ;
        }
    }
lbl:
    return 1;
}

$ 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=1, j=1, k=1;
    4|      1|    if (i > 0) {
    5|      1|        if (j == 1) {
    6|      1|            if (k == 1)
    7|      1|                return 0;
    8|      0|            else
    9|      0|                goto lbl;
   10|      0|        } else {
   11|      0|            ;
   12|      0|        }
   13|      1|    }
   14|      1|lbl:
   15|      0|    return 1;
   16|      0|}

Line #14 is a label. The goto statement is not executed. However, it was
wrongly marked as executed in llvm-cov. While removing Line #10 and #11 from
this code, this result is correct.

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