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    <head>
      <base href="https://bugs.llvm.org/">
    </head>
    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - [LLVM-COV] Execute once and return twice"
   href="https://bugs.llvm.org/show_bug.cgi?id=49429">49429</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>[LLVM-COV] Execute once and return twice
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>Runtime Libraries
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>11.0
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>PC
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>Linux
          </td>
        </tr>

        <tr>
          <th>Status</th>
          <td>NEW
          </td>
        </tr>

        <tr>
          <th>Severity</th>
          <td>normal
          </td>
        </tr>

        <tr>
          <th>Priority</th>
          <td>P
          </td>
        </tr>

        <tr>
          <th>Component</th>
          <td>libprofile library
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>unassignedbugs@nondot.org
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>cnwy1996@outlook.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>llvm-bugs@lists.llvm.org
          </td>
        </tr></table>
      <p>
        <div>
        <pre>$ clang -v
clang version 11.0.0
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /home/wangyang/llvm-project/build/bin
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7.5.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/8
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7.5.0
Candidate multilib: .;@m64
Selected multilib: .;@m64

$ cat test.c
union U {
  int f0;
  unsigned char f1;
};

int main() {
  int i = 0;
  union U u = {0};
  for (u.f1 = 0; u.f1 != -2; ++u.f1) {
    i ^= u.f1;  
    if (i < 1)  
      return 0; 
  }
  return 1;
}

$ clang -w -O0 -g -fcoverage-mapping -fprofile-instr-generate=test.profraw
test.c; ./a.out; llvm-profdata merge test.profraw -o test.profdata; llvm-cov
show a.out -instr-profile=test.profdata test.c > test.lcov; cat test.lcov
    1|       |union U {
    2|       |  int f0;
    3|       |  unsigned char f1;
    4|       |};
    5|       |
    6|      1|int main() {
    7|      1|  int i = 0;
    8|      1|  union U u = {0};
    9|      1|  for (u.f1 = 0; u.f1 != -2; ++u.f1) {
   10|      1|    i ^= u.f1;  
   11|      1|    if (i < 1)  
   12|      1|      return 0; 
   13|      1|  }
   14|      1|  return 1;
   15|      1|}
   16|       |

Line #14 should not be executed</pre>
        </div>
      </p>


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