[llvm-bugs] [Bug 45850] New: llvm-cov: wrong coverage with a function pointer points to the exit() function

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=45850

            Bug ID: 45850
           Summary: llvm-cov: wrong coverage with a function pointer
                    points to the exit() function
           Product: Runtime Libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: libprofile library
          Assignee: unassignedbugs at nondot.org
          Reporter: yangyibiao at hust.edu.cn
                CC: llvm-bugs at lists.llvm.org

$ clang --version
clang version 11.0.0 (/home/yibiao/.cache/yay/llvm-git/llvm-project
871beba234a83a2a02da9dedbd59b91a1bfbd7af)
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin

$ clang -O0 -w -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.c.lcov; cat
small.c.lcov
    1|       |void exit(int);
    2|       |void (*myexit)(int);
    3|       |
    4|       |int main()
    5|      1|{
    6|      1|  int i = 0, j = 0;
    7|      1|  myexit = exit;
    8|      3|  for (i=0;i<5;i++) {
    9|      2|    if (i)
   10|      1|      myexit(0);
   11|      2|    j++;
   12|      2|  }
   13|      1|}

***
Line 11 is wrongly marked as executed twice. myexit is a function pointer. When
setting breakpoint for Line 11 in lldb, only hit one time. 

When replace Line 10 with exit(0), the coverage will be correct as follow:
    1|       |void exit(int);
    2|       |void (*myexit)(int);
    3|       |
    4|       |int main()
    5|      1|{
    6|      1|  int i = 0, j = 0;
    7|      1|  myexit = exit;
    8|      2|  for (i=0;i<5;i++) {
    9|      2|    if (i)
   10|      1|      exit(0); // myexit(0);
   11|      1|    j++;
   12|      1|  }
   13|      1|}


$ cat small.c
void exit(int);
void (*myexit)(int);

int main()
{
  int i = 0, j = 0;
  myexit = exit;
  for (i=0;i<5;i++) {
    if (i)
      exit(0); // myexit(0);
    j++;
  }
}

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