[Bug gcov-profile/99444] New: [GCOV] Wrong coverage with "case" label in "switch" statement block

["njuwy at smail dot nju.edu.cn" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99444

            Bug ID: 99444
           Summary: [GCOV] Wrong coverage with "case" label in "switch"
                    statement block
           Product: gcc
           Version: 10.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: gcov-profile
          Assignee: unassigned at gcc dot gnu.org
          Reporter: njuwy at smail dot nju.edu.cn
                CC: marxin at gcc dot gnu.org
  Target Milestone: ---

$ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/local/libexec/gcc/x86_64-pc-linux-gnu/10.2.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../configure -enable-checking=release -enable-languages=c,c++
-disable-multilib
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 10.2.0 (GCC) 

$ cat test.c
int doit(int sel, int n, void *p) {
  int *const p0 = p;

  switch (sel) {
  case 0:
    do {
      *p0 += *p0;
    } while (--n);   
    return *p0 == 0; 
  default:
    __builtin_abort();
  }
}

int main() {
  int v0;
  v0 = 1;
  doit(0, 3, &v0);
  __builtin_exit(0);
}

$ gcc -O0 --coverage test.c;./a.out;gcov test;cat test.c.gcov
File 'test.c'
Lines executed:84.62% of 13
Creating 'test.c.gcov'

        -:    0:Source:test.c
        -:    0:Graph:test.gcno
        -:    0:Data:test.gcda
        -:    0:Runs:1
        1:    1:int doit(int sel, int n, void *p) {
        1:    2:  int *const p0 = p;
        -:    3:
        1:    4:  switch (sel) {
        3:    5:  case 0:
        -:    6:    do {
        3:    7:      *p0 += *p0;
        3:    8:    } while (--n);   
        1:    9:    return *p0 == 0; 
    #####:   10:  default:
    #####:   11:    __builtin_abort();
        -:   12:  }
        -:   13:}
        -:   14:
        1:   15:int main() {
        -:   16:  int v0;
        1:   17:  v0 = 1;
        1:   18:  doit(0, 3, &v0);
        1:   19:  __builtin_exit(0);
        -:   20:}
        -:   21:

Line #5 should only be executed once.