[Bug gcov-profile/106090] [GCOV] Wrong coverage for loop statements

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106090

--- Comment #3 from Yang Wang <njuwy at smail dot nju.edu.cn> ---
(In reply to Yang Wang from comment #2)
> (In reply to Martin Liška from comment #1)
> > No, it's correct as it only contains do_it() call that is triggered the same
> > number times as line 20 minus one.
> 
> (In reply to Martin Liška from comment #1)
> > No, it's correct as it only contains do_it() call that is triggered the same
> > number times as line 20 minus one.
> 
>         -:    0:Source:test.c
>         -:    0:Graph:test.gcno
>         -:    0:Data:test.gcda
>         -:    0:Runs:1
>         -:    1:volatile int cnt = 0;
>         -:    2:
>         -:    3:__attribute__((noinline, noclone)) static int
>         5:    4:last (void)
>         -:    5:{
>         5:    6:  return ++cnt % 5 == 0;
>         -:    7:}
>         -:    8:
>         -:    9:__attribute__((noinline, noclone)) static void
>         6:   10:do_it (void)
>         -:   11:{
>         6:   12:  asm volatile ("" : : "r" (&cnt) : "memory");
>         6:   13:}
>         -:   14:
>         1:   15:static void f1 (void)
>         -:   16:{
>         1:   17:  do_it();
>         4:   18:  for (; 0<1; do_it())
>         -:   19:    {
>         5:   20:      if (last ())
>         1:   21:	break;
>         -:   22:    }
>         1:   23:  do_it ();
>         1:   24:}
>         -:   25:
>         -:   26:int
>         1:   27:main ()
>         -:   28:{
>         1:   29:  f1 ();
>         -:   30:}
> 
> do_it() is indeed called 4 times,but I wonder how the coverage statistiscs
> of the for-statement is calculated. It doesn't become 5 untill the
> for-stamentment is completed.
>         -:    0:Source:test.c
>         -:    0:Graph:test.gcno
>         -:    0:Data:test.gcda
>         -:    0:Runs:1
>         -:    1:volatile int cnt = 0;
>         -:    2:
>         -:    3:__attribute__((noinline, noclone)) static int
>         5:    4:last (void)
>         -:    5:{
>         5:    6:  return ++cnt % 5 == 0;
>         -:    7:}
>         -:    8:
>         -:    9:__attribute__((noinline, noclone)) static void
>         6:   10:do_it (void)
>         -:   11:{
>         6:   12:  asm volatile ("" : : "r" (&cnt) : "memory");
>         6:   13:}
>         -:   14:
>         1:   15:static void f1 (void)
>         -:   16:{
>         1:   17:  do_it();
>         5:   18:  for (int a=0;0<1;do_it())
>         -:   19:    {
>         5:   20:      if (last ())
>         1:   21:	break;
>         -:   22:    }
>         1:   23:  do_it ();
>         1:   24:}
>         -:   25:
>         -:   26:int
>         1:   27:main ()
>         -:   28:{
>         1:   29:  f1 ();
>         -:   30:}

Besides, GCov doesn't seem to provide voerage statistics for "for(;;)" .
        -:    0:Source:test.c
        -:    0:Graph:test.gcno
        -:    0:Data:test.gcda
        -:    0:Runs:1
        -:    1:volatile int cnt = 0;
        -:    2:
        -:    3:__attribute__((noinline, noclone)) static int
        5:    4:last (void)
        -:    5:{
        5:    6:  return ++cnt % 5 == 0;
        -:    7:}
        -:    8:
        -:    9:__attribute__((noinline, noclone)) static void
        6:   10:do_it (void)
        -:   11:{
        6:   12:  asm volatile ("" : : "r" (&cnt) : "memory");
        6:   13:}
        -:   14:
        1:   15:static void f1 (void)
        -:   16:{
        1:   17:  do_it();
        -:   18:  for (; ; )
        -:   19:    {
        5:   20:      if (last ())
        1:   21:        break;
        4:   22:     do_it();
        -:   23:    }
        1:   24:  do_it ();
        1:   25:}
        -:   26:
        -:   27:int
        1:   28:main ()
        -:   29:{
        1:   30:  f1 ();
        -:   31:}