[Bug gcov-profile/101342] New: [Gcov] Wrong coverage with "for(;;a++)" loop statement

[Bug gcov-profile/101342] New: [Gcov] Wrong coverage with "for(;;a++)" loop statement

[byone.heng at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101342

            Bug ID: 101342
           Summary: [Gcov] Wrong coverage with "for(;;a++)"  loop
                    statement
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: gcov-profile
          Assignee: unassigned at gcc dot gnu.org
          Reporter: byone.heng at gmail dot com
                CC: marxin at gcc dot gnu.org
  Target Milestone: ---

$./gcc -v                                                                       
Using built-in specs.
COLLECT_GCC=./gcc
COLLECT_LTO_WRAPPER=/home/x/project/gcc/build/install/libexec/gcc/x86_64-pc-linux-gnu/11.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../configure --prefix=/home/x/project/gcc/build/install
--enable-checking=release --enable-languages=c,c++ --disable-multilib
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 11.0.0 20210105 (experimental) (GCC)

$cat test.c
volatile long int true_var = 1;
const long int false_var = 0;
int a=0;
int main() {
  for (;; a++) {
    int c[1];
    if( true_var > 0 )
    {
    if (a) {
      break;
      a;
      continue; /* count(1) */
    }
    continue;
    } /* count(1) */
  }
  return 0;
}

$gcc -O0 --coverage test.c;./a.out;gcov test;cat test.c.gcov

-:    1:/* { dg-options "-fprofile-arcs -ftest-coverage" } */
-:    2:/* { dg-do run { target native } } */
-:    3:
-:    4:volatile long int true_var = 1;
-:    5:const long int false_var = 0;
-:    6:
-:    7:int a=0;
-:    8:
2:    9:int main() {
1:   10:  for (;; a++) {
-:   11:    int c[1];
2:   12:    if( true_var > 0 )
-:   13:    {
2:   14:    if (a) {
1:   15:      break;
-:   16:      a;
1:   17:      continue; /* count(1) */
-:   18:    }
1:   19:    continue;
-:   20:    } /* count(1) */
-:   21:  }
-:   22:
1:   23:  return 0;
-:   24:}
-:   25:
-:   26:/* { dg-final { run-gcov gcov-pr85217.c } } */

Line 10 is wrongly marked as executed once which should be executed twice.

[Bug gcov-profile/101342] [Gcov] wrong coverage for the function with a loop statement

[byone.heng at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101342

Xiaoyuan Xie <byone.heng at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[Gcov] Wrong coverage with  |[Gcov] wrong coverage for
                   |"for(;;a++)"  loop          |the function with a loop
                   |statement                   |statement

--- Comment #1 from Xiaoyuan Xie <byone.heng at gmail dot com> ---
$./gcc -v                                                                       
Using built-in specs.
COLLECT_GCC=./gcc
COLLECT_LTO_WRAPPER=/home/x/project/gcc/build/install/libexec/gcc/x86_64-pc-linux-gnu/11.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../configure --prefix=/home/x/project/gcc/build/install
--enable-checking=release --enable-languages=c,c++ --disable-multilib
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 11.0.0 20210105 (experimental) (GCC)

$cat test.c
static short int true_var = 1;
signed char false_var = 0;
typedef unsigned V __attribute__ ((vector_size (16)));
V
foo (unsigned x, V v)
{
  do {
      v %= x;
      x = 1;
  } while (v[1]);
  return v;
}
int
main ()
{
  V x = foo (5, (V) { 0, 1 });
  if (x[0] || x[1] || x[2] || x[3])
    __builtin_abort();
  return 0;
}


$gcc -O0 --coverage test.c;./a.out;gcov test;cat test.c.gcov

        -:    1:/* { dg-do run } */
        -:    2:/* { dg-additional-options "-w -Wno-psabi" } */
        -:    3:
        -:    4:static short int true_var = 1;
        -:    5:signed char false_var = 0;
        -:    6:
        -:    7:typedef unsigned V __attribute__ ((vector_size (16)));
        -:    8:
        -:    9:V
        2:   10:foo (unsigned x, V v)
        -:   11:{
        -:   12:  do {
        2:   13:      v %= x;
        2:   14:      x = 1;
        2:   15:  } while (v[1]);
        1:   16:  return v;
        -:   17:}
        -:   18:
        -:   19:int
        1:   20:main ()
        -:   21:{
        1:   22:  V x = foo (5, (V) { 0, 1 });
        1:   23:  if (x[0] || x[1] || x[2] || x[3])
    #####:   24:    __builtin_abort();
        1:   25:  return 0;
        -:   26:}

In my opinion, line 10 should be executed one time.

[Bug gcov-profile/101342] [Gcov] wrong coverage for the function with a loop statement

[byone.heng at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101342

--- Comment #2 from Xiaoyuan Xie <byone.heng at gmail dot com> ---
I clicked the wrong button on my page and the same content was submitted twice,
please ignore the content in the description and directly read the comments 1.

[Bug gcov-profile/101342] [Gcov] wrong coverage for the function with a loop statement

[schwab@linux-m68k.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101342

--- Comment #3 from Andreas Schwab <schwab@linux-m68k.org> ---
*** Bug 101341 has been marked as a duplicate of this bug. ***