Re: [PATCH] Add condition coverage profiling

[Sebastian Huber <sebastian.huber@embedded-brains.de>]

On 08/04/2022 09:33, Jørgen Kvalsvik wrote:
> On 08/04/2022 09:28, Jørgen Kvalsvik wrote:
>> On 07/04/2022 18:53, Sebastian Huber wrote:
>>> Hello Jørgen,
>>>
>>> there could be an issue with conditions in for loops:
>>>
>>>          3:  189:  for (int a = 0; a <= 1; ++a) {
>>> branch  0 taken 2
>>> branch  1 taken 1 (fallthrough)
>>> conditions covered 0/2
>>> condition  0 not covered (true)
>>> condition  0 not covered (false)
>>>
>> Hello,
>>
>> Thanks, I'll have a look at it. There should be a for loop in the test suite,
>> but I'll add this exact example and see if I can reproduce it. This should
>> obviously be 100% covered.
> Sebastian,
> 
> I added this exact example to the test suite, but it reports 2/2 for me (linux
> amd64). Do you have a very different system, and what flags did you use?

Thanks for having a look at this. My setup is a bit more complicated. I 
use an arm cross compiler and run an application on a simulator (Qemu). 
The *.gcda files are created by gcov-tool. It is probably an issue with 
my setup, so maybe we should ignore this issue at the moment.

When I move the code to a separate translation unit:

#include <stdio.h>

static __attribute__((__noinline__)) int f(int a, int b, int c, int d)
{
   if (a || (b && c) || d) {
     return 1;
   } else {
     return 2;
   }
}

void test(void)
{
   for (int a = 0; a <= 1; ++a) {
     for (int b = 0; b <= 1; ++b) {
       for (int c = 0; c <= 1; ++c) {
         for (int d = 0; d <= 1; ++d) {
           printf("%i\n", f(a, b, c, d));
         }
       }
     }
   }
}

I get the right report:

         -:    0:Source:conds.c
         -:    0:Graph:b-xilinx_zynq_a9_qemu/conds.gcno
         -:    0:Data:b-xilinx_zynq_a9_qemu/conds.gcda
         -:    0:Runs:0
         -:    1:#include <stdio.h>
         -:    2:
function f called 16 returned 100% blocks executed 100%
        16:    3:static __attribute__((__noinline__)) int f(int a, int 
b, int c, int d)
         -:    4:{
        16:    5:  if (a || (b && c) || d) {
branch  0 taken 8 (fallthrough)
branch  1 taken 8
branch  2 taken 4 (fallthrough)
branch  3 taken 4
branch  4 taken 2 (fallthrough)
branch  5 taken 2
branch  6 taken 3 (fallthrough)
branch  7 taken 3
conditions covered 8/8
        13:    6:    return 1;
         -:    7:  } else {
         3:    8:    return 2;
         -:    9:  }
         -:   10:}
         -:   11:
function test called 1 returned 100% blocks executed 100%
         1:   12:void test(void)
         -:   13:{
         3:   14:  for (int a = 0; a <= 1; ++a) {
branch  0 taken 2
branch  1 taken 1 (fallthrough)
conditions covered 2/2
         6:   15:    for (int b = 0; b <= 1; ++b) {
branch  0 taken 4
branch  1 taken 2 (fallthrough)
conditions covered 2/2
        12:   16:      for (int c = 0; c <= 1; ++c) {
branch  0 taken 8
branch  1 taken 4 (fallthrough)
conditions covered 2/2
        24:   17:        for (int d = 0; d <= 1; ++d) {
branch  0 taken 16
branch  1 taken 8 (fallthrough)
conditions covered 2/2
        16:   18:          printf("%i\n", f(a, b, c, d));
call    0 returned 16
call    1 returned 16
         -:   19:        }
         -:   20:      }
         -:   21:    }
         -:   22:  }
         1:   23:}

For exactly the same code in another translation unit with more other 
code I get this report:

function f called 16 returned 100% blocks executed 100%
        16:  172:static __attribute__((__noinline__)) int f(int a, int 
b, int c, int d)
         -:  173:{
        16:  174:  if (a || (b && c) || d) {
branch  0 taken 8 (fallthrough)
branch  1 taken 8
branch  2 taken 4 (fallthrough)
branch  3 taken 4
branch  4 taken 2 (fallthrough)
branch  5 taken 2
branch  6 taken 3 (fallthrough)
branch  7 taken 3
conditions covered 8/8
        13:  175:    return 1;
         -:  176:  } else {
         3:  177:    return 2;
         -:  178:  }
         -:  179:}
         -:  180:
function Init called 1 returned 0% blocks executed 93%
         1:  181:static void Init( rtems_task_argument arg )
         -:  182:{
         -:  183:  struct ethernetif ethif;
         -:  184:  struct netif *netif;
         -:  185:
         -:  186:  (void) arg;
         1:  187:  netif = &ethif.netif;
         -:  188:
         3:  189:  for (int a = 0; a <= 1; ++a) {
branch  0 taken 2
branch  1 taken 1 (fallthrough)
conditions covered 0/2
condition  0 not covered (true)
condition  0 not covered (false)
         6:  190:    for (int b = 0; b <= 1; ++b) {
branch  0 taken 4
branch  1 taken 2 (fallthrough)
conditions covered 0/2
condition  0 not covered (true)
condition  0 not covered (false)
        12:  191:      for (int c = 0; c <= 1; ++c) {
branch  0 taken 8
branch  1 taken 4 (fallthrough)
conditions covered 0/2
condition  0 not covered (true)
condition  0 not covered (false)
        24:  192:        for (int d = 0; d <= 1; ++d) {
branch  0 taken 16
branch  1 taken 8 (fallthrough)
conditions covered 0/2
condition  0 not covered (true)
condition  0 not covered (false)
        16:  193:          printf("%i\n", f(a, b, c, d));
call    0 returned 16
call    1 returned 16
         -:  194:        }
         -:  195:      }
         -:  196:    }
         -:  197:  }
         1:  198:  test();
call    0 returned 1

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