[Bug gcov-profile/97919] New: [GCOV]volatile member in struct lead to incorrect code coverage

[yangyibiao at outlook dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97919

            Bug ID: 97919
           Summary: [GCOV]volatile member in struct lead to incorrect code
                    coverage
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: gcov-profile
          Assignee: unassigned at gcc dot gnu.org
          Reporter: yangyibiao at outlook dot com
                CC: marxin at gcc dot gnu.org
  Target Milestone: ---

$ cat test.c
static unsigned int s_irq[10];

static struct S {
  volatile unsigned int slock;
  unsigned int irq;
} sp[10];

static __inline__ __attribute__((always_inline)) int f1(int irq)
{
  return ((irq == 2) ? 9 : irq);
}

void f(void)
{
  struct S *up;
  int i;

  for (i=0, up=sp; i<10; i++, up++)
    up->irq = f1(s_irq[i]);
}

int main(void){ f(); }


$ gcc -O0 --coverage test.c; ./a.out; gcov test.c; cat test.c.gcov
File 'test.c'
Lines executed:100.00% of 6
Creating 'test.c.gcov'

        -:    0:Source:test.c
        -:    0:Graph:test.gcno
        -:    0:Data:test.gcda
        -:    0:Runs:1
        -:    1:static unsigned int s_irq[10];
        -:    2:
        -:    3:static struct S {
        -:    4:  volatile unsigned int slock;
        -:    5:  unsigned int irq;
        -:    6:} sp[10];
        -:    7:
        -:    8:static __inline__ __attribute__((always_inline)) int f1(int
irq)
        -:    9:{
      10*:   10:  return ((irq == 2) ? 9 : irq);
        -:   11:}
        -:   12:
        1:   13:void f(void)
        -:   14:{
        -:   15:  struct S *up;
        -:   16:  int i;
        -:   17:
       11:   18:  for (i=0, up=sp; i<10; i++, up++)
       20:   19:    up->irq = f1(s_irq[i]);
        1:   20:}
        -:   21:
        1:   22:int main(void){ f(); }

################
We can found that Line 19 is wrongly marked as executed 20 times.
When debug this program in debugger, it only hit 10 time.



$ gcc --version; gcov --version
gcc (GCC) 10.0.1 20200419 (experimental)
Copyright (C) 2020 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

gcov (GCC) 10.0.1 20200419 (experimental)
Copyright (C) 2020 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.
There is NO warranty; not even for MERCHANTABILITY or 
FITNESS FOR A PARTICULAR PURPOSE.