[Bug gcov-profile/97921] New: [GCOV]inline function with an incremental argument lead to incorrect coverage

[yangyibiao at outlook dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97921

            Bug ID: 97921
           Summary: [GCOV]inline function with an incremental argument
                    lead to incorrect 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
int v = 8;

__attribute__ ((noinline)) 
int foo(int x, ...)
{ return 0; }

extern inline __attribute__ ((always_inline, gnu_inline)) 
int bar(int x, ...)
{
  return foo(x);
}

int main()
{
  if (bar(0, ++v) != 0)
    return 1;
  return 0;
}

$ gcc -O0 --coverage test.c; ./a.out; gcov test.c; cat test.c.gcov
File 'test.c'
Lines executed:85.71% of 7
Creating 'test.c.gcov'

        -:    0:Source:test.c
        -:    0:Graph:test.gcno
        -:    0:Data:test.gcda
        -:    0:Runs:1
        -:    1:int v = 8;
        -:    2:
        -:    3:__attribute__ ((noinline)) 
        1:    4:int foo(int x, ...)
        1:    5:{ return 0; }
        -:    6:
        -:    7:extern inline __attribute__ ((always_inline, gnu_inline)) 
        -:    8:int bar(int x, ...)
        -:    9:{
        1:   10:  return foo(x);
        -:   11:}
        -:   12:
        1:   13:int main()
        -:   14:{
        2:   15:  if (bar(0, ++v) != 0)
    #####:   16:    return 1;
        1:   17:  return 0;
        -:   18:}


##########################
Line 15 is wrongly marked as executed 2 times.
When debug it in debugger and set breakpoint at Line 15, it only hit once.


$ 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.