[Bug gcov-profile/97910] New: [GCOV]"&&" lead to incorrect code coverage when multiple expressions of a single statement fall in different lines

[Bug gcov-profile/97910] New: [GCOV]"&&" lead to incorrect code coverage when multiple expressions of a single statement fall in different lines

[yangyibiao at outlook dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97910

            Bug ID: 97910
           Summary: [GCOV]"&&" lead to incorrect code coverage when
                    multiple expressions of a single statement fall in
                    different lines
           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
struct hx {
  int a, b, c;
} __attribute__ ((aligned));

static struct hx x = {0xc11f, 0xc22f, ~1};
static struct hx y = {0xfd10, 0xfe20, ~2};

int f()
{
  return ((x.a & 0x3ff0) == (y.a & 0x03ff) && 
   (x.b & 0x3ff0) == (y.b & 0x03ff));
}

int main() { f(); }

$ gcc -O0 --coverage test.c; ./a.out; gcov test.c; cat test.c.gcov
File 'test.c'
Lines executed:100.00% of 4
Creating 'test.c.gcov'

        -:    0:Source:test.c
        -:    0:Graph:test.gcno
        -:    0:Data:test.gcda
        -:    0:Runs:1
        -:    1:struct hx {
        -:    2:  int a, b, c;
        -:    3:} __attribute__ ((aligned));
        -:    4:
        -:    5:static struct hx x = {0xc11f, 0xc22f, ~1};
        -:    6:static struct hx y = {0xfd10, 0xfe20, ~2};
        -:    7:
        1:    8:int f()
        -:    9:{
       2*:   10:  return ((x.a & 0x3ff0) == (y.a & 0x03ff) && 
        1:   11:   (x.b & 0x3ff0) == (y.b & 0x03ff));
        -:   12:}
        -:   13:
        1:   14:int main() { f(); }

################################
We can found that Line #10 is wrongly marked as executed twice. 
When debug this program in debugger, Line 10 is only hit once.
Note that: When Line 10 and Line 11 in the same line, the result will be
correct. 


$ 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.

[Bug gcov-profile/97910] [GCOV]"&&" lead to incorrect code coverage when multiple expressions of a single statement fall in different lines

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97910

Martin Liška <marxin at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2020-11-20

--- Comment #1 from Martin Liška <marxin at gcc dot gnu.org> ---
Confirmed, it's related to how we generate code for the condition:

  <bb 2> :
  [pr97910.c:10:13] _1 = [pr97910.c:10:13] x.a;
  [pr97910.c:10:16] _2 = _1 & 16368;
  [pr97910.c:10:31] _3 = [pr97910.c:10:31] y.a;
  [pr97910.c:10:34] _4 = _3 & 1023;
  [pr97910.c:10:44] if (_2 == _4)
    goto <bb 3>; [INV]
  else
    goto <bb 5>; [INV]

  <bb 3> :
  [pr97910.c:11:6] _5 = [pr97910.c:11:6] x.b;
  [pr97910.c:11:9] _6 = _5 & 16368;
  [pr97910.c:11:24] _7 = [pr97910.c:11:24] y.b;
  [pr97910.c:11:27] _8 = _7 & 1023;
  [pr97910.c:10:44] if (_6 == _8)
    goto <bb 4>; [INV]
  else
    goto <bb 5>; [INV]

  <bb 4> :
  [pr97910.c:10:44] iftmp.0_11 = 1;
  [pr97910.c:10:44] goto <bb 6>; [INV]

  <bb 5> :
  [pr97910.c:10:44] iftmp.0_12 = 0;