Re: [PATCH 3/7] GCOV: add support for lines with an unexecuted lines.

[Eric Botcazou]

> It's possible to have a line of code that has a non-zero coverage.
> However, it can contain unexecuted blocks and I hope adding a
> notification can be usefull. LLVM also does that:
> 
>         -:    0:Source:ternary.c
>         -:    0:Graph:ternary.gcno
>         -:    0:Data:ternary.gcda
>         -:    0:Runs:1
>         -:    0:Programs:1
>         -:    1:int b, c, d, e;
>         -:    2:
>         1:    3:int main()
>         -:    4:{
>        1*:    5:      int a = b < 1 ? (c < 3 ? d : c) : e;
>         1:    6:        return a;
>         -:    7:}

That can be annoying for languages more expressive than C's family though.

For example Ada has built-in overflow checking for addition, which means that:

  function Add (I1, I2 : Integer) return Integer is
  begin
    return I1 + I2;
  end;

will now have the '*' symbol:

        1:    3:  function Add (I1, I2 : Integer) return Integer is
        -:    4:  begin
       1*:    5:    return I1 + I2;
        -:    6:  end;

which doesn't really make sense from the user's viewpoint.  How does LLVM deal 
with that (assuming it does)?

Testcase attached, compile with gnatmake p -fprofile-arcs -ftest-coverage.

-- 
Eric Botcazou
procedure P is

  function Add (I1, I2 : Integer) return Integer is
  begin
    return I1 + I2;
  end;

begin
  if Add (1, 2) /= 3 then
    raise Program_Error;
  end if;
end;