Re: LTO Test Case Help

[Martin Jambor <mjambor at suse dot cz>]

Hi,

On Wed, Dec 05 2018, Michael Ploujnikov wrote:
> Hi,
>
> I'm trying to write a testcase to reproduce duplicate clone symbols
> such as in https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88297 I
> started with a testcase that is known to have constprop clones and
> split it into two object files:

so as we discussed on IRC, the testcase as you posted it to the mailing
list re-defined functions in a way that would not link, with or without
LTO.

When I fixed that, I had to make the following changes in order to
trigger IPA-CP cloning:  1. I had to put the calls in main into a loop,
otherwise everything is cold and we would not clone.  2. I had to make
different foos and bars actually semantically different, otherwise
IPA-ICF unified them, as it should.

The result reproduces the bug.  The two files are below.

Martin


-------------------- 1.c --------------------

volatile int g;

void __attribute__ ((noipa))
use (int v)
{
  g = v;
}

static int __attribute__ ((noinline))
foo (int arg)
{
  return 7 * arg;
}

static int __attribute__ ((noinline))
bar (int arg)
{
  return arg * arg;
}

extern int __attribute__ ((noinline))
entry2 (void);

int  __attribute__ ((noipa))
get_opaque_number (void)
{
  return 1;
}

int main (void)
{
  int i;
  for (i = 0; i < get_opaque_number (); i++)
    {
      use (bar (3));
      use (bar (4));
      use (foo (5));
      use (foo (6));

      entry2 ();
    }
  return 0;
}

-------------------- 2.c --------------------

extern void __attribute__ ((noipa))
use (int v);


static int __attribute__ ((noinline))
foo (int arg)
{
  return 8 * arg;
}

static int __attribute__ ((noinline))
bar (int arg)
{
  return arg * arg + 3;
}

int __attribute__ ((noinline))
entry2 (void)
{
  use (bar (3));
  use (bar (4));
  use (foo (5));
  use (foo (6));
  return 0;
}