[Bug rtl-optimization/23453] [4.0/4.1 regression] miscompilation of PARI/GP on x86 with gcse after reload

[Bug rtl-optimization/23453] [4.0/4.1 regression] miscompilation of PARI/GP on x86 with gcse after reload

[bonzini at gcc dot gnu dot org]

------- Comment #8 from bonzini at gcc dot gnu dot org  2005-10-14 11:38 -------
> gcse after reload may move loads from stack around stack pointer changes. here
> is simple workaround, it is supposed to prevent gcse after reload from touching
> expressions containing stack pointer at all.

Off the top of my head, if GCSE-after-reload is designed to remove redundant
spills, will it do *anything* with your patch?


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23453

[Bug rtl-optimization/23453] [4.0/4.1 regression] miscompilation of PARI/GP on x86 with gcse after reload

[mmitchel at gcc dot gnu dot org]

------- Comment #9 from mmitchel at gcc dot gnu dot org  2005-10-31 05:09 -------
Leaving as P2.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23453

[Bug rtl-optimization/23453] [4.0/4.1 regression] miscompilation of PARI/GP on x86 with gcse after reload

[steven at gcc dot gnu dot org]

------- Comment #10 from steven at gcc dot gnu dot org  2005-11-05 10:48 -------
This doesn't fail for me with the test case from comment #6...  :-(


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23453

[Bug rtl-optimization/23453] [4.0/4.1/4.2 regression] miscompilation of PARI/GP on x86 with gcse after reload

[steven at gcc dot gnu dot org]

------- Comment #11 from steven at gcc dot gnu dot org  2005-12-15 06:50 -------
If nobody is going to fix gcse2, the right thing to do is to not set
flag_gcse_after_reload for optimize >= 3 in opts.c:

Index: opts.c
===================================================================
--- opts.c      (revision 108560)
+++ opts.c      (working copy)
@@ -588,7 +588,6 @@ decode_options (unsigned int argc, const
     {
       flag_inline_functions = 1;
       flag_unswitch_loops = 1;
-      flag_gcse_after_reload = 1;
     }

   if (optimize < 2 || optimize_size)


Obviously it would be better to just fix the bug, but so far I, for one, can't
get a handle on it.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23453

[Bug rtl-optimization/23453] [4.0/4.1/4.2 regression] miscompilation of PARI/GP on x86 with gcse after reload

[steven at gcc dot gnu dot org]

------- Comment #12 from steven at gcc dot gnu dot org  2005-12-20 10:48 -------
Almost certainly a dup of PR25196


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23453

[Bug rtl-optimization/23453] [4.0/4.1/4.2 regression] miscompilation of PARI/GP on x86 with gcse after reload

[belyshev at depni dot sinp dot msu dot ru]

------- Comment #13 from belyshev at depni dot sinp dot msu dot ru  2005-12-20 10:59 -------
Marking as dup of bug 25196 because that bug contains simpler test case.

*** This bug has been marked as a duplicate of 25196 ***


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belyshev at depni dot sinp dot msu dot ru changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |DUPLICATE


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23453

[Bug rtl-optimization/23453] [4.0/4.1/4.2 regression] miscompilation of PARI/GP on x86 with gcse after reload

[steven at gcc dot gnu dot org]

------- Comment #14 from steven at gcc dot gnu dot org  2005-12-20 16:11 -------
The patch proposed in bug 25196 comment #8 indeed makes the test case from
comment #6 in this PR work (at least, it stops it from segfaulting).


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23453

[Bug rtl-optimization/23453] [4.0/4.1 regression] miscompilation of PARI/GP on x86 with gcse after reload

[mmitchel at gcc dot gnu dot org]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.0.2                       |4.0.3


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23453

[Bug rtl-optimization/23453] [4.0/4.1 regression] miscompilation of PARI/GP on x86 with gcse after reload

[belyshev at depni dot sinp dot msu dot ru]

------- Additional Comments From belyshev at depni dot sinp dot msu dot ru  2005-08-19 19:51 -------
gcse after reload may move loads from stack around stack pointer changes. here
is simple workaround, it is supposed to prevent gcse after reload from touching
expressions containing stack pointer at all.

Index: cse.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/cse.c,v
retrieving revision 1.359
diff -u -r1.359 cse.c
--- cse.c	29 Jul 2005 05:57:37 -0000	1.359
+++ cse.c	19 Aug 2005 19:33:49 -0000
@@ -2221,6 +2221,14 @@
 		return 0;
 	      }
 	  }
+	else
+	  {
+	    if (x == stack_pointer_rtx)
+	      {
+		*do_not_record_p = 1;
+		return 0;
+	      }
+	  }
 
 	hash += ((unsigned int) REG << 7);
         hash += (have_reg_qty ? (unsigned) REG_QTY (regno) : regno);


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23453

[Bug rtl-optimization/23453] [4.0/4.1 regression] miscompilation of PARI/GP on x86 with gcse after reload

[belyshev at depni dot sinp dot msu dot ru]

------- Additional Comments From belyshev at depni dot sinp dot msu dot ru  2005-08-19 01:03 -------
Single-file testcase, compile with "-march=i486 -O2 -fomit-frame-pointer
-fno-strict-aliasing -fgcse-after-reload":

bar ()
{
  exit (0);
}

baz (x)
{
  return x;
}

foo ()
{
  abort ();
}

ker0 (int *x0, int a) 
{
  int *x, *c, *d, p, av, i, j, k, r, t, n, m, *dd;
  n = x0;
  m = x0 [0];
  x = baz (x0);
  if (a) 
    {
      if (m)
	foo ();
      for (k = 1; k <= n; k ++)
	((int **) x) [k] = foo (x [k]);
    }
  for (k = 1; k < m; k ++) 
    c [k] = 0;
  av = k;
  for (k = 0;; k ++) 
    {
      j = bar (x [k], 0, 0, 0);
      if (j > m) 
	{
	  r ++;
	  for (j = 1; j < k; j ++)
	    if (d [j])
	      ((int **) x) [k] [d [j]] = 0;
	}
      else
	{
	  foo (0, x [j]);
	  for (i = k + 1; i; i ++)
	    ((int *) x) [j] = 0;
	  for (t = 1; m; )
	    if (j) 
	      {
		p = x [t];
		for (i = k + 1; i; i ++)
		  x [t] = foo (x [i], foo (p, x [j]));
		if (av)
		  foo (k);
	      }
	}
    }
  *dd = r;
}

int main (void)
{
  int x = 0;
  ker0 (&x, 0);
  abort ();
}


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23453