[Bug tree-optimization/20803] New: Pseudo-infinite recursion in ivopts

[Bug tree-optimization/20803] New: Pseudo-infinite recursion in ivopts

[dalej at gcc dot gnu dot org]

Compile the following with -O1 in 4.0 branch.  Don't be in a hurry; I killed it
after 10 minutes, but I'm told it goes for hours.
With -fno-ivopts added it completes almost immediately.  The recursion is
in instantiate_parameters_1 called from simple_iv.

/**********************************************************************/

extern int Loop1Max,Loop2Max;
void bar(int a, int b, int c);
void foo(int parm);

/**********************************************************************/

#define x7(x) x;x;x;x;x;x;x
#define REPL(x) x7(x);x7(x);x7(x);x7(x);x7(x);x7(x)     
        // 6 * 7 = 42 (0.06 seconds compile-time for GCC 3.3, 1 year for GCC 4.0)
        // Changing REPL from 42 to 21 will reduce GCC 4.0 compile-time to 20 sec
onds.

/**********************************************************************/
void foo(int parm)
{
        register int x,y;
        register int a,b,c;

        a = b = c = parm;

        for (y=0; y<Loop2Max; ++y)
        {
                for (x=0; x<Loop1Max; ++x)
                {
                        REPL
                        (
                                a = c * a;
                                b = a * b;
                                c = parm - a;
                        );
                }
        }

        bar(a,b,c);

        return;
}

/**********************************************************************/

-- 
           Summary: Pseudo-infinite recursion in ivopts
           Product: gcc
           Version: 4.0.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: dalej at gcc dot gnu dot org
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: powerpc-apple-darwin8.0.0
  GCC host triplet: powerpc-apple-darwin8.0.0
GCC target triplet: powerpc-apple-darwin8.0.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20803

[Bug tree-optimization/20803] Pseudo-infinite recursion in ivopts

[dalej at gcc dot gnu dot org]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |sebastian dot pop at cri dot
                   |                            |ensmp dot fr


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20803

[Bug tree-optimization/20803] Pseudo-infinite recursion in ivopts

[dberlin at dberlin dot org]

------- Additional Comments From dberlin at gcc dot gnu dot org  2005-04-07 00:20 -------
Subject: Re:  New: Pseudo-infinite recursion
	in ivopts

On Thu, 2005-04-07 at 00:16 +0000, dalej at gcc dot gnu dot org wrote:
> Compile the following with -O1 in 4.0 branch.  Don't be in a hurry; I killed it
> after 10 minutes, but I'm told it goes for hours.
> With -fno-ivopts added it completes almost immediately.  The recursion is
> in instantiate_parameters_1 called from simple_iv.


One of the patches that went into 4.1 for this problem probably needs to
be backported.




-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20803

[Bug tree-optimization/20803] Pseudo-infinite recursion in ivopts

[dalej at gcc dot gnu dot org]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |rakdver at gcc dot gnu dot
                   |                            |org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20803

[Bug tree-optimization/20803] Pseudo-infinite recursion in ivopts

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-04-07 05:35 -------
I think this is very much related to PR 20742.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
  BugsThisDependsOn|                            |20742


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20803

[Bug tree-optimization/20803] Pseudo-infinite recursion in ivopts

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-04-07 06:21 -------
After looking into this testcase and the one in PR 20742 with gdb on cc1, I find that this is the same 
bug as PR 20742.

*** This bug has been marked as a duplicate of 20742 ***

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20803

[Bug tree-optimization/20803] Pseudo-infinite recursion in ivopts

[pinskia at gcc dot gnu dot org]

-- 
Bug 20803 depends on bug 20742, which changed state.

Bug 20742 Summary: [4.0 Regression] Hang in tree_ssa_iv_optimize_loop
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20742

           What    |Old Value                   |New Value
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20803