Re: middle-end/7245: ICE in find_reloads

Re: middle-end/7245: ICE in find_reloads

[Michael Matz]

The following reply was made to PR middle-end/7245; it has been noted by GNATS.

From: Michael Matz <matz@suse.de>
To: Andreas Jaeger <aj@suse.de>
Cc: <gcc-gnats@gcc.gnu.org>, Ulrich Hecht <uli@suse.de>
Subject: Re: middle-end/7245: ICE in find_reloads
Date: Tue, 9 Jul 2002 21:47:36 +0200 (CEST)

 Again for the bugtracking system.  Manually constructed answer mail ;(
 
 > (insn:QI 61 60 11 (parallel[
 >             (set (reg:CCZ 17 flags)
 >                 (compare:CCZ (ashiftrt:SI (reg/v:SI 0 eax [62])
 >                         (const_int -8 [0xfffffff8]))
 >                     (const_int 0 [0x0])))
 >             (set (reg/v:SI 1 edx [60])
 >                 (ashiftrt:SI (reg/v:SI 0 eax [62])
 >                     (const_int -8 [0xfffffff8])))
 >         ] ) 434 {*ashrsi3_cmp} (nil)
 
 The problem is, that this insn doesn't fulfill it's constraint on operand
 2, which is the -8.  It needs to be an immediate_operand() (which it is),
 with constraint "I", which means >=0 and <= 31, which it isn't.
 Constraints are first checked in reload, so only there we see, that the
 whole selection of the pattern shouldn't have happened.  I.e. I think in
 this case either the predicate immediate_operand is wrong, and shouldn't
 accept values <0, or we need another letter constraint for a range
 including some values <0.
 
 I'm not sure anymore, what happens on x86, if the shift-count is negative
 in the insn.  It's ANDed with 31, right?  In that case, we _might_ accept
 negative values in the constraint.
 
 The problem here is, that this operand can't be reloaded, so both, the
 constraint and the predicate should really match.
 
 
 Ciao,
 Michael.
 

Re: middle-end/7245: ICE in find_reloads

[sayle]

Synopsis: ICE in find_reloads

State-Changed-From-To: analyzed->closed
State-Changed-By: sayle
State-Changed-When: Sun Sep 29 09:40:03 2002
State-Changed-Why:
    I've just reconfirmed that this has been fixed both on
    the 3.2 branch and mainline by Jakub's patch:
    
    2002-07-15  Jakub Jelinek  <jakub@redhat.com>
    
            PR middle-end/7245
            * config/i386/i386.c (const_int_1_31_operand): New.
            * config/i386/i386.h (PREDICATE_CODES): Add it.
            * config/i386/i386.md (ashlsi3_cmp, ashlsi3_cmp_zext, ashlhi3_cmp,
            ashlqi3_cmp, ashrsi3_cmp, ashrsi3_cmp_zext, ashrhi3_cmp, ashrqi3_cmp,
            lshrsi3_cmp, lshrsi3_cmp_zext, lshrhi3_cmp, lshrqi3_cmp): Use it.

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=7245

Re: middle-end/7245: ICE in find_reloads

[jakub]

Synopsis: ICE in find_reloads

Responsible-Changed-From-To: unassigned->jakub
Responsible-Changed-By: jakub
Responsible-Changed-When: Wed Jul 10 09:38:19 2002
Responsible-Changed-Why:
    http://gcc.gnu.org/ml/gcc-patches/2002-07/msg00445.html

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=7245

Re: middle-end/7245: ICE in find_reloads

[paolo]

Synopsis: ICE in find_reloads

Responsible-Changed-From-To: paolo->unassigned
Responsible-Changed-By: paolo
Responsible-Changed-When: Tue Jul  9 12:46:07 2002
Responsible-Changed-Why:
    Assigned to myself by mistake.

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=7245

Re: middle-end/7245: ICE in find_reloads

[paolo]

Synopsis: ICE in find_reloads

Responsible-Changed-From-To: unassigned->paolo
Responsible-Changed-By: paolo
Responsible-Changed-When: Tue Jul  9 12:43:27 2002
Responsible-Changed-Why:
    .
State-Changed-From-To: open->analyzed
State-Changed-By: paolo
State-Changed-When: Tue Jul  9 12:43:27 2002
State-Changed-Why:
    Confirmed. Regression from GCC 2.95.3 -> high priority

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=7245

middle-end/7245: ICE in find_reloads

[aj]

>Number:         7245
>Category:       middle-end
>Synopsis:       ICE in find_reloads
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Jul 09 08:36:00 PDT 2002
>Closed-Date:
>Last-Modified:
>Originator:     aj@suse.de
>Release:        GCC 3.1.1 CVS as of 2002-07-01
>Organization:
>Environment:
i686-linux-gnu with glibc 2.2.5
>Description:
typedef struct m {
        int* c;
} m;

int mdph(m* s)
{
        int v,j,r;
        for(;;){
            v = (r>>-8);
            if(v==0) break;
            s->c[j]= v;
        }
}

generates an ICE:
$ /opt/gcc/3.1-devel/bin/gcc  -c h.c -O2 -v
Reading specs from /opt/gcc/3.1-devel/lib/gcc-lib/i686-pc-linux-gnu/3.1.1/specs
Configured with: /cvs/gcc-3_1-branch/configure --prefix=/opt/gcc/3.1-devel --enable-shared --enable-threads=posix --enable-clocale=gnu --disable-nls --enable-languages=c,c++,f77,java,objc,ada --enable-checking=misc,tree,rtl,gc --with-system-zlib
Thread model: posix
gcc version 3.1.1 20020701 (prerelease)
 /opt/gcc/3.1-devel/lib/gcc-lib/i686-pc-linux-gnu/3.1.1/cc1 -lang-c -v -D__GNUC__=3 -D__GNUC_MINOR__=1 -D__GNUC_PATCHLEVEL__=1 -D__ELF__ -Dunix -D__gnu_linux__ -Dlinux -D__ELF__ -D__unix__ -D__gnu_linux__ -D__linux__ -D__unix -D__linux -Asystem=posix -D__OPTIMIZE__ -D__STDC_HOSTED__=1 -Acpu=i386 -Amachine=i386 -Di386 -D__i386 -D__i386__ -D__tune_i686__ -D__tune_pentiumpro__ h.c -quiet -dumpbase h.c -O2 -version -o /tmp/cccOPrt7.s
GNU CPP version 3.1.1 20020701 (prerelease) (cpplib) (i386 Linux/ELF)
GNU C version 3.1.1 20020701 (prerelease) (i686-pc-linux-gnu)
        compiled by GNU C version 3.1.1 20020701 (prerelease).
ignoring nonexistent directory "/opt/gcc/3.1-devel/i686-pc-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
 /usr/local/include
 /opt/gcc/3.1-devel/include
 /opt/gcc/3.1-devel/lib/gcc-lib/i686-pc-linux-gnu/3.1.1/include
 /usr/include
End of search list.
h.c: In function `mdph':
h.c:9: warning: right shift count is negative
h.c:13: unable to generate reloads for:
(insn:QI 61 60 11 (parallel[ 
            (set (reg:CCZ 17 flags)
                (compare:CCZ (ashiftrt:SI (reg/v:SI 0 eax [62])
                        (const_int -8 [0xfffffff8]))
                    (const_int 0 [0x0])))
            (set (reg/v:SI 1 edx [60])
                (ashiftrt:SI (reg/v:SI 0 eax [62])
                    (const_int -8 [0xfffffff8])))
        ] ) 434 {*ashrsi3_cmp} (nil)
    (expr_list:REG_DEAD (reg/v:SI 0 eax [62])
        (nil)))
h.c:13: Internal compiler error in find_reloads, at reload.c:3576
Please submit a full bug report,
with preprocessed source if appropriate.
See <URL:http://www.gnu.org/software/gcc/bugs.html> for instructions.

The same error occurs in both GCC 3.1.1 CVS and GCC 3.2 CVS.
This is a regression from GCC 2.95.3.
>How-To-Repeat:
Just compile the example code.

note that according to ISO C (6.5.7 clause #4):
  The result of E1 >>  E2  ...
  If E1 has a  signed  type  and  a
  negative  value,  the  resulting  value  is 
  implementation-defined.
>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted: