[Bug c/32171] New: ICE w/ -ftree-loop-linear, gcc4.1 and 4.2

["bu dot gz dot 200-7 at src dot neostrada dot pl" <gcc-bugzilla at gcc dot gnu dot org>]

gcc segfaults on the code below (which is a simplified des.c from
nettle-1.15.tar.gz). '-ftree-loop-linear' seems to be the trigger,
at least -O1 is required too.
ICEs:
 gcc version 4.2.1 20070531 (prerelease)
 gcc version 4.1.3 20070519 (prerelease)
survives:
 gcc version 4.0.4 20061113 (prerelease)

uname -a:
Linux node 2.6.21.1-g4ead5093 #29 PREEMPT Sun May 6 22:54:15 CEST 2007 i686
GNU/Linux

$ gcc -O1 -ftree-loop-linear -c des.c
des.c: In function 'f':
des.c:4: internal compiler error: Segmentation fault

where des.c is:
---
int f( char *p );
int f( char *p )
{
  unsigned n, w;
  char a[4];

  n = 4;
  do {
    w = *p++;
    do {
      --n;
      w >>= 1;
      a[n] =  w;
    } while ( w >= 16 );
  } while ( n );

  return a[0];
}
---


-- 
           Summary: ICE w/ -ftree-loop-linear, gcc4.1 and 4.2
           Product: gcc
           Version: 4.2.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: bu dot gz dot 200-7 at src dot neostrada dot pl
GCC target triplet: i486-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32171