Re: Fix IA-64 bootstrap failure

[Jan Hubicka <jh at suse dot cz>]

> Jan Hubicka <jh@suse.cz> writes:
> 
> >> Jan Hubicka <jh@suse.cz> writes:
> >> 
> >> > I've commited as obvious the attached patch that solves the bootstrap
> >> > failure by clearing out pointer pointing to value being released.
> >> 
> >> Doesn't work for me, I still get a ICE while compiling c-decl.c on
> >> ia64-linux.
> >
> > Sorry, I missed your emails, so didin't reply earlier.
> > Do you still get the failure?
> 
> Yes.
> 
> stage1/xgcc -Bstage1/ -B/usr/local/ia64-suse-linux/bin/ -c   -g -O2 -DIN_GCC   -W -Wall -Wwrite-strings -Wstrict-prototypes -Wmissing-prototypes -pedantic -Wno-long-long -Wold-style-definition -Werror -fno-common   -DHAVE_CONFIG_H    -I. -I. -I../../gcc -I../../gcc/. -I../../gcc/../include  ../../gcc/c-decl.c -o c-decl.o
> ../../gcc/c-decl.c: In function `xref_tag':
> ../../gcc/c-decl.c:4737: internal compiler error: Segmentation fault
> Please submit a full bug report,
> with preprocessed source if appropriate.
> See <URL:http://gcc.gnu.org/bugs.html> for instructions.

Hi,
this patch solve at least same crash I can get on i386 bootstrap with
-fsched2-use-superblocks.  The problem is that we remove location list header
when it is no longer containing usefull values, but alias.c dereference it.
I believe that the scheme of removing the datastructures produce same decisions
as it would if the useless values were not recycled.

Bootstrapped/regtested i686-pc-gnu-linux, OK for mainline/3.4 branch?

2004-01-28  Jan Hubicka  <jh@suse.cz>
	* alias.c (find_base_term, get_addr):  Do not dereference NULL
	pointer when all VALUE's locations has been invalidated.
Index: alias.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/alias.c,v
retrieving revision 1.212
diff -c -3 -p -r1.212 alias.c
*** alias.c	22 Jan 2004 11:35:58 -0000	1.212
--- alias.c	28 Jan 2004 19:45:14 -0000
*************** find_base_term (rtx x)
*** 1325,1330 ****
--- 1325,1332 ----
  
      case VALUE:
        val = CSELIB_VAL_PTR (x);
+       if (!val)
+ 	return 0;
        for (l = val->locs; l; l = l->next)
  	if ((x = find_base_term (l->loc)) != 0)
  	  return x;
*************** get_addr (rtx x)
*** 1502,1515 ****
    if (GET_CODE (x) != VALUE)
      return x;
    v = CSELIB_VAL_PTR (x);
!   for (l = v->locs; l; l = l->next)
!     if (CONSTANT_P (l->loc))
!       return l->loc;
!   for (l = v->locs; l; l = l->next)
!     if (GET_CODE (l->loc) != REG && GET_CODE (l->loc) != MEM)
!       return l->loc;
!   if (v->locs)
!     return v->locs->loc;
    return x;
  }
  
--- 1504,1520 ----
    if (GET_CODE (x) != VALUE)
      return x;
    v = CSELIB_VAL_PTR (x);
!   if (v)
!     {
!       for (l = v->locs; l; l = l->next)
! 	if (CONSTANT_P (l->loc))
! 	  return l->loc;
!       for (l = v->locs; l; l = l->next)
! 	if (GET_CODE (l->loc) != REG && GET_CODE (l->loc) != MEM)
! 	  return l->loc;
!       if (v->locs)
! 	return v->locs->loc;
!     }
    return x;
  }