Re: ia64 bootstrap failure with the reload-branch

[Bernd Schmidt <bernds_cb1 at t-online dot de>]

(slowly catching up with vacation backlog)

James E Wilson wrote:

> Reload is using registers without setting regs_ever_live.  The IA-64 
> prologue code needs a temp register to save/restore b0, and it uses 
> regs_ever_live to find one.  Also, because we have variable size 
> register windows, we need the regs_ever_live info to be accurate so we 
> can set up the register windows properly.
>
> The problem happens in inherit_one_chain, but it looks like there are 
> other similar places that may have the same problem.  Ugly patch 
> attached that gets me past this problem.  We should probably get Bernd's 
> opinion on how he thinks this should be fixed.

Thanks for debugging this.  The patch isn't quite right, because setting 
additional bits in regs_ever_live may need to cause additional 
iterations of calculate_needs_all_insns.

Try the patch below - does it fix the problem?


Bernd
	* reload1.c (find_optional_reg, inherit_one_chain): Always use
	set_reload_reg to assign a register to a reload.

Index: reload1.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/reload1.c,v
retrieving revision 1.463.2.3
diff -c -p -r1.463.2.3 reload1.c
*** reload1.c	7 Apr 2005 11:21:35 -0000	1.463.2.3
--- reload1.c	7 Apr 2005 11:30:48 -0000
*************** static HARD_REG_SET *pseudo_previous_reg
*** 149,155 ****
  static HARD_REG_SET *pseudo_forbidden_regs;
  
  /* All hard regs that have been used as spill registers for any insn are
!    marked in this set.  */
  static HARD_REG_SET used_spill_regs;
  
  /* Nonzero if indirect addressing is supported on the machine; this means
--- 149,156 ----
  static HARD_REG_SET *pseudo_forbidden_regs;
  
  /* All hard regs that have been used as spill registers for any insn are
!    marked in this set.  This is used to update regs_ever_live in
!    finish_spills.  */
  static HARD_REG_SET used_spill_regs;
  
  /* Nonzero if indirect addressing is supported on the machine; this means
*************** find_optional_reg (struct reload *rl, HA
*** 2916,2926 ****
        if (i == nregs)
  	{
  	  if (do_allocate)
! 	    {
! 	      rl->nregs = nregs;
! 	      rl->reginfo.regno = suggested;
! 	      rl->reginfo.allocated = 1;
! 	    }
  	  return 1;
  	}
      }
--- 2917,2923 ----
        if (i == nregs)
  	{
  	  if (do_allocate)
! 	    set_reload_reg (rl, suggested);
  	  return 1;
  	}
      }
*************** find_optional_reg (struct reload *rl, HA
*** 2945,2955 ****
      return 0;
  
    if (do_allocate)
!     {
!       rl->nregs = HARD_REGNO_NREGS (best_reg, rl->mode);
!       rl->reginfo.regno = best_reg;
!       rl->reginfo.allocated = 1;
!     }
    return 1;
  }
  
--- 2942,2949 ----
      return 0;
  
    if (do_allocate)
!     set_reload_reg (rl, best_reg);
! 
    return 1;
  }
  
*************** inherit_one_chain (struct inherit_chain 
*** 3656,3664 ****
       as above.  */
  
    /* Change the head reload to use the inheritance register.  */
!   head_rl->nregs = HARD_REGNO_NREGS (best_reg, head_rl->mode);
!   head_rl->reginfo.regno = best_reg;
!   head_rl->reginfo.allocated = 1;
  
    /* Extend lifetime of original reload.  Set the LIVE_UNTIL_END flag so
       that following calls to compute_birth_death will preserve this
--- 3650,3656 ----
       as above.  */
  
    /* Change the head reload to use the inheritance register.  */
!   set_reload_reg (head_rl, best_reg);
  
    /* Extend lifetime of original reload.  Set the LIVE_UNTIL_END flag so
       that following calls to compute_birth_death will preserve this