Re: assign_parm_setup_block handling of parallels

[Aldy Hernandez <aldyh at redhat dot com>]

On Thu, Dec 23, 2004 at 02:37:59PM -0800, Richard Henderson wrote:
> On Thu, Dec 23, 2004 at 05:45:43PM -0400, Aldy Hernandez wrote:
> > In my limited understanding of the problem I think we can allow the
> > optimization for one-member parallels iff the hard register will span
> > more than one register.  I think this will satisfy both PPC64 and
> > Sparc64.
> 
> I can't decide whether the better check is
> 
> 	nelts > 0
> 	|| hard_regno_nregs[REGNO (elt0)][GET_MODE (elt0)] > 1

As dicussed, you prefer this option.

I have tested the following patch on ppc-linux and ppc-eabispe.  I know
you said it was OK, but could you eye it over since I had to split up
the condition?

Thanks.

	* function.c (assign_parm_setup_block): Relax condition on
	multi-register optimization.

Index: function.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/function.c,v
retrieving revision 1.600
diff -c -p -r1.600 function.c
*** function.c	11 Jan 2005 09:51:17 -0000	1.600
--- function.c	12 Jan 2005 00:27:51 -0000
*************** assign_parm_setup_block (struct assign_p
*** 2560,2601 ****
    /* If we've a non-block object that's nevertheless passed in parts,
       reconstitute it in register operations rather than on the stack.  */
    if (GET_CODE (entry_parm) == PARALLEL
!       && data->nominal_mode != BLKmode
!       && XVECLEN (entry_parm, 0) > 1
!       && use_register_for_decl (parm))
      {
!       rtx parmreg = gen_reg_rtx (data->nominal_mode);
  
!       push_to_sequence (all->conversion_insns);
  
!       /* For values returned in multiple registers, handle possible
! 	 incompatible calls to emit_group_store.
  
! 	 For example, the following would be invalid, and would have to
! 	 be fixed by the conditional below:
  
! 	   emit_group_store ((reg:SF), (parallel:DF))
! 	   emit_group_store ((reg:SI), (parallel:DI))
  
! 	 An example of this are doubles in e500 v2:
! 	   (parallel:DF (expr_list (reg:SI) (const_int 0))
! 	                (expr_list (reg:SI) (const_int 4))).  */
!       if (data->nominal_mode != data->passed_mode)
! 	{
! 	  rtx t = gen_reg_rtx (GET_MODE (entry_parm));
! 	  emit_group_store (t, entry_parm, NULL_TREE,
! 			    GET_MODE_SIZE (GET_MODE (entry_parm)));
! 	  convert_move (parmreg, t, 0);
! 	}
!       else
! 	emit_group_store (parmreg, entry_parm, data->nominal_type,
! 			  int_size_in_bytes (data->nominal_type));
  
!       all->conversion_insns = get_insns ();
!       end_sequence ();
  
!       SET_DECL_RTL (parm, parmreg);
!       return;
      }
  
    size = int_size_in_bytes (data->passed_type);
--- 2560,2606 ----
    /* If we've a non-block object that's nevertheless passed in parts,
       reconstitute it in register operations rather than on the stack.  */
    if (GET_CODE (entry_parm) == PARALLEL
!       && data->nominal_mode != BLKmode)
      {
!       rtx elt0 = XEXP (XVECEXP (entry_parm, 0, 0), 0);
  
!       if ((XVECLEN (entry_parm, 0) > 1
! 	   || hard_regno_nregs[REGNO (elt0)][GET_MODE (elt0)])
! 	  && use_register_for_decl (parm))
! 	{
! 	  rtx parmreg = gen_reg_rtx (data->nominal_mode);
  
! 	  push_to_sequence (all->conversion_insns);
  
! 	  /* For values returned in multiple registers, handle possible
! 	     incompatible calls to emit_group_store.
  
! 	     For example, the following would be invalid, and would have to
! 	     be fixed by the conditional below:
  
! 	     emit_group_store ((reg:SF), (parallel:DF))
! 	     emit_group_store ((reg:SI), (parallel:DI))
  
! 	     An example of this are doubles in e500 v2:
! 	     (parallel:DF (expr_list (reg:SI) (const_int 0))
! 	     (expr_list (reg:SI) (const_int 4))).  */
! 	  if (data->nominal_mode != data->passed_mode)
! 	    {
! 	      rtx t = gen_reg_rtx (GET_MODE (entry_parm));
! 	      emit_group_store (t, entry_parm, NULL_TREE,
! 				GET_MODE_SIZE (GET_MODE (entry_parm)));
! 	      convert_move (parmreg, t, 0);
! 	    }
! 	  else
! 	    emit_group_store (parmreg, entry_parm, data->nominal_type,
! 			      int_size_in_bytes (data->nominal_type));
  
! 	  all->conversion_insns = get_insns ();
! 	  end_sequence ();
! 
! 	  SET_DECL_RTL (parm, parmreg);
! 	  return;
! 	}
      }
  
    size = int_size_in_bytes (data->passed_type);