[patch] fix df_bb_regno_last_{def,use}_find

[Steven Bosscher <stevenb at suse dot de>]

Hi,

This patch fixes the functions mentioned in the subject, which would
return bogus results in many cases.  These functions are not used on
mainline AFAICT, but we use them a lot in the new forward propagation
pass for RTL.  Does anyone mind if I apply this to mainline?

Gr.
Steven

        * df.c (df_local_def_available_p): Handle SUBREG refs.
	(df_bb_regno_last_use_find): Fix to make it return
	what it is supposed to.
	(df_bb_regno_last_def_find): Likewise.

Index: df.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/df.c,v
retrieving revision 1.87
diff -c -3 -p -r1.87 df.c
*** df.c	28 Jul 2005 01:47:06 -0000	1.87
--- df.c	7 Oct 2005 16:13:12 -0000
*************** df_local_def_available_p (struct df *df,
*** 3262,3268 ****
    struct df_link *link;
    int def_luid = DF_INSN_LUID (df, DF_REF_INSN (def));
    int in_bb = 0;
!   unsigned int regno = REGNO (def->reg);
    basic_block bb;
  
    /* The regs must be local to BB.  */
--- 3262,3268 ----
    struct df_link *link;
    int def_luid = DF_INSN_LUID (df, DF_REF_INSN (def));
    int in_bb = 0;
!   unsigned int regno = DF_REF_REGNO (def);
    basic_block bb;
  
    /* The regs must be local to BB.  */
*************** struct ref *
*** 3300,3305 ****
--- 3300,3307 ----
  df_bb_regno_last_use_find (struct df *df, basic_block bb, unsigned int regno)
  {
    struct df_link *link;
+   struct ref *last_use = NULL;
+   bool in_bb = false;
  
    /* This assumes that the reg-use list is ordered such that for any
       BB, the last use is found first.  However, since the BBs are not
*************** df_bb_regno_last_use_find (struct df *df
*** 3309,3318 ****
      {
        struct ref *use = link->ref;
  
        if (DF_REF_BB (use) == bb)
! 	return use;
      }
!   return 0;
  }
  
  
--- 3311,3327 ----
      {
        struct ref *use = link->ref;
  
+       /* The first use in the desired block.  */
        if (DF_REF_BB (use) == bb)
! 	{
! 	  in_bb = true;
! 	  last_use = use;
! 	}
!       /* We are past the last use in the desired block.  */
!       else if (in_bb)
! 	break;
      }
!   return last_use;
  }
  
  
*************** df_bb_regno_last_def_find (struct df *df
*** 3351,3363 ****
    for (link = df->regs[regno].defs; link; link = link->next)
      {
        struct ref *def = link->ref;
!       /* The first time in the desired block.  */ 
        if (DF_REF_BB (def) == bb)
! 	  in_bb = 1;
!       /* The last def in the desired block.  */
        else if (in_bb)
!         return last_def;
!       last_def = def;
      }
    return last_def;
  }
--- 3360,3375 ----
    for (link = df->regs[regno].defs; link; link = link->next)
      {
        struct ref *def = link->ref;
! 
!       /* The first def in the desired block.  */
        if (DF_REF_BB (def) == bb)
! 	{
! 	  in_bb = true;
! 	  last_def = def;
! 	}
!       /* We are past the last def in the desired block.  */
        else if (in_bb)
! 	break;
      }
    return last_def;
  }