Combine_stack_adjustments improvement

[Jan Hubicka <hubicka at atrey dot karlin dot mff dot cuni dot cz>]

Hi
This patch allows arbitary references to stack in between of stack
adjustments - not only the loads/stores.

In future it would be nice to merge this with related register elimination
code in reload, but this don't seems to be easy task.
Honza

Thu Apr 27 21:50:56 CEST 2000  Jan Hubicka  <jh@suse.cz>
	* regmove.c (struct record_stack_memrefs_data): New.
	(record_stack_memrefs): New function.
	(combine_stack_adjustments_for_block): Use it.

*** regmove.c.old	Thu Apr 27 21:32:02 2000
--- regmove.c	Thu Apr 27 22:08:12 2000
*************** static struct csa_memlist *record_one_st
*** 2100,2105 ****
--- 2100,2106 ----
  static int try_apply_stack_adjustment
    PARAMS ((rtx, struct csa_memlist *, HOST_WIDE_INT, HOST_WIDE_INT));
  static void combine_stack_adjustments_for_block PARAMS ((basic_block));
+ static int record_stack_memrefs 	PARAMS ((rtx *, void *));
  
  
  /* Main entry point for stack adjustment combination.  */
*************** try_apply_stack_adjustment (insn, memlis
*** 2258,2263 ****
--- 2259,2309 ----
      return 0;
  }
  
+ /* Called via for_each_rtx and used to record all stack memory references in
+    the insn and discard all other stack pointer references.  */
+ struct record_stack_memrefs_data
+ {
+   rtx insn;
+   struct csa_memlist *memlist;
+ };
+ 
+ static int
+ record_stack_memrefs (xp, data)
+      rtx *xp;
+      void *data;
+ {
+   rtx x = *xp;
+   struct record_stack_memrefs_data *d =
+     (struct record_stack_memrefs_data *) data;
+   if (!x)
+     return 0;
+   switch (GET_CODE (x))
+     {
+     case MEM:
+       if (!reg_mentioned_p (stack_pointer_rtx, x))
+ 	return -1;
+       /* We are not able to handle correctly all possible memrefs containing
+          stack pointer, so this check is neccesary.  */
+       if (stack_memref_p (x))
+ 	{
+ 	  d->memlist = record_one_stack_memref (d->insn, xp, d->memlist);
+ 	  return -1;
+ 	}
+       return 1;
+     case REG:
+       /* ??? We want be able to handle non-memory stack pointer references
+          later.  For now just discard all insns refering to stack pointer
+          outside mem expressions.  We would probably want to teach
+ 	 validate_replace to simplify expressions first.  */
+       if (x == stack_pointer_rtx)
+ 	return 1;
+       break;
+     default:
+       break;
+     }
+   return 0;
+ }
+ 
  /* Subroutine of combine_stack_adjustments, called for each basic block.  */
  
  static void 
*************** combine_stack_adjustments_for_block (bb)
*** 2269,2274 ****
--- 2315,2321 ----
    struct csa_memlist *memlist = NULL;
    rtx pending_delete;
    rtx insn, next;
+   struct record_stack_memrefs_data data;
  
    for (insn = bb->head; ; insn = next)
      {
*************** combine_stack_adjustments_for_block (bb)
*** 2277,2283 ****
        pending_delete = NULL_RTX;
        next = NEXT_INSN (insn);
  
!       if (GET_RTX_CLASS (GET_CODE (insn)) != 'i')
  	goto processed;
  
        set = single_set_for_csa (insn);
--- 2324,2330 ----
        pending_delete = NULL_RTX;
        next = NEXT_INSN (insn);
  
!       if (! INSN_P (insn))
  	goto processed;
  
        set = single_set_for_csa (insn);
*************** combine_stack_adjustments_for_block (bb)
*** 2337,2359 ****
  	      goto processed;
  	    }
  
- 	  /* Find loads from stack memory and record them.  */
- 	  if (last_sp_set && stack_memref_p (src)
- 	      && ! reg_mentioned_p (stack_pointer_rtx, dest))
- 	    {
- 	      memlist = record_one_stack_memref (insn, &SET_SRC (set), memlist);
- 	      goto processed;
- 	    }
- 
- 	  /* Find stores to stack memory and record them.  */
- 	  if (last_sp_set && stack_memref_p (dest)
- 	      && ! reg_mentioned_p (stack_pointer_rtx, src))
- 	    {
- 	      memlist = record_one_stack_memref (insn, &SET_DEST (set),
- 						 memlist);
- 	      goto processed;
- 	    }
- 
  	  /* Find a predecrement of exactly the previous adjustment and
  	     turn it into a direct store.  Obviously we can't do this if
  	     there were any intervening uses of the stack pointer.  */
--- 2384,2389 ----
*************** combine_stack_adjustments_for_block (bb)
*** 2379,2384 ****
--- 2409,2424 ----
  	      goto processed;
  	    }
  	}
+ 
+       data.insn = insn;
+       data.memlist = memlist;
+       if (GET_CODE (insn) != CALL_INSN && last_sp_set
+ 	  && !for_each_rtx (&PATTERN (insn), record_stack_memrefs, &data))
+ 	{
+ 	   memlist = data.memlist;
+ 	   goto processed;
+ 	}
+       memlist = data.memlist;
  
        /* Otherwise, we were not able to process the instruction. 
  	 Do not continue collecting data across such a one.  */