Patch to improve store_expr

[Jan Hubicka]

Hi
The store_expr contains direct memset/bzero call.  I don't see purpose
why not use clear_storage infrastructure here.  The patch avoids memset
in following testcase created by Jakub:

struct c { char name[20]; };
void bar(struct c *);
void foo(void)
{
        struct c a = {"string"};
        bar(&a);
}


Wed Apr 26 16:00:25 MET DST 2000  Jan Hubicka  <jh@suse.cz>
	* expr.c (store_expr): Use clear_storage instead of direct memset
	libcall.

Index: egcs/gcc//expr.c
===================================================================
RCS file: /cvs/gcc/egcs/gcc/expr.c,v
retrieving revision 1.231
diff -c -3 -p -r1.231 expr.c
*** expr.c	2000/04/22 10:36:44	1.231
--- expr.c	2000/04/26 13:55:30
*************** store_expr (exp, target, want_value)
*** 3933,3938 ****
--- 3933,3939 ----
  		= size_binop (MIN_EXPR,
  			      make_tree (sizetype, size),
  			      size_int (TREE_STRING_LENGTH (exp)));
+ 	      int align = TYPE_ALIGN (TREE_TYPE (exp));
  	      rtx copy_size_rtx = expand_expr (copy_size, NULL_RTX,
  					       VOIDmode, 0);
  	      rtx label = 0;
*************** store_expr (exp, target, want_value)
*** 3951,3956 ****
--- 3952,3960 ----
  		{
  		  addr = plus_constant (addr, TREE_STRING_LENGTH (exp));
  		  size = plus_constant (size, - TREE_STRING_LENGTH (exp));
+ 		  align = MIN (align, (BITS_PER_UNIT
+ 				       * (INTVAL (copy_size_rtx)
+ 					  & - INTVAL (copy_size_rtx))));
  		}
  	      else
  		{
*************** store_expr (exp, target, want_value)
*** 3963,3972 ****
--- 3967,3978 ----
  				       copy_size_rtx, NULL_RTX, 0,
  				       OPTAB_LIB_WIDEN);
  
+ 		  align = BITS_PER_UNIT;
  		  label = gen_label_rtx ();
  		  emit_cmp_and_jump_insns (size, const0_rtx, LT, NULL_RTX,
  					   GET_MODE (size), 0, 0, label);
  		}
+ 	      align = MIN (align, expr_align (copy_size));
  
  	      if (size != const0_rtx)
  		{
*************** store_expr (exp, target, want_value)
*** 3977,3998 ****
  				       size, TYPE_MODE (sizetype),
   				       GEN_INT (MEMORY_USE_WO), 
  				       TYPE_MODE (integer_type_node));
! #ifdef TARGET_MEM_FUNCTIONS
! 		  emit_library_call (memset_libfunc, 0, VOIDmode, 3,
! 				     addr, ptr_mode,
! 				     const0_rtx, TYPE_MODE (integer_type_node),
! 				     convert_to_mode (TYPE_MODE (sizetype),
! 						      size,
! 						      TREE_UNSIGNED (sizetype)),
! 				     TYPE_MODE (sizetype));
! #else
! 		  emit_library_call (bzero_libfunc, 0, VOIDmode, 2,
! 				     addr, ptr_mode,
! 				     convert_to_mode (TYPE_MODE (integer_type_node),
! 						      size,
! 						      TREE_UNSIGNED (integer_type_node)),
! 				     TYPE_MODE (integer_type_node));
! #endif
  		}
  
  	      if (label)
--- 3983,3989 ----
  				       size, TYPE_MODE (sizetype),
   				       GEN_INT (MEMORY_USE_WO), 
  				       TYPE_MODE (integer_type_node));
! 		  clear_storage (gen_rtx_MEM (BLKmode, addr), size, align);
  		}
  
  	      if (label)