Patch to allow strlen expander to fail

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

Hi
This patch adds the strlen libcall and necesary code to emit_builtin_strlen
to emit libcall when strlen expander fails.
This avoids problems with expr expanded twice.

Together with the strlensi patch it ought to make gcc to deal sanely
with strlen on i386.

Honza

Sat Aug  5 18:10:24 CET 2000  Jan Hubicka  <jh@suse.cz>
	* optabs.c (init_optabs): Add strlen_libfunc.
	* expr.h (enum libfunc_index): Add LTI_strlen
	(strlen_libfunc): Nef macro.
	* builtins.c (expand_builtin_strlen): Use libcall when
	strlen expander failed.
*** optabs.c.old	Sun Mar  5 17:21:52 2000
--- optabs.c	Sun Mar  5 17:22:08 2000
*************** init_optabs ()
*** 4664,4669 ****
--- 4664,4670 ----
    bcmp_libfunc = init_one_libfunc ("__gcc_bcmp");
    memset_libfunc = init_one_libfunc ("memset");
    bzero_libfunc = init_one_libfunc ("bzero");
+   strlen_libfunc = init_one_libfunc ("strlen");
  
    throw_libfunc = init_one_libfunc ("__throw");
    rethrow_libfunc = init_one_libfunc ("__rethrow");
*** expr.h.old	Sun Mar  5 17:20:59 2000
--- expr.h	Sun Mar  5 17:21:36 2000
*************** enum libfunc_index
*** 483,488 ****
--- 483,489 ----
    LTI_bcmp,
    LTI_memset,
    LTI_bzero,
+   LTI_strlen,
  
    LTI_throw,
    LTI_rethrow,
*************** extern rtx libfunc_table[LTI_MAX];
*** 616,621 ****
--- 617,623 ----
  #define bcmp_libfunc	(libfunc_table[LTI_bcmp])
  #define memset_libfunc	(libfunc_table[LTI_memset])
  #define bzero_libfunc	(libfunc_table[LTI_bzero])
+ #define strlen_libfunc	(libfunc_table[LTI_strlen])
  
  #define throw_libfunc	(libfunc_table[LTI_throw])
  #define rethrow_libfunc	(libfunc_table[LTI_rethrow])
*** builtins.c.old	Sun Mar  5 16:25:22 2000
--- builtins.c	Sun Mar  5 17:56:32 2000
*************** expand_builtin_strlen (exp, target, mode
*** 1299,1304 ****
--- 1299,1305 ----
      return 0;
    else
      {
+       rtx pat;
        tree src = TREE_VALUE (arglist);
        tree len = c_strlen (src);
  
*************** expand_builtin_strlen (exp, target, mode
*** 1342,1354 ****
  
        if (! (*insn_data[(int)icode].operand[0].predicate) (result, insn_mode))
  	result = gen_reg_rtx (insn_mode);
!       src_rtx = memory_address (BLKmode,
! 				expand_expr (src, NULL_RTX, ptr_mode,
! 					     EXPAND_NORMAL));
! 
! 
!       if (! (*insn_data[(int)icode].operand[1].predicate) (src_rtx, Pmode))
! 	src_rtx = copy_to_mode_reg (Pmode, src_rtx);
  
        /* Check the string is readable and has an end.  */
        if (current_function_check_memory_usage)
--- 1343,1349 ----
  
        if (! (*insn_data[(int)icode].operand[0].predicate) (result, insn_mode))
  	result = gen_reg_rtx (insn_mode);
!       src_rtx = get_memory_rtx (src);
  
        /* Check the string is readable and has an end.  */
        if (current_function_check_memory_usage)
*************** expand_builtin_strlen (exp, target, mode
*** 1362,1370 ****
        if (! (*insn_data[(int)icode].operand[2].predicate) (char_rtx, char_mode))
  	char_rtx = copy_to_mode_reg (char_mode, char_rtx);
  
!       emit_insn (GEN_FCN (icode) (result,
! 				  gen_rtx_MEM (BLKmode, src_rtx),
! 				  char_rtx, GEN_INT (align));
  
        /* Return the value in the proper mode for this function.  */
        if (GET_MODE (result) == value_mode)
--- 1357,1371 ----
        if (! (*insn_data[(int)icode].operand[2].predicate) (char_rtx, char_mode))
  	char_rtx = copy_to_mode_reg (char_mode, char_rtx);
  
!       pat = GEN_FCN (icode) (result,
! 			     gen_rtx_MEM (BLKmode, src_rtx),
! 			     char_rtx, GEN_INT (align));
!       if (pat)
! 	emit_insn (pat);
!       else
! 	emit_library_call_value (strlen_libfunc, result, 0,
! 				 value_mode, 1,
! 				 XEXP (src_rtx, 0), Pmode);
  
        /* Return the value in the proper mode for this function.  */
        if (GET_MODE (result) == value_mode)