Another unrecognizable insn in current CVS snapshot

[Clinton Popetz]

On Tue, Apr 04, 2000 at 12:48:59AM -0500, James A. Bednar wrote:
> 
> Using the GCC Online Compiler Submission at
> http://www.codesourcery.com/gcc-compile.html on the following code
> generates an "Unrecognizable insn" internal compiler error (see
> attached):
> 
>   typedef struct {
>     char name[64];
>   } Name;
>   
>   typedef struct {
>     Name list[250];
>   } NameList;
>   
>   NameList names;
>   
>   void f()
>   {
>     int idx=0;
>     while (strlen(names.list[idx].name))
>       idx++;
>   }

A smaller example would be:

char list[250][64];

int f(int idx) { return (strlen(list[idx])); }


> This may be due to the same problem as my bug report of a few minutes
> ago, since the same GCC line number is mentioned in the error message
> below.  

Nope, that's just a common place for gcc to fail.

The problem is in expand_builtin_strlen, which used to do this:

      src_rtx = memory_address (BLKmode,
                                expand_expr (src, NULL_RTX, ptr_mode,
                                             EXPAND_NORMAL));
but now does this:
 
      pat  = expand_expr (src, src_reg, ptr_mode, EXPAND_SUM);

as a result of this patch:

2000-03-08  Richard Henderson  <rth@cygnus.com>

        * builtins.c (expand_builtin_strlen): Be prepared for strlensi
        to fail.  Don't pre-expand the source operand.

In the above case will result in:

(insn 22 7 13 (set (reg:SI 29)
        (plus:SI (mult:SI (reg/v:SI 26)
                (const_int 64 [0x40]))
            (symbol_ref:SI ("list")))) -1 (nil)
    (nil))

for the src.  It seems we should probably legitimize the address here.  Ok?

				-Clint

2000-04-04  Clinton Popetz  <cpopetz@cygnus.com>

	* builtins.c (expand_builtin_strlen): Force the source to
	be a memory address.

Index: builtins.c
===================================================================
RCS file: /cvs/gcc/egcs/gcc/builtins.c,v
retrieving revision 1.44
diff -c -2 -p -r1.44 builtins.c
*** builtins.c	2000/04/01 00:09:21	1.44
--- builtins.c	2000/04/04 16:35:03
*************** expand_builtin_strlen (exp, target, mode
*** 1389,1393 ****
        /* Now that we are assured of success, expand the source.  */
        start_sequence ();
!       pat = expand_expr (src, src_reg, ptr_mode, EXPAND_SUM);
        if (pat != src_reg)
  	emit_move_insn (src_reg, pat);
--- 1389,1394 ----
        /* Now that we are assured of success, expand the source.  */
        start_sequence ();
!       pat = memory_address (BLKmode, 
! 		expand_expr (src, src_reg, ptr_mode, EXPAND_SUM));
        if (pat != src_reg)
  	emit_move_insn (src_reg, pat);