[patch] cse.c: Use xmalloc instead of xrealloc in init_cse_reg_info.

[Kazu Hirata]

Hi,

Attached is a patch to replace xrealloc with xmalloc as there is not
much point preserving the contents of cse_reg_info_table.

Here is time in *microseconds* spent in init_cse_reg_info while
compiling fold-const.i (measured using the rdtsc instruction on my
x86).

original patched patched*
     131     116      640

patched* is a version of cse.c where I allocate and free the entire
cse_reg_info_table for every invocation of cse_main, which turns out
to be more expensive but by only 0.5ms.

The speed-up is very tiny, but I'd like to clean up my own mess, use
of xrealloc.

Tested on i686-pc-linux-gnu.  OK to apply?

Kazu Hirata

2005-02-19  Kazu Hirata  <kazu@cs.umass.edu>

	* cse.c (init_cse_reg_info): Use xmalloc instead of xrealloc.

Index: cse.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/cse.c,v
retrieving revision 1.342
diff -c -d -p -r1.342 cse.c
*** cse.c	10 Feb 2005 20:13:19 -0000	1.342
--- cse.c	16 Feb 2005 17:02:49 -0000
*************** init_cse_reg_info (unsigned int nregs)
*** 864,873 ****
  	}
  
        /* Reallocate the table with NEW_SIZE entries.  */
!       cse_reg_info_table = xrealloc (cse_reg_info_table,
! 				     (sizeof (struct cse_reg_info)
! 				      * new_size));
        cse_reg_info_table_size = new_size;
      }
  
    /* Do we have all of the first NREGS entries initialized?  */
--- 864,875 ----
  	}
  
        /* Reallocate the table with NEW_SIZE entries.  */
!       if (cse_reg_info_table)
! 	free (cse_reg_info_table);
!       cse_reg_info_table = xmalloc (sizeof (struct cse_reg_info)
! 				     * new_size);
        cse_reg_info_table_size = new_size;
+       cse_reg_info_table_first_uninitialized = 0;
      }
  
    /* Do we have all of the first NREGS entries initialized?  */