--- module.c.orig	2005-07-24 09:21:32.000000000 +0800
+++ module.c	2005-08-05 15:10:17.000000000 +0800
@@ -27,6 +27,7 @@
   02111-1307, USA. */
 
 #include "gpc.h"
+#include "timevar.h"
 #include "p/version.h"
 
 #ifdef EGCS
@@ -105,7 +106,8 @@
 static char *locate_file_1 (const char *, const char *);
 static const char *get_automake_switches (int);
 static struct interface_table_t *get_interface_table (tree, tree);
-static gpi_int compute_checksum (unsigned char *, gpi_int);
+static gpi_int compute_checksum_old (unsigned char *, gpi_int);
+static gpi_int compute_checksum_new (unsigned char *, gpi_int);
 static int itab_check_gpi_checksum (tree, gpi_int, int);
 static const char *file_basename (const char *);
 static int find_automake_tempfile_entry (const char *, const char *, int);
@@ -1744,7 +1748,7 @@
     }
 
   /* Write chunk to file */
-  checksum = compute_checksum (wb.outbuf, wb.outbufcount);
+  checksum = compute_checksum_new (wb.outbuf, wb.outbufcount);
   itab_check_gpi_checksum (name, checksum, 1);
   start_chunk (s, GPI_CHUNK_NODES, wb.outbufcount + sizeof (checksum));
   store_length_f (s, wb.outbuf, wb.outbufcount);
@@ -2345,13 +2357,72 @@
 }
 
 /* Compute a checksum for a GPI file.
-   @@ Simple weighted sum. Perhaps we should use MD5 or something. */
+   @@ Simple weighted sum. Unrolled.  Watch out for performance. */
+static gpi_int
+compute_checksum_old (unsigned char *buf, gpi_int size)
+{
+  gpi_int sum = 0, n = 0;
+  
+	while ( size > 4 ) {
+		sum += n * buf[n];
+		n++;
+		sum += n * buf[n];
+		n++;
+		sum += n * buf[n];
+		n++;
+		sum += n * buf[n];
+		n++;
+		size -= 4;
+	}
+	while ( size > 0 ) {
+		sum += n * buf[n];
+		n++;
+		size--;
+	}
+  return sum;
+}
+
+
+/* Compute a checksum for a GPI file.
+   @@ Shifted sum. Watch out for performance. */
 static gpi_int
-compute_checksum (unsigned char *buf, gpi_int size)
+compute_checksum_new (unsigned char *buf, gpi_int size)
 {
-  gpi_int sum = 0, n;
-  for (n = 0; n < size; n++)
-    sum += n * buf[n];
+  gpi_int sum = 0, n = 0;
+  
+  if ( size > 0x7fffffff || sizeof(int) < 4) {
+	  for (n = 0; n < size; n++)
+  	  sum += n * buf[n];
+  } else {
+	  int ni = 0;
+	  int sizei = size;
+	  int sumi = 0;
+		while ( sizei > 8 ) {
+			sumi += (int)buf[ni];
+			ni++;
+			sumi += (int)buf[ni];
+			ni++;
+			sumi += (int)buf[ni];
+			ni++;
+			sumi += (int)buf[ni];
+			ni++;
+			sumi += (int)buf[ni];
+			ni++;
+			sumi += (int)buf[ni];
+			ni++;
+			sumi += (int)buf[ni];
+			ni++;
+			sumi += (int)buf[ni];
+			ni++;
+			sizei -= 8;
+		}
+		while ( sizei > 0 ) {
+			sumi += (int)buf[ni];
+			ni++;
+			sizei--;
+		}
+		sum = sumi;
+  }
   return sum;
 }
 
@@ -3392,7 +3463,8 @@
   mseek (gpi_file, start_of_nodes + size_of_nodes - sizeof (checksum));
   LOAD_ANY_F (gpi_file, checksum);
   mseek (gpi_file, oldpos);
-  if (compute_checksum (mptr (gpi_file, start_of_nodes), size_of_nodes - sizeof (checksum)) != checksum)
+  if (compute_checksum_new (mptr (gpi_file, start_of_nodes), size_of_nodes - sizeof (checksum)) != checksum
+      && compute_checksum_old (mptr (gpi_file, start_of_nodes), size_of_nodes - sizeof (checksum)) != checksum)
     {
       error ("%s: checksum mismatch (GPI file corrupt)", current_gpi_file_name);
       exit (FATAL_EXIT_CODE);