diff --git a/gcc/Makefile.in b/gcc/Makefile.in
index 3d936f6..629d33f 100644
--- a/gcc/Makefile.in
+++ b/gcc/Makefile.in
@@ -1489,10 +1489,10 @@ BACKEND = main.o @TREEBROWSER@ libbackend.a $(CPPLIB) $(LIBDECNUMBER)
 MOSTLYCLEANFILES = insn-flags.h insn-config.h insn-codes.h \
  insn-output.c insn-recog.c insn-emit.c insn-extract.c insn-peep.c \
  insn-attr.h insn-attrtab.c insn-opinit.c insn-preds.c insn-constants.h \
- tm-preds.h tm-constrs.h \
+ tm-preds.h tm-constrs.h checksum-options \
  tree-check.h min-insn-modes.c insn-modes.c insn-modes.h \
  genrtl.h gt-*.h gtype-*.h gtype-desc.c gtyp-input.list \
- xgcc$(exeext) cpp$(exeext) cc1$(exeext) cc1*-dummy$(exeext) $(EXTRA_PASSES) \
+ xgcc$(exeext) cpp$(exeext) cc1$(exeext) $(EXTRA_PASSES) \
  $(EXTRA_PARTS) $(EXTRA_PROGRAMS) gcc-cross$(exeext) \
  $(SPECS) collect2$(exeext) lto-wrapper$(exeext) \
  gcov-iov$(build_exeext) gcov$(exeext) gcov-dump$(exeext) \
@@ -1832,14 +1832,16 @@ $(SPECS): xgcc$(exeext)
 gcc-cross$(exeext): xgcc$(exeext)
 	cp xgcc$(exeext) gcc-cross$(exeext)
 
-dummy-checksum.o : dummy-checksum.c $(CONFIG_H) $(SYSTEM_H)
+.PHONY: checksum-options
 
-cc1-dummy$(exeext): $(C_OBJS) dummy-checksum.o $(BACKEND) $(LIBDEPS)
-	+$(LINKER) $(ALL_LINKERFLAGS) $(LDFLAGS) -o $@ $(C_OBJS) \
-	  dummy-checksum.o $(BACKEND) $(LIBS) $(BACKENDLIBS)
+checksum-options:
+	echo "$(LINKER) $(ALL_LINKERFLAGS) $(LDFLAGS)" > checksum-options
 
-cc1-checksum.c : cc1-dummy$(exeext) build/genchecksum$(build_exeext)
-	build/genchecksum$(build_exeext) cc1-dummy$(exeext) > $@
+# compute checksum over all object files and the options
+cc1-checksum.c : build/genchecksum$(build_exeext) checksum-options \
+	$(C_OBJS) $(BACKEND) $(LIBDEPS) 
+	build/genchecksum$(build_exeext) $(C_OBJS) $(BACKEND) $(LIBDEPS) \
+                     checksum-options > $@
 
 cc1-checksum.o : cc1-checksum.c $(CONFIG_H) $(SYSTEM_H)
 
diff --git a/gcc/cp/Make-lang.in b/gcc/cp/Make-lang.in
index 4be40b5..62de970 100644
--- a/gcc/cp/Make-lang.in
+++ b/gcc/cp/Make-lang.in
@@ -86,17 +86,21 @@ CXX_AND_OBJCXX_OBJS = cp/call.o cp/decl.o cp/expr.o cp/pt.o cp/typeck2.o \
 # Language-specific object files for C++.
 CXX_OBJS = cp/cp-lang.o c-family/stub-objc.o $(CXX_AND_OBJCXX_OBJS)
 
-c++_OBJS = $(CXX_OBJS) dummy-checksum.o cc1plus-checksum.o cp/g++spec.o
+c++_OBJS = $(CXX_OBJS) cc1plus-checksum.o cp/g++spec.o
 
 # Use strict warnings for this front end.
 cp-warn = $(STRICT_WARN)
 
-cc1plus-dummy$(exeext): $(CXX_OBJS) dummy-checksum.o $(BACKEND) $(LIBDEPS)
-	$(LINKER) $(ALL_LINKERFLAGS) $(LDFLAGS) -o $@ \
-	      $(CXX_OBJS) dummy-checksum.o $(BACKEND) $(LIBS) $(BACKENDLIBS)
+.PHONY: checksum-options
 
-cc1plus-checksum.c : cc1plus-dummy$(exeext) build/genchecksum$(build_exeext)
-	build/genchecksum$(build_exeext) cc1plus-dummy$(exeext) > $@
+checksum-options:
+	echo "$(LINKER) $(ALL_LINKERFLAGS) $(LDFLAGS)" > checksum-options
+
+# compute checksum over all object files and the options
+cc1plus-checksum.c : build/genchecksum$(build_exeext) checksum-options \
+	$(CXX_OBJS) $(BACKEND) $(LIBDEPS) 
+	build/genchecksum$(build_exeext) $(CXX_OBJS) $(BACKEND) $(LIBDEPS) \
+                     checksum-options > $@
 
 cc1plus-checksum.o : cc1plus-checksum.c $(CONFIG_H) $(SYSTEM_H)
 
diff --git a/gcc/dummy-checksum.c b/gcc/dummy-checksum.c
deleted file mode 100644
index c90f1ca..0000000
--- a/gcc/dummy-checksum.c
+++ /dev/null
@@ -1,3 +0,0 @@
-#include "config.h"
-#include "system.h"
-EXPORTED_CONST unsigned char executable_checksum[16] = { 0 };
diff --git a/gcc/genchecksum.c b/gcc/genchecksum.c
index 235d4fe..e0c71f4 100644
--- a/gcc/genchecksum.c
+++ b/gcc/genchecksum.c
@@ -1,5 +1,5 @@
 /* Generate checksums of executables for PCH validation
-   Copyright (C) 2005, 2007, 2009
+   Copyright (C) 2005, 2007, 2009, 2010
    Free Software Foundation, Inc.
 
 This file is part of GCC.
@@ -25,15 +25,18 @@ along with GCC; see the file COPYING3.  If not see
 static void
 usage (void)
 {
-  fputs ("Usage: genchecksums <filename>\n", stderr);
+  fputs ("Usage: genchecksums <filename> ...\n", stderr);
 }
 
+/* Important: BLOCKSIZE must be a multiple of 64.  */
+#define BLOCKSIZE 4096
+
 static void
-dosum (const char *file)
+dosum (struct md5_ctx *ctx, const char *file)
 {
   FILE *f;
-  unsigned char result[16];
-  int i;
+  char buffer[BLOCKSIZE + 72];
+  size_t sum;
 
   f = fopen (file, "rb");
   if (!f)
@@ -49,30 +52,70 @@ dosum (const char *file)
       exit (1);
     }
 
-  if (md5_stream (f, result) != 0
-      || fclose (f) != 0)
+  /* Iterate over full file contents.  */
+  while (1)
+    {
+      /* We read the file in blocks of BLOCKSIZE bytes.  One call of the
+	 computation function processes the whole buffer so that with the
+	 next round of the loop another block can be read.  */
+      size_t n;
+      sum = 0;
+
+      /* Read block.  Take care for partial reads.  */
+      do
+	{
+	  n = fread (buffer + sum, 1, BLOCKSIZE - sum, f);
+
+	  sum += n;
+	}
+      while (sum < BLOCKSIZE && n != 0);
+      if (n == 0 && ferror (f))
+        exit (1);
+
+      /* If end of file is reached, end the loop.  */
+      if (n == 0)
+	break;
+
+      /* Process buffer with BLOCKSIZE bytes.  Note that
+			BLOCKSIZE % 64 == 0
+       */
+      md5_process_block (buffer, BLOCKSIZE, ctx);
+    }
+
+  /* Add the last bytes if necessary.  */
+  if (sum > 0)
+    md5_process_bytes (buffer, sum, ctx);
+
+  if (fclose (f) != 0)
      {
       fprintf (stderr, "reading %s: %s\n", file, xstrerror (errno));
       exit (1);
     }
-
-  puts ("#include \"config.h\"");
-  puts ("#include \"system.h\"");
-  fputs ("EXPORTED_CONST unsigned char executable_checksum[16] = { ", stdout);
-  for (i = 0; i < 16; i++)
-    printf ("0x%02x%s", result[i], i == 15 ? " };\n" : ", ");
 }
 
 int
 main (int argc, char ** argv)
 {
-  if (argc != 2)
+  struct md5_ctx ctx;
+  unsigned char result[16];
+  int i;
+
+  if (argc < 2)
     {
       usage ();
       return 1;
     }
 
-  dosum (argv[1]);
+  md5_init_ctx (&ctx);
+  for (i = 1; i < argc; i++) 
+    dosum (&ctx, argv[i]);
+  md5_finish_ctx (&ctx, result);
+
+  puts ("#include \"config.h\"");
+  puts ("#include \"system.h\"");
+  fputs ("EXPORTED_CONST unsigned char executable_checksum[16] = { ", stdout);
+  for (i = 0; i < 16; i++)
+    printf ("0x%02x%s", result[i], i == 15 ? " };\n" : ", ");
 
   return 0;
 }
