Vladimir Simonov(sv@sw.ru) - normailize filenames.
Useful if you crossbuild Linux app on Windows.
- Make filenames a bit shorter (constractions like ../dir/../ are collapced
  into ../dir). It sometimes helps to avoid Windows ascii-filenames length
  restriction (near to 160 bytes as I remenber).

--- gcc-4.4.2/include/filenames.h.orig	2010-01-28 14:58:49.000000000 +0300
+++ gcc-4.4.2/include/filenames.h	2010-01-28 16:26:23.000000000 +0300
@@ -52,6 +52,8 @@
 
 extern int filename_cmp (const char *s1, const char *s2);
 #define FILENAME_CMP(s1, s2)	filename_cmp(s1, s2)
+extern void filename_normalize (char *f);
+#define FILENAME_NORMALIZE(f)	filename_normalize(f)
 
 #ifdef __cplusplus
 }
--- gcc-4.4.2/libiberty/filename_cmp.c.orig	2010-01-28 14:59:04.000000000 +0300
+++ gcc-4.4.2/libiberty/filename_cmp.c	2010-01-28 16:23:36.000000000 +0300
@@ -76,3 +76,116 @@
 #endif
 }
 
+#ifdef HAVE_MEMMOVE
+#define memmove_left memmove
+#else
+static void *
+memmove_left (void *dest, const void *src, int n)
+{
+   char *d;
+   const char *s;
+   int i;
+   for (d = (char *)dest, s = (const char *)src, i = 0; i < n; i++)
+     *d++ = *s++;
+}
+#endif
+
+/*
+
+@deftypefn Extension void filename_normalize (char *@var{fn})
+
+This function tries to normalize file names inplace.
+
+@end deftypefn
+
+*/
+
+#ifndef HAVE_DOS_BASED_FILE_SYSTEM
+void
+filename_normalize (char *fn)
+#else
+static void
+filename_normalize_unix (char *fn)
+#endif
+{
+  char *p;
+  int rest;
+
+  rest = strlen (fn) + 1;
+  for (p = fn; *p != '\0' ; p++, rest--)
+    {
+      char *next;
+      const char *next2;
+      const char *next3;
+
+      next = p + 1;
+      if (*next == '\0')
+        break;
+      if (!IS_DIR_SEPARATOR( *p))
+          continue;
+      next2 = p + 2;
+      next3 = p + 3;
+      *p = '/';
+      /* don't handle some special cases, i.e. "//C/" on Microsoft Windows */
+      if (IS_DIR_SEPARATOR (*next))
+        {
+          memmove_left (next, next2, rest - 2);
+          p--;
+          continue;
+        }
+      if (*next != '.' || *next2 == '\0' || *next3 == '\0')
+          continue;
+      /* simplify "./" case */
+      if (IS_DIR_SEPARATOR (*next2))
+        {
+          memmove_left (next, next3, rest - 3);
+          rest--;
+          p--;
+          continue;
+        }
+      if (*next2 != '.' || ! IS_DIR_SEPARATOR (*next3))
+        continue;
+      while (--p >= fn)
+        {
+          if (*p == '/')
+            break;
+        }
+      if (p < fn)
+        {
+          if (*fn == '/')
+              memmove_left (p + 2, next3 + 1, rest - 4);
+          else if (*fn != '.')
+              memmove_left (p + 1, next3 + 1, rest - 4);
+          else
+            {
+              p = next - 1;
+              continue;
+            }
+        }
+      else if (*(p + 1) != '.')
+        {
+          memmove_left (p + 1, next3 + 1, rest - 4);
+          p--;
+        }
+      else
+        {
+          p = next - 1;
+          continue;
+        }
+      rest -= 2;
+    }
+}
+
+
+#ifdef HAVE_DOS_BASED_FILE_SYSTEM
+void
+filename_normalize (char *fn)
+{
+  if (IS_DIR_SEPARATOR (fn[0]) || ! IS_ABSOLUTE_PATH (fn))
+    /* Absolute path in Unix style or relative path */
+    filename_normalize_unix (fn);
+  else if (fn[1] != '\0')
+    filename_normalize_unix (fn + 2);
+}
+#endif
+
--- gcc-4.4.2/libcpp/directives.c.orig	2010-01-28 15:09:00.000000000 +0300
+++ gcc-4.4.2/libcpp/directives.c	2010-01-28 16:28:04.000000000 +0300
@@ -716,6 +716,7 @@
       return NULL;
     }
 
+  FILENAME_NORMALIZE (fname);
   if (pfile->directive == &dtable[T_PRAGMA])
     {
       /* This pragma allows extra tokens after the file name.  */
--- gcc-4.4.2/libcpp/files.c.orig	2010-02-12 11:47:27.886977300 +0300
+++ gcc-4.4.2/libcpp/files.c	2010-02-14 15:38:39.757260300 +0300
@@ -355,6 +355,7 @@
 
   if (path)
     {
+      FILENAME_NORMALIZE (path);
       hashval_t hv = htab_hash_string (path);
       char *copy;
       void **pp;