internal.h (struct cpp_reader): Add new fields: nonexistent_file_hash and nonexistent_file_ob.

	* internal.h (struct cpp_reader): Add new fields:
	nonexistent_file_hash and nonexistent_file_ob.
	* files.c: Include "obstack.h".
	(find_file_in_dir): Before trying to open the file, look up the
	path name in the hash table of nonexistent files.  After failing
	to open the file, add the path name to the hash table.
	(_cpp_find_file): Cache the results of looking up the file name
	starting with the quote and bracket chain heads, if we can.
	(nonexistent_file_hash_eq): New static function.
	(_cpp_init_files): Initialize pfile->nonexistent_file_hash and
	pfile->nonexistent_file_ob.
	(_cpp_cleanup_files): Free pfile->nonexistent_file_hash and
	pfile->nonexistent_file_ob.

From-SVN: r124929

3 files changed, 93 insertions, 4 deletions

diff --git a/libcpp/ChangeLog b/libcpp/ChangeLog
index 31d96e8b684..44023594743 100644
--- a/libcpp/ChangeLog
+++ b/libcpp/ChangeLog
@@ -1,3 +1,19 @@
+2007-05-21  Ian Lance Taylor  <iant@google.com>
+
+	* internal.h (struct cpp_reader): Add new fields:
+	nonexistent_file_hash and nonexistent_file_ob.
+	* files.c: Include "obstack.h".
+	(find_file_in_dir): Before trying to open the file, look up the
+	path name in the hash table of nonexistent files.  After failing
+	to open the file, add the path name to the hash table.
+	(_cpp_find_file): Cache the results of looking up the file name
+	starting with the quote and bracket chain heads, if we can.
+	(nonexistent_file_hash_eq): New static function.
+	(_cpp_init_files): Initialize pfile->nonexistent_file_hash and
+	pfile->nonexistent_file_ob.
+	(_cpp_cleanup_files): Free pfile->nonexistent_file_hash and
+	pfile->nonexistent_file_ob.
+
 2007-05-14  Janis Johnson  <janis187@us.ibm.com>
 
         * expr.c (cpp_classify_number): Warn about dfp constant for -pedantic.
diff --git a/libcpp/files.c b/libcpp/files.c
index 83342180590..3751184d02f 100644
--- a/libcpp/files.c
+++ b/libcpp/files.c
@@ -1,6 +1,7 @@
 /* Part of CPP library.  File handling.
    Copyright (C) 1986, 1987, 1989, 1992, 1993, 1994, 1995, 1998,
-   1999, 2000, 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
+   1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007
+   Free Software Foundation, Inc.
    Written by Per Bothner, 1994.
    Based on CCCP program by Paul Rubin, June 1986
    Adapted to ANSI C, Richard Stallman, Jan 1987
@@ -26,6 +27,7 @@ Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
 #include "cpplib.h"
 #include "internal.h"
 #include "mkdeps.h"
+#include "obstack.h"
 #include "hashtab.h"
 #include "md5.h"
 #include <dirent.h>
@@ -322,6 +324,16 @@ find_file_in_dir (cpp_reader *pfile, _cpp_file *file, bool *invalid_pch)
 
   if (path)
     {
+      hashval_t hv = htab_hash_string (path);
+      char *copy;
+      void **pp;
+
+      if (htab_find_with_hash (pfile->nonexistent_file_hash, path, hv) != NULL)
+	{
+	  file->err_no = ENOENT;
+	  return false;
+	}
+
       file->path = path;
       if (pch_open_file (pfile, file, invalid_pch))
 	return true;
@@ -335,7 +347,16 @@ find_file_in_dir (cpp_reader *pfile, _cpp_file *file, bool *invalid_pch)
 	  return true;
 	}
 
+      /* We copy the path name onto an obstack partly so that we don't
+	 leak the memory, but mostly so that we don't fragment the
+	 heap.  */
+      copy = obstack_copy0 (&pfile->nonexistent_file_ob, path,
+			    strlen (path));
       free (path);
+      pp = htab_find_slot_with_hash (pfile->nonexistent_file_hash,
+				     copy, hv, INSERT);
+      *pp = copy;
+
       file->path = file->name;
     }
   else
@@ -396,6 +417,9 @@ _cpp_find_file (cpp_reader *pfile, const char *fname, cpp_dir *start_dir, bool f
   struct file_hash_entry *entry, **hash_slot;
   _cpp_file *file;
   bool invalid_pch = false;
+  bool saw_bracket_include = false;
+  bool saw_quote_include = false;
+  struct cpp_dir *found_in_cache = NULL;
 
   /* Ensure we get no confusion between cached files and directories.  */
   if (start_dir == NULL)
@@ -448,13 +472,19 @@ _cpp_find_file (cpp_reader *pfile, const char *fname, cpp_dir *start_dir, bool f
       /* Only check the cache for the starting location (done above)
 	 and the quote and bracket chain heads because there are no
 	 other possible starting points for searches.  */
-      if (file->dir != pfile->bracket_include
-	  && file->dir != pfile->quote_include)
+      if (file->dir == pfile->bracket_include)
+	saw_bracket_include = true;
+      else if (file->dir == pfile->quote_include)
+	saw_quote_include = true;
+      else
 	continue;
 
       entry = search_cache (*hash_slot, file->dir);
       if (entry)
-	break;
+	{
+	  found_in_cache = file->dir;
+	  break;
+	}
     }
 
   if (entry)
@@ -478,6 +508,29 @@ _cpp_find_file (cpp_reader *pfile, const char *fname, cpp_dir *start_dir, bool f
   entry->u.file = file;
   *hash_slot = entry;
 
+  /* If we passed the quote or bracket chain heads, cache them also.
+     This speeds up processing if there are lots of -I options.  */
+  if (saw_bracket_include
+      && pfile->bracket_include != start_dir
+      && found_in_cache != pfile->bracket_include)
+    {
+      entry = new_file_hash_entry (pfile);
+      entry->next = *hash_slot;
+      entry->start_dir = pfile->bracket_include;
+      entry->u.file = file;
+      *hash_slot = entry;
+    }
+  if (saw_quote_include
+      && pfile->quote_include != start_dir
+      && found_in_cache != pfile->quote_include)
+    {
+      entry = new_file_hash_entry (pfile);
+      entry->next = *hash_slot;
+      entry->start_dir = pfile->quote_include;
+      entry->u.file = file;
+      *hash_slot = entry;
+    }
+
   return file;
 }
 
@@ -997,6 +1050,14 @@ file_hash_eq (const void *p, const void *q)
   return strcmp (hname, fname) == 0;
 }
 
+/* Compare entries in the nonexistent file hash table.  These are just
+   strings.  */
+static int
+nonexistent_file_hash_eq (const void *p, const void *q)
+{
+  return strcmp (p, q) == 0;
+}
+
 /* Initialize everything in this source file.  */
 void
 _cpp_init_files (cpp_reader *pfile)
@@ -1006,6 +1067,12 @@ _cpp_init_files (cpp_reader *pfile)
   pfile->dir_hash = htab_create_alloc (127, file_hash_hash, file_hash_eq,
 					NULL, xcalloc, free);
   allocate_file_hash_entries (pfile);
+  pfile->nonexistent_file_hash = htab_create_alloc (127, htab_hash_string,
+						    nonexistent_file_hash_eq,
+						    NULL, xcalloc, free);
+  _obstack_begin (&pfile->nonexistent_file_ob, 0, 0,
+		  (void *(*) (long)) xmalloc,
+		  (void (*) (void *)) free);
 }
 
 /* Finalize everything in this source file.  */
@@ -1014,6 +1081,8 @@ _cpp_cleanup_files (cpp_reader *pfile)
 {
   htab_delete (pfile->file_hash);
   htab_delete (pfile->dir_hash);
+  htab_delete (pfile->nonexistent_file_hash);
+  obstack_free (&pfile->nonexistent_file_ob, 0);
 }
 
 /* Enter a file name in the hash for the sake of cpp_included.  */
diff --git a/libcpp/internal.h b/libcpp/internal.h
index 20f42358051..9395f6aa10e 100644
--- a/libcpp/internal.h
+++ b/libcpp/internal.h
@@ -355,6 +355,10 @@ struct cpp_reader
   struct file_hash_entry *file_hash_entries;
   unsigned int file_hash_entries_allocated, file_hash_entries_used;
 
+  /* Negative path lookup hash table.  */
+  struct htab *nonexistent_file_hash;
+  struct obstack nonexistent_file_ob;
+
   /* Nonzero means don't look for #include "foo" the source-file
      directory.  */
   bool quote_ignores_source_dir;