[Emacs-diffs] master 85f6aa3 6/6: Merge several Lisp reader speedups.

[Ken Raeburn]

branch: master
commit 85f6aa33f55da97b13b5e81616f16a517d24f3d5
Merge: 87a44b9 59f3c86
Author: Ken Raeburn <address@hidden>
Commit: Ken Raeburn <address@hidden>

    Merge several Lisp reader speedups.
---
 configure.ac  |   2 +-
 src/charset.c |  14 ++--
 src/lread.c   | 221 ++++++++++++++++++++++++++++++++++++++++++++++------------
 3 files changed, 188 insertions(+), 49 deletions(-)

diff --git a/configure.ac b/configure.ac
index ef61107..65c5f92 100644
--- a/configure.ac
+++ b/configure.ac
@@ -4240,7 +4240,7 @@ AC_CHECK_HEADERS(valgrind/valgrind.h)
 
 AC_CHECK_MEMBERS([struct unipair.unicode], [], [], [[#include <linux/kd.h>]])
 
-AC_CHECK_FUNCS_ONCE([sbrk])
+AC_CHECK_FUNCS_ONCE([getc_unlocked sbrk])
 
 ok_so_far=yes
 AC_CHECK_FUNC(socket, , ok_so_far=no)
diff --git a/src/charset.c b/src/charset.c
index f0b4140..9d15375 100644
--- a/src/charset.c
+++ b/src/charset.c
@@ -198,6 +198,10 @@ static struct
 
 #define GET_TEMP_CHARSET_WORK_DECODER(CODE)    \
   (temp_charset_work->table.decoder[(CODE)])
+
+#ifndef HAVE_GETC_UNLOCKED
+#define getc_unlocked getc
+#endif
 
 
 /* Set to 1 to warn that a charset map is loaded and thus a buffer
@@ -416,15 +420,15 @@ read_hex (FILE *fp, bool *eof, bool *overflow)
   int c;
   unsigned n;
 
-  while ((c = getc (fp)) != EOF)
+  while ((c = getc_unlocked (fp)) != EOF)
     {
       if (c == '#')
        {
-         while ((c = getc (fp)) != EOF && c != '\n');
+         while ((c = getc_unlocked (fp)) != EOF && c != '\n');
        }
       else if (c == '0')
        {
-         if ((c = getc (fp)) == EOF || c == 'x')
+         if ((c = getc_unlocked (fp)) == EOF || c == 'x')
            break;
        }
     }
@@ -434,7 +438,7 @@ read_hex (FILE *fp, bool *eof, bool *overflow)
       return 0;
     }
   n = 0;
-  while (c_isxdigit (c = getc (fp)))
+  while (c_isxdigit (c = getc_unlocked (fp)))
     {
       if (INT_LEFT_SHIFT_OVERFLOW (n, 4))
        *overflow = 1;
@@ -508,7 +512,7 @@ load_charset_map_from_file (struct charset *charset, 
Lisp_Object mapfile,
       from = read_hex (fp, &eof, &overflow);
       if (eof)
        break;
-      if (getc (fp) == '-')
+      if (getc_unlocked (fp) == '-')
        to = read_hex (fp, &eof, &overflow);
       else
        to = from;
diff --git a/src/lread.c b/src/lread.c
index 88dbc23..b01cbd5 100644
--- a/src/lread.c
+++ b/src/lread.c
@@ -72,11 +72,40 @@ along with GNU Emacs.  If not, see 
<http://www.gnu.org/licenses/>.  */
 #define file_tell ftell
 #endif
 
-/* The association list of objects read with the #n=object form.
-   Each member of the list has the form (n . object), and is used to
-   look up the object for the corresponding #n# construct.
-   It must be set to nil before all top-level calls to read0.  */
-static Lisp_Object read_objects;
+#ifndef HAVE_GETC_UNLOCKED
+#define getc_unlocked getc
+#endif
+
+/* The objects or placeholders read with the #n=object form.
+
+   A hash table maps a number to either a placeholder (while the
+   object is still being parsed, in case it's referenced within its
+   own definition) or to the completed object.  With small integers
+   for keys, it's effectively little more than a vector, but it'll
+   manage any needed resizing for us.
+
+   The variable must be reset to an empty hash table before all
+   top-level calls to read0.  In between calls, it may be an empty
+   hash table left unused from the previous call (to reduce
+   allocations), or nil.  */
+static Lisp_Object read_objects_map;
+
+/* The recursive objects read with the #n=object form.
+
+   Objects that might have circular references are stored here, so
+   that recursive substitution knows not to keep processing them
+   multiple times.
+
+   Only objects that are completely processed, including substituting
+   references to themselves (but not necessarily replacing
+   placeholders for other objects still being read), are stored.
+
+   A hash table is used for efficient lookups of keys.  We don't care
+   what the value slots hold.  The variable must be set to an empty
+   hash table before all top-level calls to read0.  In between calls,
+   it may be an empty hash table left unused from the previous call
+   (to reduce allocations), or nil.  */
+static Lisp_Object read_objects_completed;
 
 /* File for get_file_char to read from.  Use by load.  */
 static FILE *instream;
@@ -445,7 +474,7 @@ readbyte_from_file (int c, Lisp_Object readcharfun)
     }
 
   block_input ();
-  c = getc (instream);
+  c = getc_unlocked (instream);
 
   /* Interrupted reads have been observed while reading over the network.  */
   while (c == EOF && ferror (instream) && errno == EINTR)
@@ -454,7 +483,7 @@ readbyte_from_file (int c, Lisp_Object readcharfun)
       maybe_quit ();
       block_input ();
       clearerr (instream);
-      c = getc (instream);
+      c = getc_unlocked (instream);
     }
 
   unblock_input ();
@@ -757,7 +786,7 @@ DEFUN ("get-file-char", Fget_file_char, Sget_file_char, 0, 
0, 0,
 {
   register Lisp_Object val;
   block_input ();
-  XSETINT (val, getc (instream));
+  XSETINT (val, getc_unlocked (instream));
   unblock_input ();
   return val;
 }
@@ -1908,6 +1937,18 @@ readevalloop (Lisp_Object readcharfun,
          || c == NO_BREAK_SPACE)
        goto read_next;
 
+      if (! HASH_TABLE_P (read_objects_map)
+         || XHASH_TABLE (read_objects_map)->count)
+       read_objects_map
+         = make_hash_table (hashtest_eq, DEFAULT_HASH_SIZE,
+                            DEFAULT_REHASH_SIZE, DEFAULT_REHASH_THRESHOLD,
+                            Qnil, Qnil);
+      if (! HASH_TABLE_P (read_objects_completed)
+         || XHASH_TABLE (read_objects_completed)->count)
+       read_objects_completed
+         = make_hash_table (hashtest_eq, DEFAULT_HASH_SIZE,
+                            DEFAULT_REHASH_SIZE, DEFAULT_REHASH_THRESHOLD,
+                            Qnil, Qnil);
       if (!NILP (Vpurify_flag) && c == '(')
        {
          val = read_list (0, readcharfun);
@@ -1915,7 +1956,6 @@ readevalloop (Lisp_Object readcharfun,
       else
        {
          UNREAD (c);
-         read_objects = Qnil;
          if (!NILP (readfun))
            {
              val = call1 (readfun, readcharfun);
@@ -1935,6 +1975,13 @@ readevalloop (Lisp_Object readcharfun,
          else
            val = read_internal_start (readcharfun, Qnil, Qnil);
        }
+      /* Empty hashes can be reused; otherwise, reset on next call.  */
+      if (HASH_TABLE_P (read_objects_map)
+         && XHASH_TABLE (read_objects_map)->count > 0)
+       read_objects_map = Qnil;
+      if (HASH_TABLE_P (read_objects_completed)
+         && XHASH_TABLE (read_objects_completed)->count > 0)
+       read_objects_completed = Qnil;
 
       if (!NILP (start) && continue_reading_p)
        start = Fpoint_marker ();
@@ -2106,7 +2153,18 @@ read_internal_start (Lisp_Object stream, Lisp_Object 
start, Lisp_Object end)
 
   readchar_count = 0;
   new_backquote_flag = 0;
-  read_objects = Qnil;
+  /* We can get called from readevalloop which may have set these
+     already.  */
+  if (! HASH_TABLE_P (read_objects_map)
+      || XHASH_TABLE (read_objects_map)->count)
+    read_objects_map
+      = make_hash_table (hashtest_eq, DEFAULT_HASH_SIZE, DEFAULT_REHASH_SIZE,
+                        DEFAULT_REHASH_THRESHOLD, Qnil, Qnil);
+  if (! HASH_TABLE_P (read_objects_completed)
+      || XHASH_TABLE (read_objects_completed)->count)
+    read_objects_completed
+      = make_hash_table (hashtest_eq, DEFAULT_HASH_SIZE, DEFAULT_REHASH_SIZE,
+                        DEFAULT_REHASH_THRESHOLD, Qnil, Qnil);
   if (EQ (Vread_with_symbol_positions, Qt)
       || EQ (Vread_with_symbol_positions, stream))
     Vread_symbol_positions_list = Qnil;
@@ -2134,6 +2192,13 @@ read_internal_start (Lisp_Object stream, Lisp_Object 
start, Lisp_Object end)
   if (EQ (Vread_with_symbol_positions, Qt)
       || EQ (Vread_with_symbol_positions, stream))
     Vread_symbol_positions_list = Fnreverse (Vread_symbol_positions_list);
+  /* Empty hashes can be reused; otherwise, reset on next call.  */
+  if (HASH_TABLE_P (read_objects_map)
+      && XHASH_TABLE (read_objects_map)->count > 0)
+    read_objects_map = Qnil;
+  if (HASH_TABLE_P (read_objects_completed)
+      && XHASH_TABLE (read_objects_completed)->count > 0)
+    read_objects_completed = Qnil;
   return retval;
 }
 
@@ -2901,7 +2966,7 @@ read1 (Lisp_Object readcharfun, int *pch, bool 
first_in_list)
              /* Copy that many characters into saved_doc_string.  */
              block_input ();
              for (i = 0; i < nskip && c >= 0; i++)
-               saved_doc_string[i] = c = getc (instream);
+               saved_doc_string[i] = c = getc_unlocked (instream);
              unblock_input ();
 
              saved_doc_string_length = i;
@@ -2974,7 +3039,7 @@ read1 (Lisp_Object readcharfun, int *pch, bool 
first_in_list)
                      /* Note: We used to use AUTO_CONS to allocate
                         placeholder, but that is a bad idea, since it
                         will place a stack-allocated cons cell into
-                        the list in read_objects, which is a
+                        the list in read_objects_map, which is a
                         staticpro'd global variable, and thus each of
                         its elements is marked during each GC.  A
                         stack-allocated object will become garbled
@@ -2983,27 +3048,62 @@ read1 (Lisp_Object readcharfun, int *pch, bool 
first_in_list)
                         different purposes, which will cause crashes
                         in GC.  */
                      Lisp_Object placeholder = Fcons (Qnil, Qnil);
-                     Lisp_Object cell = Fcons (make_number (n), placeholder);
-                     read_objects = Fcons (cell, read_objects);
+                     struct Lisp_Hash_Table *h
+                       = XHASH_TABLE (read_objects_map);
+                     EMACS_UINT hash;
+                     Lisp_Object number = make_number (n);
+
+                     ptrdiff_t i = hash_lookup (h, number, &hash);
+                     if (i >= 0)
+                       /* Not normal, but input could be malformed.  */
+                       set_hash_value_slot (h, i, placeholder);
+                     else
+                       hash_put (h, number, placeholder, hash);
 
                      /* Read the object itself.  */
                      tem = read0 (readcharfun);
 
+                     /* If it can be recursive, remember it for
+                        future substitutions.  */
+                     if (! SYMBOLP (tem)
+                         && ! NUMBERP (tem)
+                         && ! (STRINGP (tem) && !string_intervals (tem)))
+                       {
+                         struct Lisp_Hash_Table *h2
+                           = XHASH_TABLE (read_objects_completed);
+                         i = hash_lookup (h2, tem, &hash);
+                         eassert (i < 0);
+                         hash_put (h2, tem, Qnil, hash);
+                       }
+
                      /* Now put it everywhere the placeholder was...  */
-                     Fsubstitute_object_in_subtree (tem, placeholder);
+                      if (CONSP (tem))
+                        {
+                          Fsetcar (placeholder, XCAR (tem));
+                          Fsetcdr (placeholder, XCDR (tem));
+                          return placeholder;
+                        }
+                      else
+                        {
+                         Fsubstitute_object_in_subtree (tem, placeholder);
 
-                     /* ...and #n# will use the real value from now on.  */
-                     Fsetcdr (cell, tem);
+                         /* ...and #n# will use the real value from now on.  */
+                         i = hash_lookup (h, number, &hash);
+                         eassert (i >= 0);
+                         set_hash_value_slot (h, i, tem);
 
-                     return tem;
+                         return tem;
+                        }
                    }
 
                  /* #n# returns a previously read object.  */
                  if (c == '#')
                    {
-                     tem = Fassq (make_number (n), read_objects);
-                     if (CONSP (tem))
-                       return XCDR (tem);
+                     struct Lisp_Hash_Table *h
+                       = XHASH_TABLE (read_objects_map);
+                     ptrdiff_t i = hash_lookup (h, make_number (n), NULL);
+                     if (i >= 0)
+                       return HASH_VALUE (h, i);
                    }
                }
            }
@@ -3342,25 +3442,51 @@ read1 (Lisp_Object readcharfun, int *pch, bool 
first_in_list)
            if (! NILP (result))
              return unbind_to (count, result);
          }
+       {
+         Lisp_Object result;
+         ptrdiff_t nbytes = p - read_buffer;
+         ptrdiff_t nchars
+           = (multibyte
+              ? multibyte_chars_in_text ((unsigned char *) read_buffer,
+                                         nbytes)
+              : nbytes);
+
+         if (uninterned_symbol)
+           {
+             Lisp_Object name
+               = ((! NILP (Vpurify_flag)
+                   ? make_pure_string : make_specified_string)
+                  (read_buffer, nchars, nbytes, multibyte));
+             result = Fmake_symbol (name);
+           }
+         else
+           {
+             /* Don't create the string object for the name unless
+                we're going to retain it in a new symbol.
 
-       ptrdiff_t nbytes = p - read_buffer;
-       ptrdiff_t nchars
-         = (multibyte
-            ? multibyte_chars_in_text ((unsigned char *) read_buffer,
-                                       nbytes)
-            : nbytes);
-       Lisp_Object name = ((uninterned_symbol && ! NILP (Vpurify_flag)
-                            ? make_pure_string : make_specified_string)
-                           (read_buffer, nchars, nbytes, multibyte));
-       Lisp_Object result = (uninterned_symbol ? Fmake_symbol (name)
-                             : Fintern (name, Qnil));
-
-       if (EQ (Vread_with_symbol_positions, Qt)
-           || EQ (Vread_with_symbol_positions, readcharfun))
-         Vread_symbol_positions_list
-           = Fcons (Fcons (result, make_number (start_position)),
-                    Vread_symbol_positions_list);
-       return unbind_to (count, result);
+                Like intern_1 but supports multibyte names.  */
+             Lisp_Object obarray = check_obarray (Vobarray);
+             Lisp_Object tem = oblookup (obarray, read_buffer,
+                                         nchars, nbytes);
+
+             if (SYMBOLP (tem))
+               result = tem;
+             else
+               {
+                 Lisp_Object name
+                   = make_specified_string (read_buffer, nchars, nbytes,
+                                            multibyte);
+                 result = intern_driver (name, obarray, tem);
+               }
+           }
+
+         if (EQ (Vread_with_symbol_positions, Qt)
+             || EQ (Vread_with_symbol_positions, readcharfun))
+           Vread_symbol_positions_list
+             = Fcons (Fcons (result, make_number (start_position)),
+                      Vread_symbol_positions_list);
+         return unbind_to (count, result);
+       }
       }
     }
 }
@@ -3414,6 +3540,13 @@ substitute_object_recurse (Lisp_Object object, 
Lisp_Object placeholder, Lisp_Obj
   if (EQ (placeholder, subtree))
     return object;
 
+  /* For common object types that can't contain other objects, don't
+     bother looking them up; we're done.  */
+  if (SYMBOLP (subtree)
+      || (STRINGP (subtree) && !string_intervals (subtree))
+      || NUMBERP (subtree))
+    return subtree;
+
   /* If we've been to this node before, don't explore it again.  */
   if (!EQ (Qnil, Fmemq (subtree, seen_list)))
     return subtree;
@@ -3421,8 +3554,8 @@ substitute_object_recurse (Lisp_Object object, 
Lisp_Object placeholder, Lisp_Obj
   /* If this node can be the entry point to a cycle, remember that
      we've seen it.  It can only be such an entry point if it was made
      by #n=, which means that we can find it as a value in
-     read_objects.  */
-  if (!EQ (Qnil, Frassq (subtree, read_objects)))
+     read_objects_completed.  */
+  if (hash_lookup (XHASH_TABLE (read_objects_completed), subtree, NULL) >= 0)
     seen_list = Fcons (subtree, seen_list);
 
   /* Recurse according to subtree's type.
@@ -4898,8 +5031,10 @@ that are loaded before your customizations are read!  
*/);
   DEFSYM (Qdir_ok, "dir-ok");
   DEFSYM (Qdo_after_load_evaluation, "do-after-load-evaluation");
 
-  staticpro (&read_objects);
-  read_objects = Qnil;
+  staticpro (&read_objects_map);
+  read_objects_map = Qnil;
+  staticpro (&read_objects_completed);
+  read_objects_completed = Qnil;
   staticpro (&seen_list);
   seen_list = Qnil;