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[SCM] GNU M4 source repository branch, branch-1.6, updated. v1.5.89a-41-


From: Eric Blake
Subject: [SCM] GNU M4 source repository branch, branch-1.6, updated. v1.5.89a-41-gffaa885
Date: Sat, 26 Jul 2008 20:05:30 +0000

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http://git.sv.gnu.org/gitweb/?p=m4.git;a=commitdiff;h=ffaa885fc0efb39bf0ca0df0a592a1c39f92729c

The branch, branch-1.6 has been updated
       via  ffaa885fc0efb39bf0ca0df0a592a1c39f92729c (commit)
      from  38a274a6e3c1e13e2d9d1c803d64b1a5414ff603 (commit)

Those revisions listed above that are new to this repository have
not appeared on any other notification email; so we list those
revisions in full, below.

- Log -----------------------------------------------------------------
commit ffaa885fc0efb39bf0ca0df0a592a1c39f92729c
Author: Eric Blake <address@hidden>
Date:   Sat Jul 26 13:27:02 2008 -0600

    Use hash module for self-growing symbol table.
    
    * m4/gnulib-cache.m4: Import hash module.
    * src/m4.h (struct symbol): Remove next member, change stack to be
    circular.
    (SYMBOL_NEXT): Delete.
    (symtab_free): New prototype.
    * src/symtab.c (show_profile) [DEBUG_SYM]: Track more hash
    statistics, and dump to /dev/tty rather than stderr.
    (symtab): Change type.
    (hash_table_size): Delete.
    (symtab_hasher, symtab_comparator, symtab_free_entry): New
    functions.
    (symtab_init, lookup_symbol, hack_all_symbols): Rewrite to wrap
    external hash table.
    (symtab_free): New function.
    (symtab_debug) [DEBUG_SYM]: Adjust client.
    * src/m4.c (main): Call symbol table cleanup.
    * src/freeze.c (dump_symbol_CB, reverse_symbol_list): Deal with
    fact that pushdef stack is now circular.
    
    Signed-off-by: Eric Blake <address@hidden>

-----------------------------------------------------------------------

Summary of changes:
 ChangeLog          |   22 ++++
 m4/gnulib-cache.m4 |    3 +-
 src/freeze.c       |   25 ++++--
 src/m4.c           |    5 +
 src/m4.h           |    5 +-
 src/symtab.c       |  271 +++++++++++++++++++++++++++++++--------------------
 6 files changed, 213 insertions(+), 118 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index ed2acce..de44226 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,25 @@
+2008-07-26  Eric Blake  <address@hidden>
+
+       Use hash module for self-growing symbol table.
+       * m4/gnulib-cache.m4: Import hash module.
+       * src/m4.h (struct symbol): Remove next member, change stack to be
+       circular.
+       (SYMBOL_NEXT): Delete.
+       (symtab_free): New prototype.
+       * src/symtab.c (show_profile) [DEBUG_SYM]: Track more hash
+       statistics, and dump to /dev/tty rather than stderr.
+       (symtab): Change type.
+       (hash_table_size): Delete.
+       (symtab_hasher, symtab_comparator, symtab_free_entry): New
+       functions.
+       (symtab_init, lookup_symbol, hack_all_symbols): Rewrite to wrap
+       external hash table.
+       (symtab_free): New function.
+       (symtab_debug) [DEBUG_SYM]: Adjust client.
+       * src/m4.c (main): Call symbol table cleanup.
+       * src/freeze.c (dump_symbol_CB, reverse_symbol_list): Deal with
+       fact that pushdef stack is now circular.
+
 2008-07-22  Eric Blake  <address@hidden>
 
        Make symbol table opaque.
diff --git a/m4/gnulib-cache.m4 b/m4/gnulib-cache.m4
index f716908..a512830 100644
--- a/m4/gnulib-cache.m4
+++ b/m4/gnulib-cache.m4
@@ -15,7 +15,7 @@
 
 
 # Specification in the form of a command-line invocation:
-#   gnulib-tool --import --dir=. --local-dir=local --lib=libm4 
--source-base=lib --m4-base=m4 --doc-base=doc --aux-dir=build-aux --with-tests 
--no-libtool --macro-prefix=M4 announce-gen assert autobuild avltree-oset 
binary-io clean-temp cloexec close-stream closein config-h error fdl fflush 
flexmember fopen-safer fseeko gendocs getopt git-version-gen gnumakefile 
gnupload gpl-3.0 intprops memmem mkstemp obstack obstack-printf-posix progname 
quote regex stdbool stdint stdlib-safer strtod strtol unlocked-io 
vasnprintf-posix verror version-etc version-etc-fsf xalloc xmemdup0 xprintf 
xvasprintf-posix
+#   gnulib-tool --import --dir=. --local-dir=local --lib=libm4 
--source-base=lib --m4-base=m4 --doc-base=doc --aux-dir=build-aux --with-tests 
--no-libtool --macro-prefix=M4 announce-gen assert autobuild avltree-oset 
binary-io clean-temp cloexec close-stream closein config-h error fdl fflush 
flexmember fopen-safer fseeko gendocs getopt git-version-gen gnumakefile 
gnupload gpl-3.0 hash intprops memmem mkstemp obstack obstack-printf-posix 
progname quote regex stdbool stdint stdlib-safer strtod strtol unlocked-io 
vasnprintf-posix verror version-etc version-etc-fsf xalloc xmemdup0 xprintf 
xvasprintf-posix
 
 # Specification in the form of a few gnulib-tool.m4 macro invocations:
 gl_LOCAL_DIR([local])
@@ -42,6 +42,7 @@ gl_MODULES([
   gnumakefile
   gnupload
   gpl-3.0
+  hash
   intprops
   memmem
   mkstemp
diff --git a/src/freeze.c b/src/freeze.c
index 3a48b03..2a7d9dc 100644
--- a/src/freeze.c
+++ b/src/freeze.c
@@ -30,17 +30,24 @@
 static symbol *
 reverse_symbol_list (symbol *sym)
 {
-  symbol *result;
+  symbol *first = sym;
   symbol *next;
+  symbol *prev = sym;
+  symbol *result;
 
-  result = NULL;
-  while (sym)
+  assert (sym);
+  if (sym->stack == sym)
+    return sym;
+  next = sym->stack;
+  do
     {
-      next = sym->stack;
-      sym->stack = result;
-      result = sym;
+      result = prev;
       sym = next;
+      next = sym->stack;
+      sym->stack = prev;
+      prev = sym;
     }
+  while (prev != first);
   return result;
 }
 
@@ -59,8 +66,9 @@ dump_symbol_CB (symbol *sym, void *f)
   /* Process all entries in each stack from the last to the first.
      This order ensures that, at reload time, pushdef's will be
      executed with the oldest definitions first.  */
-  sym = stack = reverse_symbol_list (sym);
-  while (sym)
+  stack = sym;
+  sym = reverse_symbol_list (sym);
+  do
     {
       switch (SYMBOL_TYPE (sym))
        {
@@ -99,6 +107,7 @@ dump_symbol_CB (symbol *sym, void *f)
        }
       sym = sym->stack;
     }
+  while (sym != stack->stack);
   /* Reverse the stack once more, putting it back as it was.  */
   reverse_symbol_list (stack);
 }
diff --git a/src/m4.c b/src/m4.c
index 7f0af7e..551d80c 100644
--- a/src/m4.c
+++ b/src/m4.c
@@ -683,8 +683,13 @@ main (int argc, char *const *argv, char *const *envp)
       undivert_all ();
     }
   output_exit ();
+#ifndef NDEBUG
+  /* Only spend time freeing memory to help isolate leaks; if
+     assertions are disabled, save the time and exit now.  */
   free_regex ();
   quotearg_free ();
+  symtab_free ();
+#endif /* NDEBUG */
 #ifdef DEBUG_REGEX
   if (trace_file)
     fclose (trace_file);
diff --git a/src/m4.h b/src/m4.h
index 011439e..ff0377a 100644
--- a/src/m4.h
+++ b/src/m4.h
@@ -416,8 +416,7 @@ enum symbol_lookup
 /* Symbol table entry.  */
 struct symbol
 {
-  struct symbol *next; /* Next symbol with the same hash.  */
-  struct symbol *stack; /* Stack of shadowed symbols of the same name.  */
+  struct symbol *stack; /* Circular list for pushdef stack of symbol.  */
   bool_bitfield traced : 1;
   bool_bitfield macro_args : 1;
   bool_bitfield blind_no_args : 1;
@@ -429,7 +428,6 @@ struct symbol
   token_data data;  /* Type should be only TOKEN_TEXT or TOKEN_FUNC.  */
 };
 
-#define SYMBOL_NEXT(S)         ((S)->next)
 #define SYMBOL_TRACED(S)       ((S)->traced)
 #define SYMBOL_MACRO_ARGS(S)   ((S)->macro_args)
 #define SYMBOL_BLIND_NO_ARGS(S)        ((S)->blind_no_args)
@@ -449,6 +447,7 @@ typedef void hack_symbol (symbol *, void *);
 
 void free_symbol (symbol *);
 void symtab_init (size_t);
+void symtab_free (void);
 symbol *lookup_symbol (const char *, size_t, symbol_lookup);
 void hack_all_symbols (hack_symbol *, void *);
 
diff --git a/src/symtab.c b/src/symtab.c
index 7420e50..a9160c8 100644
--- a/src/symtab.c
+++ b/src/symtab.c
@@ -33,6 +33,8 @@
 
 #include "m4.h"
 
+#include "hash.h"
+
 #ifdef DEBUG_SYM
 /* When evaluating hash table performance, this profiling code shows
    how many collisions were encountered.  */
@@ -47,19 +49,28 @@ struct profile
 
 static struct profile profiles[5];
 static symbol_lookup current_mode;
+static unsigned long long hash_entry;
+static unsigned long long comparator_entry;
+static size_t current_size;
+static unsigned int resizes;
 
 /* On exit, show a profile of symbol table performance.  */
 static void
 show_profile (void)
 {
   int i;
+  FILE *f = fopen ("/dev/tty", "w");
   for (i = 0; i < 5; i++)
     {
-      xfprintf(stderr, "m4: lookup mode %d called %d times, %d compares, "
+      xfprintf(f, "m4: lookup mode %d called %d times, %d compares, "
               "%d misses, %lld bytes\n",
               i, profiles[i].entry, profiles[i].comparisons,
               profiles[i].misses, profiles[i].bytes);
     }
+  xfprintf(f, "m4: %llu hash callbacks, %llu compare callbacks, "
+          "%zu buckets, %u resizes\n",
+          hash_entry, comparator_entry, current_size, resizes - 1);
+  fclose (f);
 }
 
 /* Like memcmp (S1, S2, L), but also track profiling statistics.  */
@@ -87,33 +98,12 @@ profile_memcmp (const char *s1, const char *s2, size_t l)
 #endif /* DEBUG_SYM */
 
 
-/*----------------------------------------------------------------------.
-| Initialise the symbol table, by allocating the necessary storage, and |
-| zeroing all the entries.                                             |
-`----------------------------------------------------------------------*/
-
 /* Pointer to symbol table.  */
-static symbol **symtab;
-
-/* Number of buckets in symbol table.  */
-static size_t hash_table_size;
-
-void
-symtab_init (size_t size)
-{
-  hash_table_size = size;
-  symtab = (symbol **) xnmalloc (hash_table_size, sizeof *symtab);
-  memset (symtab, 0, hash_table_size * sizeof *symtab);
-
-#ifdef DEBUG_SYM
-  atexit (show_profile); /* Ignore failure, since this is debug code.  */
-#endif /* DEBUG_SYM */
-}
+static Hash_table *symtab;
 
 /*--------------------------------------------------.
 | Return a hashvalue for a string S of length LEN.  |
 `--------------------------------------------------*/
-
 static size_t
 hash (const char *s, size_t len)
 {
@@ -126,6 +116,82 @@ hash (const char *s, size_t len)
   return val;
 }
 
+/*----------------------------------------------------.
+| Wrap our hash inside signature expected by hash.h.  |
+`----------------------------------------------------*/
+static size_t
+symtab_hasher (const void *entry, size_t buckets)
+{
+#ifdef DEBUG_SYM
+  hash_entry++;
+  if (buckets != current_size)
+    {
+      resizes++;
+      current_size = buckets;
+    }
+#endif /* DEBUG_SYM */
+  const symbol *sym = (const symbol *) entry;
+  return hash (SYMBOL_NAME (sym), SYMBOL_NAME_LEN (sym)) % buckets;
+}
+
+/*----------------------------------------------.
+| Compare two hash table entries for equality.  |
+`----------------------------------------------*/
+static bool
+symtab_comparator (const void *entry_a, const void *entry_b)
+{
+#ifdef DEBUG_SYM
+  comparator_entry++;
+#endif /* DEBUG_SYM */
+  const symbol *sym_a = (const symbol *) entry_a;
+  const symbol *sym_b = (const symbol *) entry_b;
+  return (SYMBOL_NAME_LEN (sym_a) == SYMBOL_NAME_LEN (sym_b)
+         && memcmp (SYMBOL_NAME (sym_a), SYMBOL_NAME (sym_b),
+                    SYMBOL_NAME_LEN (sym_a)) == 0);
+}
+
+/*---------------------------.
+| Reclaim an entry on exit.  |
+`---------------------------*/
+static void
+symtab_free_entry (void *entry)
+{
+  symbol *sym = (symbol *) entry;
+  while (sym->stack != sym)
+    {
+      symbol *old = sym->stack;
+      sym->stack = old->stack;
+      assert (!SYMBOL_PENDING_EXPANSIONS (old));
+      free_symbol (old);
+    }
+  assert (!SYMBOL_PENDING_EXPANSIONS (sym));
+  free_symbol (sym);
+}
+
+/*--------------------------------------------------------------.
+| Initialize the symbol table, with SIZE as a hint for expected |
+| number of entries.                                           |
+`--------------------------------------------------------------*/
+void
+symtab_init (size_t size)
+{
+  symtab = hash_initialize (size, NULL, symtab_hasher, symtab_comparator,
+                           symtab_free_entry);
+
+#ifdef DEBUG_SYM
+  atexit (show_profile); /* Ignore failure, since this is debug code.  */
+#endif /* DEBUG_SYM */
+}
+
+/*------------------------.
+| Clean up entire table.  |
+`------------------------*/
+void
+symtab_free (void)
+{
+  hash_free (symtab);
+}
+
 /*--------------------------------------------.
 | Free all storage associated with a symbol.  |
 `--------------------------------------------*/
@@ -162,38 +228,23 @@ free_symbol (symbol *sym)
 symbol *
 lookup_symbol (const char *name, size_t len, symbol_lookup mode)
 {
-  size_t h;
-  int cmp = 1;
-  symbol *sym, *prev;
-  symbol **spp;
+  symbol *sym;
+  symbol *entry;
+  symbol tmp;
 
 #if DEBUG_SYM
   current_mode = mode;
   profiles[mode].entry++;
 #endif /* DEBUG_SYM */
 
-  h = hash (name, len);
-  sym = symtab[h % hash_table_size];
-
-  for (prev = NULL; sym != NULL; prev = sym, sym = sym->next)
-    {
-      cmp = (len < SYMBOL_NAME_LEN (sym) ? -1 : len > SYMBOL_NAME_LEN (sym) ? 1
-            : memcmp (SYMBOL_NAME (sym), name, len));
-      if (cmp >= 0)
-       break;
-    }
-
-  /* If just searching, return status of search.  */
-
-  if (mode == SYMBOL_LOOKUP)
-    return cmp == 0 ? sym : NULL;
-
-  /* Symbol not found.  */
-
-  spp = (prev != NULL) ?  &prev->next : &symtab[h % hash_table_size];
+  tmp.name = (char *) name;
+  tmp.len = len;
+  entry = (symbol *) hash_lookup (symtab, &tmp);
 
   switch (mode)
     {
+    case SYMBOL_LOOKUP:
+      return entry ? entry->stack : NULL;
 
     case SYMBOL_INSERT:
 
@@ -202,14 +253,15 @@ lookup_symbol (const char *name, size_t len, 
symbol_lookup mode)
         a new one; if not, just return the symbol.  If not found, just
         insert the name, and return the new symbol.  */
 
-      if (cmp == 0 && sym != NULL)
+      if (entry)
        {
+         sym = entry->stack;
          if (SYMBOL_PENDING_EXPANSIONS (sym) > 0)
            {
              symbol *old = sym;
              SYMBOL_DELETED (old) = true;
 
-             sym = (symbol *) xmalloc (sizeof (symbol));
+             sym = (symbol *) xmalloc (sizeof *sym);
              SYMBOL_TYPE (sym) = TOKEN_VOID;
              SYMBOL_TRACED (sym) = SYMBOL_TRACED (old);
              SYMBOL_NAME (sym) = xmemdup0 (name, len);
@@ -219,11 +271,20 @@ lookup_symbol (const char *name, size_t len, 
symbol_lookup mode)
              SYMBOL_DELETED (sym) = false;
              SYMBOL_PENDING_EXPANSIONS (sym) = 0;
 
-             SYMBOL_NEXT (sym) = SYMBOL_NEXT (old);
-             SYMBOL_NEXT (old) = NULL;
-             sym->stack = old->stack;
+             if (old == entry)
+               {
+                 old = (symbol *) hash_delete (symtab, entry);
+                 assert (entry == old);
+                 sym->stack = sym;
+                 entry = (symbol *) hash_insert (symtab, sym);
+                 assert (sym == entry);
+               }
+             else
+               {
+                 entry->stack = sym;
+                 sym->stack = old->stack;
+               }
              old->stack = NULL;
-             *spp = sym;
            }
          return sym;
        }
@@ -231,11 +292,13 @@ lookup_symbol (const char *name, size_t len, 
symbol_lookup mode)
 
     case SYMBOL_PUSHDEF:
 
-      /* Insert a name in the symbol table.  If there is already a symbol
-        with the name, insert this in front of it, and mark the old
-        symbol as "shadowed".  */
-
-      sym = (symbol *) xmalloc (sizeof (symbol));
+      /* Insert a name in the symbol table.  If there is already a
+        symbol with the name, add it to the pushdef stack.  Since the
+        hash table does not allow the insertion of duplicates, the
+        pushdef stack is a circular chain; the hash entry is the
+        oldest entry, which points to the newest entry; all other
+        entries point to the next older entry.  */
+      sym = (symbol *) xmalloc (sizeof *sym);
       SYMBOL_TYPE (sym) = TOKEN_VOID;
       SYMBOL_TRACED (sym) = false;
       SYMBOL_NAME (sym) = xmemdup0 (name, len);
@@ -245,17 +308,19 @@ lookup_symbol (const char *name, size_t len, 
symbol_lookup mode)
       SYMBOL_DELETED (sym) = false;
       SYMBOL_PENDING_EXPANSIONS (sym) = 0;
 
-      SYMBOL_NEXT (sym) = *spp;
-      sym->stack = NULL;
-      *spp = sym;
-
-      if (mode == SYMBOL_PUSHDEF && cmp == 0)
+      if (entry)
        {
-         sym->stack = sym->next;
-         sym->next = sym->stack->next;
-         sym->stack->next = NULL;
+         assert (mode == SYMBOL_PUSHDEF);
+         sym->stack = entry->stack;
+         entry->stack = sym;
          SYMBOL_TRACED (sym) = SYMBOL_TRACED (sym->stack);
        }
+      else
+       {
+         sym->stack = sym;
+         entry = (symbol *) hash_insert (symtab, sym);
+         assert (sym == entry);
+       }
       return sym;
 
     case SYMBOL_DELETE:
@@ -268,37 +333,36 @@ lookup_symbol (const char *name, size_t len, 
symbol_lookup mode)
         definition is still in use, let the caller free the memory
         after it is done with the symbol.  */
 
-      if (cmp != 0 || sym == NULL)
+      if (!entry)
        return NULL;
       {
        bool traced = false;
-       symbol *result = sym;
-       if (sym->stack && mode == SYMBOL_POPDEF)
+       symbol *result = sym = entry->stack;
+       if (sym != entry && mode == SYMBOL_POPDEF)
          {
            SYMBOL_TRACED (sym->stack) = SYMBOL_TRACED (sym);
-           sym->stack->next = sym->next;
-           *spp = sym->stack;
-           sym->next = NULL;
+           entry->stack = sym->stack;
            sym->stack = NULL;
            free_symbol (sym);
          }
        else
          {
            traced = SYMBOL_TRACED (sym);
-           *spp = sym->next;
-           do
+           while (sym != entry)
              {
                symbol *old = sym;
                sym = sym->stack;
-               old->next = NULL;
                old->stack = NULL;
                free_symbol (old);
              }
-           while (sym);
+           sym = (symbol *) hash_delete (symtab, entry);
+           assert (sym == entry);
+           sym->stack = NULL;
+           free_symbol (sym);
          }
        if (traced)
          {
-           sym = (symbol *) xmalloc (sizeof (symbol));
+           sym = (symbol *) xmalloc (sizeof *sym);
            SYMBOL_TYPE (sym) = TOKEN_VOID;
            SYMBOL_TRACED (sym) = true;
            SYMBOL_NAME (sym) = xmemdup0 (name, len);
@@ -308,9 +372,9 @@ lookup_symbol (const char *name, size_t len, symbol_lookup 
mode)
            SYMBOL_DELETED (sym) = false;
            SYMBOL_PENDING_EXPANSIONS (sym) = 0;
 
-           SYMBOL_NEXT (sym) = *spp;
-           sym->stack = NULL;
-           *spp = sym;
+           sym->stack = sym;
+           entry = (symbol *) hash_insert (symtab, sym);
+           assert (sym == entry);
          }
        return result;
       }
@@ -335,20 +399,17 @@ lookup_symbol (const char *name, size_t len, 
symbol_lookup mode)
 void
 hack_all_symbols (hack_symbol *func, void *data)
 {
-  size_t h;
-  symbol *sym;
+  symbol *sym = (symbol *) hash_get_first (symtab);
   symbol *next;
 
-  for (h = 0; h < hash_table_size; h++)
+  while (sym)
     {
       /* We allow func to call SYMBOL_POPDEF, which can invalidate
         sym, so we must grab the next element to traverse before
         calling func.  */
-      for (sym = symtab[h]; sym != NULL; sym = next)
-       {
-         next = SYMBOL_NEXT (sym);
-         func (sym, data);
-       }
+      next = (symbol *) hash_get_next (symtab, sym);
+      func (sym->stack, data);
+      sym = next;
     }
 }
 
@@ -396,28 +457,26 @@ symtab_debug (void)
 static void
 symtab_print_list (int i)
 {
-  symbol *sym;
+  symbol *sym = (symbol *) hash_get_first (symtab);
   symbol *stack;
-  size_t h;
 
   xprintf ("Symbol dump #%d:\n", i);
-  for (h = 0; h < hash_table_size; h++)
-    for (sym = symtab[h]; sym != NULL; sym = sym->next)
-      {
-       stack = sym;
-       do
-         {
-           xprintf ("\tname %s, len %zu, bucket %lu, addr %p, next %p, "
-                    "stack %p, flags%s%s, pending %d\n",
-                    SYMBOL_NAME (stack), SYMBOL_NAME_LEN (stack),
-                    (unsigned long int) h, stack, SYMBOL_NEXT (stack),
-                    stack->stack, SYMBOL_TRACED (stack) ? " traced" : "",
-                    SYMBOL_DELETED (stack) ? " deleted" : "",
-                    SYMBOL_PENDING_EXPANSIONS (stack));
-           stack = stack->stack;
-         }
-       while (stack);
-      }
+  while (sym)
+    {
+      stack = sym->stack;
+      do
+       {
+         xprintf ("\tname %s, len %zu, addr %p, "
+                  "stack %p, flags%s%s, pending %d\n",
+                  SYMBOL_NAME (stack), SYMBOL_NAME_LEN (stack),
+                  stack, stack->stack, SYMBOL_TRACED (stack) ? " traced" : "",
+                  SYMBOL_DELETED (stack) ? " deleted" : "",
+                  SYMBOL_PENDING_EXPANSIONS (stack));
+         stack = stack->stack;
+       }
+      while (stack != sym);
+      sym = (symbol *) hash_get_next (symtab, sym);
+    }
 }
 
 #endif /* DEBUG_SYM */


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