Re: [3/18] argv_ref speedup: avoid length recomputations

[Eric Blake]

Eric Blake <ebb9 <at> byu.net> writes:

> 2007-11-29  Eric Blake  <ebb9 <at> byu.net>
> 
>       Stage 3: cache length, rather than computing it.
>       * src/builtin.c (define_user_macro, mkstemp_helper): Use
>       pre-computed length.

On the branch (but not head, since I haven't ported --warn-macro-sequence there 
yet):

> @@ -407,7 +407,8 @@ free_regex (void)
>  `-------------------------------------------------------------------------*/
>  
>  void
> -define_user_macro (const char *name, const char *text, symbol_lookup mode)
> +define_user_macro (const char *name, size_t len, const char *text,
> +   symbol_lookup mode)
>  {
>    symbol *s;
>    char *defn = xstrdup (text ? text : "");
> @@ -423,7 +424,6 @@ define_user_macro (const char *name, const char *text, 
symbol_lookup mode)
>    if (macro_sequence_inuse && text)
>      {
>        regoff_t offset = 0;
> -      size_t len = strlen (defn);

This hunk caused a regression, because I inadvertently changed len from the 
length of the macro's definition to the length of the macro name.  And I would 
have caught it sooner, had the test suite been testing --warn-macro-sequence.
 
Checking this in:

From: Eric Blake <address@hidden>
Date: Mon, 14 Jan 2008 11:49:03 -0700
Subject: [PATCH] Fix --warn-macro-sequence regression from 2007-11-29.

* src/builtin.c (define_user_macro): Use correct length.
* doc/m4.texinfo (Arguments): Test the fix.
(History): Reword to account for new year and eventual result of
the argv_ref branch.

Signed-off-by: Eric Blake <address@hidden>
---
 ChangeLog      |    8 ++++++++
 doc/m4.texinfo |   12 +++++++-----
 src/builtin.c  |   10 ++++++----
 3 files changed, 21 insertions(+), 9 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index f3ed17f..4a20b00 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2008-01-14  Eric Blake  <address@hidden>
+
+       Fix --warn-macro-sequence regression from 2007-11-29.
+       * src/builtin.c (define_user_macro): Use correct length.
+       * doc/m4.texinfo (Arguments): Test the fix.
+       (History): Reword to account for new year and eventual result of
+       the argv_ref branch.
+
 2008-01-08  Eric Blake  <address@hidden>
 
        Bump copyright year.
diff --git a/doc/m4.texinfo b/doc/m4.texinfo
index bfdb6f2..b24cc90 100644
--- a/doc/m4.texinfo
+++ b/doc/m4.texinfo
@@ -43,7 +43,7 @@ This manual is for @acronym{GNU} M4 (version @value{VERSION}, 
@value{UPDATED}),
 a package containing an implementation of the m4 macro language.
 
 Copyright @copyright{} 1989, 1990, 1991, 1992, 1993, 1994, 2004, 2005,
-2006, 2007 Free Software Foundation, Inc.
+2006, 2007, 2008 Free Software Foundation, Inc.
 
 @quotation
 Permission is granted to copy, distribute and/or modify this document
@@ -391,9 +391,11 @@ addressed some long standing bugs in the venerable 1.4 
release.  Then in
 2005, Gary V. Vaughan collected together the many patches to
 @acronym{GNU} @code{m4} 1.4 that were floating around the net and
 released 1.4.3 and 1.4.4.  And in 2006, Eric Blake joined the team and
-prepared patches for the release of 1.4.5, 1.4.6, 1.4.7, and 1.4.8.  The
-1.4.x series remains open for bug fixes, including releases 1.4.9,
-1.4.10, and 1.4.11 in 2007.
+prepared patches for the release of 1.4.5, 1.4.6, 1.4.7, and 1.4.8.
+More bug fixes were incorporated in 2007, with releases 1.4.9 and
+1.4.10.  In 2008, Eric additionally rewrote the scanning engine to
+reduce recursive evaluation from quadratic to linear complexity for
+1.4.11.  The 1.4.x branch remains open for bug fixes.
 
 Meanwhile, development has continued on new features for @code{m4}, such
 as dynamic module loading and additional builtins.  When complete,
@@ -1830,7 +1832,7 @@ default, because it triggers a number of warnings in 
Autoconf 2.61 (and
 Autoconf uses @option{-E} to treat warnings as errors), and because it
 will still be possible to restore older behavior in M4 2.0.
 
address@hidden ignore
address@hidden options: --warn-macro-sequence
 @example
 $ @kbd{m4 --warn-macro-sequence}
 define(`foo', `$001 address@hidden@} $1')
diff --git a/src/builtin.c b/src/builtin.c
index cb5f274..e873061 100644
--- a/src/builtin.c
+++ b/src/builtin.c
@@ -1,7 +1,7 @@
 /* GNU m4 -- A simple macro processor
 
-   Copyright (C) 1989, 1990, 1991, 1992, 1993, 1994, 2000, 2004, 2006, 2007
-   Free Software Foundation, Inc.
+   Copyright (C) 1989, 1990, 1991, 1992, 1993, 1994, 2000, 2004, 2006, 2007,
+   2008 Free Software Foundation, Inc.
 
    This file is part of GNU M4.
 
@@ -424,9 +424,11 @@ define_user_macro (const char *name, size_t len, const 
char *text,
   if (macro_sequence_inuse && text)
     {
       regoff_t offset = 0;
+      len = strlen (defn);
 
-      while ((offset = re_search (&macro_sequence_buf, defn, len, offset,
-                                 len - offset, &macro_sequence_regs)) >= 0)
+      while (offset < len
+            && (offset = re_search (&macro_sequence_buf, defn, len, offset,
+                                    len - offset, &macro_sequence_regs)) >= 0)
        {
          /* Skip empty matches.  */
          if (macro_sequence_regs.start[0] == macro_sequence_regs.end[0])
-- 
1.5.3.8