Use gnulib's alloca-opt module.

* .bzrignore: Add lib/alloca.h.
* Makefile.in (GNULIB_MODULES): Add alloca-opt.
* configure.in (AC_FUNC_ALLOCA): Remove almost all the alloca stuff,
as gnulib now does that for us.  Put alloca check after gl_INIT.
* lib/gnulib.mk, m4/gl-comp.m4: Regenerate.
* lib/alloca.in.h, m4/alloca.m4: New files, from gnulib.

ChangeLog

@@ -1,3 +1,13 @@
+2011-06-21  Paul Eggert  <eggert@cs.ucla.edu>
+
+	Use gnulib's alloca-opt module.
+	* .bzrignore: Add lib/alloca.h.
+	* Makefile.in (GNULIB_MODULES): Add alloca-opt.
+	* configure.in (AC_FUNC_ALLOCA): Remove almost all the alloca stuff,
+	as gnulib now does that for us.  Put alloca check after gl_INIT.
+	* lib/gnulib.mk, m4/gl-comp.m4: Regenerate.
+	* lib/alloca.in.h, m4/alloca.m4: New files, from gnulib.
+
 2011-06-21  Leo Liu  <sdl.web@gmail.com>
 
 	* m4/sha256.m4:

Makefile.in

@@ -332,6 +332,7 @@ DOS_gnulib_comp.m4 = gl-comp.m4
 # $(gnulib_srcdir) (relative to $(srcdir) and should have build tools
 # as per $(gnulib_srcdir)/DEPENDENCIES.
 GNULIB_MODULES = \
+  alloca-opt \
   careadlinkat crypto/md5 crypto/sha1 crypto/sha256 crypto/sha512 dtoastr \
   filemode getloadavg getopt-gnu ignore-value intprops lstat mktime readlink \
   socklen stdarg stdio strftime strtoumax symlink sys_stat

configure.in

@@ -990,7 +990,7 @@ AC_SYS_LARGEFILE
 
 ## If user specified a crt-dir, use that unconditionally.
 if test "X$CRT_DIR" = "X"; then
-  
+
   case "$canonical" in
     x86_64-*-linux-gnu* | s390x-*-linux-gnu*)
     ## On x86-64 and s390x GNU/Linux distributions, the standard library
@@ -2565,15 +2565,6 @@ if test $emacs_cv_netdb_declares_h_errno = yes; then
   AC_DEFINE(HAVE_H_ERRNO, 1, [Define to 1 if netdb.h declares h_errno.])
 fi
 
-AC_FUNC_ALLOCA
-
-dnl src/alloca.c has been removed.  Could also check if $ALLOCA is set?
-dnl FIXME is there an autoconf test that does the right thing, without
-dnl needing to call A_M_E afterwards?
-if test x"$ac_cv_func_alloca_works" != xyes; then
-   AC_MSG_ERROR( [a system implementation of alloca is required] )
-fi
-
 # fmod, logb, and frexp are found in -lm on most systems.
 # On HPUX 9.01, -lm does not contain logb, so check for sqrt.
 AC_CHECK_LIB(m, sqrt)
@@ -2687,6 +2678,14 @@ gl_ASSERT_NO_GNULIB_POSIXCHECK
 gl_ASSERT_NO_GNULIB_TESTS
 gl_INIT
 
+# Check for alloca.
+dnl src/alloca.c has been removed.  Could also check if $ALLOCA is set?
+dnl FIXME is there an autoconf test that does the right thing, without
+dnl needing to call A_M_E afterwards?
+if test x"$ac_cv_func_alloca_works" != xyes; then
+   AC_MSG_ERROR( [a system implementation of alloca is required] )
+fi
+
 # UNIX98 PTYs.
 AC_CHECK_FUNCS(grantpt)
 
@@ -3534,20 +3533,7 @@ AH_BOTTOM([
 
 #include <string.h>
 #include <stdlib.h>
-
+#include <alloca.h>
-#ifdef HAVE_ALLOCA_H
-# include <alloca.h>
-#elif defined __GNUC__
-# define alloca __builtin_alloca
-#elif defined _AIX
-# define alloca __alloca
-#else
-# include <stddef.h>
-# ifdef  __cplusplus
-extern "C"
-# endif
-void *alloca (size_t);
-#endif
 
 #ifndef HAVE_STRCHR
 #define strchr(a, b) index (a, b)

lib/alloca.in.h

@@ -0,0 +1,56 @@
+/* Memory allocation on the stack.
+
+   Copyright (C) 1995, 1999, 2001-2004, 2006-2011 Free Software Foundation,
+   Inc.
+
+   This program is free software; you can redistribute it and/or modify it
+   under the terms of the GNU General Public License as published
+   by the Free Software Foundation; either version 3, or (at your option)
+   any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received a copy of the GNU General Public
+   License along with this program; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
+   USA.  */
+
+/* Avoid using the symbol _ALLOCA_H here, as Bison assumes _ALLOCA_H
+   means there is a real alloca function.  */
+#ifndef _GL_ALLOCA_H
+#define _GL_ALLOCA_H
+
+/* alloca (N) returns a pointer to N bytes of memory
+   allocated on the stack, which will last until the function returns.
+   Use of alloca should be avoided:
+     - inside arguments of function calls - undefined behaviour,
+     - in inline functions - the allocation may actually last until the
+       calling function returns,
+     - for huge N (say, N >= 65536) - you never know how large (or small)
+       the stack is, and when the stack cannot fulfill the memory allocation
+       request, the program just crashes.
+ */
+
+#ifndef alloca
+# ifdef __GNUC__
+#  define alloca __builtin_alloca
+# elif defined _AIX
+#  define alloca __alloca
+# elif defined _MSC_VER
+#  include <malloc.h>
+#  define alloca _alloca
+# elif defined __DECC && defined __VMS
+#  define alloca __ALLOCA
+# else
+#  include <stddef.h>
+#  ifdef  __cplusplus
+extern "C"
+#  endif
+void *alloca (size_t);
+# endif
+#endif
+
+#endif /* _GL_ALLOCA_H */

lib/gnulib.mk

@@ -9,7 +9,7 @@
 # the same distribution terms as the rest of that program.
 #
 # Generated by gnulib-tool.
-# Reproduce by: gnulib-tool --import --dir=. --lib=libgnu --source-base=lib --m4-base=m4 --doc-base=doc --tests-base=tests --aux-dir=. --makefile-name=gnulib.mk --conditional-dependencies --no-libtool --macro-prefix=gl --no-vc-files careadlinkat crypto/md5 crypto/sha1 crypto/sha256 crypto/sha512 dtoastr filemode getloadavg getopt-gnu ignore-value intprops lstat mktime readlink socklen stdarg stdio strftime strtoumax symlink sys_stat
+# Reproduce by: gnulib-tool --import --dir=. --lib=libgnu --source-base=lib --m4-base=m4 --doc-base=doc --tests-base=tests --aux-dir=. --makefile-name=gnulib.mk --conditional-dependencies --no-libtool --macro-prefix=gl --no-vc-files alloca-opt careadlinkat crypto/md5 crypto/sha1 crypto/sha256 crypto/sha512 dtoastr filemode getloadavg getopt-gnu ignore-value intprops lstat mktime readlink socklen stdarg stdio strftime strtoumax symlink sys_stat
 
 
 MOSTLYCLEANFILES += core *.stackdump
@@ -21,6 +21,29 @@ libgnu_a_LIBADD = $(gl_LIBOBJS)
 libgnu_a_DEPENDENCIES = $(gl_LIBOBJS)
 EXTRA_libgnu_a_SOURCES =
 
+## begin gnulib module alloca-opt
+
+BUILT_SOURCES += $(ALLOCA_H)
+
+# We need the following in order to create <alloca.h> when the system
+# doesn't have one that works with the given compiler.
+if GL_GENERATE_ALLOCA_H
+alloca.h: alloca.in.h $(top_builddir)/config.status
+	$(AM_V_GEN)rm -f $@-t $@ && \
+	{ echo '/* DO NOT EDIT! GENERATED AUTOMATICALLY! */'; \
+	  cat $(srcdir)/alloca.in.h; \
+	} > $@-t && \
+	mv -f $@-t $@
+else
+alloca.h: $(top_builddir)/config.status
+	rm -f $@
+endif
+MOSTLYCLEANFILES += alloca.h alloca.h-t
+
+EXTRA_DIST += alloca.in.h
+
+## end   gnulib module alloca-opt
+
 ## begin gnulib module allocator
 
 libgnu_a_SOURCES += allocator.c

m4/alloca.m4

@@ -0,0 +1,121 @@
+# alloca.m4 serial 12
+dnl Copyright (C) 2002-2004, 2006-2007, 2009-2011 Free Software Foundation,
+dnl Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+AC_DEFUN([gl_FUNC_ALLOCA],
+[
+  AC_REQUIRE([AC_FUNC_ALLOCA])
+  if test $ac_cv_func_alloca_works = no; then
+    gl_PREREQ_ALLOCA
+  fi
+
+  # Define an additional variable used in the Makefile substitution.
+  if test $ac_cv_working_alloca_h = yes; then
+    AC_CACHE_CHECK([for alloca as a compiler built-in], [gl_cv_rpl_alloca], [
+      AC_EGREP_CPP([Need own alloca], [
+#if defined __GNUC__ || defined _AIX || defined _MSC_VER
+        Need own alloca
+#endif
+        ], [gl_cv_rpl_alloca=yes], [gl_cv_rpl_alloca=no])
+    ])
+    if test $gl_cv_rpl_alloca = yes; then
+      dnl OK, alloca can be implemented through a compiler built-in.
+      AC_DEFINE([HAVE_ALLOCA], [1],
+        [Define to 1 if you have 'alloca' after including <alloca.h>,
+         a header that may be supplied by this distribution.])
+      ALLOCA_H=alloca.h
+    else
+      dnl alloca exists as a library function, i.e. it is slow and probably
+      dnl a memory leak. Don't define HAVE_ALLOCA in this case.
+      ALLOCA_H=
+    fi
+  else
+    ALLOCA_H=alloca.h
+  fi
+  AC_SUBST([ALLOCA_H])
+  AM_CONDITIONAL([GL_GENERATE_ALLOCA_H], [test -n "$ALLOCA_H"])
+])
+
+# Prerequisites of lib/alloca.c.
+# STACK_DIRECTION is already handled by AC_FUNC_ALLOCA.
+AC_DEFUN([gl_PREREQ_ALLOCA], [:])
+
+# This works around a bug in autoconf <= 2.68.
+# See <http://lists.gnu.org/archive/html/bug-gnulib/2011-06/msg00277.html>.
+
+m4_version_prereq([2.69], [] ,[
+
+# This is taken from the following Autoconf patch:
+# http://git.savannah.gnu.org/cgit/autoconf.git/commit/?id=6cd9f12520b0d6f76d3230d7565feba1ecf29497
+
+# _AC_LIBOBJ_ALLOCA
+# -----------------
+# Set up the LIBOBJ replacement of `alloca'.  Well, not exactly
+# AC_LIBOBJ since we actually set the output variable `ALLOCA'.
+# Nevertheless, for Automake, AC_LIBSOURCES it.
+m4_define([_AC_LIBOBJ_ALLOCA],
+[# The SVR3 libPW and SVR4 libucb both contain incompatible functions
+# that cause trouble.  Some versions do not even contain alloca or
+# contain a buggy version.  If you still want to use their alloca,
+# use ar to extract alloca.o from them instead of compiling alloca.c.
+AC_LIBSOURCES(alloca.c)
+AC_SUBST([ALLOCA], [\${LIBOBJDIR}alloca.$ac_objext])dnl
+AC_DEFINE(C_ALLOCA, 1, [Define to 1 if using `alloca.c'.])
+
+AC_CACHE_CHECK(whether `alloca.c' needs Cray hooks, ac_cv_os_cray,
+[AC_EGREP_CPP(webecray,
+[#if defined CRAY && ! defined CRAY2
+webecray
+#else
+wenotbecray
+#endif
+], ac_cv_os_cray=yes, ac_cv_os_cray=no)])
+if test $ac_cv_os_cray = yes; then
+  for ac_func in _getb67 GETB67 getb67; do
+    AC_CHECK_FUNC($ac_func,
+		  [AC_DEFINE_UNQUOTED(CRAY_STACKSEG_END, $ac_func,
+				      [Define to one of `_getb67', `GETB67',
+				       `getb67' for Cray-2 and Cray-YMP
+				       systems. This function is required for
+				       `alloca.c' support on those systems.])
+    break])
+  done
+fi
+
+AC_CACHE_CHECK([stack direction for C alloca],
+	       [ac_cv_c_stack_direction],
+[AC_RUN_IFELSE([AC_LANG_SOURCE(
+[AC_INCLUDES_DEFAULT
+int
+find_stack_direction (int *addr, int depth)
+{
+  int dir, dummy = 0;
+  if (! addr)
+    addr = &dummy;
+  *addr = addr < &dummy ? 1 : addr == &dummy ? 0 : -1;
+  dir = depth ? find_stack_direction (addr, depth - 1) : 0;
+  return dir + dummy;
+}
+
+int
+main (int argc, char **argv)
+{
+  return find_stack_direction (0, argc + !argv + 20) < 0;
+}])],
+	       [ac_cv_c_stack_direction=1],
+	       [ac_cv_c_stack_direction=-1],
+	       [ac_cv_c_stack_direction=0])])
+AH_VERBATIM([STACK_DIRECTION],
+[/* If using the C implementation of alloca, define if you know the
+   direction of stack growth for your system; otherwise it will be
+   automatically deduced at runtime.
+	STACK_DIRECTION > 0 => grows toward higher addresses
+	STACK_DIRECTION < 0 => grows toward lower addresses
+	STACK_DIRECTION = 0 => direction of growth unknown */
+@%:@undef STACK_DIRECTION])dnl
+AC_DEFINE_UNQUOTED(STACK_DIRECTION, $ac_cv_c_stack_direction)
+])# _AC_LIBOBJ_ALLOCA
+])

m4/gl-comp.m4

@@ -26,6 +26,7 @@ AC_DEFUN([gl_EARLY],
   m4_pattern_allow([^gl_LIBOBJS$])dnl a variable
   m4_pattern_allow([^gl_LTLIBOBJS$])dnl a variable
   AC_REQUIRE([AC_PROG_RANLIB])
+  # Code from module alloca-opt:
   # Code from module allocator:
   # Code from module arg-nonnull:
   # Code from module c++defs:
@@ -94,6 +95,7 @@ AC_DEFUN([gl_INIT],
   m4_pushdef([gl_LIBSOURCES_DIR], [])
   gl_COMMON
   gl_source_base='lib'
+gl_FUNC_ALLOCA
 AC_CHECK_FUNCS_ONCE([readlinkat])
 gl_MD5
 gl_SHA1
@@ -392,6 +394,7 @@ AC_DEFUN([gl_FILE_LIST], [
   build-aux/arg-nonnull.h
   build-aux/c++defs.h
   build-aux/warn-on-use.h
+  lib/alloca.in.h
   lib/allocator.c
   lib/allocator.h
   lib/careadlinkat.c
@@ -445,6 +448,7 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/unistd.in.h
   lib/verify.h
   m4/00gnulib.m4
+  m4/alloca.m4
   m4/c-strtod.m4
   m4/extensions.m4
   m4/filemode.m4