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bug#15550: Improve support for popcount and counting trailing zeros.


From: Paul Eggert
Subject: bug#15550: Improve support for popcount and counting trailing zeros.
Date: Mon, 07 Oct 2013 00:46:32 -0700
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.0

I'd like to install this patch soon.
Most of it is generated automatically from admin/merge-gnulib.

I'm CC'ing this to Eli to give him a heads-up about
the Microsoft-related side of this.  I assume that
nt/gnulib.mk needs to be edited at some point, but
that's better done by someone with Windows expertise.

=== modified file 'ChangeLog'
--- ChangeLog   2013-10-04 07:36:22 +0000
+++ ChangeLog   2013-10-07 07:36:08 +0000
@@ -1,3 +1,15 @@
+2013-10-07  Paul Eggert  <address@hidden>
+
+       Improve support for popcount and counting trailing zeros.
+       Do this by using the Gnulib modules for this.
+       This should generate faster code on non-GCC, non-MSC platforms,
+       and make the code a bit more portable, at least in theory.
+       * lib/count-one-bits.c, lib/count-one-bits.h:
+       * lib/count-trailing-zeros.c, lib/count-trailing-zeros.h:
+       * m4/count-one-bits.m4, m4/count-trailing-zeros.m4:
+       New files, copied from gnulib.
+       * lib/gnulib.mk, m4/gnulib-comp.m4: Regenerate.
+
 2013-10-04  Paul Eggert  <address@hidden>
 
        Use hardware insns for byteswapping on glibc hosts that support it.

=== modified file 'admin/ChangeLog'
--- admin/ChangeLog     2013-10-04 07:36:22 +0000
+++ admin/ChangeLog     2013-10-07 07:36:08 +0000
@@ -1,3 +1,9 @@
+2013-10-07  Paul Eggert  <address@hidden>
+
+       Improve support for popcount and counting trailing zeros.
+       * merge-gnulib (GNULIB_MODULES): Add count-one-bits
+       and count-trailing-zeros.
+
 2013-10-04  Paul Eggert  <address@hidden>
 
        Use hardware support for byteswapping on glibc x86 etc.

=== modified file 'admin/merge-gnulib'
--- admin/merge-gnulib  2013-10-04 07:36:22 +0000
+++ admin/merge-gnulib  2013-10-07 07:36:08 +0000
@@ -27,7 +27,8 @@
 
 GNULIB_MODULES='
   alloca-opt byteswap c-ctype c-strcase
-  careadlinkat close-stream crypto/md5 crypto/sha1 crypto/sha256 crypto/sha512
+  careadlinkat close-stream count-one-bits count-trailing-zeros
+  crypto/md5 crypto/sha1 crypto/sha256 crypto/sha512
   dtoastr dtotimespec dup2 environ execinfo faccessat
   fcntl fcntl-h fdatasync fdopendir filemode fstatat fsync
   getloadavg getopt-gnu gettime gettimeofday

=== added file 'lib/count-one-bits.c'
--- lib/count-one-bits.c        1970-01-01 00:00:00 +0000
+++ lib/count-one-bits.c        2013-10-07 07:36:08 +0000
@@ -0,0 +1,7 @@
+#include <config.h>
+#define COUNT_ONE_BITS_INLINE _GL_EXTERN_INLINE
+#include "count-one-bits.h"
+
+#if 1500 <= _MSC_VER && (defined _M_IX86 || defined _M_X64)
+int popcount_support = -1;
+#endif

=== added file 'lib/count-one-bits.h'
--- lib/count-one-bits.h        1970-01-01 00:00:00 +0000
+++ lib/count-one-bits.h        2013-10-07 07:36:08 +0000
@@ -0,0 +1,136 @@
+/* count-one-bits.h -- counts the number of 1-bits in a word.
+   Copyright (C) 2007-2013 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 of the License, 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, see <http://www.gnu.org/licenses/>.  */
+
+/* Written by Ben Pfaff.  */
+
+#ifndef COUNT_ONE_BITS_H
+#define COUNT_ONE_BITS_H 1
+
+#include <limits.h>
+#include <stdlib.h>
+
+#ifndef _GL_INLINE_HEADER_BEGIN
+ #error "Please include config.h first."
+#endif
+_GL_INLINE_HEADER_BEGIN
+#ifndef COUNT_ONE_BITS_INLINE
+# define COUNT_ONE_BITS_INLINE _GL_INLINE
+#endif
+
+/* Expand to code that computes the number of 1-bits of the local
+   variable 'x' of type TYPE (an unsigned integer type) and return it
+   from the current function.  */
+#define COUNT_ONE_BITS_GENERIC(TYPE)                                   \
+    do                                                                  \
+      {                                                                 \
+        int count = 0;                                                  \
+        int bits;                                                       \
+        for (bits = 0; bits < sizeof (TYPE) * CHAR_BIT; bits += 32)     \
+          {                                                             \
+            count += count_one_bits_32 (x);                             \
+            x = x >> 31 >> 1;                                           \
+          }                                                             \
+        return count;                                                   \
+      }                                                                 \
+    while (0)
+
+/* Assuming the GCC builtin is BUILTIN and the MSC builtin is MSC_BUILTIN,
+   expand to code that computes the number of 1-bits of the local
+   variable 'x' of type TYPE (an unsigned integer type) and return it
+   from the current function.  */
+#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
+# define COUNT_ONE_BITS(BUILTIN, MSC_BUILTIN, TYPE) return BUILTIN (x)
+#else
+
+/* Compute and return the number of 1-bits set in the least
+   significant 32 bits of X. */
+COUNT_ONE_BITS_INLINE int
+count_one_bits_32 (unsigned int x)
+{
+  x = ((x & 0xaaaaaaaaU) >> 1) + (x & 0x55555555U);
+  x = ((x & 0xccccccccU) >> 2) + (x & 0x33333333U);
+  x = (x >> 16) + (x & 0xffff);
+  x = ((x & 0xf0f0) >> 4) + (x & 0x0f0f);
+  return (x >> 8) + (x & 0x00ff);
+}
+
+# if 1500 <= _MSC_VER && (defined _M_IX86 || defined _M_X64)
+
+/* While gcc falls back to its own generic code if the machine
+   on which it's running doesn't support popcount, with Microsoft's
+   compiler we need to detect and fallback ourselves.  */
+#  pragma intrinsic __cpuid
+#  pragma intrinsic __popcnt
+#  pragma intrinsic __popcnt64
+
+/* Return nonzero if popcount is supported.  */
+
+/* 1 if supported, 0 if not supported, -1 if unknown.  */
+extern int popcount_support;
+
+COUNT_ONE_BITS_INLINE int
+popcount_supported (void)
+{
+  if (popcount_support < 0)
+    {
+      int cpu_info[4];
+      __cpuid (cpu_info, 1);
+      popcount_support = (cpu_info[2] >> 23) & 1;  /* See MSDN.  */
+    }
+  return popcount_support;
+}
+
+#  define COUNT_ONE_BITS(BUILTIN, MSC_BUILTIN, TYPE)    \
+     do                                                 \
+       {                                                \
+         if (popcount_supported ())                     \
+           return MSC_BUILTIN (x);                      \
+         else                                           \
+           COUNT_ONE_BITS_GENERIC (TYPE);               \
+       }                                                \
+     while (0)
+# else
+#  define COUNT_ONE_BITS(BUILTIN, MSC_BUILTIN, TYPE)   \
+     COUNT_ONE_BITS_GENERIC (TYPE)
+# endif
+#endif
+
+/* Compute and return the number of 1-bits set in X. */
+COUNT_ONE_BITS_INLINE int
+count_one_bits (unsigned int x)
+{
+  COUNT_ONE_BITS (__builtin_popcount, __popcnt, unsigned int);
+}
+
+/* Compute and return the number of 1-bits set in X. */
+COUNT_ONE_BITS_INLINE int
+count_one_bits_l (unsigned long int x)
+{
+  COUNT_ONE_BITS (__builtin_popcountl, __popcnt, unsigned long int);
+}
+
+#if HAVE_UNSIGNED_LONG_LONG_INT
+/* Compute and return the number of 1-bits set in X. */
+COUNT_ONE_BITS_INLINE int
+count_one_bits_ll (unsigned long long int x)
+{
+  COUNT_ONE_BITS (__builtin_popcountll, __popcnt64, unsigned long long int);
+}
+#endif
+
+_GL_INLINE_HEADER_END
+
+#endif /* COUNT_ONE_BITS_H */

=== added file 'lib/count-trailing-zeros.c'
--- lib/count-trailing-zeros.c  1970-01-01 00:00:00 +0000
+++ lib/count-trailing-zeros.c  2013-10-07 07:36:08 +0000
@@ -0,0 +1,3 @@
+#include <config.h>
+#define COUNT_TRAILING_ZEROS_INLINE _GL_EXTERN_INLINE
+#include "count-trailing-zeros.h"

=== added file 'lib/count-trailing-zeros.h'
--- lib/count-trailing-zeros.h  1970-01-01 00:00:00 +0000
+++ lib/count-trailing-zeros.h  2013-10-07 07:36:08 +0000
@@ -0,0 +1,106 @@
+/* count-trailing-zeros.h -- counts the number of trailing 0 bits in a word.
+   Copyright 2013 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 of the License, 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, see <http://www.gnu.org/licenses/>.  */
+
+/* Written by Paul Eggert.  */
+
+#ifndef COUNT_TRAILING_ZEROS_H
+#define COUNT_TRAILING_ZEROS_H 1
+
+#include <limits.h>
+#include <stdlib.h>
+
+#ifndef _GL_INLINE_HEADER_BEGIN
+ #error "Please include config.h first."
+#endif
+_GL_INLINE_HEADER_BEGIN
+#ifndef COUNT_TRAILING_ZEROS_INLINE
+# define COUNT_TRAILING_ZEROS_INLINE _GL_INLINE
+#endif
+
+/* Assuming the GCC builtin is BUILTIN and the MSC builtin is MSC_BUILTIN,
+   expand to code that computes the number of trailing zeros of the local
+   variable 'x' of type TYPE (an unsigned integer type) and return it
+   from the current function.  */
+#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
+# define COUNT_TRAILING_ZEROS(BUILTIN, MSC_BUILTIN, TYPE)               \
+  return x ? BUILTIN (x) : CHAR_BIT * sizeof x;
+#elif _MSC_VER
+# pragma intrinsic _BitScanForward
+# pragma intrinsic _BitScanForward64
+# define COUNT_TRAILING_ZEROS(BUILTIN, MSC_BUILTIN, TYPE)               \
+    do                                                                  \
+      {                                                                 \
+        unsigned long result;                                           \
+        return MSC_BUILTIN (&result, x) ? result : CHAR_BIT * sizeof x; \
+      }                                                                 \
+    while (0)
+#else
+# define COUNT_TRAILING_ZEROS(BUILTIN, MSC_BUILTIN, TYPE)               \
+    do                                                                  \
+      {                                                                 \
+        int count = 0;                                                  \
+        if (! x)                                                        \
+          return CHAR_BIT * sizeof x;                                   \
+        for (count = 0;                                                 \
+             (count < CHAR_BIT * sizeof x - 32                          \
+              && ! (x & 0xffffffffU));                                  \
+             count += 32)                                               \
+          x = x >> 31 >> 1;                                             \
+        return count + count_trailing_zeros_32 (x);                     \
+      }                                                                 \
+    while (0)
+
+/* Compute and return the number of trailing zeros in the least
+   significant 32 bits of X.  One of these bits must be nonzero.  */
+COUNT_TRAILING_ZEROS_INLINE int
+count_trailing_zeros_32 (unsigned int x)
+{
+  /* http://graphics.stanford.edu/~seander/bithacks.html */
+  static const char de_Bruijn_lookup[32] = {
+    0, 1, 28, 2, 29, 14, 24, 3, 30, 22, 20, 15, 25, 17, 4, 8,
+    31, 27, 13, 23, 21, 19, 16, 7, 26, 12, 18, 6, 11, 5, 10, 9
+  };
+  return de_Bruijn_lookup[(((x & -x) * 0x077cb531U) & 0xffffffffU) >> 27];
+}
+#endif
+
+/* Compute and return the number of trailing zeros in X. */
+COUNT_TRAILING_ZEROS_INLINE int
+count_trailing_zeros (unsigned int x)
+{
+  COUNT_TRAILING_ZEROS (__builtin_ctz, _BitScanForward, unsigned int);
+}
+
+/* Compute and return the number of trailing zeros in X. */
+COUNT_TRAILING_ZEROS_INLINE int
+count_trailing_zeros_l (unsigned long int x)
+{
+  COUNT_TRAILING_ZEROS (__builtin_ctzl, _BitScanForward, unsigned long int);
+}
+
+#if HAVE_UNSIGNED_LONG_LONG_INT
+/* Compute and return the number of trailing zeros in X. */
+COUNT_TRAILING_ZEROS_INLINE int
+count_trailing_zeros_ll (unsigned long long int x)
+{
+  COUNT_TRAILING_ZEROS (__builtin_ctzll, _BitScanForward64,
+                        unsigned long long int);
+}
+#endif
+
+_GL_INLINE_HEADER_END
+
+#endif

=== modified file 'lib/gnulib.mk'
--- lib/gnulib.mk       2013-10-04 07:36:22 +0000
+++ lib/gnulib.mk       2013-10-07 07:36:08 +0000
@@ -21,7 +21,7 @@
 # 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=build-aux 
--avoid=close --avoid=dup --avoid=fchdir --avoid=fstat --avoid=malloc-posix 
--avoid=msvc-inval --avoid=msvc-nothrow --avoid=open --avoid=openat-die 
--avoid=opendir --avoid=raise --avoid=save-cwd --avoid=select 
--avoid=sigprocmask --avoid=sys_types --avoid=threadlib 
--makefile-name=gnulib.mk --conditional-dependencies --no-libtool 
--macro-prefix=gl --no-vc-files alloca-opt byteswap c-ctype c-strcase 
careadlinkat close-stream crypto/md5 crypto/sha1 crypto/sha256 crypto/sha512 
dtoastr dtotimespec dup2 environ execinfo faccessat fcntl fcntl-h fdatasync 
fdopendir filemode fstatat fsync getloadavg getopt-gnu gettime gettimeofday 
intprops largefile lstat manywarnings memrchr mkostemp mktime pipe2 pselect 
pthread_sigmask putenv qacl readlink readlinkat sig2str socklen stat-time 
stdalign stdarg stdbool stdio strftime strtoimax strtoumax symlin
 k sys_sta
t sys_time time timer-time timespec-add timespec-sub unsetenv utimens warnings
+# Reproduce by: gnulib-tool --import --dir=. --lib=libgnu --source-base=lib 
--m4-base=m4 --doc-base=doc --tests-base=tests --aux-dir=build-aux 
--avoid=close --avoid=dup --avoid=fchdir --avoid=fstat --avoid=malloc-posix 
--avoid=msvc-inval --avoid=msvc-nothrow --avoid=open --avoid=openat-die 
--avoid=opendir --avoid=raise --avoid=save-cwd --avoid=select 
--avoid=sigprocmask --avoid=sys_types --avoid=threadlib 
--makefile-name=gnulib.mk --conditional-dependencies --no-libtool 
--macro-prefix=gl --no-vc-files alloca-opt byteswap c-ctype c-strcase 
careadlinkat close-stream count-one-bits count-trailing-zeros crypto/md5 
crypto/sha1 crypto/sha256 crypto/sha512 dtoastr dtotimespec dup2 environ 
execinfo faccessat fcntl fcntl-h fdatasync fdopendir filemode fstatat fsync 
getloadavg getopt-gnu gettime gettimeofday intprops largefile lstat 
manywarnings memrchr mkostemp mktime pipe2 pselect pthread_sigmask putenv qacl 
readlink readlinkat sig2str socklen stat-time stdalign stdarg stdbool stdio
  strftime
 strtoimax strtoumax symlink sys_stat sys_time time timer-time timespec-add 
timespec-sub unsetenv utimens warnings
 
 
 MOSTLYCLEANFILES += core *.stackdump
@@ -132,6 +132,22 @@
 
 ## end   gnulib module close-stream
 
+## begin gnulib module count-one-bits
+
+libgnu_a_SOURCES += count-one-bits.c
+
+EXTRA_DIST += count-one-bits.h
+
+## end   gnulib module count-one-bits
+
+## begin gnulib module count-trailing-zeros
+
+libgnu_a_SOURCES += count-trailing-zeros.c
+
+EXTRA_DIST += count-trailing-zeros.h
+
+## end   gnulib module count-trailing-zeros
+
 ## begin gnulib module crypto/md5
 
 libgnu_a_SOURCES += md5.c

=== added file 'm4/count-one-bits.m4'
--- m4/count-one-bits.m4        1970-01-01 00:00:00 +0000
+++ m4/count-one-bits.m4        2013-10-07 07:36:08 +0000
@@ -0,0 +1,12 @@
+# count-one-bits.m4 serial 3
+dnl Copyright (C) 2007, 2009-2013 Free Software Foundation, 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_COUNT_ONE_BITS],
+[
+  dnl We don't need (and can't compile) count_one_bits_ll
+  dnl unless the type 'unsigned long long int' exists.
+  AC_REQUIRE([AC_TYPE_UNSIGNED_LONG_LONG_INT])
+])

=== added file 'm4/count-trailing-zeros.m4'
--- m4/count-trailing-zeros.m4  1970-01-01 00:00:00 +0000
+++ m4/count-trailing-zeros.m4  2013-10-07 07:36:08 +0000
@@ -0,0 +1,12 @@
+# count-trailing-zeros.m4
+dnl Copyright (C) 2013 Free Software Foundation, 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_COUNT_TRAILING_ZEROS],
+[
+  dnl We don't need (and can't compile) count_trailing_zeros_ll
+  dnl unless the type 'unsigned long long int' exists.
+  AC_REQUIRE([AC_TYPE_UNSIGNED_LONG_LONG_INT])
+])

=== modified file 'm4/gnulib-comp.m4'
--- m4/gnulib-comp.m4   2013-10-04 07:36:22 +0000
+++ m4/gnulib-comp.m4   2013-10-07 07:36:08 +0000
@@ -48,6 +48,8 @@
   # Code from module careadlinkat:
   # Code from module clock-time:
   # Code from module close-stream:
+  # Code from module count-one-bits:
+  # Code from module count-trailing-zeros:
   # Code from module crypto/md5:
   # Code from module crypto/sha1:
   # Code from module crypto/sha256:
@@ -175,6 +177,8 @@
   gl_CLOCK_TIME
   gl_CLOSE_STREAM
   gl_MODULE_INDICATOR([close-stream])
+  gl_COUNT_ONE_BITS
+  gl_COUNT_TRAILING_ZEROS
   gl_MD5
   gl_SHA1
   gl_SHA256
@@ -806,6 +810,10 @@
   lib/careadlinkat.h
   lib/close-stream.c
   lib/close-stream.h
+  lib/count-one-bits.c
+  lib/count-one-bits.h
+  lib/count-trailing-zeros.c
+  lib/count-trailing-zeros.h
   lib/dirent.in.h
   lib/dosname.h
   lib/dtoastr.c
@@ -919,6 +927,8 @@
   m4/c-strtod.m4
   m4/clock_time.m4
   m4/close-stream.m4
+  m4/count-one-bits.m4
+  m4/count-trailing-zeros.m4
   m4/dirent_h.m4
   m4/dup2.m4
   m4/environ.m4

=== modified file 'src/ChangeLog'
--- src/ChangeLog       2013-10-06 15:59:11 +0000
+++ src/ChangeLog       2013-10-07 07:36:08 +0000
@@ -1,3 +1,22 @@
+2013-10-07  Paul Eggert  <address@hidden>
+
+       Improve support for popcount and counting trailing zeros.
+       * data.c: Include <count-one-bits.h>, <count-trailing-zeros.h>.
+       (USE_MSC_POPCOUNT, POPCOUNT_STATIC_INLINE)
+       (NEED_GENERIC_POPCOUNT, popcount_size_t_generic)
+       (popcount_size_t_msc, popcount_size_t_gcc):
+       Remove; now done by Gnulib.
+       (popcount_size_t): Now a macro that defers to Gnulib.
+       (count_trailing_zero_bits): Return int, for consistency with
+       Gnulib and because Emacs prefers signed to unsigned int.
+       Don't assume that size_t is either unsigned int or unsigned long
+       or unsigned long long.
+       (size_t_to_host_endian): Do not assume that size_t is either
+       exactly 32 or exactly 64 bits wide.
+       * lisp.h (BITS_PER_SIZE_T): Define consistently with BITS_PER_LONG
+       etc., so that it's now an enum constant, not a macro.
+       No need to assume that it's either 32 or 64.
+
 2013-10-06  Jan Djärv  <address@hidden>
 
        * nsterm.m (ns_update_begin): If native fullscreen and no toolbar,

=== modified file 'src/data.c'
--- src/data.c  2013-10-04 07:36:22 +0000
+++ src/data.c  2013-10-07 07:36:08 +0000
@@ -22,6 +22,8 @@
 #include <stdio.h>
 
 #include <byteswap.h>
+#include <count-one-bits.h>
+#include <count-trailing-zeros.h>
 #include <intprops.h>
 
 #include "lisp.h"
@@ -2971,107 +2973,15 @@
   return (((size_t) 1) << (nr_bits % BITS_PER_SIZE_T)) - 1;
 }
 
-#if _MSC_VER >= 1500 && (defined _M_IX86 || defined _M_X64)
-# define USE_MSC_POPCOUNT
-# define POPCOUNT_STATIC_INLINE static inline
-#elif __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
-# define USE_GCC_POPCOUNT
-# if 199901L <= __STDC_VERSION__ || !__STRICT_ANSI__
-#  define POPCOUNT_STATIC_INLINE static inline
-# endif
-#else
-# define NEED_GENERIC_POPCOUNT
-#endif
-#ifndef POPCOUNT_STATIC_INLINE
-# define POPCOUNT_STATIC_INLINE static
-#endif
-
-#ifdef USE_MSC_POPCOUNT
-# define NEED_GENERIC_POPCOUNT
-#endif
-
-#ifdef NEED_GENERIC_POPCOUNT
-POPCOUNT_STATIC_INLINE unsigned int
-popcount_size_t_generic (size_t val)
-{
-    unsigned short j;
-    unsigned int count = 0;
-
-    for (j = 0; j < BITS_PER_SIZE_T; ++j)
-      count += !!((((size_t) 1) << j) & val);
-
-    return count;
-}
-#endif
-
-#ifdef USE_MSC_POPCOUNT
-POPCOUNT_STATIC_INLINE unsigned int
-popcount_size_t_msc (size_t val)
-{
-  unsigned int count;
-
-#pragma intrinsic __cpuid
-  /* While gcc falls back to its own generic code if the machine on
-     which it's running doesn't support popcount, we need to perform the
-     detection and fallback ourselves when compiling with Microsoft's
-     compiler.  */
-
-    static enum {
-      popcount_unknown_support,
-      popcount_use_generic,
-      popcount_use_intrinsic
-    } popcount_state;
-
-    if (popcount_state == popcount_unknown_support)
-      {
-        int cpu_info[4];
-        __cpuid (cpu_info, 1);
-        if (cpu_info[2] & (1<<23)) /* See MSDN.  */
-          popcount_state = popcount_use_intrinsic;
-        else
-          popcount_state = popcount_use_generic;
-      }
-
-    if (popcount_state == popcount_use_intrinsic)
-      {
-# if BITS_PER_SIZE_T == 64
-#  pragma intrinsic __popcnt64
-      count = __popcnt64 (val);
-# else
-#  pragma intrinsic __popcnt
-    count = __popcnt (val);
-# endif
-      }
-    else
-      count = popcount_size_t_generic (val);
-
-    return count;
-}
-#endif /* USE_MSC_POPCOUNT */
-
-#ifdef USE_GCC_POPCOUNT
-POPCOUNT_STATIC_INLINE unsigned int
-popcount_size_t_gcc (size_t val)
-{
-# if BITS_PER_SIZE_T == 64
-  return __builtin_popcountll (val);
-# else
-  return __builtin_popcount (val);
-# endif
-}
-#endif /* USE_GCC_POPCOUNT */
-
-POPCOUNT_STATIC_INLINE unsigned int
-popcount_size_t (size_t val)
-{
-#if defined USE_MSC_POPCOUNT
-  return popcount_size_t_msc (val);
-#elif defined USE_GCC_POPCOUNT
-  return popcount_size_t_gcc (val);
-#else
-  return popcount_size_t_generic (val);
-#endif
-}
+#if SIZE_MAX <= UINT_MAX
+# define popcount_size_t count_one_bits
+#elif SIZE_MAX <= ULONG_MAX
+# define popcount_size_t count_one_bits_l
+#elif SIZE_MAX <= ULLONG_MAX
+# define popcount_size_t count_one_bits_ll
+#else
+# error "size_t wider than long long? Please file a bug report."
+#endif
 
 enum bool_vector_op { bool_vector_exclusive_or,
                       bool_vector_union,
@@ -3143,55 +3053,54 @@
 
 /* Compute the number of trailing zero bits in val.  If val is zero,
    return the number of bits in val.  */
-static unsigned int
+static int
 count_trailing_zero_bits (size_t val)
 {
+  if (SIZE_MAX == UINT_MAX)
+    return count_trailing_zeros (val);
+  if (SIZE_MAX == ULONG_MAX)
+    return count_trailing_zeros_l (val);
+# if HAVE_UNSIGNED_LONG_LONG_INT
+  if (SIZE_MAX == ULLONG_MAX)
+    return count_trailing_zeros_ll (val);
+# endif
+
+  /* The rest of this code is for the unlikely platform where size_t differs
+     in width from unsigned int, unsigned long, and unsigned long long.  */
   if (val == 0)
     return CHAR_BIT * sizeof (val);
-
-#if defined USE_GCC_POPCOUNT && BITS_PER_SIZE_T == 64
-  return __builtin_ctzll (val);
-#elif defined USE_GCC_POPCOUNT && BITS_PER_SIZE_T == 32
-  return __builtin_ctz (val);
-#elif _MSC_VER && BITS_PER_SIZE_T == 64
-# pragma intrinsic _BitScanForward64
-  {
-    /* No support test needed: support since 386.  */
-    unsigned long result;
-    _BitScanForward64 (&result, val);
-    return (unsigned int) result;
-  }
-#elif _MSC_VER && BITS_PER_SIZE_T == 32
-# pragma intrinsic _BitScanForward
-  {
-    /* No support test needed: support since 386.  */
-    unsigned long result;
-    _BitScanForward (&result, val);
-    return (unsigned int) result;
-  }
-#else
-  {
-    unsigned int count;
-    count = 0;
-    for (val = ~val; val & 1; val >>= 1)
-      ++count;
-
-    return count;
-  }
-#endif
+  if (SIZE_MAX <= UINT_MAX)
+    return count_trailing_zeros (val);
+  if (SIZE_MAX <= ULONG_MAX)
+    return count_trailing_zeros_l (val);
+  {
+# if HAVE_UNSIGNED_LONG_LONG_INT
+    verify (SIZE_MAX <= ULLONG_MAX);
+    return count_trailing_zeros_ll (val);
+# else
+    verify (SIZE_MAX <= ULONG_MAX);
+# endif
+  }
 }
 
 static size_t
 size_t_to_host_endian (size_t val)
 {
-#ifdef WORDS_BIGENDIAN
-# if BITS_PER_SIZE_T == 64
+#ifndef WORDS_BIGENDIAN
+  return val;
+#elif SIZE_MAX >> 31 == 1
+  return bswap_32 (val);
+#elif SIZE_MAX >> 31 >> 31 >> 1 == 1
   return bswap_64 (val);
-# else
-  return bswap_32 (val);
-# endif
 #else
-  return val;
+  int i;
+  size_t r = 0;
+  for (i = 0; i < sizeof val; i++)
+    {
+      r = (r << CHAR_BIT) | (val & ((1u << CHAR_BIT) - 1));
+      val >>= CHAR_BIT;
+    }
+  return r;
 #endif
 }
 

=== modified file 'src/lisp.h'
--- src/lisp.h  2013-10-04 07:36:22 +0000
+++ src/lisp.h  2013-10-07 07:36:08 +0000
@@ -71,6 +71,7 @@
     BITS_PER_SHORT     = CHAR_BIT * sizeof (short),
     BITS_PER_INT       = CHAR_BIT * sizeof (int),
     BITS_PER_LONG      = CHAR_BIT * sizeof (long int),
+    BITS_PER_SIZE_T    = CHAR_BIT * sizeof (size_t),
     BITS_PER_EMACS_INT = CHAR_BIT * sizeof (EMACS_INT)
   };
 
@@ -4366,12 +4367,6 @@
     return 0;
 }
 
-#if ((SIZE_MAX >> 31) >> 1) & 1
-# define BITS_PER_SIZE_T 64
-#else
-# define BITS_PER_SIZE_T 32
-#endif
-
 /* Round x to the next multiple of y.  Does not overflow.  Evaluates
    arguments repeatedly.  */
 #define ROUNDUP(x,y) ((y)*((x)/(y) + ((x)%(y)!=0)))






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