misc: add clz wrapper for builtin

* spot/bricks/brick-bitlevel, spot/misc/Makefile.am,
spot/misc/bitset.hh, spot/misc/clz.cc,
spot/misc/clz.hh, spot/misc/fixpool.hh: here.

spot/bricks/brick-bitlevel

@@ -37,6 +37,7 @@
 
 #include <atomic>
 #include <cstring>
+#include <spot/misc/clz.hh>
 
 #ifndef BRICK_BITLEVEL_H
 #define BRICK_BITLEVEL_H
@@ -182,19 +183,19 @@ static inline unsigned MSB( T x ) {
 template<>
 inline unsigned MSB< unsigned int >( unsigned int x ) {
     static const unsigned long bits = sizeof( unsigned int ) * 8 - 1;
-    return bits - __builtin_clz( x );
+    return bits - spot::clz( x );
 }
 
 template<>
 inline unsigned MSB< unsigned long >( unsigned long x ) {
     static const unsigned bits = sizeof( unsigned long ) * 8 - 1;
-    return bits - __builtin_clzl( x );
+    return bits - spot::clz( x );
 }
 
 template<>
 inline unsigned MSB< unsigned long long >( unsigned long long x ) {
     static const unsigned bits = sizeof( unsigned long long ) * 8 - 1;
-    return bits - __builtin_clzll( x );
+    return bits - spot::clz( x );
 }
 
 // gets only Most Significant Bit

spot/misc/Makefile.am

@@ -36,6 +36,7 @@ misc_HEADERS = \
   bitvect.hh \
   casts.hh \
   common.hh \
+  clz.hh \
   escape.hh \
   fixpool.hh \
   formater.hh \
@@ -63,6 +64,7 @@ libmisc_la_SOURCES = \
   bareword.cc \
   bitset.cc \
   bitvect.cc \
+  clz.cc \
   escape.cc \
   formater.cc \
   game.cc \

spot/misc/bitset.hh

@@ -22,6 +22,7 @@
 #include <array>
 #include <spot/misc/hashfunc.hh>
 #include <spot/misc/common.hh>
+#include <spot/misc/clz.hh>
 
 namespace spot
 {
@@ -362,7 +363,7 @@ namespace spot
               continue;
             }
 #ifdef __GNUC__
-          res += 8*sizeof(word_t) - __builtin_clz(v);
+          res += 8*sizeof(word_t) - clz(v);
 #else
           while (v)
             {

spot/misc/clz.cc

+// -*- coding: utf-8 -*-
+// Copyright (C) 2018 Laboratoire de Recherche et Développement
+// de l'Epita (LRDE).
+//
+// This file is part of Spot, a model checking library.
+//
+// Spot 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.
+//
+// Spot 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/>.
+
+#include "config.h"
+#include <spot/misc/clz.hh>
+
+namespace spot
+{
+  // use gcc and clang built-in functions
+  // both compilers use the same function names, and define __GNUC__
+#if __GNUC__
+  template<class T>
+  struct _clz;
+
+  template<>
+  struct _clz<unsigned>
+  {
+    unsigned
+    operator()(unsigned n) const noexcept
+    {
+      return __builtin_clz(n);
+    }
+  };
+
+  template<>
+  struct _clz<unsigned long>
+  {
+    unsigned long
+    operator()(unsigned long n) const noexcept
+    {
+      return __builtin_clzl(n);
+    }
+  };
+
+  template<>
+  struct _clz<unsigned long long>
+  {
+    unsigned long long
+    operator()(unsigned long long n) const noexcept
+    {
+      return __builtin_clzll(n);
+    }
+  };
+
+  size_t
+  clz(unsigned n)
+  {
+    return _clz<unsigned>()(n);
+  }
+
+  size_t
+  clz(unsigned long n)
+  {
+    return _clz<unsigned long>()(n);
+  }
+
+  size_t
+  clz(unsigned long long n)
+  {
+    return _clz<unsigned long long>()(n);
+  }
+#else
+  size_t
+  clz(unsigned n)
+  {
+    size_t res = CHAR_BIT*sizeof(size_t);
+    while (n)
+      {
+        --res;
+        n >>= 1;
+      }
+    return res;
+  }
+
+  size_t
+  clz(unsigned long n)
+  {
+    size_t res = CHAR_BIT*sizeof(unsigned long);
+    while (n)
+      {
+        --res;
+        n >>= 1;
+      }
+    return res;
+  }
+
+  size_t
+  clz(unsigned long long n)
+  {
+    size_t res = CHAR_BIT*sizeof(unsigned long long);
+    while (n)
+      {
+        --res;
+        n >>= 1;
+      }
+    return res;
+  }
+#endif
+}

spot/misc/clz.hh

+// -*- coding: utf-8 -*-
+// Copyright (C) 2018 Laboratoire de Recherche et Développement
+// de l'Epita (LRDE).
+//
+// This file is part of Spot, a model checking library.
+//
+// Spot 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.
+//
+// Spot 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/>.
+
+#pragma once
+
+#include <spot/misc/common.hh>
+#include <cstddef>
+#include <climits>
+
+namespace spot
+{
+  SPOT_API size_t clz(unsigned n);
+
+  SPOT_API size_t clz(unsigned long n);
+
+  SPOT_API size_t clz(unsigned long long n);
+}

spot/misc/fixpool.hh

@@ -20,8 +20,7 @@
 #pragma once
 
 #include <spot/misc/common.hh>
-#include <climits>
-#include <cstddef>
+#include <spot/misc/clz.hh>
 
 #if SPOT_DEBUG && defined(HAVE_VALGRIND_MEMCHECK_H)
 #include <valgrind/memcheck.h>
@@ -59,8 +58,7 @@ namespace spot
               return size;
             // small numbers are best aligned to the next power of 2
             else if (size < alignof(std::max_align_t))
-              return size_t{1} << (CHAR_BIT*sizeof(size_t) -
-                                   __builtin_clz(size));
+              return size_t{1} << (CHAR_BIT*sizeof(size_t) - clz(size));
             else
               {
                 size_t mask = alignof(std::max_align_t)-1;