mt_allocator (__mt_alloc<>::_Tune): Add _M_align, the alignment requested.

2004-06-18  Paolo Carlini  <pcarlini@suse.de>

	* include/ext/mt_allocator (__mt_alloc<>::_Tune): Add _M_align,
	the alignment requested.
	(__mt_alloc<>::_Tune::_Tune): Tweak consistently.
	(__mt_alloc<>::allocate): Use it instead of sizeof(_Block_record).
	(__mt_alloc<>::deallocate): Likewise.

From-SVN: r83372

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index bd7da02e485ab43e110acdf9049ec3394d5d5067..fe64565e4eec7f7c9660287c7e025bbae0404791 100644 (file)
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,11 @@
+2004-06-18  Paolo Carlini  <pcarlini@suse.de>
+
+       * include/ext/mt_allocator (__mt_alloc<>::_Tune): Add _M_align,
+       the alignment requested.
+       (__mt_alloc<>::_Tune::_Tune): Tweak consistently.
+       (__mt_alloc<>::allocate): Use it instead of sizeof(_Block_record).
+       (__mt_alloc<>::deallocate): Likewise.
+
 2004-06-18  Paolo Carlini  <pcarlini@suse.de>
 
        PR libstdc++/16020

diff --git a/libstdc++-v3/include/ext/mt_allocator.h b/libstdc++-v3/include/ext/mt_allocator.h
index 9737700bda74d6929f644a3afbab398349ab56ac..8812c2df44b26f856a5bcc7dbbf8c15c2d836fc9 100644 (file)
--- a/libstdc++-v3/include/ext/mt_allocator.h
+++ b/libstdc++-v3/include/ext/mt_allocator.h
@@ -118,12 +118,18 @@ namespace __gnu_cxx
       // assigned and explained in detail below.
       struct _Tune
       {
+       // Alignment needed.
+       // NB: In any case must be >= sizeof(_Block_record), that
+       // is 4 on 32 bit machines and 8 on 64 bit machines.
+       size_t  _M_align;
+
        // Allocation requests (after round-up to power of 2) below
        // this value will be handled by the allocator. A raw new/
        // call will be used for requests larger than this value.
        size_t  _M_max_bytes; 
 
-       // Size in bytes of the smallest bin (must be a power of 2).
+       // Size in bytes of the smallest bin.
+       // NB: Must be a power of 2 and >= _M_align.
        size_t  _M_min_bin;
 
        // In order to avoid fragmenting and minimize the number of
@@ -150,18 +156,19 @@ namespace __gnu_cxx
      
        explicit
        _Tune()
-       : _M_max_bytes(128), _M_min_bin(8),
+       : _M_align(8), _M_max_bytes(128), _M_min_bin(8),
          _M_chunk_size(4096 - 4 * sizeof(void*)), 
          _M_max_threads(4096), _M_freelist_headroom(10), 
          _M_force_new(getenv("GLIBCXX_FORCE_NEW") ? true : false)
        { }
 
        explicit
-       _Tune(size_t __maxb, size_t __minbin, size_t __chunk,
-             size_t __maxthreads, size_t __headroom, bool __force) 
-       : _M_max_bytes(__maxb), _M_min_bin(__minbin), _M_chunk_size(__chunk), 
-         _M_max_threads(__maxthreads), _M_freelist_headroom(__headroom), 
-         _M_force_new(__force)
+       _Tune(size_t __align, size_t __maxb, size_t __minbin,
+             size_t __chunk, size_t __maxthreads, size_t __headroom,
+             bool __force) 
+       : _M_align(__align), _M_max_bytes(__maxb), _M_min_bin(__minbin),
+         _M_chunk_size(__chunk), _M_max_threads(__maxthreads),
+         _M_freelist_headroom(__headroom), _M_force_new(__force)
        { }
       };
 
@@ -306,8 +313,10 @@ namespace __gnu_cxx
       _Block_record* __block = NULL;
       if (__bin._M_first[__thread_id] == NULL)
        {
+         // NB: For alignment reasons, we can't use the first _M_align
+         // bytes, even when sizeof(_Block_record) < _M_align.
          const size_t __bin_size = ((_S_options._M_min_bin << __which)
-                                    + sizeof(_Block_record));
+                                    + _S_options._M_align);
          size_t __block_count = _S_options._M_chunk_size / __bin_size;   
 
          // Are we using threads?
@@ -399,7 +408,7 @@ namespace __gnu_cxx
        }
 #endif
 
-      char* __c = reinterpret_cast<char*>(__block) + sizeof(_Block_record);
+      char* __c = reinterpret_cast<char*>(__block) + _S_options._M_align;
       return static_cast<_Tp*>(static_cast<void*>(__c));
     }
   
@@ -421,7 +430,7 @@ namespace __gnu_cxx
       const size_t __which = _S_binmap[__bytes];
       const _Bin_record& __bin = _S_bin[__which];
 
-      char* __c = reinterpret_cast<char*>(__p) - sizeof(_Block_record);
+      char* __c = reinterpret_cast<char*>(__p) - _S_options._M_align;
       _Block_record* __block = reinterpret_cast<_Block_record*>(__c);
       
 #ifdef __GTHREADS