1 files changed, 53 insertions, 0 deletions
diff --git a/malloc/malloc-internal.h b/malloc/malloc-internal.h
index 98afd14040..a3df8c30ba 100644
--- a/malloc/malloc-internal.h
+++ b/malloc/malloc-internal.h
@@ -19,6 +19,59 @@
 #ifndef _MALLOC_INTERNAL_H
 #define _MALLOC_INTERNAL_H
 
+#include <malloc-machine.h>
+#include <malloc-sysdep.h>
+
+/* INTERNAL_SIZE_T is the word-size used for internal bookkeeping of
+   chunk sizes.
+
+   The default version is the same as size_t.
+
+   While not strictly necessary, it is best to define this as an
+   unsigned type, even if size_t is a signed type. This may avoid some
+   artificial size limitations on some systems.
+
+   On a 64-bit machine, you may be able to reduce malloc overhead by
+   defining INTERNAL_SIZE_T to be a 32 bit `unsigned int' at the
+   expense of not being able to handle more than 2^32 of malloced
+   space. If this limitation is acceptable, you are encouraged to set
+   this unless you are on a platform requiring 16byte alignments. In
+   this case the alignment requirements turn out to negate any
+   potential advantages of decreasing size_t word size.
+
+   Implementors: Beware of the possible combinations of:
+     - INTERNAL_SIZE_T might be signed or unsigned, might be 32 or 64 bits,
+       and might be the same width as int or as long
+     - size_t might have different width and signedness as INTERNAL_SIZE_T
+     - int and long might be 32 or 64 bits, and might be the same width
+
+   To deal with this, most comparisons and difference computations
+   among INTERNAL_SIZE_Ts should cast them to unsigned long, being
+   aware of the fact that casting an unsigned int to a wider long does
+   not sign-extend. (This also makes checking for negative numbers
+   awkward.) Some of these casts result in harmless compiler warnings
+   on some systems.  */
+#ifndef INTERNAL_SIZE_T
+# define INTERNAL_SIZE_T size_t
+#endif
+
+/* The corresponding word size.  */
+#define SIZE_SZ (sizeof (INTERNAL_SIZE_T))
+
+/* MALLOC_ALIGNMENT is the minimum alignment for malloc'ed chunks.  It
+   must be a power of two at least 2 * SIZE_SZ, even on machines for
+   which smaller alignments would suffice. It may be defined as larger
+   than this though. Note however that code and data structures are
+   optimized for the case of 8-byte alignment.  */
+#ifndef MALLOC_ALIGNMENT
+# define MALLOC_ALIGNMENT (2 * SIZE_SZ < __alignof__ (long double) \
+                           ? __alignof__ (long double) : 2 * SIZE_SZ)
+#endif
+
+/* The corresponding bit mask value.  */
+#define MALLOC_ALIGN_MASK (MALLOC_ALIGNMENT - 1)
+
+
 /* Called in the parent process before a fork.  */
 void __malloc_fork_lock_parent (void) internal_function attribute_hidden;