* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * This source file is part of SableVM.                            *
 *                                                                 *
 * See the file "LICENSE" for the copyright information and for    *
 * the terms and conditions for copying, distribution and          *
 * modification of this source file.                               *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *

*** SableVM small memory footprint ***

Purpose
=======

To generate the smallest binary at compile time and use the smallest amount of
memory at run time.

This is generally useful for systems with memory constraints.


TODO
====

* Optimize memory consumption at run time.


How to enable it
================

Add the --enable-small-footprint flag to the configure script.


How to save additional static memory footprint
===============================================

A common way to save additional static memory footprint is to use the ``strip''
utility (generally found in the GNU binutils package) to remove the symbols
from the shared object.


How it works
============

The _SABLEVM_SMALL_FOOTPRINT macro
----------------------------------

This macro is being used at compile time to trigger which code should be
included to generate the smallest binary.

The ``XXXXX_sfp.c'' files
-----------------------------

These files contain their respective ``XXXXX.c'' functionnality that is being
refactored in a more generic way.  This allows us to reuse code and save some
static memory footprint.

For instance, the file ``error_throwing_sfp.c'' contains the functionnality
of the file ``error_throwing.c'' in a space-efficient manner.


Splay tree
----------

Data structures that need to be included in a splay tree
(typically found in types.h) should be declared in the following way:

struct _svmt_sequence_node_struct
{
	/*
	 * Splay tree node pointers need to be at the beginning of the struct
	 * and in the same order as shown here.
	 */
	_svmt_sequence_node *parent;
	_svmt_sequence_node *left;
	_svmt_sequence_node *right;

	/*
	 * Object specific
	 */
	size_t instructions_length;
	jint *instructions;
	size_t implementation_length;
	void *implementation;
};

The above rule needs to be followed at all times since splay_tree_sfp.c
depends on it to perform its work, using an explicit cast of type
_svmt_splay_tree_node.  See splay_tree_sfp.c for more details.