irgmod.c

/*
 * Copyright (C) 1995-2008 University of Karlsruhe.  All right reserved.
 *
 * This file is part of libFirm.
 *
 * This file may be distributed and/or modified under the terms of the
 * GNU General Public License version 2 as published by the Free Software
 * Foundation and appearing in the file LICENSE.GPL included in the
 * packaging of this file.
 *
 * Licensees holding valid libFirm Professional Edition licenses may use
 * this file in accordance with the libFirm Commercial License.
 * Agreement provided with the Software.
 *
 * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
 * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE.
 */

/**
 * @file
 * @brief    Support for ir graph modification.
 * @author   Martin Trapp, Christian Schaefer, Goetz Lindenmaier
 * @version  $Id$
 */
#include "config.h"

#include "irflag_t.h"
#include "irgwalk.h"
#include "irnode_t.h"
#include "irgraph_t.h"
#include "irgmod.h"
#include "array.h"
#include "ircons.h"
#include "irhooks.h"
#include "iredges_t.h"
#include "irtools.h"
#include "error.h"

/**
 * Turns a node into a "useless" Tuple.  The Tuple just forms a tuple
 * from several inputs.
 * This is useful if a node returning a tuple is removed, but the Projs
 * extracting values from the tuple are not available.
 */
void turn_into_tuple(ir_node *node, int arity)
{
	ir_graph *irg = get_irn_irg(node);
	ir_node **in  = ALLOCAN(ir_node*, arity);
	int       i;

	/* construct a new in array, with every input being bad */
	for (i = 0; i < arity; ++i) {
		in[i] = new_r_Bad(irg);
	}
	set_irn_in(node, arity, in);
	set_irn_op(node, op_Tuple);
}

/**
 * Insert irnode `new' in place of irnode `old'
 * Since `new' may be bigger than `old' replace `old'
 * by an op_Id which is smaller than everything.
 */
void exchange(ir_node *old, ir_node *nw)
{
	ir_graph *irg;

	assert(old && nw);
	assert(old != nw && "Exchanging node with itself is not allowed");

	irg = get_irn_irg(old);
	assert(irg == get_irn_irg(nw) && "New node must be in same irg as old node");

	hook_replace(old, nw);

	/*
	 * If new outs are on, we can skip the id node creation and reroute
	 * the edges from the old node to the new directly.
	 */
	if (edges_activated(irg)) {
		/* copy all dependencies from old to new */
		add_irn_deps(nw, old);

		edges_reroute(old, nw, irg);
		edges_reroute_kind(old, nw, EDGE_KIND_DEP, irg);
		edges_node_deleted(old, irg);
		/* noone is allowed to reference this node anymore */
		set_irn_op(old, op_Deleted);
	} else {
		/* Else, do it the old-fashioned way. */
		ir_node *block;

		hook_turn_into_id(old);

		block = old->in[0];
		if (! block) {
			block = is_Block(nw) ? nw : get_nodes_block(nw);

			if (! block) {
				panic("cannot find legal block for id");
			}
		}

		if (get_irn_op(old)->opar == oparity_dynamic) {
			DEL_ARR_F(get_irn_in(old));
		}

		old->op    = op_Id;
		old->in    = NEW_ARR_D (ir_node *, irg->obst, 2);
		old->in[0] = block;
		old->in[1] = nw;
	}
}

/*--------------------------------------------------------------------*/
/*  Functionality for collect_phis                                    */
/*--------------------------------------------------------------------*/

/**
 * Walker: links all Phi nodes to their Blocks lists,
 *         all Proj nodes to there predecessors.
 */
static void collect_phiprojs_walker(ir_node *n, void *env)
{
	ir_node *pred;
	(void) env;

	if (is_Phi(n)) {
		ir_node *block = get_nodes_block(n);
		add_Block_phi(block, n);
	} else if (is_Proj(n)) {
		pred = n;
		do {
			pred = get_Proj_pred(pred);
		} while (is_Proj(pred));

		set_irn_link(n, get_irn_link(pred));
		set_irn_link(pred, n);
	}
}

void collect_phiprojs(ir_graph *irg)
{
	assert((ir_resources_reserved(irg) & (IR_RESOURCE_IRN_LINK|IR_RESOURCE_PHI_LIST)) ==
		(IR_RESOURCE_IRN_LINK|IR_RESOURCE_PHI_LIST));
	irg_walk_graph(irg, firm_clear_node_and_phi_links, collect_phiprojs_walker, NULL);
}

/*--------------------------------------------------------------------*/
/*  Functionality for part_block                                      */
/*--------------------------------------------------------------------*/

/**
 * Moves node and all predecessors of node from from_bl to to_bl.
 * Does not move predecessors of Phi nodes (or block nodes).
 */
static void move(ir_node *node, ir_node *from_bl, ir_node *to_bl)
{
	int i, arity;

	/* move this node */
	set_nodes_block(node, to_bl);

	/* move its Projs */
	if (get_irn_mode(node) == mode_T) {
		ir_node *proj = get_irn_link(node);
		while (proj) {
			if (get_nodes_block(proj) == from_bl)
				set_nodes_block(proj, to_bl);
			proj = get_irn_link(proj);
		}
	}

	/* recursion ... */
	if (is_Phi(node))
		return;

	arity = get_irn_arity(node);
	for (i = 0; i < arity; i++) {
		ir_node *pred = get_irn_n(node, i);
		if (get_nodes_block(pred) == from_bl)
			move(pred, from_bl, to_bl);
	}
}

void part_block(ir_node *node)
{
	ir_node *new_block, *old_block;
	ir_node *phi, *jmp;
	ir_graph *rem = current_ir_graph;

	/* Turn off optimizations so that blocks are not merged again. */
	int rem_opt = get_opt_optimize();
	set_optimize(0);

	current_ir_graph = get_irn_irg(node);

	/* Transform the control flow */
	old_block = get_nodes_block(node);
	new_block = new_Block(get_Block_n_cfgpreds(old_block),
	                      get_Block_cfgpred_arr(old_block));

	/* create a jump from new_block to old_block, which is now the lower one */
	jmp = new_r_Jmp(new_block);
	set_irn_in(old_block, 1, &jmp);

	/* move node and its predecessors to new_block */
	move(node, old_block, new_block);

	/* move Phi nodes to new_block */
	phi = get_Block_phis(old_block);
	set_Block_phis(new_block, phi);
	set_Block_phis(old_block, NULL);
	while (phi) {
		set_nodes_block(phi, new_block);
		phi = get_Phi_next(phi);
	}

	set_optimize(rem_opt);
	current_ir_graph = rem;
}

void kill_node(ir_node *node)
{
	ir_graph *irg = get_irn_irg(node);
	ir_node *bad = get_irg_bad(irg);
	int i;

	for (i = get_irn_arity(node) - 1; i >= -1; --i) {
		set_irn_n(node, i, bad);
	}
	exchange(node, bad);
}