irnode.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   Representation of an intermediate operation.
 * @author  Martin Trapp, Christian Schaefer, Goetz Lindenmaier, Michael Beck
 * @version $Id$
 */
#include "config.h"

#include <string.h>

#include "ident.h"
#include "irnode_t.h"
#include "irgraph_t.h"
#include "irmode_t.h"
#include "irbackedge_t.h"
#include "irdump.h"
#include "irop_t.h"
#include "irprog_t.h"
#include "iredgekinds.h"
#include "iredges_t.h"
#include "ircons.h"

#include "irhooks.h"
#include "irtools.h"

#include "beinfo.h"

/* some constants fixing the positions of nodes predecessors
   in the in array */
#define CALL_PARAM_OFFSET     2
#define FUNCCALL_PARAM_OFFSET 1
#define SEL_INDEX_OFFSET      2
#define RETURN_RESULT_OFFSET  1  /* mem is not a result */
#define END_KEEPALIVE_OFFSET  0

static const char *pnc_name_arr [] = {
	"pn_Cmp_False", "pn_Cmp_Eq", "pn_Cmp_Lt", "pn_Cmp_Le",
	"pn_Cmp_Gt", "pn_Cmp_Ge", "pn_Cmp_Lg", "pn_Cmp_Leg",
	"pn_Cmp_Uo", "pn_Cmp_Ue", "pn_Cmp_Ul", "pn_Cmp_Ule",
	"pn_Cmp_Ug", "pn_Cmp_Uge", "pn_Cmp_Ne", "pn_Cmp_True"
};

/**
 * returns the pnc name from an pnc constant
 */
const char *get_pnc_string(int pnc) {
	assert(pnc >= 0 && pnc <
			(int) (sizeof(pnc_name_arr)/sizeof(pnc_name_arr[0])));
	return pnc_name_arr[pnc];
}

/*
 * Calculates the negated (Complement(R)) pnc condition.
 */
pn_Cmp get_negated_pnc(long pnc, ir_mode *mode) {
	pnc ^= pn_Cmp_True;

	/* do NOT add the Uo bit for non-floating point values */
	if (! mode_is_float(mode))
		pnc &= ~pn_Cmp_Uo;

	return (pn_Cmp) pnc;
}

/* Calculates the inversed (R^-1) pnc condition, i.e., "<" --> ">" */
pn_Cmp get_inversed_pnc(long pnc) {
	long code    = pnc & ~(pn_Cmp_Lt|pn_Cmp_Gt);
	long lesser  = pnc & pn_Cmp_Lt;
	long greater = pnc & pn_Cmp_Gt;

	code |= (lesser ? pn_Cmp_Gt : 0) | (greater ? pn_Cmp_Lt : 0);

	return (pn_Cmp) code;
}

/**
 * Indicates, whether additional data can be registered to ir nodes.
 * If set to 1, this is not possible anymore.
 */
static int forbid_new_data = 0;

/**
 * The amount of additional space for custom data to be allocated upon
 * creating a new node.
 */
unsigned firm_add_node_size = 0;


/* register new space for every node */
unsigned firm_register_additional_node_data(unsigned size) {
	assert(!forbid_new_data && "Too late to register additional node data");

	if (forbid_new_data)
		return 0;

	return firm_add_node_size += size;
}


void init_irnode(void) {
	/* Forbid the addition of new data to an ir node. */
	forbid_new_data = 1;
}

/*
 * irnode constructor.
 * Create a new irnode in irg, with an op, mode, arity and
 * some incoming irnodes.
 * If arity is negative, a node with a dynamic array is created.
 */
ir_node *
new_ir_node(dbg_info *db, ir_graph *irg, ir_node *block, ir_op *op, ir_mode *mode,
            int arity, ir_node **in)
{
	ir_node *res;
	size_t node_size = offsetof(ir_node, attr) + op->attr_size + firm_add_node_size;
	char *p;
	int i;

	assert(irg);
	assert(op);
	assert(mode);
	p = obstack_alloc(irg->obst, node_size);
	memset(p, 0, node_size);
	res = (ir_node *)(p + firm_add_node_size);

	res->kind     = k_ir_node;
	res->op       = op;
	res->mode     = mode;
	res->visited  = 0;
	res->node_idx = irg_register_node_idx(irg, res);
	res->link     = NULL;
	res->deps     = NULL;

	if (arity < 0) {
		res->in = NEW_ARR_F(ir_node *, 1);  /* 1: space for block */
	} else {
		/* not nice but necessary: End and Sync must always have a flexible array */
		if (op == op_End || op == op_Sync)
			res->in = NEW_ARR_F(ir_node *, (arity+1));
		else
			res->in = NEW_ARR_D(ir_node *, irg->obst, (arity+1));
		memcpy(&res->in[1], in, sizeof(ir_node *) * arity);
	}

	res->in[0] = block;
	set_irn_dbg_info(res, db);
	res->out = NULL;

#ifdef DEBUG_libfirm
	res->node_nr = get_irp_new_node_nr();
#endif

	for (i = 0; i < EDGE_KIND_LAST; ++i)
		INIT_LIST_HEAD(&res->edge_info[i].outs_head);

	/* don't put this into the for loop, arity is -1 for some nodes! */
	edges_notify_edge(res, -1, res->in[0], NULL, irg);
	for (i = 1; i <= arity; ++i)
		edges_notify_edge(res, i - 1, res->in[i], NULL, irg);

	hook_new_node(irg, res);
	if (get_irg_phase_state(irg) == phase_backend) {
		be_info_new_node(res);
	}

	return res;
}

/*-- getting some parameters from ir_nodes --*/

int (is_ir_node)(const void *thing) {
	return _is_ir_node(thing);
}

int (get_irn_intra_arity)(const ir_node *node) {
	return _get_irn_intra_arity(node);
}

int (get_irn_inter_arity)(const ir_node *node) {
	return _get_irn_inter_arity(node);
}

int (*_get_irn_arity)(const ir_node *node) = _get_irn_intra_arity;

int (get_irn_arity)(const ir_node *node) {
	return _get_irn_arity(node);
}

/* Returns the array with ins. This array is shifted with respect to the
   array accessed by get_irn_n: The block operand is at position 0 not -1.
   (@@@ This should be changed.)
   The order of the predecessors in this array is not guaranteed, except that
   lists of operands as predecessors of Block or arguments of a Call are
   consecutive. */
ir_node **get_irn_in(const ir_node *node) {
	assert(node);
#ifdef INTERPROCEDURAL_VIEW
	if (get_interprocedural_view()) { /* handle Filter and Block specially */
		if (get_irn_opcode(node) == iro_Filter) {
			assert(node->attr.filter.in_cg);
			return node->attr.filter.in_cg;
		} else if (get_irn_opcode(node) == iro_Block && node->attr.block.in_cg) {
			return node->attr.block.in_cg;
		}
		/* else fall through */
	}
#endif /* INTERPROCEDURAL_VIEW */
	return node->in;
}

void set_irn_in(ir_node *node, int arity, ir_node **in) {
	int i;
	ir_node *** pOld_in;
	ir_graph *irg = current_ir_graph;

	assert(node);
#ifdef INTERPROCEDURAL_VIEW
	if (get_interprocedural_view()) { /* handle Filter and Block specially */
		ir_opcode code = get_irn_opcode(node);
		if (code  == iro_Filter) {
			assert(node->attr.filter.in_cg);
			pOld_in = &node->attr.filter.in_cg;
		} else if (code == iro_Block && node->attr.block.in_cg) {
			pOld_in = &node->attr.block.in_cg;
		} else {
			pOld_in = &node->in;
		}
	} else
#endif /* INTERPROCEDURAL_VIEW */
		pOld_in = &node->in;


	for (i = 0; i < arity; i++) {
		if (i < ARR_LEN(*pOld_in)-1)
			edges_notify_edge(node, i, in[i], (*pOld_in)[i+1], irg);
		else
			edges_notify_edge(node, i, in[i], NULL,            irg);
	}
	for (;i < ARR_LEN(*pOld_in)-1; i++) {
		edges_notify_edge(node, i, NULL, (*pOld_in)[i+1], irg);
	}

	if (arity != ARR_LEN(*pOld_in) - 1) {
		ir_node * block = (*pOld_in)[0];
		*pOld_in = NEW_ARR_D(ir_node *, irg->obst, arity + 1);
		(*pOld_in)[0] = block;
	}
	fix_backedges(irg->obst, node);

	memcpy((*pOld_in) + 1, in, sizeof(ir_node *) * arity);
}

ir_node *(get_irn_intra_n)(const ir_node *node, int n) {
	return _get_irn_intra_n (node, n);
}

ir_node *(get_irn_inter_n)(const ir_node *node, int n) {
	return _get_irn_inter_n (node, n);
}

ir_node *(*_get_irn_n)(const ir_node *node, int n) = _get_irn_intra_n;

ir_node *(get_irn_n)(const ir_node *node, int n) {
	return _get_irn_n(node, n);
}

void set_irn_n(ir_node *node, int n, ir_node *in) {
	assert(node && node->kind == k_ir_node);
	assert(-1 <= n);
	assert(n < get_irn_arity(node));
	assert(in && in->kind == k_ir_node);

	if ((n == -1) && (get_irn_opcode(node) == iro_Filter)) {
		/* Change block pred in both views! */
		node->in[n + 1] = in;
		assert(node->attr.filter.in_cg);
		node->attr.filter.in_cg[n + 1] = in;
		return;
	}
#ifdef INTERPROCEDURAL_VIEW
	if (get_interprocedural_view()) { /* handle Filter and Block specially */
		if (get_irn_opcode(node) == iro_Filter) {
			assert(node->attr.filter.in_cg);
			node->attr.filter.in_cg[n + 1] = in;
			return;
		} else if (get_irn_opcode(node) == iro_Block && node->attr.block.in_cg) {
			node->attr.block.in_cg[n + 1] = in;
			return;
		}
		/* else fall through */
	}
#endif /* INTERPROCEDURAL_VIEW */

	/* Call the hook */
	hook_set_irn_n(node, n, in, node->in[n + 1]);

	/* Here, we rely on src and tgt being in the current ir graph */
	edges_notify_edge(node, n, in, node->in[n + 1], current_ir_graph);

	node->in[n + 1] = in;
}

int add_irn_n(ir_node *node, ir_node *in) {
	int pos;
	ir_graph *irg = get_irn_irg(node);

	assert(node->op->opar == oparity_dynamic);
	pos = ARR_LEN(node->in) - 1;
	ARR_APP1(ir_node *, node->in, in);
	edges_notify_edge(node, pos, node->in[pos + 1], NULL, irg);

	/* Call the hook */
	hook_set_irn_n(node, pos, node->in[pos + 1], NULL);

	return pos;
}

void del_Sync_n(ir_node *n, int i)
{
	int      arity     = get_Sync_n_preds(n);
	ir_node *last_pred = get_Sync_pred(n, arity - 1);
	set_Sync_pred(n, i, last_pred);
	edges_notify_edge(n, arity - 1, NULL, last_pred, get_irn_irg(n));
	ARR_SHRINKLEN(get_irn_in(n), arity);
}

int (get_irn_deps)(const ir_node *node) {
	return _get_irn_deps(node);
}

ir_node *(get_irn_dep)(const ir_node *node, int pos) {
	return _get_irn_dep(node, pos);
}

void (set_irn_dep)(ir_node *node, int pos, ir_node *dep) {
	_set_irn_dep(node, pos, dep);
}

int add_irn_dep(ir_node *node, ir_node *dep) {
	int res = 0;

	/* DEP edges are only allowed in backend phase */
	assert(get_irg_phase_state(get_irn_irg(node)) == phase_backend);
	if (node->deps == NULL) {
		node->deps = NEW_ARR_F(ir_node *, 1);
		node->deps[0] = dep;
	} else {
		int i, n;
		int first_zero = -1;

		for(i = 0, n = ARR_LEN(node->deps); i < n; ++i) {
			if(node->deps[i] == NULL)
				first_zero = i;

			if(node->deps[i] == dep)
				return i;
		}

		if (first_zero >= 0) {
			node->deps[first_zero] = dep;
			res = first_zero;
		} else {
			ARR_APP1(ir_node *, node->deps, dep);
			res = n;
		}
	}

	edges_notify_edge_kind(node, res, dep, NULL, EDGE_KIND_DEP, get_irn_irg(node));

	return res;
}

void add_irn_deps(ir_node *tgt, ir_node *src) {
	int i, n;

	for (i = 0, n = get_irn_deps(src); i < n; ++i)
		add_irn_dep(tgt, get_irn_dep(src, i));
}


ir_mode *(get_irn_mode)(const ir_node *node) {
	return _get_irn_mode(node);
}

void (set_irn_mode)(ir_node *node, ir_mode *mode) {
	_set_irn_mode(node, mode);
}

ir_modecode get_irn_modecode(const ir_node *node) {
	assert(node);
	return node->mode->code;
}

/** Gets the string representation of the mode .*/
const char *get_irn_modename(const ir_node *node) {
	assert(node);
	return get_mode_name(node->mode);
}

ident *get_irn_modeident(const ir_node *node) {
	assert(node);
	return get_mode_ident(node->mode);
}

ir_op *(get_irn_op)(const ir_node *node) {
	return _get_irn_op(node);
}

/* should be private to the library: */
void (set_irn_op)(ir_node *node, ir_op *op) {
	_set_irn_op(node, op);
}

unsigned (get_irn_opcode)(const ir_node *node) {
	return _get_irn_opcode(node);
}

const char *get_irn_opname(const ir_node *node) {
	assert(node);
	if (is_Phi0(node)) return "Phi0";
	return get_id_str(node->op->name);
}

ident *get_irn_opident(const ir_node *node) {
	assert(node);
	return node->op->name;
}

ir_visited_t (get_irn_visited)(const ir_node *node) {
	return _get_irn_visited(node);
}

void (set_irn_visited)(ir_node *node, ir_visited_t visited) {
	_set_irn_visited(node, visited);
}

void (mark_irn_visited)(ir_node *node) {
	_mark_irn_visited(node);
}

int (irn_visited)(const ir_node *node) {
	return _irn_visited(node);
}

int (irn_visited_else_mark)(ir_node *node) {
	return _irn_visited_else_mark(node);
}

void (set_irn_link)(ir_node *node, void *link) {
	_set_irn_link(node, link);
}

void *(get_irn_link)(const ir_node *node) {
	return _get_irn_link(node);
}

op_pin_state (get_irn_pinned)(const ir_node *node) {
	return _get_irn_pinned(node);
}

op_pin_state (is_irn_pinned_in_irg) (const ir_node *node) {
	return _is_irn_pinned_in_irg(node);
}

void set_irn_pinned(ir_node *node, op_pin_state state) {
	/* due to optimization an opt may be turned into a Tuple */
	if (is_Tuple(node))
		return;

	assert(node && get_op_pinned(get_irn_op(node)) >= op_pin_state_exc_pinned);
	assert(state == op_pin_state_pinned || state == op_pin_state_floats);

	node->attr.except.pin_state = state;
}

/* Outputs a unique number for this node */
long get_irn_node_nr(const ir_node *node) {
	assert(node);
#ifdef DEBUG_libfirm
	return node->node_nr;
#else
	return (long)PTR_TO_INT(node);
#endif
}

const_attr *get_irn_const_attr(ir_node *node) {
	assert(is_Const(node));
	return &node->attr.con;
}

long get_irn_proj_attr(ir_node *node) {
	/* BEWARE: check for true Proj node here, no Filter */
	assert(node->op == op_Proj);
	return node->attr.proj;
}

alloc_attr *get_irn_alloc_attr(ir_node *node) {
	assert(is_Alloc(node));
	return &node->attr.alloc;
}

free_attr *get_irn_free_attr(ir_node *node) {
	assert(is_Free(node));
	return &node->attr.free;
}

symconst_attr *get_irn_symconst_attr(ir_node *node) {
	assert(is_SymConst(node));
	return &node->attr.symc;
}

ir_type *get_irn_call_attr(ir_node *node) {
	assert(is_Call(node));
	return node->attr.call.cld_tp = skip_tid(node->attr.call.cld_tp);
}

sel_attr *get_irn_sel_attr(ir_node *node) {
	assert(is_Sel(node));
	return &node->attr.sel;
}

phi_attr *get_irn_phi_attr(ir_node *node) {
	return &node->attr.phi;
}

block_attr *get_irn_block_attr(ir_node *node) {
	assert(is_Block(node));
	return &node->attr.block;
}

load_attr *get_irn_load_attr(ir_node *node) {
	assert(is_Load(node));
	return &node->attr.load;
}

store_attr *get_irn_store_attr(ir_node *node) {
	assert(is_Store(node));
	return &node->attr.store;
}

except_attr *get_irn_except_attr(ir_node *node) {
	assert(node->op == op_Div || node->op == op_Quot ||
	       node->op == op_DivMod || node->op == op_Mod || node->op == op_Call || node->op == op_Alloc || node->op == op_Bound);
	return &node->attr.except;
}

divmod_attr *get_irn_divmod_attr(ir_node *node) {
	assert(node->op == op_Div || node->op == op_Quot ||
	       node->op == op_DivMod || node->op == op_Mod);
	return &node->attr.divmod;
}

void *(get_irn_generic_attr)(ir_node *node) {
	assert(is_ir_node(node));
	return _get_irn_generic_attr(node);
}

const void *(get_irn_generic_attr_const)(const ir_node *node) {
	assert(is_ir_node(node));
	return _get_irn_generic_attr_const(node);
}

unsigned (get_irn_idx)(const ir_node *node) {
	assert(is_ir_node(node));
	return _get_irn_idx(node);
}

int get_irn_pred_pos(ir_node *node, ir_node *arg) {
	int i;
	for (i = get_irn_arity(node) - 1; i >= 0; i--) {
		if (get_irn_n(node, i) == arg)
			return i;
	}
	return -1;
}

/** manipulate fields of individual nodes **/

/* this works for all except Block */
ir_node *get_nodes_block(const ir_node *node) {
	assert(node->op != op_Block);
	return get_irn_n(node, -1);
}

void set_nodes_block(ir_node *node, ir_node *block) {
	assert(node->op != op_Block);
	set_irn_n(node, -1, block);
}

/* this works for all except Block */
ir_node *get_nodes_MacroBlock(const ir_node *node) {
	assert(node->op != op_Block);
	return get_Block_MacroBlock(get_irn_n(node, -1));
}

/* Test whether arbitrary node is frame pointer, i.e. Proj(pn_Start_P_frame_base)
 * from Start.  If so returns frame type, else Null. */
ir_type *is_frame_pointer(const ir_node *n) {
	if (is_Proj(n) && (get_Proj_proj(n) == pn_Start_P_frame_base)) {
		ir_node *start = get_Proj_pred(n);
		if (is_Start(start)) {
			return get_irg_frame_type(get_irn_irg(start));
		}
	}
	return NULL;
}

/* Test whether arbitrary node is tls pointer, i.e. Proj(pn_Start_P_tls)
 * from Start.  If so returns tls type, else Null. */
ir_type *is_tls_pointer(const ir_node *n) {
	if (is_Proj(n) && (get_Proj_proj(n) == pn_Start_P_tls)) {
		ir_node *start = get_Proj_pred(n);
		if (is_Start(start)) {
			return get_tls_type();
		}
	}
	return NULL;
}

/* Test whether arbitrary node is value arg base, i.e. Proj(pn_Start_P_value_arg_base)
 * from Start.  If so returns 1, else 0. */
int is_value_arg_pointer(const ir_node *n) {
	if (is_Proj(n) &&
		(get_Proj_proj(n) == pn_Start_P_value_arg_base) &&
		is_Start(get_Proj_pred(n)))
		return 1;
	return 0;
}

/* Returns an array with the predecessors of the Block. Depending on
   the implementation of the graph data structure this can be a copy of
   the internal representation of predecessors as well as the internal
   array itself. Therefore writing to this array might obstruct the ir. */
ir_node **get_Block_cfgpred_arr(ir_node *node) {
	assert(is_Block(node));
	return (ir_node **)&(get_irn_in(node)[1]);
}

int (get_Block_n_cfgpreds)(const ir_node *node) {
	return _get_Block_n_cfgpreds(node);
}

ir_node *(get_Block_cfgpred)(const ir_node *node, int pos) {
	return _get_Block_cfgpred(node, pos);
}

void set_Block_cfgpred(ir_node *node, int pos, ir_node *pred) {
	assert(is_Block(node));
	set_irn_n(node, pos, pred);
}

ir_node *(get_Block_cfgpred_block)(const ir_node *node, int pos) {
	return _get_Block_cfgpred_block(node, pos);
}

int get_Block_matured(const ir_node *node) {
	assert(is_Block(node));
	return (int)node->attr.block.is_matured;
}

void set_Block_matured(ir_node *node, int matured) {
	assert(is_Block(node));
	node->attr.block.is_matured = matured;
}

ir_visited_t (get_Block_block_visited)(const ir_node *node) {
	return _get_Block_block_visited(node);
}

void (set_Block_block_visited)(ir_node *node, ir_visited_t visit) {
	_set_Block_block_visited(node, visit);
}

/* For this current_ir_graph must be set. */
void (mark_Block_block_visited)(ir_node *node) {
	_mark_Block_block_visited(node);
}

int (Block_block_visited)(const ir_node *node) {
	return _Block_block_visited(node);
}

ir_node *get_Block_graph_arr(ir_node *node, int pos) {
	assert(is_Block(node));
	return node->attr.block.graph_arr[pos+1];
}

void set_Block_graph_arr(ir_node *node, int pos, ir_node *value) {
	assert(is_Block(node));
	node->attr.block.graph_arr[pos+1] = value;
}

#ifdef INTERPROCEDURAL_VIEW
void set_Block_cg_cfgpred_arr(ir_node *node, int arity, ir_node *in[]) {
	assert(is_Block(node));
	if (node->attr.block.in_cg == NULL || arity != ARR_LEN(node->attr.block.in_cg) - 1) {
		node->attr.block.in_cg = NEW_ARR_D(ir_node *, current_ir_graph->obst, arity + 1);
		node->attr.block.in_cg[0] = NULL;
		node->attr.block.cg_backedge = new_backedge_arr(current_ir_graph->obst, arity);
		{
			/* Fix backedge array.  fix_backedges() operates depending on
			   interprocedural_view. */
			int ipv = get_interprocedural_view();
			set_interprocedural_view(1);
			fix_backedges(current_ir_graph->obst, node);
			set_interprocedural_view(ipv);
		}
	}
	memcpy(node->attr.block.in_cg + 1, in, sizeof(ir_node *) * arity);
}

void set_Block_cg_cfgpred(ir_node *node, int pos, ir_node *pred) {
	assert(is_Block(node) && node->attr.block.in_cg &&
	       0 <= pos && pos < ARR_LEN(node->attr.block.in_cg) - 1);
	node->attr.block.in_cg[pos + 1] = pred;
}

ir_node **get_Block_cg_cfgpred_arr(ir_node *node) {
	assert(is_Block(node));
	return node->attr.block.in_cg == NULL ? NULL : node->attr.block.in_cg  + 1;
}

int get_Block_cg_n_cfgpreds(const ir_node *node) {
	assert(is_Block(node));
	return node->attr.block.in_cg == NULL ? 0 : ARR_LEN(node->attr.block.in_cg) - 1;
}

ir_node *get_Block_cg_cfgpred(const ir_node *node, int pos) {
	assert(is_Block(node) && node->attr.block.in_cg);
	return node->attr.block.in_cg[pos + 1];
}

void remove_Block_cg_cfgpred_arr(ir_node *node) {
	assert(is_Block(node));
	node->attr.block.in_cg = NULL;
}
#endif /* INTERPROCEDURAL_VIEW */

ir_node *(set_Block_dead)(ir_node *block) {
	return _set_Block_dead(block);
}

int (is_Block_dead)(const ir_node *block) {
	return _is_Block_dead(block);
}

ir_extblk *get_Block_extbb(const ir_node *block) {
	ir_extblk *res;
	assert(is_Block(block));
	res = block->attr.block.extblk;
	assert(res == NULL || is_ir_extbb(res));
	return res;
}

void set_Block_extbb(ir_node *block, ir_extblk *extblk) {
	assert(is_Block(block));
	assert(extblk == NULL || is_ir_extbb(extblk));
	block->attr.block.extblk = extblk;
}

/* Returns the macro block header of a block.*/
ir_node *get_Block_MacroBlock(const ir_node *block) {
	ir_node *mbh;
	assert(is_Block(block));
	mbh = get_irn_n(block, -1);
	/* once macro block header is respected by all optimizations,
	   this assert can be removed */
	assert(mbh != NULL);
	return mbh;
}

/* Sets the macro block header of a block. */
void set_Block_MacroBlock(ir_node *block, ir_node *mbh) {
	assert(is_Block(block));
	assert(is_Block(mbh));
	set_irn_n(block, -1, mbh);
}

/* returns the macro block header of a node. */
ir_node *get_irn_MacroBlock(const ir_node *n) {
	if (! is_Block(n)) {
		n = get_nodes_block(n);
		/* if the Block is Bad, do NOT try to get it's MB, it will fail. */
		if (is_Bad(n))
			return (ir_node *)n;
	}
	return get_Block_MacroBlock(n);
}