opt_ldst.c 62.8 KB
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/*
 * 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   Dataflow driven Load/Store optimizations, uses some ideas from
 *          VanDrunen's LEPRE
 * @author  Michael Beck
 * @version $Id$
 */
#include "config.h"

#include "irnode_t.h"
#include "irflag_t.h"
#include "array_t.h"
#include "ircons.h"
#include "irdom.h"
#include "irgmod.h"
#include "irgwalk.h"
#include "irouts.h"
#include "irgraph.h"
#include "irgopt.h"
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#include "iropt.h"
#include "iroptimize.h"
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#include "irnodemap.h"
#include "raw_bitset.h"
#include "debug.h"
#include "error.h"
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#include "irpass.h"
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/* maximum number of output Proj's */
#define MAX_PROJ (pn_Load_max > pn_Store_max ? pn_Load_max : pn_Store_max)

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/**
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 * Mapping an address to an dense ID.
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 */
typedef struct address_entry_t {
	unsigned id;          /**< The ID */
} address_entry;

/**
 * Memop-flags.
 */
enum memop_flags {
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	FLAG_KILL_ALL    = 1, /**< KILL all addresses */
	FLAG_KILLED_NODE = 2, /**< this node was killed */
	FLAG_EXCEPTION   = 4, /**< this node has exception flow */
	FLAG_IGNORE      = 8, /**< ignore this node (volatile or other) */
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};

/**
 * A value: This represents a value stored at a given address in
 * memory. Do not confuse with values from value numbering.
 */
typedef struct value_t value_t;
struct value_t {
	ir_node  *address;    /**< the address of this value */
	ir_node  *value;      /**< the value itself */
	ir_mode  *mode;       /**< the mode of the value */
	unsigned id;          /**< address id */
};

/**
 * A memop describes an memory-related operation.
 * These are Loads/Store and all other ops that might modify
 * memory (Calls, CopyB) or causing exceptions.
 */
typedef struct memop_t memop_t;
struct memop_t {
	value_t  value;      /**< the value of this memop: only defined for Load/Store */
	ir_node  *node;      /**< the memory op itself */
	ir_node  *mem;       /**< the memory FROM this node */
	ir_node  *replace;   /**< the replacement node if this memop is replaced */
	memop_t  *next;      /**< links to the next memory op in the block in forward order. */
	memop_t  *prev;      /**< links to the previous memory op in the block in forward order. */
	unsigned flags;      /**< memop flags */
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	ir_node  *projs[MAX_PROJ]; /**< Projs of this memory op */
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};

/**
 * Additional data for every basic block.
 */
typedef struct block_t block_t;
struct block_t {
	memop_t  *memop_forward;     /**< topologically sorted list of memory ops in this block */
	memop_t  *memop_backward;    /**< last memop in the list */
	unsigned *avail_out;         /**< out-set of available addresses */
	memop_t  **id_2_memop_avail; /**< maps avail address ids to memops */
	unsigned *anticL_in;         /**< in-set of anticipated Load addresses */
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	memop_t  **id_2_memop_antic; /**< maps anticipated address ids to memops */
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	ir_node  *block;             /**< the associated block */
	block_t  *forward_next;      /**< next block entry for forward iteration */
	block_t  *backward_next;     /**< next block entry for backward iteration */
	memop_t  *avail;             /**< used locally for the avail map */
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	memop_t  **trans_results;    /**< used to cached translated nodes due antic calculation. */
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};

/**
 * Metadata for this pass.
 */
typedef struct ldst_env_t {
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	struct obstack  obst;              /**< obstack for temporary data */
	ir_nodemap_t    adr_map;           /**< Map addresses to */
	block_t         *forward;          /**< Inverse post-order list of all blocks Start->End */
	block_t         *backward;         /**< Inverse post-order list of all blocks End->Start */
	ir_node         *start_bl;         /**< start block of the current graph */
	ir_node         *end_bl;           /**< end block of the current graph */
	unsigned        *curr_set;         /**< current set of addresses */
	memop_t         **curr_id_2_memop; /**< current map of address ids to memops */
	unsigned        curr_adr_id;       /**< number for address mapping */
	unsigned        n_mem_ops;         /**< number of memory operations (Loads/Stores) */
	unsigned        rbs_size;          /**< size of all bitsets in bytes */
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	int             max_cfg_preds;     /**< maximum number of block cfg predecessors */
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	int             changed;           /**< Flags for changed graph state */
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#ifdef DEBUG_libfirm
	ir_node         **id_2_address;    /**< maps an id to the used address */
#endif
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} ldst_env;

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/* the one and only environment */
static ldst_env env;

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#ifdef DEBUG_libfirm

static firm_dbg_module_t *dbg;

/**
 * Dumps the block list.
 *
 * @param ldst environment
 */
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static void dump_block_list(ldst_env *env)
{
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	block_t *entry;
	memop_t *op;
	int     i;

	for (entry = env->forward; entry != NULL; entry = entry->forward_next) {
		DB((dbg, LEVEL_2, "%+F {", entry->block));

		i = 0;
		for (op = entry->memop_forward; op != NULL; op = op->next) {
			if (i == 0) {
				DB((dbg, LEVEL_2, "\n\t"));
			}			DB((dbg, LEVEL_2, "%+F", op->node));
			if ((op->flags & FLAG_KILL_ALL) == FLAG_KILL_ALL)
				DB((dbg, LEVEL_2, "X"));
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			else if (op->flags & FLAG_KILL_ALL)
				DB((dbg, LEVEL_2, "K"));
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			DB((dbg, LEVEL_2, ", "));

			i = (i + 1) & 3;
		}
		DB((dbg, LEVEL_2, "\n}\n\n"));
	}
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}  /* dump_block_list */
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/**
 * Dumps the current set.
 *
 * @param bl   current block
 * @param s    name of the set
 */
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static void dump_curr(block_t *bl, const char *s)
{
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	unsigned end = env.rbs_size - 1;
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	unsigned pos;
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	int      i;

	DB((dbg, LEVEL_2, "%s[%+F] = {", s, bl->block));
	i = 0;
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	for (pos = rbitset_next(env.curr_set, 0, 1); pos < end; pos = rbitset_next(env.curr_set, pos + 1, 1)) {
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		memop_t *op = env.curr_id_2_memop[pos];
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		if (i == 0) {
			DB((dbg, LEVEL_2, "\n\t"));
		}
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		DB((dbg, LEVEL_2, "<%+F, %+F>, ", op->value.address, op->value.value));
		i = (i + 1) & 3;
	}
	DB((dbg, LEVEL_2, "\n}\n"));
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}  /* dump_curr */
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#else
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static void dump_block_list(ldst_env *env)
{
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	(void) env;
}
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static void dump_curr(block_t *bl, const char *s)
{
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	(void) bl;
	(void) s;
}
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#endif /* DEBUG_libfirm */

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/** Get the block entry for a block node */
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static block_t *get_block_entry(const ir_node *block)
{
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	assert(is_Block(block));

	return get_irn_link(block);
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}  /* get_block_entry */
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/** Get the memop entry for a memory operation node */
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static memop_t *get_irn_memop(const ir_node *irn)
{
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	assert(! is_Block(irn));
	return get_irn_link(irn);
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}  /* get_irn_memop */
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/**
 * Walk over the memory edges from definition to users.
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 * This ensures, that even operation without memory output are found.
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 *
 * @param irn   start node
 * @param pre   pre walker function
 * @param post  post walker function
 * @param ctx   context parameter for the walker functions
 */
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static void walk_memory(ir_node *irn, irg_walk_func *pre, irg_walk_func *post, void *ctx)
{
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	int     i;
	ir_mode *mode;

	mark_irn_visited(irn);

	if (pre)
		pre(irn, ctx);

	mode = get_irn_mode(irn);
	if (mode == mode_M) {
		/* every successor uses memory */
		for (i = get_irn_n_outs(irn) - 1; i >= 0; --i) {
			ir_node *succ = get_irn_out(irn, i);

			if (! irn_visited(succ))
				walk_memory(succ, pre, post, ctx);
		}
	} else if (mode == mode_T) {
		/* only some Proj's uses memory */
		for (i = get_irn_n_outs(irn) - 1; i >= 0; --i) {
			ir_node *proj = get_irn_out(irn, i);

			if (get_irn_mode(proj) == mode_M && ! irn_visited(proj))
				walk_memory(proj, pre, post, ctx);
		}
	}
	if (post)
		post(irn, ctx);
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}  /* walk_memory */
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/**
 * Walks over all memory nodes of a graph.
 *
 * @param irg   a graph
 * @param pre   pre walker function
 * @param post  post walker function
 * @param ctx   context parameter for the walker functions
 */
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static void walk_memory_irg(ir_graph *irg, irg_walk_func pre, irg_walk_func post, void *ctx)
{
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	inc_irg_visited(irg);

	ir_reserve_resources(irg, IR_RESOURCE_IRN_VISITED);

	/*
	 * there are two possible sources for memory: initial_mem and nomem
	 * we ignore nomem as this should NOT change the memory
	 */
	walk_memory(get_irg_initial_mem(irg), pre, post, ctx);

	ir_free_resources(irg, IR_RESOURCE_IRN_VISITED);
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}  /* walk_memory_irg */
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/**
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 * Register an address and allocate a (sparse, 0..n) ID for it.
 *
 * @param adr  the IR-node representing the address
 *
 * @return the allocated id
 */
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static unsigned register_address(ir_node *adr)
{
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	address_entry *entry;

	/* skip Confirms and Casts */
restart:
	if (is_Confirm(adr)) {
		adr = get_Confirm_value(adr);
		goto restart;
	}
	if (is_Cast(adr)) {
		adr = get_Cast_op(adr);
		goto restart;
	}

	entry = ir_nodemap_get(&env.adr_map, adr);

	if (entry == NULL) {
		/* new address */
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		entry = OALLOC(&env.obst, address_entry);
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		entry->id = env.curr_adr_id++;
		ir_nodemap_insert(&env.adr_map, adr, entry);

		DB((dbg, LEVEL_3, "ADDRESS %+F has ID %u\n", adr, entry->id));
#ifdef DEBUG_libfirm
		ARR_APP1(ir_node *, env.id_2_address, adr);
#endif
	}
	return entry->id;
}  /* register_address */


/**
 * translate an address through a Phi node into a given predecessor
 * block.
 *
 * @param address  the address
 * @param block    the block
 * @param pos      the position of the predecessor in block
 */
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static ir_node *phi_translate(ir_node *address, const ir_node *block, int pos)
{
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	if (is_Phi(address) && get_nodes_block(address) == block)
		address = get_Phi_pred(address, pos);
	return address;
}  /* phi_translate */

/**
 * Walker: allocate an block entry for every block
 * and register all potential addresses.
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 */
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static void prepare_blocks(ir_node *irn, void *ctx)
{
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	(void)ctx;
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	if (is_Block(irn)) {
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		block_t *entry = OALLOC(&env.obst, block_t);
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		int     n;

		entry->memop_forward    = NULL;
		entry->memop_backward   = NULL;
		entry->avail_out        = NULL;
		entry->id_2_memop_avail = NULL;
		entry->anticL_in        = NULL;
		entry->id_2_memop_antic = NULL;
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		entry->block            = irn;
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		entry->forward_next     = NULL;
		entry->backward_next    = NULL;
		entry->avail            = NULL;
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		entry->trans_results    = NULL;
		set_irn_link(irn, entry);
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		set_Block_phis(irn, NULL);
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		/* use block marks to track unreachable blocks */
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		set_Block_mark(irn, 0);
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		n = get_Block_n_cfgpreds(irn);
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		if (n > env.max_cfg_preds)
			env.max_cfg_preds = n;
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	} else {
		ir_mode *mode = get_irn_mode(irn);

		if (mode_is_reference(mode)) {
			/*
			 * Register ALL possible addresses: this is overkill yet but
			 * simpler then doing it for all possible translated addresses
			 * (which would be sufficient in the moment.
			 */
			(void)register_address(irn);
		}
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	}
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}  /* prepare_blocks */
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/**
 * Post-Walker, link in all Phi's
 */
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static void link_phis(ir_node *irn, void *ctx)
{
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	(void)ctx;
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	if (is_Phi(irn)) {
		ir_node *block = get_nodes_block(irn);
		add_Block_phi(block, irn);
	}
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}  /* link_phis */
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/**
 * Block walker: creates the inverse post-order list for the CFG.
 */
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static void inverse_post_order(ir_node *block, void *ctx)
{
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	block_t *entry = get_block_entry(block);

	(void)ctx;
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	/* mark this block IS reachable from start */
	set_Block_mark(block, 1);

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	/* create the list in inverse order */
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	entry->forward_next = env.forward;
	env.forward         = entry;

	/* remember the first visited (last in list) entry, needed for later */
	if (env.backward == NULL)
		env.backward = entry;
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}  /* inverse_post_order */
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/**
 * Block walker: create backward links for the memops of a block.
 */
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static void collect_backward(ir_node *block, void *ctx)
{
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	block_t *entry = get_block_entry(block);
	memop_t *last, *op;

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	(void)ctx;
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	/*
	 * Do NOT link in the end block yet. We want it to be
	 * the first in the list. This is NOT guaranteed by the walker
	 * if we have endless loops.
	 */
	if (block != env.end_bl) {
		entry->backward_next = env.backward;

		/* create the list in inverse order */
		env.backward = entry;
	}
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	/* create backward links for all memory ops */
	last = NULL;
	for (op = entry->memop_forward; op != NULL; op = op->next) {
		op->prev = last;
		last     = op;
	}
	entry->memop_backward = last;
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}  /* collect_backward */
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/**
 * Allocate a memop.
 *
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 * @param irn  the IR-node representing the memop or NULL
 *             if this is a translated (virtual) memop
 *
 * @return the allocated memop
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 */
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static memop_t *alloc_memop(ir_node *irn)
{
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	memop_t *m = OALLOC(&env.obst, memop_t);
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	m->value.address = NULL;
	m->value.value   = NULL;
	m->value.mode    = NULL;

	m->node          = irn;
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	m->mem           = NULL;
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	m->replace       = NULL;
	m->next          = NULL;
	m->flags         = 0;

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	memset(m->projs, 0, sizeof(m->projs));

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	if (irn != NULL)
		set_irn_link(irn, m);
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	return m;
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}  /* alloc_memop */
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/**
 * Create a memop for a Phi-replacement.
 *
 * @param op   the memop to clone
 * @param phi  the Phi-node representing the new value
 */
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static memop_t *clone_memop_phi(memop_t *op, ir_node *phi)
{
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	memop_t *m = OALLOC(&env.obst, memop_t);
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	m->value         = op->value;
	m->value.value   = phi;

	m->node          = phi;
	m->replace       = NULL;
	m->next          = NULL;
	m->flags         = 0;

	set_irn_link(phi, m);
	return m;
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}  /* clone_memop_phi */
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/**
 * Return the memory properties of a call node.
 *
 * @param call  the call node
 *
 * return a bitset of mtp_property_const and mtp_property_pure
 */
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static unsigned get_Call_memory_properties(ir_node *call)
{
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	ir_type *call_tp = get_Call_type(call);
	unsigned prop = get_method_additional_properties(call_tp);

	/* check first the call type */
	if ((prop & (mtp_property_const|mtp_property_pure)) == 0) {
		/* try the called entity */
		ir_node *ptr = get_Call_ptr(call);

		if (is_Global(ptr)) {
			ir_entity *ent = get_Global_entity(ptr);

			prop = get_entity_additional_properties(ent);
		}
	}
	return prop & (mtp_property_const|mtp_property_pure);
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}  /* get_Call_memory_properties */
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/**
 * Returns an entity if the address ptr points to a constant one.
 *
 * @param ptr  the address
 *
 * @return an entity or NULL
 */
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static ir_entity *find_constant_entity(ir_node *ptr)
{
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	for (;;) {
		if (is_SymConst(ptr) && get_SymConst_kind(ptr) == symconst_addr_ent) {
			return get_SymConst_entity(ptr);
		} else if (is_Sel(ptr)) {
			ir_entity *ent = get_Sel_entity(ptr);
			ir_type   *tp  = get_entity_owner(ent);

			/* Do not fiddle with polymorphism. */
			if (is_Class_type(get_entity_owner(ent)) &&
				((get_entity_n_overwrites(ent)    != 0) ||
				(get_entity_n_overwrittenby(ent) != 0)   ) )
				return NULL;

			if (is_Array_type(tp)) {
				/* check bounds */
				int i, n;

				for (i = 0, n = get_Sel_n_indexs(ptr); i < n; ++i) {
					ir_node *bound;
					tarval *tlower, *tupper;
					ir_node *index = get_Sel_index(ptr, i);
					tarval *tv     = computed_value(index);

					/* check if the index is constant */
					if (tv == tarval_bad)
						return NULL;

					bound  = get_array_lower_bound(tp, i);
					tlower = computed_value(bound);
					bound  = get_array_upper_bound(tp, i);
					tupper = computed_value(bound);

					if (tlower == tarval_bad || tupper == tarval_bad)
						return NULL;

					if (tarval_cmp(tv, tlower) & pn_Cmp_Lt)
						return NULL;
					if (tarval_cmp(tupper, tv) & pn_Cmp_Lt)
						return NULL;

					/* ok, bounds check finished */
				}
			}

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			if (get_entity_linkage(ent) == IR_LINKAGE_CONSTANT)
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				return ent;

			/* try next */
			ptr = get_Sel_ptr(ptr);
		} else if (is_Add(ptr)) {
			ir_node *l = get_Add_left(ptr);
			ir_node *r = get_Add_right(ptr);

			if (get_irn_mode(l) == get_irn_mode(ptr) && is_Const(r))
				ptr = l;
			else if (get_irn_mode(r) == get_irn_mode(ptr) && is_Const(l))
				ptr = r;
			else
				return NULL;

			/* for now, we support only one addition, reassoc should fold all others */
			if (! is_SymConst(ptr) && !is_Sel(ptr))
				return NULL;
		} else if (is_Sub(ptr)) {
			ir_node *l = get_Sub_left(ptr);
			ir_node *r = get_Sub_right(ptr);

			if (get_irn_mode(l) == get_irn_mode(ptr) &&	is_Const(r))
				ptr = l;
			else
				return NULL;
			/* for now, we support only one subtraction, reassoc should fold all others */
			if (! is_SymConst(ptr) && !is_Sel(ptr))
				return NULL;
		} else
			return NULL;
	}
}  /* find_constant_entity */

/**
 * Return the Selection index of a Sel node from dimension n
 */
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static long get_Sel_array_index_long(ir_node *n, int dim)
{
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	ir_node *index = get_Sel_index(n, dim);
	assert(is_Const(index));
	return get_tarval_long(get_Const_tarval(index));
}  /* get_Sel_array_index_long */

/**
 * Returns the accessed component graph path for an
 * node computing an address.
 *
 * @param ptr    the node computing the address
 * @param depth  current depth in steps upward from the root
 *               of the address
 */
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static compound_graph_path *rec_get_accessed_path(ir_node *ptr, int depth)
{
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	compound_graph_path *res = NULL;
	ir_entity           *root, *field, *ent;
	int                 path_len, pos, idx;
	tarval              *tv;
	ir_type             *tp;

	if (is_SymConst(ptr)) {
		/* a SymConst. If the depth is 0, this is an access to a global
		 * entity and we don't need a component path, else we know
		 * at least its length.
		 */
		assert(get_SymConst_kind(ptr) == symconst_addr_ent);
		root = get_SymConst_entity(ptr);
		res = (depth == 0) ? NULL : new_compound_graph_path(get_entity_type(root), depth);
	} else if (is_Sel(ptr)) {
		/* it's a Sel, go up until we find the root */
		res = rec_get_accessed_path(get_Sel_ptr(ptr), depth+1);
		if (res == NULL)
			return NULL;

		/* fill up the step in the path at the current position */
		field    = get_Sel_entity(ptr);
		path_len = get_compound_graph_path_length(res);
		pos      = path_len - depth - 1;
		set_compound_graph_path_node(res, pos, field);

		if (is_Array_type(get_entity_owner(field))) {
			assert(get_Sel_n_indexs(ptr) == 1 && "multi dim arrays not implemented");
			set_compound_graph_path_array_index(res, pos, get_Sel_array_index_long(ptr, 0));
		}
	} else if (is_Add(ptr)) {
		ir_node *l    = get_Add_left(ptr);
		ir_node *r    = get_Add_right(ptr);
		ir_mode *mode = get_irn_mode(ptr);
		tarval  *tmp;

		if (is_Const(r) && get_irn_mode(l) == mode) {
			ptr = l;
			tv  = get_Const_tarval(r);
		} else {
			ptr = r;
			tv  = get_Const_tarval(l);
		}
ptr_arith:
		mode = get_tarval_mode(tv);
		tmp  = tv;

		/* ptr must be a Sel or a SymConst, this was checked in find_constant_entity() */
		if (is_Sel(ptr)) {
			field = get_Sel_entity(ptr);
		} else {
			field = get_SymConst_entity(ptr);
		}
		idx = 0;
		for (ent = field;;) {
			unsigned size;
			tarval   *sz, *tv_index, *tlower, *tupper;
			ir_node  *bound;

			tp = get_entity_type(ent);
			if (! is_Array_type(tp))
				break;
			ent = get_array_element_entity(tp);
			size = get_type_size_bytes(get_entity_type(ent));
			sz   = new_tarval_from_long(size, mode);

			tv_index = tarval_div(tmp, sz);
			tmp      = tarval_mod(tmp, sz);

			if (tv_index == tarval_bad || tmp == tarval_bad)
				return NULL;

			assert(get_array_n_dimensions(tp) == 1 && "multiarrays not implemented");
			bound  = get_array_lower_bound(tp, 0);
			tlower = computed_value(bound);
			bound  = get_array_upper_bound(tp, 0);
			tupper = computed_value(bound);

			if (tlower == tarval_bad || tupper == tarval_bad)
				return NULL;

			if (tarval_cmp(tv_index, tlower) & pn_Cmp_Lt)
				return NULL;
			if (tarval_cmp(tupper, tv_index) & pn_Cmp_Lt)
				return NULL;

			/* ok, bounds check finished */
			++idx;
		}
		if (! tarval_is_null(tmp)) {
			/* access to some struct/union member */
			return NULL;
		}

		/* should be at least ONE array */
		if (idx == 0)
			return NULL;

		res = rec_get_accessed_path(ptr, depth + idx);
		if (res == NULL)
			return NULL;

		path_len = get_compound_graph_path_length(res);
		pos      = path_len - depth - idx;

		for (ent = field;;) {
			unsigned size;
			tarval   *sz, *tv_index;
			long     index;

			tp = get_entity_type(ent);
			if (! is_Array_type(tp))
				break;
			ent = get_array_element_entity(tp);
			set_compound_graph_path_node(res, pos, ent);

			size = get_type_size_bytes(get_entity_type(ent));
			sz   = new_tarval_from_long(size, mode);

			tv_index = tarval_div(tv, sz);
			tv       = tarval_mod(tv, sz);

			/* worked above, should work again */
			assert(tv_index != tarval_bad && tv != tarval_bad);

			/* bounds already checked above */
			index = get_tarval_long(tv_index);
			set_compound_graph_path_array_index(res, pos, index);
			++pos;
		}
	} else if (is_Sub(ptr)) {
		ir_node *l = get_Sub_left(ptr);
		ir_node *r = get_Sub_right(ptr);

		ptr = l;
		tv  = get_Const_tarval(r);
		tv  = tarval_neg(tv);
		goto ptr_arith;
	}
	return res;
}  /* rec_get_accessed_path */

/**
 * Returns an access path or NULL.  The access path is only
 * valid, if the graph is in phase_high and _no_ address computation is used.
 */
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static compound_graph_path *get_accessed_path(ir_node *ptr)
{
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	compound_graph_path *gr = rec_get_accessed_path(ptr, 0);
	return gr;
}  /* get_accessed_path */

typedef struct path_entry {
	ir_entity         *ent;
	struct path_entry *next;
	long              index;
} path_entry;

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static ir_node *rec_find_compound_ent_value(ir_node *ptr, path_entry *next)
{
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	path_entry       entry, *p;
	ir_entity        *ent, *field;
	ir_initializer_t *initializer;
	tarval           *tv;
	ir_type          *tp;
	unsigned         n;

	entry.next = next;
	if (is_SymConst(ptr)) {
		/* found the root */
		ent         = get_SymConst_entity(ptr);
		initializer = get_entity_initializer(ent);
		for (p = next; p != NULL;) {
			if (initializer->kind != IR_INITIALIZER_COMPOUND)
				return NULL;
			n  = get_initializer_compound_n_entries(initializer);
			tp = get_entity_type(ent);

			if (is_Array_type(tp)) {
				ent = get_array_element_entity(tp);
				if (ent != p->ent) {
					/* a missing [0] */
					if (0 >= n)
						return NULL;
					initializer = get_initializer_compound_value(initializer, 0);
					continue;
				}
			}
			if (p->index >= (int) n)
				return NULL;
			initializer = get_initializer_compound_value(initializer, p->index);

			ent = p->ent;
			p   = p->next;
		}
		tp = get_entity_type(ent);
		while (is_Array_type(tp)) {
			ent = get_array_element_entity(tp);
			tp = get_entity_type(ent);
			/* a missing [0] */
			n  = get_initializer_compound_n_entries(initializer);
			if (0 >= n)
				return NULL;
			initializer = get_initializer_compound_value(initializer, 0);
		}

		switch (initializer->kind) {
		case IR_INITIALIZER_CONST:
			return get_initializer_const_value(initializer);
		case IR_INITIALIZER_TARVAL:
		case IR_INITIALIZER_NULL:
		default:
			return NULL;
		}
	} else if (is_Sel(ptr)) {
		entry.ent = field = get_Sel_entity(ptr);
		tp = get_entity_owner(field);
		if (is_Array_type(tp)) {
			assert(get_Sel_n_indexs(ptr) == 1 && "multi dim arrays not implemented");
			entry.index = get_Sel_array_index_long(ptr, 0) - get_array_lower_bound_int(tp, 0);
		} else {
			int i, n_members = get_compound_n_members(tp);
			for (i = 0; i < n_members; ++i) {
				if (get_compound_member(tp, i) == field)
					break;
			}
			if (i >= n_members) {
				/* not found: should NOT happen */
				return NULL;
			}
			entry.index = i;
		}
		return rec_find_compound_ent_value(get_Sel_ptr(ptr), &entry);
	}  else if (is_Add(ptr)) {
		ir_node  *l = get_Add_left(ptr);
		ir_node  *r = get_Add_right(ptr);
		ir_mode  *mode;
		unsigned pos;

		if (is_Const(r)) {
			ptr = l;
			tv  = get_Const_tarval(r);
		} else {
			ptr = r;
			tv  = get_Const_tarval(l);
		}
ptr_arith:
		mode = get_tarval_mode(tv);

		/* ptr must be a Sel or a SymConst, this was checked in find_constant_entity() */
		if (is_Sel(ptr)) {
			field = get_Sel_entity(ptr);
		} else {
			field = get_SymConst_entity(ptr);
		}

		/* count needed entries */
		pos = 0;
		for (ent = field;;) {
			tp = get_entity_type(ent);
			if (! is_Array_type(tp))
				break;
			ent = get_array_element_entity(tp);
			++pos;
		}
		/* should be at least ONE entry */
		if (pos == 0)
			return NULL;

		/* allocate the right number of entries */
		NEW_ARR_A(path_entry, p, pos);

		/* fill them up */
		pos = 0;
		for (ent = field;;) {
			unsigned size;
			tarval   *sz, *tv_index, *tlower, *tupper;
			long     index;
			ir_node  *bound;

			tp = get_entity_type(ent);
			if (! is_Array_type(tp))
				break;
			ent = get_array_element_entity(tp);
			p[pos].ent  = ent;
			p[pos].next = &p[pos + 1];

			size = get_type_size_bytes(get_entity_type(ent));
			sz   = new_tarval_from_long(size, mode);

			tv_index = tarval_div(tv, sz);
			tv       = tarval_mod(tv, sz);

			if (tv_index == tarval_bad || tv == tarval_bad)
				return NULL;

			assert(get_array_n_dimensions(tp) == 1 && "multiarrays not implemented");
			bound  = get_array_lower_bound(tp, 0);
			tlower = computed_value(bound);
			bound  = get_array_upper_bound(tp, 0);
			tupper = computed_value(bound);

			if (tlower == tarval_bad || tupper == tarval_bad)
				return NULL;

			if (tarval_cmp(tv_index, tlower) & pn_Cmp_Lt)
				return NULL;
			if (tarval_cmp(tupper, tv_index) & pn_Cmp_Lt)
				return NULL;

			/* ok, bounds check finished */
			index = get_tarval_long(tv_index);
			p[pos].index = index;
			++pos;
		}
		if (! tarval_is_null(tv)) {
			/* hmm, wrong access */
			return NULL;
		}
		p[pos - 1].next = next;
		return rec_find_compound_ent_value(ptr, p);
	} else if (is_Sub(ptr)) {
		ir_node *l = get_Sub_left(ptr);
		ir_node *r = get_Sub_right(ptr);

		ptr = l;
		tv  = get_Const_tarval(r);
		tv  = tarval_neg(tv);
		goto ptr_arith;
	}
	return NULL;
}  /* rec_find_compound_ent_value */

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static ir_node *find_compound_ent_value(ir_node *ptr)
{
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	return rec_find_compound_ent_value(ptr, NULL);
}  /* find_compound_ent_value */

/**
 * Mark a Load memop to be replace by a definition
 *
 * @param op  the Load memop
 */
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static void mark_replace_load(memop_t *op, ir_node *def)
{
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	op->replace = def;
	op->flags |= FLAG_KILLED_NODE;
	env.changed = 1;
}  /* mark_replace_load */

/**
 * Mark a Store memop to be removed.
 *
 * @param op  the Store memop
 */
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static void mark_remove_store(memop_t *op)
{
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	op->flags |= FLAG_KILLED_NODE;
	env.changed = 1;
}  /* mark_remove_store */

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/**
 * Update a memop for a Load.
 *
 * @param m  the memop
 */
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static void update_Load_memop(memop_t *m)
{
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	int       i;
	ir_node   *load = m->node;
	ir_node   *ptr;
	ir_entity *ent;
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	if (get_Load_volatility(load) == volatility_is_volatile)
		m->flags |= FLAG_IGNORE;

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	ptr = get_Load_ptr(load);

	m->value.address = ptr;
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	for (i = get_irn_n_outs(load) - 1; i >= 0; --i) {
		ir_node *proj = get_irn_out(load, i);
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		long    pn;
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		/* beware of keep edges */
		if (is_End(proj))
			continue;

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		pn = get_Proj_proj(proj);
		m->projs[pn] = proj;
		switch (pn) {
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		case pn_Load_res:
			m->value.value = proj;
			m->value.mode  = get_irn_mode(proj);
			break;
		case pn_Load_X_except:
			m->flags |= FLAG_EXCEPTION;
			break;
		case pn_Load_M:
			m->mem = proj;
			break;
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		case pn_Load_X_regular:
			break;
		default:
			panic("Unsupported Proj from Load %+F", proj);
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		}
	}

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	/* check if we can determine the entity that will be loaded */
	ent = find_constant_entity(ptr);

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	if (ent != NULL && get_entity_visibility(ent) != ir_visibility_external) {
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		/* a static allocation that is not external: there should be NO exception
		 * when loading even if we cannot replace the load itself. */
		ir_node *value = NULL;

		/* no exception, clear the m fields as it might be checked later again */
		if (m->projs[pn_Load_X_except]) {
			exchange(m->projs[pn_Load_X_except], new_Bad());
			m->projs[pn_Load_X_except] = NULL;
			m->flags &= ~FLAG_EXCEPTION;
			env.changed = 1;
		}
		if (m->projs[pn_Load_X_regular]) {
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			exchange(m->projs[pn_Load_X_regular], new_r_Jmp(get_nodes_block(load)));
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			m->projs[pn_Load_X_regular] = NULL;
			env.changed = 1;
		}

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		if (get_entity_linkage(ent) & IR_LINKAGE_CONSTANT) {
			if (ent->initializer) {
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				/* new style initializer */
				value = find_compound_ent_value(ptr);
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			} else if (entity_has_compound_ent_values(ent)) {
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				/* old style initializer */
				compound_graph_path *path = get_accessed_path(ptr);

				if (path != NULL) {
					assert(is_proper_compound_graph_path(path, get_compound_graph_path_length(path)-1));

					value = get_compound_ent_value_by_path(ent, path);
					DB((dbg, LEVEL_1, "  Constant access at %F%F resulted in %+F\n", ent, path, value));
					free_compound_graph_path(path);
				}
			}
			if (value != NULL)
				value = can_replace_load_by_const(load, value);
		}

		if (value != NULL) {
			/* we completely replace the load by this value */
			DB((dbg, LEVEL_1, "Replacing Load %+F by constant %+F\n", m->node, value));
			mark_replace_load(m, value);
			return;
		}
	}

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	if (m->value.value != NULL && !(m->flags & FLAG_IGNORE)) {
		/* only create an address if this node is NOT killed immediately or ignored */
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		m->value.id = register_address(ptr);
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		++env.n_mem_ops;
	} else {
		/* no user, KILL it */
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		mark_replace_load(m, NULL);
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	}
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}  /* update_Load_memop */
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/**
 * Update a memop for a Store.
 *
 * @param m  the memop
 */
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static void update_Store_memop(memop_t *m)
{
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	int     i;
	ir_node *store = m->node;
	ir_node *adr   = get_Store_ptr(store);

	if (get_Store_volatility(store) == volatility_is_volatile) {
		m->flags |= FLAG_IGNORE;
	} else {
		/* only create an address if this node is NOT ignored */
		m->value.id = register_address(adr);
		++env.n_mem_ops;
	}

	m->value.address = adr;

	for (i = get_irn_n_outs(store) - 1; i >= 0; --i) {
		ir_node *proj = get_irn_out(store, i);
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		long    pn;
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		/* beware of keep edges */
		if (is_End(proj))
			continue;

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		pn = get_Proj_proj(proj);
		m->projs[pn] = proj;
		switch (pn) {
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		case pn_Store_X_except:
			m->flags |= FLAG_EXCEPTION;
			break;
		case pn_Store_M:
			m->mem = proj;
			break;
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		case pn_Store_X_regular:
			break;
		default:
			panic("Unsupported Proj from Store %+F", proj);
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		}
	}
	m->value.value = get_Store_value(store);
	m->value.mode  = get_irn_mode(m->value.value);
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}  /* update_Store_memop */
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/**
 * Update a memop for a Call.
 *
 * @param m  the memop
 */
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static void update_Call_memop(memop_t *m)
{
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	ir_node  *call = m->node;
	unsigned prop  = get_Call_memory_properties(call);
	int      i;

	if (prop & mtp_property_const) {
		/* A constant call did NOT use memory at all, we
		   can kick it from the list. */
	} else if (prop & mtp_property_pure) {
		/* pure calls READ memory */
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		m->flags = 0;
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	} else
		m->flags = FLAG_KILL_ALL;

	for (i = get_irn_n_outs(call) - 1; i >= 0; --i) {
		ir_node *proj = get_irn_out(call, i);

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		/* beware of keep edges */
		if (is_End(proj))
			continue;

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		switch (get_Proj_proj(proj)) {
		case pn_Call_X_except:
			m->flags |= FLAG_EXCEPTION;
			break;
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		case pn_Call_M:
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			m->mem = proj;
			break;
		}
	}
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}  /* update_Call_memop */
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/**
 * Update a memop for a Div/Mod/Quot/DivMod.
 *
 * @param m  the memop
 */
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static void update_DivOp_memop(memop_t *m)
{
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	ir_node *div = m->node;
	int     i;

	for (i = get_irn_n_outs(div) - 1; i >= 0; --i) {
		ir_node *proj = get_irn_out(div, i);

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		/* beware of keep edges */
		if (is_End(proj))
			continue;

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		switch (get_Proj_proj(proj)) {
		case pn_Generic_X_except:
			m->flags |= FLAG_EXCEPTION;
			break;
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		case pn_Generic_M:
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			m->mem = proj;
			break;
		}
	}
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}  /* update_DivOp_memop */
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/**
 * Update a memop for a Phi.
 *
 * @param m  the memop
 */
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static void update_Phi_memop(memop_t *m)
{
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	/* the Phi is it's own mem */
	m->mem = m->node;
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}  /* update_Phi_memop */
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/**
 * Memory walker: collect all memory ops and build topological lists.
 */
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static void collect_memops(ir_node *irn, void *ctx)
{
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	memop_t  *op;
	ir_node  *block;
	block_t  *entry;

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	(void) ctx;
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	if (is_Proj(irn)) {
		/* we can safely ignore ProjM's except the initial memory */
		if (irn != get_irg_initial_mem(current_ir_graph))
			return;
	}

	op    = alloc_memop(irn);
	block = get_nodes_block(irn);
	entry = get_block_entry(block);

	if (is_Phi(irn)) {
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		update_Phi_memop(op);
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		/* Phis must be always placed first */
		op->next = entry->memop_forward;
		entry->memop_forward = op;
		if (entry->memop_backward == NULL)
			entry->memop_backward = op;
	} else {
		switch (get_irn_opcode(irn)) {
		case iro_Load:
			update_Load_memop(op);
			break;
		case iro_Store:
			update_Store_memop(op);
			break;
		case iro_Call:
			update_Call_memop(op);
			break;
		case iro_Sync:
		case iro_Pin:
			op->mem = irn;
			break;
		case iro_Proj:
			/* initial memory */
			op->mem = irn;
			break;
		case iro_Return:
		case iro_End:
			/* we can those to find the memory edge */
			break;
		case iro_Div:
		case iro_DivMod:
		case iro_Quot:
		case iro_Mod:
			update_DivOp_memop(op);
			break;

		case iro_Builtin:
			/* TODO: handle some builtins */
		default:
			/* unsupported operation */
			op->flags = FLAG_KILL_ALL;
		}


		/* all other should be placed last */
		if (entry->memop_backward == NULL) {
			entry->memop_forward = entry->memop_backward = op;
		} else {
			entry->memop_backward->next = op;
			entry->memop_backward       = op;
		}
	}
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}  /* collect_memops */
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/**
 * Find an address in the current set.
 *
 * @param value  the value to be searched for
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 *
 * @return a memop for the value or NULL if the value does
 *         not exists in the set or cannot be converted into
 *         the requested mode
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 */
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static memop_t *find_address(const value_t *value)
{
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	if (rbitset_is_set(env.curr_set, value->id)) {
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		memop_t *res = env.curr_id_2_memop[value->id];
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		if (res->value.mode == value->mode)
			return res;
		/* allow hidden casts */
		if (get_mode_arithmetic(res->value.mode) == irma_twos_complement &&
		    get_mode_arithmetic(value->mode) == irma_twos_complement &&
		    get_mode_size_bits(res->value.mode) == get_mode_size_bits(value->mode))
			return res;
	}
	return NULL;
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}  /* find_address */
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/**
 * Find an address in the avail_out set.
 *
 * @param bl     the block
 */
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static memop_t *find_address_avail(const block_t *bl, unsigned id, const ir_mode *mode)
{
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	if (rbitset_is_set(bl->avail_out, id)) {
		memop_t *res = bl->id_2_memop_avail[id];
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		if (res->value.mode == mode)
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			return res;
		/* allow hidden casts */
		if (get_mode_arithmetic(res->value.mode) == irma_twos_complement &&
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		    get_mode_arithmetic(mode) == irma_twos_complement &&
		    get_mode_size_bits(res->value.mode) == get_mode_size_bits(mode))
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			return res;
	}
	return NULL;
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}  /* find_address_avail */
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/**
 * Kill all addresses from the current set.
 */
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static void kill_all(void)
{
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	rbitset_clear_all(env.curr_set, env.rbs_size);

	/* set sentinel */
	rbitset_set(env.curr_set, env.rbs_size - 1);
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}  /* kill_all */
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/**
 * Kill memops that are not alias free due to a Store value from the current set.
 *
 * @param value  the Store value
 */
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static void kill_memops(const value_t *value)
{
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	unsigned end = env.rbs_size - 1;
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	unsigned pos;
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	for (pos = rbitset_next(env.curr_set, 0, 1); pos < end; pos = rbitset_next(env.curr_set, pos + 1, 1)) {
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		memop_t *op = env.curr_id_2_memop[pos];
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		if (ir_no_alias != get_alias_relation(current_ir_graph, value->address, value->mode,
			                                  op->value.address, op->value.mode)) {
			rbitset_clear(env.curr_set, pos);
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			env.curr_id_2_memop[pos] = NULL;
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			DB((dbg, LEVEL_2, "KILLING %+F because of possible alias address %+F\n", op->node, value->address));
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		}
	}
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}  /* kill_memops */
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/**
 * Add the value of a memop to the current set.
 *
 * @param op  the memory op
 */
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static void add_memop(memop_t *op)
{
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	rbitset_set(env.curr_set, op->value.id);
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	env.curr_id_2_memop[op->value.id] = op;
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}  /* add_memop */
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/**
 * Add the value of a memop to the avail_out set.
 *
 * @param bl  the block
 * @param op  the memory op
 */
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static void add_memop_avail(block_t *bl, memop_t *op)
{
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	rbitset_set(bl->avail_out, op->value.id);
	bl->id_2_memop_avail[op->value.id] = op;
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}  /* add_memop_avail */
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/**
 * Check, if we can convert a value of one mode to another mode
 * without changing the representation of bits.
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 *
 * @param from  the original mode
 * @param to    the destination mode
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 */
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static int can_convert_to(const ir_mode *from, const ir_mode *to)
{
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	if (get_mode_arithmetic(from) == irma_twos_complement &&
	    get_mode_arithmetic(to) == irma_twos_complement &&
	    get_mode_size_bits(from) == get_mode_size_bits(to))
		return 1;
	return 0;
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}  /* can_convert_to */
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/**
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 * Add a Conv to the requested mode if needed.
 *
 * @param irn   the IR-node to convert
 * @param mode  the destination mode
 *
 * @return the possible converted node or NULL
 *         if the conversion is not possible
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static ir_node *conv_to(ir_node *irn, ir_mode *mode)
{
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	ir_mode *other = get_irn_mode(irn);
	if (other != mode) {
		/* different modes: check if conversion is possible without changing the bits */
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		if (can_convert_to(other, mode)) {
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			ir_node *block = get_nodes_block(irn);
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			return new_r_Conv(block, irn, mode);
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		}
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		/* otherwise not possible ... yet */
		return NULL;
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	}
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	return irn;
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}  /* conv_to */
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/**
 * Update the address of an value if this address was a load result
 * and the load is killed now.
 *
 * @param value  the value whose address is updated
 */
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static void update_address(value_t *value)
{
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	if (is_Proj(value->address)) {
		ir_node *load = get_Proj_pred(value->address);

		if (is_Load(load)) {
			const memop_t *op = get_irn_memop(load);

			if (op->flags & FLAG_KILLED_NODE)
				value->address = op->replace;
		}
	}
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}  /* update_address */
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/**
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 * Do forward dataflow analysis on the given block and calculate the
 * GEN and KILL in the current (avail) set.
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 *
 * @param bl  the block
 */
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static void calc_gen_kill_avail(block_t *bl)
{
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	memop_t *op;
	ir_node *def;

	for (op = bl->memop_forward; op != NULL; op = op->next) {
		switch (get_irn_opcode(op->node)) {
		case iro_Phi:
			/* meet */
			break;
		case iro_Sync:
			/* join */
			break;
		case iro_Load:
			if (! (op->flags & (FLAG_KILLED_NODE|FLAG_IGNORE))) {
				/* do we have this already? */
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				memop_t *other;

				update_address(&op->value);
				other = find_address(&op->value);
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				if (other != NULL && other != op) {
					def = conv_to(other->value.value, op->value.mode);
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					if (def != NULL) {
#ifdef DEBUG_libfirm
						if (is_Store(other->node)) {
							/* RAW */
							DB((dbg, LEVEL_1, "RAW %+F <- %+F(%+F)\n", op->node, def, other->node));
						} else {
							/* RAR */
							DB((dbg, LEVEL_1, "RAR %+F <- %+F(%+F)\n", op->node, def, other->node));
						}
#endif
						mark_replace_load(op, def);
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						/* do NOT change the memop table */
						continue;
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					}
				}
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				/* add this value */
				add_memop(op);
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			}
			break;
		case iro_Store:
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			if (! (op->flags & FLAG_KILLED_NODE)) {
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				/* do we have this store already */
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				memop_t *other;

				update_address(&op->value);
				other = find_address(&op->value);
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				if (other != NULL) {
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					if (is_Store(other->node)) {
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						if (op != other && !(other->flags & FLAG_IGNORE) &&
						    get_nodes_block(other->node) == get_nodes_block(op->node)) {
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							/*
							 * A WAW in the same block we can kick the first store.
							 * This is a shortcut: we know that the second Store will be anticipated
							 * then in an case.
							 */
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							DB((dbg, LEVEL_1, "WAW %+F <- %+F\n", other->node, op->node));
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							mark_remove_store(other);
							/* FIXME: a Load might be get freed due to this killed store */
						}
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					} else if (other->value.value == op->value.value && !(op->flags & FLAG_IGNORE)) {
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						/* WAR */
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						DB((dbg, LEVEL_1, "WAR %+F <- %+F\n", op->node, other->node));
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						mark_remove_store(op);
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						/* do NOT change the memop table */
						continue;
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					}
				}
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				/* KILL all possible aliases */
				kill_memops(&op->value);
				/* add this value */
				add_memop(op)