X-Git-Url: http://nsz.repo.hu/git/?a=blobdiff_plain;f=ir%2Fbe%2Fbespill.c;h=2dae0bc96363814bfa747c0a48e642e027c1296b;hb=e243eb2e9e8a9f5e57e166950a1a0a8ab25e92a9;hp=16277632b86598a2259060e16388cf3cc43b0c4c;hpb=32a664cf05ce77aa410e334fdea34a851c36143f;p=libfirm

diff --git a/ir/be/bespill.c b/ir/be/bespill.c
index 16277632b..2dae0bc96 100644
--- a/ir/be/bespill.c
+++ b/ir/be/bespill.c
@@ -1,264 +1,714 @@
-/**
- * Author:      Daniel Grund, Sebastian Hack
+/*
+ * Author:      Daniel Grund, Sebastian Hack, Matthias Braun
  * Date:		29.09.2005
  * Copyright:   (c) Universitaet Karlsruhe
  * Licence:     This file protected by GPL -  GNU GENERAL PUBLIC LICENSE.
+ * CVS-Id:      $Id$
  */
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <stdlib.h>
 
 #include "pset.h"
 #include "irnode_t.h"
 #include "ircons_t.h"
 #include "iredges_t.h"
+#include "irbackedge_t.h"
+#include "irprintf.h"
+#include "ident_t.h"
+#include "type_t.h"
+#include "entity_t.h"
 #include "debug.h"
-
-#include "besched.h"
+#include "irgwalk.h"
+#include "array.h"
+#include "pdeq.h"
+#include "unionfind.h"
+#include "execfreq.h"
+
+#include "belive_t.h"
+#include "besched_t.h"
 #include "bespill.h"
+#include "belive_t.h"
 #include "benode_t.h"
+#include "bechordal_t.h"
+#include "bejavacoal.h"
+#include "benodesets.h"
+#include "bespilloptions.h"
+#include "bestatevent.h"
+
+// only rematerialise when costs are less than REMAT_COST_LIMIT
+// TODO determine a good value here...
+#define REMAT_COST_LIMIT	10
 
 typedef struct _reloader_t reloader_t;
-typedef struct _spill_info_t spill_info_t;
 
 struct _reloader_t {
 	reloader_t *next;
-	ir_node *reloader;
+	ir_node    *reloader;
+	ir_node    *rematted_node;
+	int        allow_remat;     /**< the node may be rematted instead of reloaded if global remat option is on */
 };
 
-struct _spill_info_t {
+typedef struct _spill_info_t {
+	/** the value that should get spilled */
 	ir_node *spilled_node;
+	/** list of places where the value should get reloaded */
 	reloader_t *reloaders;
-};
 
-typedef struct _spill_ctx_t {
-	ir_node *spilled;  /**< The spilled node. */
-	ir_node *user;     /**< The node this spill is for. */
-	ir_node *spill;    /**< The spill itself. */
-} spill_ctx_t;
+	/** the spill node, or a PhiM node */
+	ir_node *spill;
+	/** if we had the value of a phi spilled before but not the phi itself then
+	 * this field contains the spill for the phi value */
+	ir_node *old_spill;
+
+	/** the register class in which the reload should be placed */
+	const arch_register_class_t *reload_cls;
+} spill_info_t;
 
 struct _spill_env_t {
-	firm_dbg_module_t *dbg;
-	const arch_register_class_t *cls;
-	const be_main_session_env_t *session;
+	const arch_env_t *arch_env;
+	ir_graph *irg;
 	struct obstack obst;
-	set *spill_ctxs;
-	set *spills;				/**< all spill_info_t's, which must be placed */
-	pset *mem_phis;				/**< set of all special spilled phis. allocated and freed seperately */
-	decide_irn_t is_mem_phi;	/**< callback func to decide if a phi needs special spilling */
-	void *data;					/**< data passed to all callbacks */
-};
+	be_irg_t *birg;
+	int spill_cost;     /**< the cost of a single spill node */
+	int reload_cost;    /**< the cost of a reload node */
+	set *spills;        /**< all spill_info_t's, which must be placed */
+	pset *mem_phis;     /**< set of all special spilled phis. allocated and freed separately */
 
-static int cmp_spillctx(const void *a, const void *b, size_t n) {
-	const spill_ctx_t *p = a;
-	const spill_ctx_t *q = b;
-	return !(p->user == q->user && p->spilled == q->spilled);
-}
+	DEBUG_ONLY(firm_dbg_module_t *dbg;)
+};
 
+/**
+ * Compare two spill infos.
+ */
 static int cmp_spillinfo(const void *x, const void *y, size_t size) {
 	const spill_info_t *xx = x;
 	const spill_info_t *yy = y;
-	return ! (xx->spilled_node == yy->spilled_node);
+	return xx->spilled_node != yy->spilled_node;
 }
 
-spill_env_t *be_new_spill_env(firm_dbg_module_t *dbg, const be_main_session_env_t *session,
-		const arch_register_class_t *cls, decide_irn_t is_mem_phi, void *data) {
-	spill_env_t *env = malloc(sizeof(env[0]));
-	env->spill_ctxs = new_set(cmp_spillctx, 1024);
-	env->spills     = new_set(cmp_spillinfo, 1024);
-	env->session    = session;
-	env->cls        = cls;
-	env->dbg        = dbg;
-	env->is_mem_phi = is_mem_phi;
-	env->data       = data;
+/**
+ * Returns spill info for a specific value (returns NULL if the info doesn't
+ * exist yet)
+ */
+static spill_info_t *find_spillinfo(const spill_env_t *env, ir_node *value) {
+	spill_info_t info;
+	int hash = nodeset_hash(value);
+
+	info.spilled_node = value;
+
+	return set_find(env->spills, &info, sizeof(info), hash);
+}
+
+/**
+ * Returns spill info for a specific value (the value that is to be spilled)
+ */
+static spill_info_t *get_spillinfo(const spill_env_t *env, ir_node *value) {
+	spill_info_t info, *res;
+	int hash = nodeset_hash(value);
+
+	info.spilled_node = value;
+	res = set_find(env->spills, &info, sizeof(info), hash);
+
+	if (res == NULL) {
+		info.reloaders = NULL;
+		info.spill = NULL;
+		info.old_spill = NULL;
+		info.reload_cls = NULL;
+		res = set_insert(env->spills, &info, sizeof(info), hash);
+	}
+
+	return res;
+}
+
+DEBUG_ONLY(
+/* Sets the debug module of a spill environment. */
+void be_set_spill_env_dbg_module(spill_env_t *env, firm_dbg_module_t *dbg) {
+	env->dbg = dbg;
+}
+)
+
+/* Creates a new spill environment. */
+spill_env_t *be_new_spill_env(be_irg_t *birg) {
+	spill_env_t *env	= xmalloc(sizeof(env[0]));
+	env->spills			= new_set(cmp_spillinfo, 1024);
+	env->irg            = be_get_birg_irg(birg);
+	env->birg           = birg;
+	env->arch_env       = birg->main_env->arch_env;
+	env->mem_phis		= pset_new_ptr_default();
+	// TODO, ask backend about costs..., or even ask backend whether we should
+	// rematerialize...
+	env->spill_cost     = 8;
+	env->reload_cost    = 5;
 	obstack_init(&env->obst);
 	return env;
 }
 
-void be_delete_spill_env(spill_env_t *senv) {
-	del_set(senv->spill_ctxs);
-	del_set(senv->spills);
-	obstack_free(&senv->obst, NULL);
-	free(senv);
+/* Deletes a spill environment. */
+void be_delete_spill_env(spill_env_t *env) {
+	del_set(env->spills);
+	del_pset(env->mem_phis);
+	obstack_free(&env->obst, NULL);
+	free(env);
 }
 
-static spill_ctx_t *be_get_spill_ctx(set *sc, ir_node *to_spill, ir_node *ctx_irn) {
-	spill_ctx_t templ;
+/*
+ *  ____  _                  ____      _                 _
+ * |  _ \| | __ _  ___ ___  |  _ \ ___| | ___   __ _  __| |___
+ * | |_) | |/ _` |/ __/ _ \ | |_) / _ \ |/ _ \ / _` |/ _` / __|
+ * |  __/| | (_| | (_|  __/ |  _ <  __/ | (_) | (_| | (_| \__ \
+ * |_|   |_|\__,_|\___\___| |_| \_\___|_|\___/ \__,_|\__,_|___/
+ *
+ */
+
+void be_add_remat(spill_env_t *env, ir_node *to_spill, ir_node *before, ir_node *rematted_node) {
+	spill_info_t *spill_info;
+	reloader_t *reloader;
+
+	spill_info = get_spillinfo(env, to_spill);
+
+	/* add the remat information */
+	reloader                = obstack_alloc(&env->obst, sizeof(reloader[0]));
+	reloader->next          = spill_info->reloaders;
+	reloader->reloader      = before;
+	reloader->rematted_node = rematted_node;
+	reloader->allow_remat   = 1;
 
-	templ.spilled = to_spill;
-	templ.user    = ctx_irn;
-	templ.spill   = NULL;
+	spill_info->reloaders  = reloader;
 
-	return set_insert(sc, &templ, sizeof(templ), HASH_COMBINE(HASH_PTR(to_spill), HASH_PTR(ctx_irn)));
+	DBG((env->dbg, LEVEL_1, "creating spillinfo for %+F, will be rematerialized before %+F\n",
+		to_spill, before));
 }
 
-static ir_node *be_spill_irn(spill_env_t *senv, ir_node *irn, ir_node *ctx_irn) {
-	spill_ctx_t *ctx;
-	DBG((senv->dbg, LEVEL_1, "%+F in ctx %+F\n", irn, ctx_irn));
+void be_add_reload(spill_env_t *env, ir_node *to_spill, ir_node *before,
+		const arch_register_class_t *reload_cls, int allow_remat)
+{
+	spill_info_t *info;
+	reloader_t *rel;
+
+	info = get_spillinfo(env, to_spill);
 
-	ctx = be_get_spill_ctx(senv->spill_ctxs, irn, ctx_irn);
-	if(!ctx->spill) {
-		const be_main_env_t *env = senv->session->main_env;
-		ctx->spill = be_spill(env->node_factory, env->arch_env, irn);
+	if (is_Phi(to_spill)) {
+		int i, arity;
+
+		/* create spillinfos for the phi arguments */
+		for (i = 0, arity = get_irn_arity(to_spill); i < arity; ++i) {
+			ir_node *arg = get_irn_n(to_spill, i);
+			get_spillinfo(env, arg);
+		}
+
+#if 1
+		// hackery... sometimes the morgan algo spilled the value of a phi,
+		// the belady algo decides later to spill the whole phi, then sees the
+		// spill node and adds a reload for that spill node, problem is the
+		// reload gets attach to that same spill (and is totally unnecessary)
+		if (info->old_spill != NULL &&
+			(before == info->old_spill || value_dominates(before, info->old_spill)))
+		{
+			printf("spilledphi hack was needed...\n");
+			before = sched_next(info->old_spill);
+		}
+#endif
 	}
 
-	return ctx->spill;
+	/* put reload into list */
+	rel                = obstack_alloc(&env->obst, sizeof(rel[0]));
+	rel->next          = info->reloaders;
+	rel->reloader      = before;
+	rel->rematted_node = NULL;
+	rel->allow_remat   = allow_remat;
+
+	info->reloaders  = rel;
+	assert(info->reload_cls == NULL || info->reload_cls == reload_cls);
+	info->reload_cls = reload_cls;
+
+	DBG((env->dbg, LEVEL_1, "creating spillinfo for %+F, will be reloaded before %+F, may%s be rematerialized\n",
+		to_spill, before, allow_remat ? "" : " not"));
 }
 
+static ir_node *get_reload_insertion_point(ir_node *block, int pos) {
+	ir_node *predblock, *last;
+
+	/* simply add the reload to the beginning of the block if we only have 1 predecessor
+	 * (we don't need to check for phis as there can't be any in a block with only 1 pred)
+	 */
+	if(get_Block_n_cfgpreds(block) == 1) {
+		assert(!is_Phi(sched_first(block)));
+		return sched_first(block);
+	}
+
+	/* We have to reload the value in pred-block */
+	predblock = get_Block_cfgpred_block(block, pos);
+	last = sched_last(predblock);
+
+	/* we might have projs and keepanys behind the jump... */
+	while(is_Proj(last) || be_is_Keep(last)) {
+		last = sched_prev(last);
+		assert(!sched_is_end(last));
+	}
+
+	if(!is_cfop(last)) {
+		ir_graph *irg = get_irn_irg(block);
+		ir_node *startblock = get_irg_start_block(irg);
+
+		last = sched_next(last);
+		// last node must be a cfop, only exception is the start block
+		assert(last	== startblock);
+	}
+
+	// add the reload before the (cond-)jump
+	return last;
+}
+
+void be_add_reload_on_edge(spill_env_t *env, ir_node *to_spill, ir_node *block, int pos,
+		const arch_register_class_t *reload_cls, int allow_remat)
+{
+	ir_node *before = get_reload_insertion_point(block, pos);
+	be_add_reload(env, to_spill, before, reload_cls, allow_remat);
+}
+
+void be_spill_phi(spill_env_t *env, ir_node *node) {
+	spill_info_t* spill;
+	int i, arity;
+
+	assert(is_Phi(node));
+
+	pset_insert_ptr(env->mem_phis, node);
+
+	// create spillinfos for the phi arguments
+	spill = get_spillinfo(env, node);
+	for(i = 0, arity = get_irn_arity(node); i < arity; ++i) {
+		ir_node *arg = get_irn_n(node, i);
+		get_spillinfo(env, arg);
+	}
+
+	// if we had a spill for the phi value before, then remove this spill from
+	// schedule, as we will remove it in the insert spill/reload phase
+	if(spill->spill != NULL && !is_Phi(spill->spill)) {
+		assert(spill->old_spill == NULL);
+		spill->old_spill = spill->spill;
+		spill->spill = NULL;
+	}
+}
+
+/*
+ *   ____                _         ____        _ _ _
+ *  / ___|_ __ ___  __ _| |_ ___  / ___| _ __ (_) | |___
+ * | |   | '__/ _ \/ _` | __/ _ \ \___ \| '_ \| | | / __|
+ * | |___| | |  __/ (_| | ||  __/  ___) | |_) | | | \__ \
+ *  \____|_|  \___|\__,_|\__\___| |____/| .__/|_|_|_|___/
+ *                                      |_|
+ */
+
+/**
+ * Schedules a node after an instruction. (That is the place after all projs and phis
+ * that are scheduled after the instruction)
+ * This function also skips phi nodes at the beginning of a block
+ */
+static void sched_add_after_insn(ir_node *sched_after, ir_node *node) {
+	ir_node *next = sched_next(sched_after);
+	while(is_Proj(next) || is_Phi(next)) {
+		next = sched_next(next);
+	}
+	assert(next != NULL);
+
+	if(sched_is_end(next)) {
+		sched_add_after(sched_last(get_nodes_block(sched_after)), node);
+	} else {
+		sched_add_before(next, node);
+	}
+}
+
+/**
+ * Creates a spill.
+ *
+ * @param senv      the spill environment
+ * @param irn       the node that should be spilled
+ * @param ctx_irn   an user of the spilled node
+ *
+ * @return a be_Spill node
+ */
+static void spill_irn(spill_env_t *env, spill_info_t *spillinfo) {
+	ir_node *to_spill = spillinfo->spilled_node;
+
+	DBG((env->dbg, LEVEL_1, "%+F\n", to_spill));
+
+	/* Trying to spill an already spilled value, no need for a new spill
+	 * node then, we can simply connect to the same one for this reload
+	 *
+	 * (although rematerialization code should handle most of these cases
+	 * this can still happen when spilling Phis)
+	 */
+	if(be_is_Reload(to_spill)) {
+		spillinfo->spill = get_irn_n(to_spill, be_pos_Reload_mem);
+		return;
+	}
+
+	if (arch_irn_is(env->arch_env, to_spill, dont_spill)) {
+		assert(0 && "Attempt to spill a node marked 'dont_spill'");
+	}
+
+	spillinfo->spill = be_spill(env->arch_env, to_spill);
+	sched_add_after_insn(to_spill, spillinfo->spill);
+}
+
+static void spill_node(spill_env_t *env, spill_info_t *spillinfo);
+
 /**
- * If the first usage of a phi result would be out of memory
+ * If the first usage of a Phi result would be out of memory
  * there is no sense in allocating a register for it.
  * Thus we spill it and all its operands to the same spill slot.
  * Therefore the phi/dataB becomes a phi/Memory
+ *
+ * @param senv      the spill environment
+ * @param phi       the Phi node that should be spilled
+ * @param ctx_irn   an user of the spilled node
  */
-static ir_node *be_spill_phi(spill_env_t *senv, ir_node *phi, ir_node *ctx_irn) {
-	int i, n = get_irn_arity(phi);
-	ir_node **ins, *bl = get_nodes_block(phi);
-	ir_graph *irg = senv->session->irg;
-	spill_ctx_t *ctx;
+static void spill_phi(spill_env_t *env, spill_info_t *spillinfo) {
+	ir_node *phi = spillinfo->spilled_node;
+	int i;
+	int arity = get_irn_arity(phi);
+	ir_node     *block    = get_nodes_block(phi);
+	ir_node     **ins;
 
 	assert(is_Phi(phi));
-	DBG((senv->dbg, LEVEL_1, "%+F in ctx %+F\n", phi, ctx_irn));
-
-	/* search an existing spill for this context */
-	ctx = be_get_spill_ctx(senv->spill_ctxs, phi, ctx_irn);
-
-	/* if not found spill the phi */
-	if(!ctx->spill) {
-		/* build a new PhiM with dummy in-array */
-		ins  = malloc(n * sizeof(ins[0]));
-		for(i=0; i<n; ++i)
-			ins[i] = new_r_Unknown(irg, mode_M);
-		ctx->spill = new_r_Phi(senv->session->irg, bl, n, ins, mode_M);
-		free(ins);
-
-		/* re-wire the phiM */
-		for(i=0; i<n; ++i) {
-			ir_node *arg = get_irn_n(phi, i);
-			ir_node *sub_res;
-
-			if(is_Phi(arg) && pset_find_ptr(senv->mem_phis, arg))
-				sub_res = be_spill_phi(senv, arg, ctx_irn);
-			else
-				sub_res = be_spill_irn(senv, arg, ctx_irn);
-
-			set_irn_n(ctx->spill, i, sub_res);
+
+	/* build a new PhiM */
+	ins = alloca(sizeof(ir_node*) * arity);
+	for(i = 0; i < arity; ++i) {
+		ins[i] = get_irg_bad(env->irg);
+	}
+	spillinfo->spill = new_r_Phi(env->irg, block, arity, ins, mode_M);
+
+	for(i = 0; i < arity; ++i) {
+		ir_node *arg = get_irn_n(phi, i);
+		spill_info_t *arg_info = get_spillinfo(env, arg);
+
+		spill_node(env, arg_info);
+
+		set_irn_n(spillinfo->spill, i, arg_info->spill);
+	}
+
+	// rewire reloads from old_spill to phi
+	if(spillinfo->old_spill != NULL) {
+		const ir_edge_t *edge, *next;
+		ir_node *old_spill = spillinfo->old_spill;
+
+		foreach_out_edge_safe(old_spill, edge, next) {
+			ir_node* reload = get_edge_src_irn(edge);
+			assert(be_is_Reload(reload) || is_Phi(reload));
+			set_irn_n(reload, get_edge_src_pos(edge), spillinfo->spill);
 		}
+		set_irn_n(old_spill, be_pos_Spill_val, new_Bad());
+		//sched_remove(old_spill);
+		spillinfo->old_spill = NULL;
 	}
-	return ctx->spill;
 }
 
-static ir_node *be_spill_node(spill_env_t *senv, ir_node *to_spill) {
-	ir_node *res;
-	if (pset_find_ptr(senv->mem_phis, to_spill))
-		res = be_spill_phi(senv, to_spill, to_spill);
-	else
-		res = be_spill_irn(senv, to_spill, to_spill);
+/**
+ * Spill a node.
+ *
+ * @param senv      the spill environment
+ * @param to_spill  the node that should be spilled
+ */
+static void spill_node(spill_env_t *env, spill_info_t *spillinfo) {
+	ir_node *to_spill;
+
+	// the node should be tagged for spilling already...
+	if(spillinfo->spill != NULL)
+		return;
+
+	to_spill = spillinfo->spilled_node;
+	if (is_Phi(to_spill) && pset_find_ptr(env->mem_phis, spillinfo->spilled_node)) {
+		spill_phi(env, spillinfo);
+	} else {
+		spill_irn(env, spillinfo);
+	}
+}
 
-	return res;
+/*
+ *
+ *  ____                      _            _       _ _
+ * |  _ \ ___ _ __ ___   __ _| |_ ___ _ __(_) __ _| (_)_______
+ * | |_) / _ \ '_ ` _ \ / _` | __/ _ \ '__| |/ _` | | |_  / _ \
+ * |  _ <  __/ | | | | | (_| | ||  __/ |  | | (_| | | |/ /  __/
+ * |_| \_\___|_| |_| |_|\__,_|\__\___|_|  |_|\__,_|_|_/___\___|
+ *
+ */
+
+/**
+ * Tests whether value @p arg is available before node @p reloader
+ * @returns 1 if value is available, 0 otherwise
+ */
+static int is_value_available(spill_env_t *env, ir_node *arg, ir_node *reloader) {
+	if(is_Unknown(arg) || arg == new_NoMem())
+		return 1;
+
+	if(be_is_Spill(arg))
+		return 1;
+
+	if(arg == get_irg_frame(env->irg))
+		return 1;
+
+	// hack for now (happens when command should be inserted at end of block)
+	if(is_Block(reloader)) {
+		return 0;
+	}
+
+	/*
+	 * Ignore registers are always available
+	 */
+	if(arch_irn_is(env->arch_env, arg, ignore)) {
+		return 1;
+	}
+
+#if 0
+ 	/* the following test does not work while spilling,
+	 * because the liveness info is not adapted yet to the effects of the
+	 * additional spills/reloads.
+	 */
+
+	/* we want to remat before the insn reloader
+	 * thus an arguments is alive if
+	 *   - it interferes with the reloaders result
+	 *   - or it is (last-) used by reloader itself
+	 */
+	if (values_interfere(env->birg->lv, reloader, arg)) {
+		return 1;
+	}
+
+	arity = get_irn_arity(reloader);
+	for (i = 0; i < arity; ++i) {
+		ir_node *rel_arg = get_irn_n(reloader, i);
+		if (rel_arg == arg)
+			return 1;
+	}
+#endif
+
+ 	return 0;
 }
 
-static void phi_walker(ir_node *irn, void *env) {
-	spill_env_t *senv = env;
-	const arch_env_t *arch = senv->session->main_env->arch_env;
+/**
+ * Checks whether the node can principally be rematerialized
+ */
+static int is_remat_node(spill_env_t *env, ir_node *node) {
+	const arch_env_t *arch_env = env->arch_env;
+
+	assert(!be_is_Spill(node));
 
-	if (is_Phi(irn) && arch_irn_has_reg_class(arch, irn, 0, senv->cls)
-			&& senv->is_mem_phi(irn, senv->data)) {
-		DBG((senv->dbg, LEVEL_1, "  %+F\n", irn));
-		pset_insert_ptr(senv->mem_phis, irn);
+	if(arch_irn_is(arch_env, node, rematerializable)) {
+		return 1;
 	}
+
+	if(be_is_StackParam(node))
+		return 1;
+
+	return 0;
 }
 
-void be_insert_spills_reloads(spill_env_t *senv, pset *reload_set) {
-	ir_graph *irg = senv->session->irg;
-	ir_node *irn;
-	spill_info_t *si;
-	struct obstack ob;
-
-	obstack_init(&ob);
-
-	/* get all special spilled phis */
-	DBG((senv->dbg, LEVEL_1, "Mem-phis:\n"));
-	senv->mem_phis = pset_new_ptr_default();
-	irg_walk_graph(senv->session->irg, phi_walker, NULL, senv);
-
-	/* Add reloads for mem_phis */
-	/* BETTER: These reloads (1) should only be inserted, if they are really needed */
-	DBG((senv->dbg, LEVEL_1, "Reloads for mem-phis:\n"));
-	for(irn = pset_first(senv->mem_phis); irn; irn = pset_next(senv->mem_phis)) {
-		const ir_edge_t *e;
-		DBG((senv->dbg, LEVEL_1, " Mem-phi %+F\n", irn));
-		foreach_out_edge(irn, e) {
-			ir_node *user = e->src;
-			if (is_Phi(user) && !pset_find_ptr(senv->mem_phis, user)) {
-					DBG((senv->dbg, LEVEL_1, " non-mem-phi user %+F\n", user));
-					ir_node *use_bl = get_nodes_block(user);
-					be_add_reload_on_edge(senv, irn, use_bl, e->pos); /* (1) */
-			}
-		}
+/**
+ * Check if a node is rematerializable. This tests for the following conditions:
+ *
+ * - The node itself is rematerializable
+ * - All arguments of the node are available or also rematerialisable
+ * - The costs for the rematerialisation operation is less or equal a limit
+ *
+ * Returns the costs needed for rematerialisation or something
+ * > REMAT_COST_LIMIT if remat is not possible.
+ */
+static int check_remat_conditions_costs(spill_env_t *env, ir_node *spilled, ir_node *reloader, int parentcosts) {
+	int i, arity;
+	int argremats;
+	int costs = 0;
+
+	if(!is_remat_node(env, spilled))
+		return REMAT_COST_LIMIT;
+
+	if(be_is_Reload(spilled)) {
+		costs += 2;
+	} else {
+		costs += arch_get_op_estimated_cost(env->arch_env, spilled);
+	}
+	if(parentcosts + costs >= REMAT_COST_LIMIT) {
+		return REMAT_COST_LIMIT;
 	}
 
-	/* process each spilled node */
-	DBG((senv->dbg, LEVEL_1, "Insert spills and reloads:\n"));
-	for(si = set_first(senv->spills); si; si = set_next(senv->spills)) {
-		reloader_t *rld;
-		ir_node **reloads;
-		int n_reloads = 0;
-		ir_mode *mode = get_irn_mode(si->spilled_node);
+	argremats = 0;
+	for(i = 0, arity = get_irn_arity(spilled); i < arity; ++i) {
+		ir_node *arg = get_irn_n(spilled, i);
 
-		/* go through all reloads for this spill */
-		for(rld = si->reloaders; rld; rld = rld->next) {
-			/* the spill for this reloader */
-			ir_node *spill   = be_spill_node(senv, si->spilled_node);
-
-			/* the reload */
-			ir_node *bl      = is_Block(rld->reloader) ? rld->reloader : get_nodes_block(rld->reloader);
-			ir_node *reload  = new_Reload(senv->session->main_env->node_factory,
-														senv->cls, irg, bl, mode, spill);
-
-			DBG((senv->dbg, LEVEL_1, " %+F of %+F before %+F\n", reload, si->spilled_node, rld->reloader));
-			if(reload_set)
-				pset_insert_ptr(reload_set, reload);
-
-			/* remember the reaload */
-			obstack_ptr_grow(&ob, reload);
-			sched_add_before(rld->reloader, reload);
-			n_reloads++;
+		if(is_value_available(env, arg, reloader))
+			continue;
+
+		// we have to rematerialize the argument as well...
+		if(argremats >= 1) {
+			/* we only support rematerializing 1 argument at the moment,
+			 * so that we don't have to care about register pressure
+			 */
+			return REMAT_COST_LIMIT;
 		}
+		argremats++;
+
+		costs += check_remat_conditions_costs(env, arg, reloader, parentcosts + costs);
+		if(parentcosts + costs >= REMAT_COST_LIMIT)
+			return REMAT_COST_LIMIT;
+	}
 
-		assert(n_reloads > 0);
-		reloads = obstack_finish(&ob);
-		be_introduce_copies_ignore(senv->session->dom_front, si->spilled_node,
-				n_reloads, reloads, senv->mem_phis);
-		obstack_free(&ob, reloads);
+	return costs;
+}
+
+static int check_remat_conditions(spill_env_t *env, ir_node *spilled, ir_node *reloader) {
+	int costs = check_remat_conditions_costs(env, spilled, reloader, 0);
+
+	return costs < REMAT_COST_LIMIT;
+}
+
+/**
+ * Re-materialize a node.
+ *
+ * @param senv      the spill environment
+ * @param spilled   the node that was spilled
+ * @param reloader  a irn that requires a reload
+ */
+static ir_node *do_remat(spill_env_t *env, ir_node *spilled, ir_node *reloader) {
+	int i, arity;
+	ir_node *res;
+	ir_node *bl;
+	ir_node **ins;
+
+	if(is_Block(reloader)) {
+		bl = reloader;
+	} else {
+		bl = get_nodes_block(reloader);
 	}
 
-	obstack_free(&ob, NULL);
+	ins = alloca(get_irn_arity(spilled) * sizeof(ins[0]));
+	for(i = 0, arity = get_irn_arity(spilled); i < arity; ++i) {
+		ir_node *arg = get_irn_n(spilled, i);
 
-	for(irn = pset_first(senv->mem_phis); irn; irn = pset_next(senv->mem_phis)) {
-		int i, n;
-		for(i = 0, n = get_irn_arity(irn); i < n; ++i)
-			set_irn_n(irn, i, new_r_Bad(senv->session->irg));
-		sched_remove(irn);
+		if(is_value_available(env, arg, reloader)) {
+			ins[i] = arg;
+		} else {
+			ins[i] = do_remat(env, arg, reloader);
+		}
 	}
 
-	del_pset(senv->mem_phis);
+	/* create a copy of the node */
+	res = new_ir_node(get_irn_dbg_info(spilled), env->irg, bl,
+		get_irn_op(spilled),
+		get_irn_mode(spilled),
+		get_irn_arity(spilled),
+		ins);
+	copy_node_attr(spilled, res);
+	new_backedge_info(res);
+	sched_reset(res);
+
+	DBG((env->dbg, LEVEL_1, "Insert remat %+F of %+F before reloader %+F\n", res, spilled, reloader));
+
+	/* insert in schedule */
+	sched_add_before(reloader, res);
+
+	return res;
 }
 
-void be_add_reload(spill_env_t *senv, ir_node *to_spill, ir_node *before) {
-	spill_info_t templ, *res;
-	reloader_t *rel;
+int be_get_reload_costs(spill_env_t *env, ir_node *to_spill, ir_node *before) {
+	spill_info_t *spill_info;
 
-//	assert(get_irn_opcode(to_spill) != iro_Unknown);
+	if(be_do_remats) {
+		// is the node rematerializable?
+		int costs = check_remat_conditions_costs(env, to_spill, before, 0);
+		if(costs < REMAT_COST_LIMIT)
+			return costs;
+	}
+
+	// do we already have a spill?
+	spill_info = find_spillinfo(env, to_spill);
+	if(spill_info != NULL && spill_info->spill != NULL)
+		return env->reload_cost;
 
-	templ.spilled_node = to_spill;
-	templ.reloaders    = NULL;
-	res = set_insert(senv->spills, &templ, sizeof(templ), HASH_PTR(to_spill));
+	return env->spill_cost + env->reload_cost;
+}
 
-	rel           = obstack_alloc(&senv->obst, sizeof(rel[0]));
-	rel->reloader = before;
-	rel->next     = res->reloaders;
-	res->reloaders = rel;
+int be_get_reload_costs_on_edge(spill_env_t *env, ir_node *to_spill, ir_node *block, int pos) {
+	ir_node *before = get_reload_insertion_point(block, pos);
+	return be_get_reload_costs(env, to_spill, before);
 }
 
-void be_add_reload_on_edge(spill_env_t *senv, ir_node *to_spill, ir_node *bl, int pos) {
-	ir_node *insert_bl = get_irn_arity(bl) == 1 ? sched_first(bl) : get_Block_cfgpred_block(bl, pos);
-	be_add_reload(senv, to_spill, insert_bl);
+/*
+ *  ___                     _     ____      _                 _
+ * |_ _|_ __  ___  ___ _ __| |_  |  _ \ ___| | ___   __ _  __| |___
+ *  | || '_ \/ __|/ _ \ '__| __| | |_) / _ \ |/ _ \ / _` |/ _` / __|
+ *  | || | | \__ \  __/ |  | |_  |  _ <  __/ | (_) | (_| | (_| \__ \
+ * |___|_| |_|___/\___|_|   \__| |_| \_\___|_|\___/ \__,_|\__,_|___/
+ *
+ */
+
+void be_insert_spills_reloads(spill_env_t *env) {
+	const arch_env_t *arch_env = env->arch_env;
+	int              remats    = 0;
+	int              reloads   = 0;
+	int              spills    = 0;
+	spill_info_t     *si;
+
+	/* process each spilled node */
+	for (si = set_first(env->spills); si; si = set_next(env->spills)) {
+		reloader_t *rld;
+		ir_mode    *mode   = get_irn_mode(si->spilled_node);
+		pset       *values = pset_new_ptr(16);
+
+		DBG((env->dbg, LEVEL_1, "\nhandling all reloaders of %+F:\n", si->spilled_node));
+
+		/* go through all reloads for this spill */
+		for (rld = si->reloaders; rld; rld = rld->next) {
+			ir_node *new_val;
+
+			if (rld->rematted_node != NULL) {
+				new_val = rld->rematted_node;
+				remats++;
+				sched_add_before(rld->reloader, new_val);
+			}
+			else if (be_do_remats && rld->allow_remat && check_remat_conditions(env, si->spilled_node, rld->reloader)) {
+				new_val = do_remat(env, si->spilled_node, rld->reloader);
+				remats++;
+			}
+			else {
+				/* make sure we have a spill */
+				if (si->spill == NULL) {
+					spill_node(env, si);
+					spills++;
+				}
+
+				/* create a reload */
+				new_val = be_reload(arch_env, si->reload_cls, rld->reloader, mode, si->spill);
+				reloads++;
+			}
+
+			DBG((env->dbg, LEVEL_1, " %+F of %+F before %+F\n", new_val, si->spilled_node, rld->reloader));
+			pset_insert_ptr(values, new_val);
+		}
+
+		if (pset_count(values) > 0) {
+			/* introduce copies, rewire the uses */
+			pset_insert_ptr(values, si->spilled_node);
+			be_ssa_constr_set_ignore(env->birg->dom_front, env->birg->lv, values, env->mem_phis);
+		}
+
+		del_pset(values);
+
+		si->reloaders = NULL;
+	}
+
+#ifdef FIRM_STATISTICS
+	if (be_stat_ev_is_active()) {
+		be_stat_ev("spill_spills", spills);
+		be_stat_ev("spill_reloads", reloads);
+		be_stat_ev("spill_remats", remats);
+	}
+#endif /* FIRM_STATISTICS */
+
+	be_remove_dead_nodes_from_schedule(env->irg);
+	//be_liveness_recompute(env->birg->lv);
+	be_invalidate_liveness(env->birg);
 }