X-Git-Url: http://nsz.repo.hu/git/?a=blobdiff_plain;f=ir%2Fopt%2Fopt_osr.c;h=275ee2e6914dad9c7106cd2fd26a69754eadf9ff;hb=64f5f0cf11fe4a0d4753060e45639604d725652d;hp=9ae4a3f39711076afe993edd3dec84db8a24d170;hpb=863d31d7a5c8210432fef88b30fc3e8353131538;p=libfirm

diff --git a/ir/opt/opt_osr.c b/ir/opt/opt_osr.c
index 9ae4a3f39..275ee2e69 100644
--- a/ir/opt/opt_osr.c
+++ b/ir/opt/opt_osr.c
@@ -1,52 +1,67 @@
+/*
+ * Copyright (C) 1995-2011 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.
+ */
+
 /**
- * Project:     libFIRM
- * File name:   ir/opt/opt_osr.c
- * Purpose:     Operator Strength Reduction, based on
- *              Keith D. Cooper, L. Taylor Simpson, Christopher A. Vick
- * Author:      Michael Beck
- * Modified by:
- * Created:     12.5.2006
- * CVS-ID:      $Id$
- * Copyright:   (c) 2006 Universität Karlsruhe
- * Licence:     This file protected by GPL -  GNU GENERAL PUBLIC LICENSE.
+ * @file
+ * @brief   Operator Strength Reduction.
+ * @date    12.5.2006
+ * @author  Michael Beck
+ * @brief
+ *  Implementation of the Operator Strength Reduction algorithm
+ *  by Keith D. Cooper, L. Taylor Simpson, Christopher A. Vick.
+ *  Extended version.
  */
-#ifdef HAVE_CONFIG_H
 #include "config.h"
-#endif
-
-#ifdef HAVE_MALLOC_H
-#include <malloc.h>
-#endif
-#ifdef HAVE_ALLOCA_H
-#include <alloca.h>
-#endif
 
-#include "opt_osr.h"
+#include "adt/pdeq.h"
+#include "iroptimize.h"
 #include "irgraph.h"
 #include "ircons.h"
 #include "irop_t.h"
-#include "irloop.h"
 #include "irdom.h"
 #include "irgmod.h"
 #include "irflag_t.h"
 #include "irgwalk.h"
 #include "irouts.h"
+#include "iredges.h"
 #include "debug.h"
 #include "obst.h"
 #include "set.h"
 #include "tv.h"
 #include "hashptr.h"
+#include "util.h"
 #include "irtools.h"
 #include "irloop_t.h"
 #include "array.h"
 #include "firmstat.h"
+#include "error.h"
+#include "irpass_t.h"
 
 /** The debug handle. */
 DEBUG_ONLY(static firm_dbg_module_t *dbg;)
 
 /** A scc. */
 typedef struct scc {
-	ir_node *head;		/**< the head of the list */
+	ir_node   *head; /**< the head of the list */
+	ir_tarval *init; /**< the init value iff only one exists. */
+	ir_tarval *incr; /**< the induction variable increment if only a single const exists. */
+	unsigned   code; /**< == iro_Add if +incr, iro_Sub if -incr, 0 if not analysed, iro_Bad else */
 } scc;
 
 /** A node entry */
@@ -64,14 +79,15 @@ typedef struct node_entry {
 typedef struct iv_env {
 	struct obstack obst;    /**< an obstack for allocations */
 	ir_node  **stack;       /**< the node stack */
-	int      tos;           /**< tos index */
+	size_t   tos;           /**< tos index */
 	unsigned nextDFSnum;    /**< the current DFS number */
 	unsigned POnum;         /**< current post order number */
 	set      *quad_map;     /**< a map from (op, iv, rc) to node */
 	set      *lftr_edges;   /**< the set of lftr edges */
 	unsigned replaced;      /**< number of replaced ops */
 	unsigned lftr_replaced; /**< number of applied linear function test replacements */
-	unsigned flags;         /**< additional flags */
+	unsigned osr_flags;     /**< additional flags steering the transformation */
+	unsigned need_postpass; /**< set, if a post pass is needed to fix Add and Sub nodes */
 	/** Function called to process a SCC. */
 	void (*process_scc)(scc *pscc, struct iv_env *env);
 } iv_env;
@@ -80,7 +96,7 @@ typedef struct iv_env {
  * An entry in the (op, node, node) -> node map.
  */
 typedef struct quadruple_t {
-	ir_opcode code;  /**< the opcode of the reduced operation */
+	unsigned   code; /**< the opcode of the reduced operation */
 	ir_node   *op1;  /**< the first operand the reduced operation */
 	ir_node   *op2;  /**< the second operand of the reduced operation */
 
@@ -93,7 +109,7 @@ typedef struct quadruple_t {
 typedef struct LFTR_edge {
 	ir_node   *src;   /**< the source node */
 	ir_node   *dst;   /**< the destination node */
-	ir_opcode code;   /**< the opcode that must be applied */
+	unsigned  code;   /**< the opcode that must be applied */
 	ir_node   *rc;    /**< the region const that must be applied */
 } LFTR_edge;
 
@@ -103,30 +119,40 @@ static ir_node *reduce(ir_node *orig, ir_node *iv, ir_node *rc, iv_env *env);
 /**
  * Compare two LFTR edges.
  */
-static int LFTR_cmp(const void *e1, const void *e2, size_t size) {
-	const LFTR_edge *l1 = e1;
-	const LFTR_edge *l2 = e2;
+static int LFTR_cmp(const void *e1, const void *e2, size_t size)
+{
+	const LFTR_edge *l1 = (const LFTR_edge*)e1;
+	const LFTR_edge *l2 = (const LFTR_edge*)e2;
+	(void) size;
 
 	return l1->src != l2->src;
-}
+}  /* LFTR_cmp */
 
-#if 0
 /**
  * Find a LFTR edge.
+ *
+ * @param src  the source node of the transition
  */
-static LFTR_edge *LFTR_find(ir_node *src, iv_env *env) {
+static LFTR_edge *LFTR_find(ir_node *src, iv_env *env)
+{
 	LFTR_edge key;
 
 	key.src  = src;
 
-	return set_find(env->lftr_edges, &key, sizeof(key), HASH_PTR(src));
-}
-#endif
+	return set_find(LFTR_edge, env->lftr_edges, &key, sizeof(key), hash_ptr(src));
+}  /* LFTR_find */
 
 /**
  * Add a LFTR edge.
+ *
+ * @param src   the source node of the edge
+ * @param dst   the destination node of the edge
+ * @param code  the opcode of the transformed transition
+ * @param rc    the region const used in the transition
+ * @param env   the environment
  */
-static void LFTR_add(ir_node *src, ir_node *dst, ir_opcode code, ir_node *rc, iv_env *env) {
+static void LFTR_add(ir_node *src, ir_node *dst, unsigned code, ir_node *rc, iv_env *env)
+{
 	LFTR_edge key;
 
 	key.src  = src;
@@ -138,23 +164,37 @@ static void LFTR_add(ir_node *src, ir_node *dst, ir_opcode code, ir_node *rc, iv
 	 * There might be more than one edge here. This is rather bad
 	 * because we currently store only one.
 	 */
-//	assert(LFTR_find(src, env) == NULL);
-	set_insert(env->lftr_edges, &key, sizeof(key), HASH_PTR(src));
-}
+	(void)set_insert(LFTR_edge, env->lftr_edges, &key, sizeof(key), hash_ptr(src));
+}  /* LFTR_add */
 
 /**
- * Gets the node_entry of a node
+ * Gets the node_entry of a node.
+ *
+ * @param irn  the node
+ * @param env  the environment
  */
-static node_entry *get_irn_ne(ir_node *irn, iv_env *env) {
-	node_entry *e = get_irn_link(irn);
+static node_entry *get_irn_ne(ir_node *irn, iv_env *env)
+{
+	node_entry *e = (node_entry*)get_irn_link(irn);
 
-	if (! e) {
-		e = obstack_alloc(&env->obst, sizeof(*e));
-		memset(e, 0, sizeof(*e));
+	if (e == NULL) {
+		e = OALLOCZ(&env->obst, node_entry);
 		set_irn_link(irn, e);
 	}
 	return e;
-}
+}  /* get_irn_ne */
+
+/**
+ * Gets the scc from an induction variable.
+ *
+ * @param iv   any node of the induction variable
+ * @param env  the environment
+ */
+static scc *get_iv_scc(ir_node *iv, iv_env *env)
+{
+	node_entry *e = get_irn_ne(iv, env);
+	return e->pscc;
+}  /* get_iv_scc */
 
 /**
  * Check if irn is an IV.
@@ -164,9 +204,10 @@ static node_entry *get_irn_ne(ir_node *irn, iv_env *env) {
  *
  * @returns the header if it is one, NULL else
  */
-static ir_node *is_iv(ir_node *irn, iv_env *env) {
+static ir_node *is_iv(ir_node *irn, iv_env *env)
+{
 	return get_irn_ne(irn, env)->header;
-}
+}  /* is_iv */
 
 /**
  * Check if irn is a region constant.
@@ -175,21 +216,24 @@ static ir_node *is_iv(ir_node *irn, iv_env *env) {
  * @param irn           the node to check
  * @param header_block  the header block of the induction variable
  */
-static int is_rc(ir_node *irn, ir_node *header_block) {
+static int is_rc(ir_node *irn, ir_node *header_block)
+{
 	ir_node *block = get_nodes_block(irn);
 
 	return (block != header_block) && block_dominates(block, header_block);
-}
+}  /* is_rc */
 
 /**
  * Set compare function for the quad set.
  */
-static int quad_cmp(const void *e1, const void *e2, size_t size) {
-	const quadruple_t *c1 = e1;
-	const quadruple_t *c2 = e2;
+static int quad_cmp(const void *e1, const void *e2, size_t size)
+{
+	const quadruple_t *c1 = (const quadruple_t*)e1;
+	const quadruple_t *c2 = (const quadruple_t*)e2;
+	(void) size;
 
 	return c1->code != c2->code || c1->op1 != c2->op1 || c1->op2 != c2->op2;
-}
+}  /* quad_cmp */
 
 /**
  * Check if an reduced operation was already calculated.
@@ -201,19 +245,19 @@ static int quad_cmp(const void *e1, const void *e2, size_t size) {
  *
  * @return the already reduced node or NULL if this operation is not yet reduced
  */
-static ir_node *search(ir_opcode code, ir_node *op1, ir_node *op2, iv_env *env) {
+static ir_node *search(unsigned code, ir_node *op1, ir_node *op2, iv_env *env)
+{
 	quadruple_t key, *entry;
 
 	key.code = code;
 	key.op1 = op1;
 	key.op2 = op2;
 
-	entry = set_find(env->quad_map, &key, sizeof(key),
-	                 (code * 9) ^ HASH_PTR(op1) ^HASH_PTR(op2));
+	entry = set_find(quadruple_t, env->quad_map, &key, sizeof(key), (code * 9) ^ hash_ptr(op1) ^ hash_ptr(op2));
 	if (entry)
 		return entry->res;
 	return NULL;
-}
+}  /* search */
 
 /**
  * Add an reduced operation.
@@ -224,7 +268,8 @@ static ir_node *search(ir_opcode code, ir_node *op1, ir_node *op2, iv_env *env)
  * @param result  the result of the reduced operation
  * @param env     the environment
  */
-static void add(ir_opcode code, ir_node *op1, ir_node *op2, ir_node *result, iv_env *env) {
+static void add(unsigned code, ir_node *op1, ir_node *op2, ir_node *result, iv_env *env)
+{
 	quadruple_t key;
 
 	key.code = code;
@@ -232,9 +277,8 @@ static void add(ir_opcode code, ir_node *op1, ir_node *op2, ir_node *result, iv_
 	key.op2  = op2;
 	key.res  = result;
 
-	set_insert(env->quad_map, &key, sizeof(key),
-	           (code * 9) ^ HASH_PTR(op1) ^HASH_PTR(op2));
-}
+	(void)set_insert(quadruple_t, env->quad_map, &key, sizeof(key), (code * 9) ^ hash_ptr(op1) ^ hash_ptr(op2));
+}  /* add */
 
 /**
  * Find a location where to place a bin-op whose operands are in
@@ -247,12 +291,13 @@ static void add(ir_opcode code, ir_node *op1, ir_node *op2, ir_node *result, iv_
  * that either block1 dominates block2 or vice versa. So, just return
  * the "smaller" one.
  */
-static ir_node *find_location(ir_node *block1, ir_node *block2) {
+static ir_node *find_location(ir_node *block1, ir_node *block2)
+{
 	if (block_dominates(block1, block2))
 		return block2;
 	assert(block_dominates(block2, block1));
 	return block1;
-}
+}  /* find_location */
 
 /**
  * Create a node that executes an op1 code op1 operation.
@@ -265,27 +310,26 @@ static ir_node *find_location(ir_node *block1, ir_node *block2) {
  *
  * @return the newly created node
  */
-static ir_node *do_apply(ir_opcode code, dbg_info *db, ir_node *op1, ir_node *op2, ir_mode *mode) {
-	ir_graph *irg = current_ir_graph;
+static ir_node *do_apply(unsigned code, dbg_info *db, ir_node *op1, ir_node *op2, ir_mode *mode)
+{
 	ir_node *result;
 	ir_node *block = find_location(get_nodes_block(op1), get_nodes_block(op2));
 
 	switch (code) {
 	case iro_Mul:
-		result = new_rd_Mul(db, irg, block, op1, op2, mode);
+		result = new_rd_Mul(db, block, op1, op2, mode);
 		break;
 	case iro_Add:
-		result = new_rd_Add(db, irg, block, op1, op2, mode);
+		result = new_rd_Add(db, block, op1, op2, mode);
 		break;
 	case iro_Sub:
-		result = new_rd_Sub(db, irg, block, op1, op2, mode);
+		result = new_rd_Sub(db, block, op1, op2, mode);
 		break;
 	default:
-		assert(0);
-		result = NULL;
+		panic("Unsupported opcode");
 	}
 	return result;
-}
+}  /* do_apply */
 
 /**
  * The Apply operation.
@@ -298,27 +342,29 @@ static ir_node *do_apply(ir_opcode code, dbg_info *db, ir_node *op1, ir_node *op
  *
  * @return the newly created node
  */
-static ir_node *apply(ir_node *orig, ir_node *op1, ir_node *op2, iv_env *env) {
-	ir_opcode code = get_irn_opcode(orig);
+static ir_node *apply(ir_node *header, ir_node *orig, ir_node *op1, ir_node *op2, iv_env *env)
+{
+	unsigned code = get_irn_opcode(orig);
 	ir_node *result = search(code, op1, op2, env);
 
-	if (! result) {
+	if (result == NULL) {
 		dbg_info *db = get_irn_dbg_info(orig);
 		ir_node *op1_header = get_irn_ne(op1, env)->header;
 		ir_node *op2_header = get_irn_ne(op2, env)->header;
 
-		if (op1_header != NULL && is_rc(op2, op1_header)) {
+		if (op1_header == header && is_rc(op2, op1_header)) {
 			result = reduce(orig, op1, op2, env);
 		}
-		else if (op2_header != NULL && is_rc(op1, op2_header)) {
+		else if (op2_header == header && is_rc(op1, op2_header)) {
 			result = reduce(orig, op2, op1, env);
 		}
 		else {
 			result = do_apply(code, db, op1, op2, get_irn_mode(orig));
-			get_irn_ne(result, env)->header = NULL;		}
+			get_irn_ne(result, env)->header = NULL;
+		}
 	}
 	return result;
-}
+}  /* apply */
 
 /**
  * The Reduce operation.
@@ -331,22 +377,31 @@ static ir_node *apply(ir_node *orig, ir_node *op1, ir_node *op2, iv_env *env) {
  *
  * @return the reduced node
  */
-static ir_node *reduce(ir_node *orig, ir_node *iv, ir_node *rc, iv_env *env) {
-	ir_opcode code = get_irn_opcode(orig);
+static ir_node *reduce(ir_node *orig, ir_node *iv, ir_node *rc, iv_env *env)
+{
+	unsigned code = get_irn_opcode(orig);
 	ir_node *result = search(code, iv, rc, env);
 
-	if (! result) {
+	/* check if we have already done this operation on the iv */
+	if (result == NULL) {
 		node_entry *e, *iv_e;
-		int i, n;
+		int i;
 		ir_mode *mode = get_irn_mode(orig);
 
 		result = exact_copy(iv);
 
-		/* Beware: we must always create a new nduction variable with the same mode
-		   as the node we are replacing. Espicially this means the mode might be changed
-		   from P to I and back. This is always possible, because we have only Phi, Add
-		   and Sub nodes. */
-		set_irn_mode(result, mode);
+		if (get_irn_mode(result) != mode) {
+			/*
+			 * Beware: we must always create a new induction variable with the same mode
+			 * as the node we are replacing. Especially this means the mode might be changed
+			 * from P to I and back. This is always possible, because we have only Phi, Add
+			 * and Sub nodes.
+			 * However, this might lead to AddIs(Iu,Is) which we must fix. The best way to do this
+			 * seems to be a post-pass, or we might end with useless Conv's.
+			 */
+			set_irn_mode(result, mode);
+			env->need_postpass = 1;
+		}
 		add(code, iv, rc, result, env);
 		DB((dbg, LEVEL_3, "   Created new %+F for %+F (%s %+F)\n", result, iv,
 			get_irn_opname(orig), rc));
@@ -358,60 +413,258 @@ static ir_node *reduce(ir_node *orig, ir_node *iv, ir_node *rc, iv_env *env) {
 		/* create the LFTR edge */
 		LFTR_add(iv, result, code, rc, env);
 
-		n = get_irn_arity(result);
-		for (i = 0; i < n; ++i) {
+		for (i = get_irn_arity(result) - 1; i >= 0; --i) {
 			ir_node *o = get_irn_n(result, i);
 
 			e = get_irn_ne(o, env);
 			if (e->header == iv_e->header)
 				o = reduce(orig, o, rc, env);
-			else if (is_Phi(result))
-				o = apply(orig, o, rc, env);
-			else {
-				if (code == iro_Mul)
-					o = apply(orig, o, rc, env);
-			}
+			else if (is_Phi(result) || code == iro_Mul)
+				o = apply(iv_e->header, orig, o, rc, env);
 			set_irn_n(result, i, o);
 		}
-	}
-	else {
+	} else {
 		DB((dbg, LEVEL_3, "   Already Created %+F for %+F (%s %+F)\n", result, iv,
 			get_irn_opname(orig), rc));
 	}
 	return result;
-}
+}  /* reduce */
 
 /**
- * The Replace operation.
+ * Update the scc for a newly created IV.
+ */
+static void update_scc(ir_node *iv, node_entry *e, iv_env *env)
+{
+	scc     *pscc   = e->pscc;
+	ir_node *header = e->header;
+	waitq    *wq = new_waitq();
+
+	DB((dbg, LEVEL_2, "  Creating SCC for new an induction variable:\n  "));
+	pscc->head = NULL;
+	waitq_put(wq, iv);
+	do {
+		ir_node    *irn = (ir_node*)waitq_get(wq);
+		node_entry *ne  = get_irn_ne(irn, env);
+		int        i;
+
+		ne->pscc   = pscc;
+		ne->next   = pscc->head;
+		pscc->head = irn;
+		DB((dbg, LEVEL_2, " %+F,", irn));
+
+		for (i = get_irn_arity(irn) - 1; i >= 0; --i) {
+			ir_node    *pred = get_irn_n(irn, i);
+			node_entry *pe   = get_irn_ne(pred, env);
+
+			if (pe->header == header && pe->pscc == NULL) {
+				/* set the pscc here to ensure that the node is NOT enqueued another time */
+				pe->pscc = pscc;
+				waitq_put(wq, pred);
+			}
+		}
+	} while (! waitq_empty(wq));
+	del_waitq(wq);
+	DB((dbg, LEVEL_2, "\n"));
+}  /* update_scc */
+
+/**
+ * The Replace operation. We found a node representing iv (+,-,*) rc
+ * that can be removed by replacing the induction variable iv by a new
+ * one that 'applies' the operation 'irn'.
  *
  * @param irn   the node that will be replaced
  * @param iv    the induction variable
  * @param rc    the region constant
  * @param env   the environment
  */
-static int replace(ir_node *irn, ir_node *iv, ir_node *rc, iv_env *env) {
+static int replace(ir_node *irn, ir_node *iv, ir_node *rc, iv_env *env)
+{
 	ir_node *result;
-	ir_loop *iv_loop  = get_irn_loop(get_nodes_block(iv));
-	ir_loop *irn_loop = get_irn_loop(get_nodes_block(irn));
-
-	/* only replace nodes that are in the same (or deeper loops) */
-	if (get_loop_depth(irn_loop) >= get_loop_depth(iv_loop)) {
-		DB((dbg, LEVEL_2, "  Replacing %+F\n", irn));
-
-		result = reduce(irn, iv, rc, env);
-		if (result != irn) {
-			node_entry *e, *iv_e;
-
-			hook_strength_red(current_ir_graph, irn);
-			exchange(irn, result);
-			e = get_irn_ne(result, env);
-			iv_e = get_irn_ne(iv, env);
-			e->header = iv_e->header;
+
+	DB((dbg, LEVEL_2, "  Replacing %+F\n", irn));
+
+	result = reduce(irn, iv, rc, env);
+	if (result != irn) {
+		node_entry *e;
+
+		hook_strength_red(get_irn_irg(irn), irn);
+		exchange(irn, result);
+		e = get_irn_ne(result, env);
+		if (e->pscc == NULL) {
+			e->pscc = OALLOCZ(&env->obst, scc);
+			update_scc(result, e, env);
 		}
+		++env->replaced;
 		return 1;
 	}
 	return 0;
-}
+}  /* replace */
+
+#if 0
+/**
+ * check if a given node is a mul with 2, 4, 8
+ */
+static int is_x86_shift_const(ir_node *mul)
+{
+	ir_node *rc;
+
+	if (! is_Mul(mul))
+		return 0;
+
+	/* normalization put constants on the right side */
+	rc = get_Mul_right(mul);
+	if (is_Const(rc)) {
+		ir_tarval *tv = get_Const_tarval(rc);
+
+		if (tarval_is_long(tv)) {
+			long value = get_tarval_long(tv);
+
+			if (value == 2 || value == 4 || value == 8) {
+				/* do not reduce multiplications by 2, 4, 8 */
+				return 1;
+			}
+		}
+	}
+	return 0;
+}  /* is_x86_shift_const */
+#endif
+
+/**
+ * Check if an IV represents a counter with constant limits.
+ *
+ * @param iv    any node of the induction variable
+ * @param env   the environment
+ */
+static int is_counter_iv(ir_node *iv, iv_env *env)
+{
+	node_entry *e         = get_irn_ne(iv, env);
+	scc        *pscc      = e->pscc;
+	ir_node    *have_init = NULL;
+	ir_node    *have_incr = NULL;
+	ir_opcode  code       = iro_Bad;
+	ir_node    *irn;
+
+	if (pscc->code != 0) {
+		/* already analysed */
+		return pscc->code != iro_Bad;
+	}
+
+	pscc->code = iro_Bad;
+	for (irn = pscc->head; irn != NULL; irn = e->next) {
+		if (is_Add(irn)) {
+			if (have_incr != NULL)
+				return 0;
+
+			have_incr = get_Add_right(irn);
+			if (! is_Const(have_incr)) {
+				have_incr = get_Add_left(irn);
+				if (! is_Const(have_incr))
+					return 0;
+			}
+			code = iro_Add;
+		} else if (is_Sub(irn)) {
+			if (have_incr != NULL)
+				return 0;
+
+			have_incr = get_Sub_right(irn);
+			if (! is_Const(have_incr))
+				return 0;
+			code = iro_Sub;
+		} else if (is_Phi(irn)) {
+			int i;
+
+			for (i = get_Phi_n_preds(irn) - 1; i >= 0; --i) {
+				ir_node    *pred = get_Phi_pred(irn, i);
+				node_entry *ne   = get_irn_ne(pred, env);
+
+				if (ne->header == e->header)
+					continue;
+				if (have_init != NULL)
+					return 0;
+				have_init = pred;
+				if (! is_Const(pred))
+					return 0;
+			}
+		} else
+			return 0;
+		e = get_irn_ne(irn, env);
+	}
+	pscc->init = get_Const_tarval(have_init);
+	pscc->incr = get_Const_tarval(have_incr);
+	pscc->code = code;
+	return code != iro_Bad;
+}  /* is_counter_iv */
+
+/**
+ * Check the users of an induction variable for register pressure.
+ *
+ * @param iv    any node of the induction variable
+ * @param env   the environment
+ *
+ * @return non-zero if the register pressure is estimated
+ *         to not increase, zero else
+ */
+static int check_users_for_reg_pressure(ir_node *iv, iv_env *env)
+{
+	ir_node    *irn;
+	ir_node    *have_user = NULL;
+	ir_node    *have_cmp  = NULL;
+	node_entry *e         = get_irn_ne(iv, env);
+	scc        *pscc      = e->pscc;
+
+	for (irn = pscc->head; irn != NULL; irn = e->next) {
+		foreach_out_edge(irn, edge) {
+			ir_node    *user = get_edge_src_irn(edge);
+			node_entry *ne = get_irn_ne(user, env);
+
+			if (e->header == ne->header) {
+				/* found user from the same IV */
+				continue;
+			}
+			if (is_Cmp(user)) {
+				if (have_cmp != NULL) {
+					/* more than one cmp, for now end here */
+					return 0;
+				}
+				have_cmp = user;
+			} else {
+				/* user is a real user of the IV */
+				if (have_user != NULL) {
+					/* found the second user */
+					return 0;
+				}
+				have_user = user;
+			}
+		}
+		e = get_irn_ne(irn, env);
+	}
+
+	if (have_user == NULL) {
+		/* no user, ignore */
+		return 1;
+	}
+
+	if (have_cmp == NULL) {
+		/* fine, only one user, try to reduce */
+		return 1;
+	}
+	/*
+	 * We found one user AND at least one cmp.
+	 * We should check here if we can transform the Cmp.
+	 *
+	 * For now our capabilities for doing linear function test
+	 * are limited, so check if the iv has the right form: Only ONE
+	 * Phi, only one Add/Sub with a Const.
+	 */
+	if (! is_counter_iv(iv, env))
+		return 0;
+
+	/*
+	 * Ok, we have only one increment AND it is a Const, we might be able
+	 * to do a linear function test replacement, so go on.
+	 */
+	return 1;
+}  /* check_users_for_reg_pressure */
 
 /**
  * Check if a node can be replaced (+, -, *).
@@ -421,10 +674,11 @@ static int replace(ir_node *irn, ir_node *iv, ir_node *rc, iv_env *env) {
  *
  * @return non-zero if irn should be Replace'd
  */
-static int check_replace(ir_node *irn, iv_env *env) {
+static int check_replace(ir_node *irn, iv_env *env)
+{
 	ir_node   *left, *right, *iv, *rc;
 	ir_op     *op  = get_irn_op(irn);
-	ir_opcode code = get_op_code(op);
+	unsigned  code = get_op_code(op);
 	ir_node   *liv, *riv;
 
 	switch (code) {
@@ -447,21 +701,10 @@ static int check_replace(ir_node *irn, iv_env *env) {
 		}
 
 		if (iv) {
-			if (code == iro_Mul && env->flags & osr_flag_ignore_x86_shift) {
-				if (is_Const(rc)) {
-					tarval *tv = get_Const_tarval(rc);
-
-					if (tarval_is_long(tv)) {
-						long value = get_tarval_long(tv);
-
-						if (value == 2 || value == 4 || value == 8) {
-							/* do not reduce multiplications by 2, 4, 8 */
-							break;
-						}
-					}
-				}
+			if (env->osr_flags & osr_flag_keep_reg_pressure) {
+				if (! check_users_for_reg_pressure(iv, env))
+					return 0;
 			}
-
 			return replace(irn, iv, rc, env);
 		}
 		break;
@@ -469,7 +712,7 @@ static int check_replace(ir_node *irn, iv_env *env) {
 		break;
 	}
 	return 0;
-}
+}  /* check_replace */
 
 /**
  * Check which SCC's are induction variables.
@@ -477,7 +720,8 @@ static int check_replace(ir_node *irn, iv_env *env) {
  * @param pscc  a SCC
  * @param env   the environment
  */
-static void classify_iv(scc *pscc, iv_env *env) {
+static void classify_iv(scc *pscc, iv_env *env)
+{
 	ir_node *irn, *next, *header = NULL;
 	node_entry *b, *h = NULL;
 	int j, only_phi, num_outside;
@@ -485,7 +729,7 @@ static void classify_iv(scc *pscc, iv_env *env) {
 
 	/* find the header block for this scc */
 	for (irn = pscc->head; irn; irn = next) {
-		node_entry *e = get_irn_link(irn);
+		node_entry *e = (node_entry*)get_irn_link(irn);
 		ir_node *block = get_nodes_block(irn);
 
 		next = e->next;
@@ -512,8 +756,26 @@ static void classify_iv(scc *pscc, iv_env *env) {
 
 		next = e->next;
 		switch (get_irn_opcode(irn)) {
-		case iro_Add:
 		case iro_Sub:
+			only_phi = 0;
+			{
+				ir_node    *left        = get_Sub_left(irn);
+				node_entry *left_entry  = get_irn_ne(left, env);
+				ir_node    *right       = get_Sub_right(irn);
+				node_entry *right_entry = get_irn_ne(right, env);
+
+				if (left_entry->pscc != e->pscc ||
+				    (right_entry->pscc != e->pscc && !is_rc(right, header))) {
+					/*
+					 * Not an induction variable.
+					 * Region constant are only allowed on right hand side.
+					 */
+					goto fail;
+				}
+			}
+			break;
+
+		case iro_Add:
 			only_phi = 0;
 			/* fall through */
 		case iro_Phi:
@@ -572,28 +834,28 @@ fail:
 		node_entry *e = get_irn_ne(irn, env);
 
 		next = e->next;
-		if (! check_replace(irn, env))
-			e->header = NULL;
+		e->header = NULL;
 	}
-}
+}  /* classify_iv */
 
 /**
- * Process a SCC for the operator strength reduction.
+ * Process an SCC for the operator strength reduction.
  *
  * @param pscc  the SCC
  * @param env   the environment
  */
-static void process_scc(scc *pscc, iv_env *env) {
+static void process_scc(scc *pscc, iv_env *env)
+{
 	ir_node *head = pscc->head;
-	node_entry *e = get_irn_link(head);
+	node_entry *e = (node_entry*)get_irn_link(head);
 
 #ifdef DEBUG_libfirm
 	{
 		ir_node *irn, *next;
 
 		DB((dbg, LEVEL_4, " SCC at %p:\n ", pscc));
-		for (irn = pscc->head; irn; irn = next) {
-			node_entry *e = get_irn_link(irn);
+		for (irn = pscc->head; irn != NULL; irn = next) {
+			node_entry *e = (node_entry*)get_irn_link(irn);
 
 			next = e->next;
 
@@ -609,17 +871,21 @@ static void process_scc(scc *pscc, iv_env *env) {
 	} else {
 		classify_iv(pscc, env);
 	}
-}
+}  /* process_scc */
 
 /**
  * If an SCC is a Phi only cycle, remove it.
+ *
+ * @param pscc  an SCC that consists of Phi nodes only
+ * @param env   the environment
  */
-static void remove_phi_cycle(scc *pscc, iv_env *env) {
+static void remove_phi_cycle(scc *pscc, iv_env *env)
+{
 	ir_node *irn, *next;
 	int j;
 	ir_node *out_rc;
 
-	/* check if this scc contains only Phi, Add or Sub nodes */
+	/* check if this scc contains only Phi nodes */
 	out_rc      = NULL;
 	for (irn = pscc->head; irn; irn = next) {
 		node_entry *e = get_irn_ne(irn, env);
@@ -652,17 +918,18 @@ static void remove_phi_cycle(scc *pscc, iv_env *env) {
 		exchange(irn, out_rc);
 	}
 	++env->replaced;
-}
+}  /* remove_phi_cycle */
 
 /**
- * Process a SCC for the Phi cycle removement.
+ * Process a SCC for the Phi cycle remove.
  *
  * @param pscc  the SCC
  * @param env   the environment
  */
-static void process_phi_only_scc(scc *pscc, iv_env *env) {
+static void process_phi_only_scc(scc *pscc, iv_env *env)
+{
 	ir_node *head = pscc->head;
-	node_entry *e = get_irn_link(head);
+	node_entry *e = (node_entry*)get_irn_link(head);
 
 #ifdef DEBUG_libfirm
 	{
@@ -670,7 +937,7 @@ static void process_phi_only_scc(scc *pscc, iv_env *env) {
 
 		DB((dbg, LEVEL_4, " SCC at %p:\n ", pscc));
 		for (irn = pscc->head; irn; irn = next) {
-			node_entry *e = get_irn_link(irn);
+			node_entry *e = (node_entry*)get_irn_link(irn);
 
 			next = e->next;
 
@@ -682,7 +949,7 @@ static void process_phi_only_scc(scc *pscc, iv_env *env) {
 
 	if (e->next != NULL)
 		remove_phi_cycle(pscc, env);
-}
+}  /* process_phi_only_scc */
 
 
 /**
@@ -691,20 +958,21 @@ static void process_phi_only_scc(scc *pscc, iv_env *env) {
  * @param env   the environment
  * @param n     the node to push
  */
-static void push(iv_env *env, ir_node *n) {
+static void push(iv_env *env, ir_node *n)
+{
 	node_entry *e;
 
 	if (env->tos == ARR_LEN(env->stack)) {
-		int nlen = ARR_LEN(env->stack) * 2;
+		size_t nlen = ARR_LEN(env->stack) * 2;
 		ARR_RESIZE(ir_node *, env->stack, nlen);
 	}
 	env->stack[env->tos++] = n;
 	e = get_irn_ne(n, env);
 	e->in_stack = 1;
-}
+}  /* push */
 
 /**
- * pop a node from the stack
+ * Pop a node from the stack.
  *
  * @param env   the environment
  *
@@ -717,7 +985,7 @@ static ir_node *pop(iv_env *env)
 
 	e->in_stack = 0;
 	return n;
-}
+}  /* pop */
 
 /**
  * Do Tarjan's SCC algorithm and drive OSR.
@@ -738,11 +1006,10 @@ static void dfs(ir_node *irn, iv_env *env)
 		for (i = 0; i < n; ++i) {
 			ir_node *pred = get_irn_n(irn, i);
 
-			if (irn_not_visited(pred))
+			if (!irn_visited(pred))
 				dfs(pred, env);
 		}
-	}
-	else {
+	} else {
 		ir_node *block = get_nodes_block(irn);
 
 		node->DFSnum = env->nextDFSnum++;
@@ -750,7 +1017,7 @@ static void dfs(ir_node *irn, iv_env *env)
 		push(env, irn);
 
 		/* handle the block */
-		if (irn_not_visited(block))
+		if (!irn_visited(block))
 			dfs(block, env);
 
 		n = get_irn_arity(irn);
@@ -758,7 +1025,7 @@ static void dfs(ir_node *irn, iv_env *env)
 			ir_node *pred = get_irn_n(irn, i);
 			node_entry *o = get_irn_ne(pred, env);
 
-			if (irn_not_visited(pred)) {
+			if (!irn_visited(pred)) {
 				dfs(pred, env);
 				node->low = MIN(node->low, o->low);
 			}
@@ -766,10 +1033,9 @@ static void dfs(ir_node *irn, iv_env *env)
 				node->low = MIN(o->DFSnum, node->low);
 		}
 		if (node->low == node->DFSnum) {
-			scc *pscc = obstack_alloc(&env->obst, sizeof(*pscc));
+			scc *pscc = OALLOCZ(&env->obst, scc);
 			ir_node *x;
 
-			pscc->head = NULL;
 			do {
 				node_entry *e;
 
@@ -783,7 +1049,7 @@ static void dfs(ir_node *irn, iv_env *env)
 			env->process_scc(pscc, env);
 		}
 	}
-}
+}  /* dfs */
 
 /**
  * Do the DFS by starting at the End node of a graph.
@@ -791,66 +1057,47 @@ static void dfs(ir_node *irn, iv_env *env)
  * @param irg  the graph to process
  * @param env  the environment
  */
-static void do_dfs(ir_graph *irg, iv_env *env) {
-	ir_graph *rem = current_ir_graph;
-	ir_node *end = get_irg_end(irg);
-	int i, n;
+static void do_dfs(ir_graph *irg, iv_env *env)
+{
+	ir_node  *end = get_irg_end(irg);
+	int i;
+
+	ir_reserve_resources(irg, IR_RESOURCE_IRN_VISITED);
 
-	current_ir_graph = irg;
 	inc_irg_visited(irg);
 
 	/* visit all visible nodes */
 	dfs(end, env);
 
 	/* visit the keep-alives */
-	n = get_End_n_keepalives(end);
-	for (i = 0; i < n; ++i) {
+	for (i = get_End_n_keepalives(end) - 1; i >= 0; --i) {
 		ir_node *ka = get_End_keepalive(end, i);
 
-		if (irn_not_visited(ka))
+		if (!irn_visited(ka))
 			dfs(ka, env);
 	}
 
-	current_ir_graph = rem;
-}
+	ir_free_resources(irg, IR_RESOURCE_IRN_VISITED);
+}  /* do_dfs */
 
 /**
  * Post-block-walker: assign the post-order number.
  */
-static void assign_po(ir_node *block, void *ctx) {
-	iv_env *env = ctx;
+static void assign_po(ir_node *block, void *ctx)
+{
+	iv_env *env = (iv_env*)ctx;
 	node_entry *e = get_irn_ne(block, env);
 
 	e->POnum = env->POnum++;
-}
-
-#if 0
-/**
- * Follows the LFTR edges and return the last node in the chain.
- *
- * @param irn  the node that should be followed
- * @param env  the IV environment
- *
- * @note
- * In the current implementation only the last edge is stored, so
- * only one chain exists. That's why we might miss some opportunities.
- */
-static ir_node *followEdges(ir_node *irn, iv_env *env) {
-	for (;;) {
-		LFTR_edge *e = LFTR_find(irn, env);
-		if (e)
-			irn = e->dst;
-		else
-			return irn;
-	}
-}
+}  /* assign_po */
 
 /**
  * Apply one LFTR edge operation.
  * Return NULL if the transformation cannot be done safely without
  * an Overflow.
  *
- * @param rc   the IV node that should be translated
+ * @param iv   the induction variable
+ * @param rc   the constant that should be translated
  * @param e    the LFTR edge
  * @param env  the IV environment
  *
@@ -861,13 +1108,26 @@ static ir_node *followEdges(ir_node *irn, iv_env *env) {
  * In the current implementation only the last edge is stored, so
  * only one chain exists. That's why we might miss some opportunities.
  */
-static ir_node *applyOneEdge(ir_node *rc, LFTR_edge *e, iv_env *env) {
-	if (env->flags & osr_flag_lftr_with_ov_check) {
-		tarval *tv_l, *tv_r, *tv;
+static ir_node *applyOneEdge(ir_node *iv, ir_node *rc, LFTR_edge *e, iv_env *env)
+{
+	if (env->osr_flags & osr_flag_lftr_with_ov_check) {
+		ir_tarval *tv_l, *tv_r, *tv, *tv_init, *tv_incr, *tv_end;
 		tarval_int_overflow_mode_t ovmode;
+		scc *pscc;
+		ir_graph *irg;
+
+		if (! is_counter_iv(iv, env)) {
+			DB((dbg, LEVEL_4, " not counter IV"));
+			return NULL;
+		}
 
 		/* overflow can only be decided for Consts */
 		if (! is_Const(e->rc)) {
+			if (e->code == iro_Add && mode_is_reference(get_irn_mode(e->rc))) {
+				/* However we allow ONE Pointer Add, as pointer arithmetic with wrap
+				   around is undefined anyway */
+				return do_apply(e->code, NULL, rc, e->rc, get_irn_mode(e->rc));
+			}
 			DB((dbg, LEVEL_4, " = UNKNOWN (%+F)", e->rc));
 			return NULL;
 		}
@@ -878,33 +1138,61 @@ static ir_node *applyOneEdge(ir_node *rc, LFTR_edge *e, iv_env *env) {
 		ovmode = tarval_get_integer_overflow_mode();
 		tarval_set_integer_overflow_mode(TV_OVERFLOW_BAD);
 
+		pscc    = get_iv_scc(iv, env);
+		tv_incr = pscc->incr;
+		tv_init = pscc->init;
+
+		/*
+		 * Check that no overflow occurs:
+		 * init must be transformed without overflow
+		 * the new rc must be transformed without overflow
+		 * rc +/- incr must be possible without overflow
+		 */
 		switch (e->code) {
 		case iro_Mul:
-			tv = tarval_mul(tv_l, tv_r);
+			tv      = tarval_mul(tv_l, tv_r);
+			tv_init = tarval_mul(tv_init, tv_r);
+			tv_incr = tarval_mul(tv_incr, tv_r);
 			DB((dbg, LEVEL_4, " * %+F", tv_r));
 			break;
 		case iro_Add:
-			tv = tarval_add(tv_l, tv_r);
+			tv      = tarval_add(tv_l, tv_r);
+			tv_init = tarval_add(tv_init, tv_r);
 			DB((dbg, LEVEL_4, " + %+F", tv_r));
 			break;
 		case iro_Sub:
-			tv = tarval_sub(tv_l, tv_r);
+			tv      = tarval_sub(tv_l, tv_r, NULL);
+			tv_init = tarval_sub(tv_init, tv_r, NULL);
 			DB((dbg, LEVEL_4, " - %+F", tv_r));
 			break;
 		default:
-			assert(0);
-			tv = tarval_bad;
+			panic("Unsupported opcode");
+		}
+
+		if (tv == tarval_bad || tv_init == tarval_bad) {
+			tarval_set_integer_overflow_mode(ovmode);
+			DB((dbg, LEVEL_4, " = OVERFLOW"));
+			return NULL;
+		}
+
+		if (pscc->code == iro_Add) {
+			tv_end = tarval_add(tv, tv_incr);
+		} else {
+			assert(pscc->code == iro_Sub);
+			tv_end = tarval_sub(tv, tv_incr, NULL);
 		}
+
 		tarval_set_integer_overflow_mode(ovmode);
 
-		if (tv == tarval_bad) {
+		if (tv_end == tarval_bad) {
 			DB((dbg, LEVEL_4, " = OVERFLOW"));
 			return NULL;
 		}
-		return new_r_Const(current_ir_graph, get_irn_n(rc, -1), get_tarval_mode(tv), tv);
+		irg = get_irn_irg(iv);
+		return new_r_Const(irg, tv);
 	}
-	return do_apply(e->code, NULL, rc, e->rc, get_irn_mode(rc));
-}
+	return do_apply(e->code, NULL, rc, e->rc, get_irn_mode(e->dst));
+}  /* applyOneEdge */
 
 /**
  * Applies the operations represented by the LFTR edges to a
@@ -912,18 +1200,23 @@ static ir_node *applyOneEdge(ir_node *rc, LFTR_edge *e, iv_env *env) {
  * Return NULL if the transformation cannot be done safely without
  * an Overflow.
  *
- * @param iv   the IV node that starts the LFTR edge chain
+ * @param pIV  points to the IV node that starts the LFTR edge chain
+ *             after translation points to the new IV
  * @param rc   the region constant that should be translated
  * @param env  the IV environment
  *
  * @return the translated region constant or NULL
  *         if the translation was not possible
  */
-static ir_node *applyEdges(ir_node *iv, ir_node *rc, iv_env *env) {
-	ir_node *irn = iv;
-
-	if (env->flags & osr_flag_lftr_with_ov_check) {
+static ir_node *applyEdges(ir_node **pIV, ir_node *rc, iv_env *env)
+{
+	ir_node *iv = *pIV;
+	if (env->osr_flags & osr_flag_lftr_with_ov_check) {
 		/* overflow can only be decided for Consts */
+		if (! is_counter_iv(iv, env)) {
+			DB((dbg, LEVEL_4, "not counter IV\n", rc));
+			return NULL;
+		}
 		if (! is_Const(rc)) {
 			DB((dbg, LEVEL_4, " = UNKNOWN (%+F)\n", rc));
 			return NULL;
@@ -931,30 +1224,31 @@ static ir_node *applyEdges(ir_node *iv, ir_node *rc, iv_env *env) {
 		DB((dbg, LEVEL_4, "%+F", get_Const_tarval(rc)));
 	}
 
-	for (irn = iv; rc;) {
-		LFTR_edge *e = LFTR_find(irn, env);
-		if (e) {
-			rc = applyOneEdge(rc, e, env);
-			irn = e->dst;
-		}
-		else
+	for (; rc;) {
+		LFTR_edge *e = LFTR_find(iv, env);
+		if (e != NULL) {
+			rc = applyOneEdge(iv, rc, e, env);
+			iv = e->dst;
+		} else
 			break;
 	}
 	DB((dbg, LEVEL_3, "\n"));
+	*pIV = iv;
 	return rc;
-}
+}  /* applyEdges */
 
 /**
  * Walker, finds Cmp(iv, rc) or Cmp(rc, iv)
  * and tries to optimize them.
  */
-static void do_lftr(ir_node *cmp, void *ctx) {
-	iv_env *env = ctx;
+static void do_lftr(ir_node *cmp, void *ctx)
+{
+	iv_env *env = (iv_env*)ctx;
 	ir_node *left, *right, *liv, *riv;
 	ir_node *iv, *rc;
 	ir_node *nleft = NULL, *nright = NULL;
 
-	if (get_irn_op(cmp) != op_Cmp)
+	if (!is_Cmp(cmp))
 		return;
 
 	left  = get_Cmp_left(cmp);
@@ -965,18 +1259,14 @@ static void do_lftr(ir_node *cmp, void *ctx) {
 	if (liv && is_rc(right, liv)) {
 		iv = left; rc = right;
 
-		nright = applyEdges(iv, rc, env);
-		if (nright && nright != rc) {
-			nleft = followEdges(iv, env);
-		}
+		nright = applyEdges(&iv, rc, env);
+		nleft  = iv;
 	}
 	else if (riv && is_rc(left, riv)) {
 		iv = right; rc = left;
 
-		nleft = applyEdges(iv, rc, env);
-		if (nleft && nleft != rc) {
-			nright = followEdges(iv, env);
-		}
+		nleft  = applyEdges(&iv, rc, env);
+		nright = iv;
 	}
 
 	if (nleft && nright) {
@@ -985,7 +1275,7 @@ static void do_lftr(ir_node *cmp, void *ctx) {
 		set_Cmp_right(cmp, nright);
 		++env->lftr_replaced;
 	}
-}
+}  /* do_lftr */
 
 /**
  * do linear function test replacement.
@@ -993,133 +1283,215 @@ static void do_lftr(ir_node *cmp, void *ctx) {
  * @param irg   the graph that should be optimized
  * @param env   the IV environment
  */
-static void lftr(ir_graph *irg, iv_env *env) {
+static void lftr(ir_graph *irg, iv_env *env)
+{
 	irg_walk_graph(irg, NULL, do_lftr, env);
-}
-#endif
+}  /* lftr */
 
-/**
- * Pre-walker: set all node links to NULL and fix the
- * block of Proj nodes.
- */
-static void clear_and_fix(ir_node *irn, void *env)
+/* Remove any Phi cycles with only one real input. */
+void remove_phi_cycles(ir_graph *irg)
 {
-	set_irn_link(irn, NULL);
-
-	if (is_Proj(irn)) {
-		ir_node *pred = get_Proj_pred(irn);
-		set_irn_n(irn, -1, get_irn_n(pred, -1));
-	}
-}
-
-/* Performs Operator Strength Reduction for the passed graph. */
-void opt_osr(ir_graph *irg, unsigned flags) {
-	iv_env   env;
-	ir_graph *rem;
-
-	if (! get_opt_strength_red()) {
-		/* only kill Phi cycles  */
-		remove_phi_cycles(irg);
-		return;
-	}
+	iv_env env;
 
-	rem = current_ir_graph;
-	current_ir_graph = irg;
+	assure_irg_properties(irg,
+		IR_GRAPH_PROPERTY_CONSISTENT_DOMINANCE
+		| IR_GRAPH_PROPERTY_CONSISTENT_OUTS
+		| IR_GRAPH_PROPERTY_CONSISTENT_OUT_EDGES);
 
-	FIRM_DBG_REGISTER(dbg, "firm.opt.osr");
+	FIRM_DBG_REGISTER(dbg, "firm.opt.remove_phi");
 
-	DB((dbg, LEVEL_1, "Doing Operator Strength Reduction for %+F\n", irg));
+	DB((dbg, LEVEL_1, "Doing Phi cycle removement for %+F\n", irg));
 
 	obstack_init(&env.obst);
 	env.stack         = NEW_ARR_F(ir_node *, 128);
 	env.tos           = 0;
 	env.nextDFSnum    = 0;
 	env.POnum         = 0;
-	env.quad_map      = new_set(quad_cmp, 64);
-	env.lftr_edges    = new_set(LFTR_cmp, 64);
+	env.quad_map      = NULL;
+	env.lftr_edges    = NULL;
 	env.replaced      = 0;
 	env.lftr_replaced = 0;
-	env.flags         = flags;
-	env.process_scc   = process_scc;
+	env.osr_flags     = 0;
+	env.need_postpass = 0;
+	env.process_scc   = process_phi_only_scc;
 
 	/* Clear all links and move Proj nodes into the
-	   the same block as it's predecessors.
-	   This can improve the placement of new nodes.
+	 * the same block as their predecessors.
+	 * This can improve the placement of new nodes.
 	 */
-	irg_walk_graph(irg, NULL, clear_and_fix, NULL);
-
-	/* we need dominance */
-	assure_doms(irg);
-	assure_irg_outs(irg);
+	irg_walk_graph(irg, NULL, firm_clear_link, NULL);
 
 	/* calculate the post order number for blocks. */
 	irg_out_block_walk(get_irg_start_block(irg), NULL, assign_po, &env);
 
 	/* calculate the SCC's and drive OSR. */
+	ir_reserve_resources(irg, IR_RESOURCE_IRN_LINK);
 	do_dfs(irg, &env);
+	ir_free_resources(irg, IR_RESOURCE_IRN_LINK);
 
 	if (env.replaced) {
-		/* try linear function test replacements */
-		//lftr(irg, &env);
-
-		set_irg_outs_inconsistent(irg);
-		DB((dbg, LEVEL_1, "Replacements: %u + %u (lftr)\n\n", env.replaced, env.lftr_replaced));
+		DB((dbg, LEVEL_1, "remove_phi_cycles: %u Cycles removed\n\n",
+		    env.replaced));
 	}
 
-	del_set(env.lftr_edges);
-	del_set(env.quad_map);
 	DEL_ARR_F(env.stack);
 	obstack_free(&env.obst, NULL);
 
-	current_ir_graph = rem;
+	confirm_irg_properties(irg, IR_GRAPH_PROPERTIES_CONTROL_FLOW);
 }
 
-/* Remove any Phi cycles with only one real input. */
-void remove_phi_cycles(ir_graph *irg) {
-	iv_env   env;
-	ir_graph *rem;
+ir_graph_pass_t *remove_phi_cycles_pass(const char *name)
+{
+	return def_graph_pass(name ? name : "remove_phi_cycles", remove_phi_cycles);
+}  /* remove_phi_cycles_pass */
 
-	rem = current_ir_graph;
-	current_ir_graph = irg;
+/**
+ * Post-walker: fix Add and Sub nodes that where results of I<->P conversions.
+ */
+static void fix_adds_and_subs(ir_node *irn, void *ctx)
+{
+	(void) ctx;
 
-	FIRM_DBG_REGISTER(dbg, "firm.opt.remove_phi");
+	if (is_Add(irn)) {
+		ir_mode *mode = get_irn_mode(irn);
 
-	DB((dbg, LEVEL_1, "Doing Phi cycle removement for %+F\n", irg));
+		if (mode_is_int(mode)) {
+			ir_node *pred;
+
+			pred = get_Add_left(irn);
+			if (get_irn_mode(pred) != mode) {
+				ir_node *block = get_nodes_block(pred);
+
+				pred = new_r_Conv(block, pred, mode);
+				set_Add_left(irn, pred);
+			}
+			pred = get_Add_right(irn);
+			if (get_irn_mode(pred) != mode) {
+				ir_node *block = get_nodes_block(pred);
+
+				pred = new_r_Conv(block, pred, mode);
+				set_Add_right(irn, pred);
+			}
+		}
+	} else if (is_Sub(irn)) {
+		ir_mode *mode = get_irn_mode(irn);
+
+		if (mode_is_int(mode)) {
+			ir_node *left   = get_Sub_left(irn);
+			ir_node *right  = get_Sub_right(irn);
+			ir_mode *l_mode = get_irn_mode(left);
+			ir_mode *r_mode = get_irn_mode(right);
+
+			if (mode_is_int(l_mode) && mode_is_int(r_mode)) {
+				if (l_mode != mode) {
+					ir_node *block = get_nodes_block(left);
+
+					left = new_r_Conv(block, left, mode);
+					set_Sub_left(irn, left);
+				}
+				if (r_mode != mode) {
+					ir_node *block = get_nodes_block(right);
+
+					right = new_r_Conv(block, right, mode);
+					set_Sub_right(irn, right);
+				}
+			}
+		} else if (mode_is_reference(mode)) {
+			ir_node *left   = get_Sub_left(irn);
+			ir_node *right  = get_Sub_right(irn);
+			ir_mode *l_mode = get_irn_mode(left);
+			ir_mode *r_mode = get_irn_mode(right);
+			if (mode_is_int(l_mode)) {
+				/* Usually, Sub(I*,P) is an error, hence the verifier rejects it.
+				 * However, it is correct in this case, so add Conv to make verifier happy. */
+				ir_node *block = get_nodes_block(right);
+				ir_node *lconv = new_r_Conv(block, left, r_mode);
+				assert(mode_is_reference(r_mode));
+				set_Sub_left(irn, lconv);
+			}
+		}
+	}
+}  /* fix_adds_and_subs */
+
+/* Performs Operator Strength Reduction for the passed graph. */
+void opt_osr(ir_graph *irg, unsigned flags)
+{
+	iv_env env;
+
+	FIRM_DBG_REGISTER(dbg, "firm.opt.osr");
+
+	assure_irg_properties(irg,
+		IR_GRAPH_PROPERTY_CONSISTENT_DOMINANCE
+		| IR_GRAPH_PROPERTY_CONSISTENT_OUTS
+		| IR_GRAPH_PROPERTY_CONSISTENT_OUT_EDGES);
+
+	DB((dbg, LEVEL_1, "Doing Operator Strength Reduction for %+F\n", irg));
 
 	obstack_init(&env.obst);
 	env.stack         = NEW_ARR_F(ir_node *, 128);
 	env.tos           = 0;
 	env.nextDFSnum    = 0;
 	env.POnum         = 0;
-	env.quad_map      = NULL;
-	env.lftr_edges    = NULL;
+	env.quad_map      = new_set(quad_cmp, 64);
+	env.lftr_edges    = new_set(LFTR_cmp, 64);
 	env.replaced      = 0;
 	env.lftr_replaced = 0;
-	env.flags         = 0;
-	env.process_scc   = process_phi_only_scc;
+	env.osr_flags     = flags;
+	env.need_postpass = 0;
+	env.process_scc   = process_scc;
 
 	/* Clear all links and move Proj nodes into the
-	   the same block as it's predecessors.
-	   This can improve the placement of new nodes.
+	 * the same block as its predecessors.
+	 * This can improve the placement of new nodes.
 	 */
-	irg_walk_graph(irg, NULL, clear_and_fix, NULL);
+	irg_walk_graph(irg, NULL, firm_clear_link, NULL);
 
-	/* we need dominance */
-	assure_irg_outs(irg);
-
-	/* calculate the post order number for blocks. */
-	irg_out_block_walk(get_irg_start_block(irg), NULL, assign_po, &env);
+	irg_block_edges_walk(get_irg_start_block(irg), NULL, assign_po, &env);
 
 	/* calculate the SCC's and drive OSR. */
+	ir_reserve_resources(irg, IR_RESOURCE_IRN_LINK);
 	do_dfs(irg, &env);
 
 	if (env.replaced) {
-		set_irg_outs_inconsistent(irg);
-                DB((dbg, LEVEL_1, "remove_phi_cycles: %u Cycles removed\n\n", env.replaced));
+		if (env.need_postpass)
+			irg_walk_graph(irg, NULL, fix_adds_and_subs, &env);
+
+		/* try linear function test replacements */
+		lftr(irg, &env);
+		(void)lftr;
+
+		DB((dbg, LEVEL_1, "Replacements: %u + %u (lftr)\n\n", env.replaced, env.lftr_replaced));
 	}
+	ir_free_resources(irg, IR_RESOURCE_IRN_LINK);
 
+	del_set(env.lftr_edges);
+	del_set(env.quad_map);
 	DEL_ARR_F(env.stack);
 	obstack_free(&env.obst, NULL);
 
-	current_ir_graph = rem;
+	confirm_irg_properties(irg, IR_GRAPH_PROPERTIES_NONE);
 }
+
+typedef struct pass_t {
+	ir_graph_pass_t pass;
+	unsigned        flags;
+} pass_t;
+
+/**
+* Wrapper for running opt_osr() as an ir_graph pass.
+*/
+static int pass_wrapper(ir_graph *irg, void *context)
+{
+	pass_t *pass = (pass_t*)context;
+	opt_osr(irg, pass->flags);
+	return 0;
+}  /* pass_wrapper */
+
+ir_graph_pass_t *opt_osr_pass(const char *name, unsigned flags)
+{
+	pass_t *pass = XMALLOCZ(pass_t);
+
+	pass->flags = flags;
+	return def_graph_pass_constructor(
+		&pass->pass, name ? name : "osr", pass_wrapper);
+}  /* opt_osr_pass */