move load mode shrinking into ldst phase
[libfirm] / ir / opt / opt_osr.c
index d739746..275ee2e 100644 (file)
@@ -1,51 +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.
- * Purpose:     Operator Strength Reduction,
- *              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.
- */
-#ifdef HAVE_CONFIG_H
+ * @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.
+ */
 #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;)
 
-/* Use the link field to mark IV's */
-#define MARK_LOOP_IV(loop)   set_loop_link((loop), (loop))
-#define UNMARK_LOOP_IV(loop) set_loop_link((loop), NULL)
-#define IS_LOOP_IV(loop)     (get_loop_link(loop) != NULL)
-
 /** A scc. */
 typedef struct scc {
-       ir_node *head;          /**< the head of the list */
-       ir_node *header;        /**< the header block of this scc */
-       int     is_iv;      /**< true, if this scc is an IV */
+       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 */
@@ -61,54 +77,609 @@ typedef struct node_entry {
 
 /** The environment. */
 typedef struct iv_env {
-       node_entry *entries;   /**< the node entry array */
-       struct obstack obst;   /**< an obstack for allocations */
-       ir_node  **stack;      /**< the node stack */
-       int      tos;          /**< tos index */
-       unsigned nextDFSnum;   /**< the current DFS number */
-       unsigned replaced;     /**< number of replaced ops */
-       unsigned POnum;        /**< current post order number */
+       struct obstack obst;    /**< an obstack for allocations */
+       ir_node  **stack;       /**< the node stack */
+       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 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;
 
 /**
- * Check if irn is an IV.
+ * An entry in the (op, node, node) -> node map.
  */
-static scc *is_iv(ir_node *irn, iv_env *env) {
-       int idx = get_irn_idx(irn);
-       node_entry *e = &env->entries[idx];
+typedef struct quadruple_t {
+       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 */
 
-       return e->pscc && e->pscc->is_iv ? e->pscc : NULL;
-}
+       ir_node   *res; /**< the reduced operation */
+} quadruple_t;
+
+/**
+ * A LFTR edge.
+ */
+typedef struct LFTR_edge {
+       ir_node   *src;   /**< the source node */
+       ir_node   *dst;   /**< the destination node */
+       unsigned  code;   /**< the opcode that must be applied */
+       ir_node   *rc;    /**< the region const that must be applied */
+} LFTR_edge;
+
+/* forward */
+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 = (const LFTR_edge*)e1;
+       const LFTR_edge *l2 = (const LFTR_edge*)e2;
+       (void) size;
+
+       return l1->src != l2->src;
+}  /* LFTR_cmp */
+
+/**
+ * Find a LFTR edge.
+ *
+ * @param src  the source node of the transition
+ */
+static LFTR_edge *LFTR_find(ir_node *src, iv_env *env)
+{
+       LFTR_edge key;
+
+       key.src  = src;
+
+       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, unsigned code, ir_node *rc, iv_env *env)
+{
+       LFTR_edge key;
+
+       key.src  = src;
+       key.dst  = dst;
+       key.code = code;
+       key.rc   = rc;
+
+       /*
+        * There might be more than one edge here. This is rather bad
+        * because we currently store only one.
+        */
+       (void)set_insert(LFTR_edge, env->lftr_edges, &key, sizeof(key), hash_ptr(src));
+}  /* LFTR_add */
+
+/**
+ * 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 = (node_entry*)get_irn_link(irn);
+
+       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.
+ *
+ * @param irn  the node to check
+ * @param env  the environment
+ *
+ * @returns the header if it is one, NULL else
+ */
+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.
+ * The block or irn must strictly dominate the header block.
+ *
+ * @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_dominates(block, header_block);
-}
+       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 = (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.
+ *
+ * @param code  the opcode of the operation
+ * @param op1   the first operand of the operation
+ * @param op2   the second operand of the operation
+ * @param env   the environment
+ *
+ * @return the already reduced node or NULL if this operation is not yet reduced
+ */
+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(quadruple_t, env->quad_map, &key, sizeof(key), (code * 9) ^ hash_ptr(op1) ^ hash_ptr(op2));
+       if (entry)
+               return entry->res;
+       return NULL;
+}  /* search */
 
 /**
- * Do the replacement operation.
+ * Add an reduced operation.
+ *
+ * @param code    the opcode of the operation
+ * @param op1     the first operand of the operation
+ * @param op2     the second operand of the operation
+ * @param result  the result of the reduced operation
+ * @param env     the environment
+ */
+static void add(unsigned code, ir_node *op1, ir_node *op2, ir_node *result, iv_env *env)
+{
+       quadruple_t key;
+
+       key.code = code;
+       key.op1  = op1;
+       key.op2  = op2;
+       key.res  = result;
+
+       (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
+ * block1 and block2.
+ *
+ * @param block1  the block of the first operand
+ * @param block2  the block of the second operand
+ *
+ * Note that we know here that such a place must exists. Moreover, this means
+ * 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)
+{
+       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.
+ *
+ * @param code   the opcode to execute
+ * @param db     debug info to add to the new node
+ * @param op1    the first operand
+ * @param op2    the second operand
+ * @param mode   the mode of the new operation
+ *
+ * @return the newly created node
+ */
+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, block, op1, op2, mode);
+               break;
+       case iro_Add:
+               result = new_rd_Add(db, block, op1, op2, mode);
+               break;
+       case iro_Sub:
+               result = new_rd_Sub(db, block, op1, op2, mode);
+               break;
+       default:
+               panic("Unsupported opcode");
+       }
+       return result;
+}  /* do_apply */
+
+/**
+ * The Apply operation.
+ *
+ * @param orig   the node that represent the original operation and determines
+ *               the opcode, debug-info and mode of a newly created one
+ * @param op1    the first operand
+ * @param op2    the second operand
+ * @param env    the environment
+ *
+ * @return the newly created node
+ */
+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 == 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 == header && is_rc(op2, op1_header)) {
+                       result = reduce(orig, op1, op2, env);
+               }
+               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;
+               }
+       }
+       return result;
+}  /* apply */
+
+/**
+ * The Reduce operation.
+ *
+ * @param orig   the node that represent the original operation and determines
+ *               the opcode, debug-info and mode of a newly created one
+ * @param iv     the induction variable
+ * @param rc     the region constant
+ * @param env    the environment
+ *
+ * @return the reduced node
+ */
+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);
+
+       /* check if we have already done this operation on the iv */
+       if (result == NULL) {
+               node_entry *e, *iv_e;
+               int i;
+               ir_mode *mode = get_irn_mode(orig);
+
+               result = exact_copy(iv);
+
+               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));
+
+               iv_e = get_irn_ne(iv, env);
+               e    = get_irn_ne(result, env);
+               e->header = iv_e->header;
+
+               /* create the LFTR edge */
+               LFTR_add(iv, result, code, rc, env);
+
+               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) || code == iro_Mul)
+                               o = apply(iv_e->header, orig, o, rc, env);
+                       set_irn_n(result, i, o);
+               }
+       } else {
+               DB((dbg, LEVEL_3, "   Already Created %+F for %+F (%s %+F)\n", result, iv,
+                       get_irn_opname(orig), rc));
+       }
+       return result;
+}  /* reduce */
+
+/**
+ * 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 void 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;
+
        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 node can be replaced
+ * check if a given node is a mul with 2, 4, 8
  */
-static void check_replace(ir_node *irn, iv_env *env) {
-       ir_node *left, *right, *iv, *rc;
-       ir_op   *op  = get_irn_op(irn);
-       opcode  code = get_op_code(op);
-       scc     *liv, *riv;
+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 (+, -, *).
+ *
+ * @param irn   the node to check
+ * @param env   the environment
+ *
+ * @return non-zero if irn should be Replace'd
+ */
+static int check_replace(ir_node *irn, iv_env *env)
+{
+       ir_node   *left, *right, *iv, *rc;
+       ir_op     *op  = get_irn_op(irn);
+       unsigned  code = get_op_code(op);
+       ir_node   *liv, *riv;
 
        switch (code) {
        case iro_Mul:
@@ -121,37 +692,48 @@ static void check_replace(ir_node *irn, iv_env *env) {
 
                liv = is_iv(left, env);
                riv = is_iv(right, env);
-               if (liv && is_rc(right, liv->header)) {
+               if (liv && is_rc(right, liv)) {
                        iv = left; rc = right;
                }
-               else if (is_op_commutative(op) &&
-                       riv && is_rc(left, riv->header)) {
+               else if (riv && is_op_commutative(op) &&
+                                   is_rc(left, riv)) {
                        iv = right; rc = left;
                }
 
                if (iv) {
-                       replace(irn, iv, rc, env);
-                       ++env->replaced;
+                       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;
+       default:
+               break;
        }
-}
+       return 0;
+}  /* check_replace */
 
 /**
- * check which SCC's are induction variables
+ * Check which SCC's are induction variables.
+ *
+ * @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 *h, *b;
-       int j;
+       node_entry *b, *h = NULL;
+       int j, only_phi, num_outside;
+       ir_node *out_rc;
 
        /* 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;
-               b = &env->entries[get_irn_idx(block)];
+               b = get_irn_ne(block, env);
 
                if (header) {
                        if (h->POnum < b->POnum) {
@@ -164,19 +746,42 @@ static void classify_iv(scc *pscc, iv_env *env) {
                        h      = b;
                }
        }
-       pscc->header = header;
 
+       /* check if this scc contains only Phi, Add or Sub nodes */
+       only_phi    = 1;
+       num_outside = 0;
+       out_rc      = NULL;
        for (irn = pscc->head; irn; irn = next) {
-               node_entry *e = get_irn_link(irn);
+               node_entry *e = get_irn_ne(irn, 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:
                        for (j = get_irn_arity(irn) - 1; j >= 0; --j) {
-                               ir_node *pred = get_irn_n(irn, j);
-                               node_entry *pe = &env->entries[get_irn_idx(pred)];
+                               ir_node *pred  = get_irn_n(irn, j);
+                               node_entry *pe = get_irn_ne(pred, env);
 
                                if (pe->pscc != e->pscc) {
                                        /* not in the same SCC, must be a region const */
@@ -184,6 +789,12 @@ static void classify_iv(scc *pscc, iv_env *env) {
                                                /* not an induction variable */
                                                goto fail;
                                        }
+                                       if (! out_rc) {
+                                               out_rc = pred;
+                                               ++num_outside;
+                                       } else if (out_rc != pred) {
+                                               ++num_outside;
+                                       }
                                }
                        }
                        break;
@@ -193,128 +804,199 @@ static void classify_iv(scc *pscc, iv_env *env) {
                }
        }
        /* found an induction variable */
-       DB((dbg, LEVEL_2, "  Found an induction variable in %+F\n", pscc->head));
-       pscc->is_iv = 1;
+       DB((dbg, LEVEL_2, "  Found an induction variable:\n  "));
+       if (only_phi && num_outside == 1) {
+               /* a phi cycle with only one real predecessor can be collapsed */
+               DB((dbg, LEVEL_2, "  Found an USELESS Phi cycle:\n  "));
+
+               for (irn = pscc->head; irn; irn = next) {
+                       node_entry *e = get_irn_ne(irn, env);
+                       next = e->next;
+                       e->header = NULL;
+                       exchange(irn, out_rc);
+               }
+               ++env->replaced;
+               return;
+       }
+
+       /* set the header for every node in this scc */
+       for (irn = pscc->head; irn; irn = next) {
+               node_entry *e = get_irn_ne(irn, env);
+               e->header = header;
+               next = e->next;
+               DB((dbg, LEVEL_2, " %+F,", irn));
+       }
+       DB((dbg, LEVEL_2, "\n"));
        return;
 
 fail:
        for (irn = pscc->head; irn; irn = next) {
-               node_entry *e = get_irn_link(irn);
+               node_entry *e = get_irn_ne(irn, env);
 
                next = e->next;
-               check_replace(irn, env);
+               e->header = NULL;
        }
-}
+}  /* classify_iv */
 
 /**
- * Do the replacement: We must do this as an additional step because
- * of our loop-tree structure.
+ * Process an SCC for the operator strength reduction.
+ *
+ * @param pscc  the SCC
+ * @param env   the environment
  */
-static void find_replacement(ir_loop *loop, iv_env *env) {
-       int i, n;
+static void process_scc(scc *pscc, iv_env *env)
+{
+       ir_node *head = pscc->head;
+       node_entry *e = (node_entry*)get_irn_link(head);
 
-       if (! IS_LOOP_IV(loop)) {
-               /* do replacements */
-               n = get_loop_n_nodes(loop);
-               for (i = 0; i < n; ++i) {
-                       ir_node *irn = get_loop_node(loop, i);
-                       ir_node *left, *right, *iv, *rc;
-                       opcode code = get_irn_opcode(irn);
+#ifdef DEBUG_libfirm
+       {
+               ir_node *irn, *next;
 
-                       switch (code) {
-                       case iro_Mul:
-                       case iro_Add:
-                       case iro_Sub:
-                               iv = rc = NULL;
+               DB((dbg, LEVEL_4, " SCC at %p:\n ", pscc));
+               for (irn = pscc->head; irn != NULL; irn = next) {
+                       node_entry *e = (node_entry*)get_irn_link(irn);
 
-                               left  = get_binop_left(irn);
-                               right = get_binop_right(irn);
+                       next = e->next;
 
-                               if (is_iv(left, env) && is_rc(right, left)) {
-                                       iv = left; rc = right;
-                               }
-                               else if (code != iro_Sub &&
-                                       is_iv(right, env) && is_rc(left, right)) {
-                                       iv = right; rc = left;
-                               }
+                       DB((dbg, LEVEL_4, " %+F,", irn));
+               }
+               DB((dbg, LEVEL_4, "\n"));
+       }
+#endif
+
+       if (e->next == NULL) {
+               /* this SCC has only a single member */
+               check_replace(head, 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)
+{
+       ir_node *irn, *next;
+       int j;
+       ir_node *out_rc;
+
+       /* 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);
 
-                               if (iv) {
-                                       replace(irn, iv, rc, env);
-                                       ++env->replaced;
+               next = e->next;
+               if (! is_Phi(irn))
+                       return;
+
+               for (j = get_irn_arity(irn) - 1; j >= 0; --j) {
+                       ir_node *pred  = get_irn_n(irn, j);
+                       node_entry *pe = get_irn_ne(pred, env);
+
+                       if (pe->pscc != e->pscc) {
+                               /* not in the same SCC, must be the only input */
+                               if (! out_rc) {
+                                       out_rc = pred;
+                               } else if (out_rc != pred) {
+                                       return;
                                }
-                               break;
                        }
                }
        }
-       n = get_loop_n_sons(loop);
-       for (i = 0; i < n; ++i) {
-               ir_loop *child = get_loop_son(loop, i);
-               find_replacement(child, env);
+       /* found a Phi cycle */
+       DB((dbg, LEVEL_2, "  Found an USELESS Phi cycle:\n  "));
+
+       for (irn = pscc->head; irn; irn = next) {
+               node_entry *e = get_irn_ne(irn, env);
+               next = e->next;
+               e->header = NULL;
+               exchange(irn, out_rc);
        }
-}
+       ++env->replaced;
+}  /* remove_phi_cycle */
 
 /**
- * Process a SCC given as a list.
+ * Process a SCC for the Phi cycle remove.
+ *
+ * @param pscc  the SCC
+ * @param env   the environment
  */
-static void process_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);
-
-       pscc->is_iv = 0;
+       node_entry *e = (node_entry*)get_irn_link(head);
 
 #ifdef DEBUG_libfirm
        {
                ir_node *irn, *next;
 
-               DB((dbg, LEVEL_3, " SCC at %p:\n ", pscc));
+               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;
 
-                       DB((dbg, LEVEL_3, " %+F,", irn));
+                       DB((dbg, LEVEL_4, " %+F,", irn));
                }
-               DB((dbg, LEVEL_3, "\n"));
+               DB((dbg, LEVEL_4, "\n"));
        }
 #endif
 
-       if (e->next == NULL) {
-               /* this SCC has only a single member */
-               check_replace(head, env);
-       }
-       else {
-               classify_iv(pscc, env);
-       }
-}
+       if (e->next != NULL)
+               remove_phi_cycle(pscc, env);
+}  /* process_phi_only_scc */
+
 
 /**
  * Push a node onto the stack.
+ *
+ * @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;
-       env->entries[get_irn_idx(n)].in_stack = 1;
-}
+       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
  *
  * @return  The topmost node
  */
 static ir_node *pop(iv_env *env)
 {
-  ir_node *n = env->stack[--env->tos];
-  env->entries[get_irn_idx(n)].in_stack = 0;
-  return n;
-}
+       ir_node *n = env->stack[--env->tos];
+       node_entry *e = get_irn_ne(n, env);
+
+       e->in_stack = 0;
+       return n;
+}  /* pop */
 
+/**
+ * Do Tarjan's SCC algorithm and drive OSR.
+ *
+ * @param irn  start at this node
+ * @param env  the environment
+ */
 static void dfs(ir_node *irn, iv_env *env)
 {
        int i, n;
-       node_entry *node = &env->entries[get_irn_idx(irn)];
+       node_entry *node = get_irn_ne(irn, env);
 
        mark_irn_visited(irn);
 
@@ -324,11 +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++;
@@ -336,15 +1017,15 @@ 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);
                for (i = 0; i < n; ++i) {
                        ir_node *pred = get_irn_n(irn, i);
-                       node_entry *o = &env->entries[get_irn_idx(pred)];
+                       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);
                        }
@@ -352,100 +1033,465 @@ 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;
 
                                x = pop(env);
-                               e = &env->entries[get_irn_idx(x)];
+                               e = get_irn_ne(x, env);
                                e->pscc    = pscc;
                                e->next    = pscc->head;
                                pscc->head = x;
-
-                               /* link the node entry for easier access */
-                               set_irn_link(x, e);
                        } while (x != irn);
 
-                       process_scc(pscc, env);
+                       env->process_scc(pscc, env);
                }
        }
-}
+}  /* dfs */
 
 /**
- * Do the DFS by starting end the End node
+ * Do the DFS by starting at the End node of a graph.
+ *
+ * @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;
-       int idx = get_irn_idx(block);
+static void assign_po(ir_node *block, void *ctx)
+{
+       iv_env *env = (iv_env*)ctx;
+       node_entry *e = get_irn_ne(block, env);
 
-       env->entries[idx].POnum = env->POnum++;
-}
+       e->POnum = env->POnum++;
+}  /* assign_po */
 
-/* Performs Operator Strength Reduction for the passed graph. */
-void opt_osr(ir_graph *irg) {
-       iv_env env;
+/**
+ * Apply one LFTR edge operation.
+ * Return NULL if the transformation cannot be done safely without
+ * an Overflow.
+ *
+ * @param iv   the induction variable
+ * @param rc   the constant that should be translated
+ * @param e    the LFTR edge
+ * @param env  the IV environment
+ *
+ * @return the translated region constant or NULL
+ *         if the translation was not possible
+ *
+ * @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 *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;
+               }
+
+               tv_l = get_Const_tarval(rc);
+               tv_r = get_Const_tarval(e->rc);
+
+               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_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_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, NULL);
+                       tv_init = tarval_sub(tv_init, tv_r, NULL);
+                       DB((dbg, LEVEL_4, " - %+F", tv_r));
+                       break;
+               default:
+                       panic("Unsupported opcode");
+               }
 
-       if (! get_opt_strength_red())
+               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_end == tarval_bad) {
+                       DB((dbg, LEVEL_4, " = OVERFLOW"));
+                       return NULL;
+               }
+               irg = get_irn_irg(iv);
+               return new_r_Const(irg, tv);
+       }
+       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
+ * region constant and returns the value.
+ * Return NULL if the transformation cannot be done safely without
+ * an Overflow.
+ *
+ * @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 **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;
+               }
+               DB((dbg, LEVEL_4, "%+F", get_Const_tarval(rc)));
+       }
+
+       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 = (iv_env*)ctx;
+       ir_node *left, *right, *liv, *riv;
+       ir_node *iv, *rc;
+       ir_node *nleft = NULL, *nright = NULL;
+
+       if (!is_Cmp(cmp))
                return;
 
-       FIRM_DBG_REGISTER(dbg, "firm.opt.osr");
-       firm_dbg_set_mask(dbg, SET_LEVEL_2);
+       left  = get_Cmp_left(cmp);
+       right = get_Cmp_right(cmp);
 
-       /* and dominance as well */
-       assure_doms(irg);
+       liv = is_iv(left, env);
+       riv = is_iv(right, env);
+       if (liv && is_rc(right, liv)) {
+               iv = left; rc = right;
 
-       DB((dbg, LEVEL_1, "Doing Operator Strength Reduction for %+F\n", irg));
+               nright = applyEdges(&iv, rc, env);
+               nleft  = iv;
+       }
+       else if (riv && is_rc(left, riv)) {
+               iv = right; rc = left;
+
+               nleft  = applyEdges(&iv, rc, env);
+               nright = iv;
+       }
+
+       if (nleft && nright) {
+               DB((dbg, LEVEL_2, "  LFTR for %+F\n", cmp));
+               set_Cmp_left(cmp, nleft);
+               set_Cmp_right(cmp, nright);
+               ++env->lftr_replaced;
+       }
+}  /* do_lftr */
+
+/**
+ * do linear function test replacement.
+ *
+ * @param irg   the graph that should be optimized
+ * @param env   the IV environment
+ */
+static void lftr(ir_graph *irg, iv_env *env)
+{
+       irg_walk_graph(irg, NULL, do_lftr, env);
+}  /* lftr */
+
+/* Remove any Phi cycles with only one real input. */
+void remove_phi_cycles(ir_graph *irg)
+{
+       iv_env env;
 
-       env.entries    = NEW_ARR_F(node_entry, get_irg_last_idx(irg));
-       memset(env.entries, 0, get_irg_last_idx(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.remove_phi");
+
+       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.replaced   = 0;
-       env.POnum      = 0;
+       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.replaced      = 0;
+       env.lftr_replaced = 0;
+       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 their predecessors.
+        * This can improve the placement of new nodes.
+        */
+       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);
 
-       /* calculate the post order number */
-       irg_block_walk_graph(irg, NULL, assign_po, &env);
+       if (env.replaced) {
+               DB((dbg, LEVEL_1, "remove_phi_cycles: %u Cycles removed\n\n",
+                   env.replaced));
+       }
 
+       DEL_ARR_F(env.stack);
+       obstack_free(&env.obst, NULL);
+
+       confirm_irg_properties(irg, IR_GRAPH_PROPERTIES_CONTROL_FLOW);
+}
+
+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 */
+
+/**
+ * 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;
+
+       if (is_Add(irn)) {
+               ir_mode *mode = get_irn_mode(irn);
+
+               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      = new_set(quad_cmp, 64);
+       env.lftr_edges    = new_set(LFTR_cmp, 64);
+       env.replaced      = 0;
+       env.lftr_replaced = 0;
+       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 its predecessors.
+        * This can improve the placement of new nodes.
+        */
+       irg_walk_graph(irg, NULL, firm_clear_link, NULL);
+
+       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);
-               set_irg_loopinfo_inconsistent(irg);
+               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));
        }
-       DB((dbg, LEVEL_1, "Replacements: %u\n\n", env.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);
-       DEL_ARR_F(env.entries);
+
+       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 */