[libfirm] / ir / be / ia32 / ia32_optimize.c

/*
 * Copyright (C) 1995-2008 University of Karlsruhe.  All right reserved.
 *
 * This file is part of libFirm.
 *
 * This file may be distributed and/or modified under the terms of the
 * GNU General Public License version 2 as published by the Free Software
 * Foundation and appearing in the file LICENSE.GPL included in the
 * packaging of this file.
 *
 * Licensees holding valid libFirm Professional Edition licenses may use
 * this file in accordance with the libFirm Commercial License.
 * Agreement provided with the Software.
 *
 * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
 * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE.
 */

/**
 * @file
 * @brief       Implements several optimizations for IA32.
 * @author      Matthias Braun, Christian Wuerdig
 * @version     $Id$
 */
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include "irnode.h"
#include "irprog_t.h"
#include "ircons.h"
#include "irtools.h"
#include "firm_types.h"
#include "iredges.h"
#include "tv.h"
#include "irgmod.h"
#include "irgwalk.h"
#include "height.h"
#include "irbitset.h"
#include "irprintf.h"
#include "error.h"

#include "../be_t.h"
#include "../beabi.h"
#include "../benode_t.h"
#include "../besched_t.h"
#include "../bepeephole.h"

#include "ia32_new_nodes.h"
#include "ia32_optimize.h"
#include "bearch_ia32_t.h"
#include "gen_ia32_regalloc_if.h"
#include "ia32_common_transform.h"
#include "ia32_transform.h"
#include "ia32_dbg_stat.h"
#include "ia32_util.h"
#include "ia32_architecture.h"

DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)

static const arch_env_t *arch_env;
static ia32_code_gen_t  *cg;

/**
 * Returns non-zero if the given node produces
 * a zero flag.
 *
 * @param node  the node to check
 * @param pn    if >= 0, the projection number of the used result
 */
static int produces_zero_flag(ir_node *node, int pn)
{
        ir_node                     *count;
        const ia32_immediate_attr_t *imm_attr;

        if (!is_ia32_irn(node))
                return 0;

        if (pn >= 0) {
                if (pn != pn_ia32_res)
                        return 0;
        }

        switch (get_ia32_irn_opcode(node)) {
        case iro_ia32_Add:
        case iro_ia32_Adc:
        case iro_ia32_And:
        case iro_ia32_Or:
        case iro_ia32_Xor:
        case iro_ia32_Sub:
        case iro_ia32_Sbb:
        case iro_ia32_Neg:
        case iro_ia32_Inc:
        case iro_ia32_Dec:
                return 1;

        case iro_ia32_ShlD:
        case iro_ia32_ShrD:
        case iro_ia32_Shl:
        case iro_ia32_Shr:
        case iro_ia32_Sar:
                assert(n_ia32_ShlD_count == n_ia32_ShrD_count);
                assert(n_ia32_Shl_count == n_ia32_Shr_count
                                && n_ia32_Shl_count == n_ia32_Sar_count);
                if (is_ia32_ShlD(node) || is_ia32_ShrD(node)) {
                        count = get_irn_n(node, n_ia32_ShlD_count);
                } else {
                        count = get_irn_n(node, n_ia32_Shl_count);
                }
                /* when shift count is zero the flags are not affected, so we can only
                 * do this for constants != 0 */
                if (!is_ia32_Immediate(count))
                        return 0;

                imm_attr = get_ia32_immediate_attr_const(count);
                if (imm_attr->symconst != NULL)
                        return 0;
                if ((imm_attr->offset & 0x1f) == 0)
                        return 0;
                return 1;

        default:
                break;
        }
        return 0;
}

/**
 * If the given node has not mode_T, creates a mode_T version (with a result Proj).
 *
 * @param node  the node to change
 *
 * @return the new mode_T node (if the mode was changed) or node itself
 */
static ir_node *turn_into_mode_t(ir_node *node)
{
        ir_node               *block;
        ir_node               *res_proj;
        ir_node               *new_node;
        const arch_register_t *reg;

        if(get_irn_mode(node) == mode_T)
                return node;

        assert(get_irn_mode(node) == mode_Iu);

        new_node = exact_copy(node);
        set_irn_mode(new_node, mode_T);

        block    = get_nodes_block(new_node);
        res_proj = new_r_Proj(current_ir_graph, block, new_node, mode_Iu,
                              pn_ia32_res);

        reg = arch_get_irn_register(arch_env, node);
        arch_set_irn_register(arch_env, res_proj, reg);

        sched_add_before(node, new_node);
        be_peephole_exchange(node, res_proj);
        return new_node;
}

/**
 * Peephole optimization for Test instructions.
 * We can remove the Test, if a zero flags was produced which is still
 * live.
 */
static void peephole_ia32_Test(ir_node *node)
{
        ir_node         *left  = get_irn_n(node, n_ia32_Test_left);
        ir_node         *right = get_irn_n(node, n_ia32_Test_right);
        ir_node         *flags_proj;
        ir_node         *block;
        ir_mode         *flags_mode;
        int              pn    = -1;
        ir_node         *schedpoint;
        const ir_edge_t *edge;

        assert(n_ia32_Test_left == n_ia32_Test8Bit_left
                        && n_ia32_Test_right == n_ia32_Test8Bit_right);

        /* we need a test for 0 */
        if(left != right)
                return;

        block = get_nodes_block(node);
        if(get_nodes_block(left) != block)
                return;

        if(is_Proj(left)) {
                pn   = get_Proj_proj(left);
                left = get_Proj_pred(left);
        }

        /* happens rarely, but if it does code will panic' */
        if (is_ia32_Unknown_GP(left))
                return;

        /* walk schedule up and abort when we find left or some other node destroys
           the flags */
        schedpoint = sched_prev(node);
        while(schedpoint != left) {
                schedpoint = sched_prev(schedpoint);
                if(arch_irn_is(arch_env, schedpoint, modify_flags))
                        return;
                if(schedpoint == block)
                        panic("couldn't find left");
        }

        /* make sure only Lg/Eq tests are used */
        foreach_out_edge(node, edge) {
                ir_node *user = get_edge_src_irn(edge);
                int      pnc  = get_ia32_condcode(user);

                if(pnc != pn_Cmp_Eq && pnc != pn_Cmp_Lg) {
                        return;
                }
        }

        if(!produces_zero_flag(left, pn))
                return;

        left = turn_into_mode_t(left);

        flags_mode = ia32_reg_classes[CLASS_ia32_flags].mode;
        flags_proj = new_r_Proj(current_ir_graph, block, left, flags_mode,
                                pn_ia32_flags);
        arch_set_irn_register(arch_env, flags_proj, &ia32_flags_regs[REG_EFLAGS]);

        assert(get_irn_mode(node) != mode_T);

        be_peephole_exchange(node, flags_proj);
}

/**
 * AMD Athlon works faster when RET is not destination of
 * conditional jump or directly preceded by other jump instruction.
 * Can be avoided by placing a Rep prefix before the return.
 */
static void peephole_ia32_Return(ir_node *node) {
        ir_node *block, *irn;

        if (!ia32_cg_config.use_pad_return)
                return;

        block = get_nodes_block(node);

        /* check if this return is the first on the block */
        sched_foreach_reverse_from(node, irn) {
                switch (get_irn_opcode(irn)) {
                case beo_Return:
                        /* the return node itself, ignore */
                        continue;
                case beo_Barrier:
                        /* ignore the barrier, no code generated */
                        continue;
                case beo_IncSP:
                        /* arg, IncSP 0 nodes might occur, ignore these */
                        if (be_get_IncSP_offset(irn) == 0)
                                continue;
                        return;
                case iro_Phi:
                        continue;
                default:
                        return;
                }
        }

        /* ensure, that the 3 byte return is generated
         * actually the emitter tests again if the block beginning has a label and
         * isn't just a fallthrough */
        be_Return_set_emit_pop(node, 1);
}

/* only optimize up to 48 stores behind IncSPs */
#define MAXPUSH_OPTIMIZE        48

/**
 * Tries to create Push's from IncSP, Store combinations.
 * The Stores are replaced by Push's, the IncSP is modified
 * (possibly into IncSP 0, but not removed).
 */
static void peephole_IncSP_Store_to_push(ir_node *irn)
{
        int      i, maxslot, inc_ofs;
        ir_node  *node;
        ir_node  *stores[MAXPUSH_OPTIMIZE];
        ir_node  *block;
        ir_graph *irg;
        ir_node  *curr_sp;
        ir_mode  *spmode;

        memset(stores, 0, sizeof(stores));

        assert(be_is_IncSP(irn));

        inc_ofs = be_get_IncSP_offset(irn);
        if (inc_ofs < 4)
                return;

        /*
         * We first walk the schedule after the IncSP node as long as we find
         * suitable Stores that could be transformed to a Push.
         * We save them into the stores array which is sorted by the frame offset/4
         * attached to the node
         */
        maxslot = -1;
        for (node = sched_next(irn); !sched_is_end(node); node = sched_next(node)) {
                ir_node *mem;
                int offset;
                int storeslot;

                /* it has to be a Store */
                if (!is_ia32_Store(node))
                        break;

                /* it has to use our sp value */
                if (get_irn_n(node, n_ia32_base) != irn)
                        continue;
                /* Store has to be attached to NoMem */
                mem = get_irn_n(node, n_ia32_mem);
                if (!is_NoMem(mem))
                        continue;

                /* unfortunately we can't support the full AMs possible for push at the
                 * moment. TODO: fix this */
                if (get_ia32_am_scale(node) > 0 || !is_ia32_NoReg_GP(get_irn_n(node, n_ia32_index)))
                        break;

                offset = get_ia32_am_offs_int(node);
                /* we should NEVER access uninitialized stack BELOW the current SP */
                assert(offset >= 0);

                offset = inc_ofs - 4 - offset;

                /* storing at half-slots is bad */
                if ((offset & 3) != 0)
                        break;

                if (offset < 0 || offset >= MAXPUSH_OPTIMIZE * 4)
                        continue;
                storeslot = offset >> 2;

                /* storing into the same slot twice is bad (and shouldn't happen...) */
                if (stores[storeslot] != NULL)
                        break;

                stores[storeslot] = node;
                if (storeslot > maxslot)
                        maxslot = storeslot;
        }

        curr_sp = be_get_IncSP_pred(irn);

        /* walk through the Stores and create Pushs for them */
        block  = get_nodes_block(irn);
        spmode = get_irn_mode(irn);
        irg    = cg->irg;
        for (i = 0; i <= maxslot; ++i) {
                const arch_register_t *spreg;
                ir_node *push;
                ir_node *val, *mem, *mem_proj;
                ir_node *store = stores[i];
                ir_node *noreg = ia32_new_NoReg_gp(cg);

                if (store == NULL)
                        break;

                val = get_irn_n(store, n_ia32_unary_op);
                mem = get_irn_n(store, n_ia32_mem);
                spreg = arch_get_irn_register(cg->arch_env, curr_sp);

                push = new_rd_ia32_Push(get_irn_dbg_info(store), irg, block, noreg, noreg, mem, val, curr_sp);

                sched_add_before(irn, push);

                /* create stackpointer Proj */
                curr_sp = new_r_Proj(irg, block, push, spmode, pn_ia32_Push_stack);
                arch_set_irn_register(cg->arch_env, curr_sp, spreg);

                /* create memory Proj */
                mem_proj = new_r_Proj(irg, block, push, mode_M, pn_ia32_Push_M);

                /* use the memproj now */
                be_peephole_exchange(store, mem_proj);

                inc_ofs -= 4;
        }

        be_set_IncSP_offset(irn, inc_ofs);
        be_set_IncSP_pred(irn, curr_sp);
}

/**
 * Return true if a mode can be stored in the GP register set
 */
static INLINE int mode_needs_gp_reg(ir_mode *mode) {
        if (mode == mode_fpcw)
                return 0;
        if (get_mode_size_bits(mode) > 32)
                return 0;
        return mode_is_int(mode) || mode_is_reference(mode) || mode == mode_b;
}

/**
 * Tries to create Pops from Load, IncSP combinations.
 * The Loads are replaced by Pops, the IncSP is modified
 * (possibly into IncSP 0, but not removed).
 */
static void peephole_Load_IncSP_to_pop(ir_node *irn)
{
        const arch_register_t *esp = &ia32_gp_regs[REG_ESP];
        int      i, maxslot, inc_ofs, ofs;
        ir_node  *node, *pred_sp, *block;
        ir_node  *loads[MAXPUSH_OPTIMIZE];
        ir_graph *irg;
        unsigned regmask = 0;
        unsigned copymask = ~0;

        memset(loads, 0, sizeof(loads));
        assert(be_is_IncSP(irn));

        inc_ofs = -be_get_IncSP_offset(irn);
        if (inc_ofs < 4)
                return;

        /*
         * We first walk the schedule before the IncSP node as long as we find
         * suitable Loads that could be transformed to a Pop.
         * We save them into the stores array which is sorted by the frame offset/4
         * attached to the node
         */
        maxslot = -1;
        pred_sp = be_get_IncSP_pred(irn);
        for (node = sched_prev(irn); !sched_is_end(node); node = sched_prev(node)) {
                ir_node *mem;
                int offset;
                int loadslot;
                const arch_register_t *sreg, *dreg;

                /* it has to be a Load */
                if (!is_ia32_Load(node)) {
                        if (be_is_Copy(node)) {
                                if (!mode_needs_gp_reg(get_irn_mode(node))) {
                                        /* not a GP copy, ignore */
                                        continue;
                                }
                                dreg = arch_get_irn_register(arch_env, node);
                                sreg = arch_get_irn_register(arch_env, be_get_Copy_op(node));
                                if (regmask & copymask & (1 << sreg->index)) {
                                        break;
                                }
                                if (regmask & copymask & (1 << dreg->index)) {
                                        break;
                                }
                                /* we CAN skip Copies if neither the destination nor the source
                                 * is not in our regmask, ie none of our future Pop will overwrite it */
                                regmask |= (1 << dreg->index) | (1 << sreg->index);
                                copymask &= ~((1 << dreg->index) | (1 << sreg->index));
                                continue;
                        }
                        break;
                }

                /* we can handle only GP loads */
                if (!mode_needs_gp_reg(get_ia32_ls_mode(node)))
                        continue;

                /* it has to use our predecessor sp value */
                if (get_irn_n(node, n_ia32_base) != pred_sp) {
                        /* it would be ok if this load does not use a Pop result,
                         * but we do not check this */
                        break;
                }
                /* Load has to be attached to Spill-Mem */
                mem = skip_Proj(get_irn_n(node, n_ia32_mem));
                if (!is_Phi(mem) && !is_ia32_Store(mem) && !is_ia32_Push(mem))
                        break;

                /* should have NO index */
                if (get_ia32_am_scale(node) > 0 || !is_ia32_NoReg_GP(get_irn_n(node, n_ia32_index)))
                        break;

                offset = get_ia32_am_offs_int(node);
                /* we should NEVER access uninitialized stack BELOW the current SP */
                assert(offset >= 0);

                /* storing at half-slots is bad */
                if ((offset & 3) != 0)
                        break;

                if (offset < 0 || offset >= MAXPUSH_OPTIMIZE * 4)
                        continue;
                /* ignore those outside the possible windows */
                if (offset > inc_ofs - 4)
                        continue;
                loadslot = offset >> 2;

                /* loading from the same slot twice is bad (and shouldn't happen...) */
                if (loads[loadslot] != NULL)
                        break;

                dreg = arch_get_irn_register(arch_env, node);
                if (regmask & (1 << dreg->index)) {
                        /* this register is already used */
                        break;
                }
                regmask |= 1 << dreg->index;

                loads[loadslot] = node;
                if (loadslot > maxslot)
                        maxslot = loadslot;
        }

        if (maxslot < 0)
                return;

        /* find the first slot */
        for (i = maxslot; i >= 0; --i) {
                ir_node *load = loads[i];

                if (load == NULL)
                        break;
        }

        ofs = inc_ofs - (maxslot + 1) * 4;
        inc_ofs = (i+1) * 4;

        /* create a new IncSP if needed */
        block = get_nodes_block(irn);
        irg   = cg->irg;
        if (inc_ofs > 0) {
                pred_sp = be_new_IncSP(esp, irg, block, pred_sp, -inc_ofs, be_get_IncSP_align(irn));
                sched_add_before(irn, pred_sp);
        }

        /* walk through the Loads and create Pops for them */
        for (++i; i <= maxslot; ++i) {
                ir_node *load = loads[i];
                ir_node *mem, *pop;
                const ir_edge_t *edge, *tmp;
                const arch_register_t *reg;

                mem = get_irn_n(load, n_ia32_mem);
                reg = arch_get_irn_register(arch_env, load);

                pop = new_rd_ia32_Pop(get_irn_dbg_info(load), irg, block, mem, pred_sp);
                arch_set_irn_register(arch_env, pop, reg);

                /* create stackpointer Proj */
                pred_sp = new_r_Proj(irg, block, pop, mode_Iu, pn_ia32_Pop_stack);
                arch_set_irn_register(arch_env, pred_sp, esp);

                sched_add_before(irn, pop);

                /* rewire now */
                foreach_out_edge_safe(load, edge, tmp) {
                        ir_node *proj = get_edge_src_irn(edge);

                        set_Proj_pred(proj, pop);
                }

                /* we can remove the Load now */
                sched_remove(load);
                kill_node(load);
        }

        be_set_IncSP_offset(irn, -ofs);
        be_set_IncSP_pred(irn, pred_sp);
}


/**
 * Find a free GP register if possible, else return NULL.
 */
static const arch_register_t *get_free_gp_reg(void)
{
        int i;

        for(i = 0; i < N_ia32_gp_REGS; ++i) {
                const arch_register_t *reg = &ia32_gp_regs[i];
                if(arch_register_type_is(reg, ignore))
                        continue;

                if(be_peephole_get_value(CLASS_ia32_gp, i) == NULL)
                        return &ia32_gp_regs[i];
        }

        return NULL;
}

/**
 * Creates a Pop instruction before the given schedule point.
 *
 * @param dbgi        debug info
 * @param irg         the graph
 * @param block       the block
 * @param stack       the previous stack value
 * @param schedpoint  the new node is added before this node
 * @param reg         the register to pop
 *
 * @return the new stack value
 */
static ir_node *create_pop(dbg_info *dbgi, ir_graph *irg, ir_node *block,
                           ir_node *stack, ir_node *schedpoint,
                           const arch_register_t *reg)
{
        const arch_register_t *esp = &ia32_gp_regs[REG_ESP];
        ir_node *pop;
        ir_node *keep;
        ir_node *val;
        ir_node *in[1];

        pop   = new_rd_ia32_Pop(dbgi, irg, block, new_NoMem(), stack);

        stack = new_r_Proj(irg, block, pop, mode_Iu, pn_ia32_Pop_stack);
        arch_set_irn_register(arch_env, stack, esp);
        val   = new_r_Proj(irg, block, pop, mode_Iu, pn_ia32_Pop_res);
        arch_set_irn_register(arch_env, val, reg);

        sched_add_before(schedpoint, pop);

        in[0] = val;
        keep = be_new_Keep(&ia32_reg_classes[CLASS_ia32_gp], irg, block, 1, in);
        sched_add_before(schedpoint, keep);

        return stack;
}

/**
 * Creates a Push instruction before the given schedule point.
 *
 * @param dbgi        debug info
 * @param irg         the graph
 * @param block       the block
 * @param stack       the previous stack value
 * @param schedpoint  the new node is added before this node
 * @param reg         the register to pop
 *
 * @return the new stack value
 */
static ir_node *create_push(dbg_info *dbgi, ir_graph *irg, ir_node *block,
                            ir_node *stack, ir_node *schedpoint)
{
        const arch_register_t *esp = &ia32_gp_regs[REG_ESP];

        ir_node *val   = ia32_new_Unknown_gp(cg);
        ir_node *noreg = ia32_new_NoReg_gp(cg);
        ir_node *nomem = get_irg_no_mem(irg);
        ir_node *push  = new_rd_ia32_Push(dbgi, irg, block, noreg, noreg, nomem, val, stack);
        sched_add_before(schedpoint, push);

        stack = new_r_Proj(irg, block, push, mode_Iu, pn_ia32_Push_stack);
        arch_set_irn_register(arch_env, stack, esp);

        return stack;
}

/**
 * Optimize an IncSp by replacing it with Push/Pop.
 */
static void peephole_be_IncSP(ir_node *node)
{
        const arch_register_t *esp = &ia32_gp_regs[REG_ESP];
        const arch_register_t *reg;
        ir_graph              *irg = current_ir_graph;
        dbg_info              *dbgi;
        ir_node               *block;
        ir_node               *stack;
        int                    offset;

        /* first optimize incsp->incsp combinations */
        node = be_peephole_IncSP_IncSP(node);

        /* transform IncSP->Store combinations to Push where possible */
        peephole_IncSP_Store_to_push(node);

        /* transform Load->IncSP combinations to Pop where possible */
        peephole_Load_IncSP_to_pop(node);

        if (arch_get_irn_register(arch_env, node) != esp)
                return;

        /* replace IncSP -4 by Pop freereg when possible */
        offset = be_get_IncSP_offset(node);
        if ((offset != -8 || ia32_cg_config.use_add_esp_8) &&
            (offset != -4 || ia32_cg_config.use_add_esp_4) &&
            (offset != +4 || ia32_cg_config.use_sub_esp_4) &&
            (offset != +8 || ia32_cg_config.use_sub_esp_8))
                return;

        if (offset < 0) {
                /* we need a free register for pop */
                reg = get_free_gp_reg();
                if (reg == NULL)
                        return;

                dbgi  = get_irn_dbg_info(node);
                block = get_nodes_block(node);
                stack = be_get_IncSP_pred(node);

                stack = create_pop(dbgi, irg, block, stack, node, reg);

                if (offset == -8) {
                        stack = create_pop(dbgi, irg, block, stack, node, reg);
                }
        } else {
                dbgi  = get_irn_dbg_info(node);
                block = get_nodes_block(node);
                stack = be_get_IncSP_pred(node);
                stack = create_push(dbgi, irg, block, stack, node);

                if (offset == +8) {
                        stack = create_push(dbgi, irg, block, stack, node);
                }
        }

        be_peephole_exchange(node, stack);
}

/**
 * Peephole optimisation for ia32_Const's
 */
static void peephole_ia32_Const(ir_node *node)
{
        const ia32_immediate_attr_t *attr = get_ia32_immediate_attr_const(node);
        const arch_register_t       *reg;
        ir_graph                    *irg = current_ir_graph;
        ir_node                     *block;
        dbg_info                    *dbgi;
        ir_node                     *produceval;
        ir_node                     *xor;
        ir_node                     *noreg;

        /* try to transform a mov 0, reg to xor reg reg */
        if (attr->offset != 0 || attr->symconst != NULL)
                return;
        if (ia32_cg_config.use_mov_0)
                return;
        /* xor destroys the flags, so no-one must be using them */
        if (be_peephole_get_value(CLASS_ia32_flags, REG_EFLAGS) != NULL)
                return;

        reg = arch_get_irn_register(arch_env, node);
        assert(be_peephole_get_reg_value(reg) == NULL);

        /* create xor(produceval, produceval) */
        block      = get_nodes_block(node);
        dbgi       = get_irn_dbg_info(node);
        produceval = new_rd_ia32_ProduceVal(dbgi, irg, block);
        arch_set_irn_register(arch_env, produceval, reg);

        noreg = ia32_new_NoReg_gp(cg);
        xor   = new_rd_ia32_Xor(dbgi, irg, block, noreg, noreg, new_NoMem(),
                                produceval, produceval);
        arch_set_irn_register(arch_env, xor, reg);

        sched_add_before(node, produceval);
        sched_add_before(node, xor);

        be_peephole_exchange(node, xor);
}

static INLINE int is_noreg(ia32_code_gen_t *cg, const ir_node *node)
{
        return node == cg->noreg_gp;
}

static ir_node *create_immediate_from_int(ia32_code_gen_t *cg, int val)
{
        ir_graph *irg         = current_ir_graph;
        ir_node  *start_block = get_irg_start_block(irg);
        ir_node  *immediate   = new_rd_ia32_Immediate(NULL, irg, start_block, NULL,
                                                      0, val);
        arch_set_irn_register(cg->arch_env, immediate, &ia32_gp_regs[REG_GP_NOREG]);

        return immediate;
}

static ir_node *create_immediate_from_am(ia32_code_gen_t *cg,
                                         const ir_node *node)
{
        ir_graph  *irg     = get_irn_irg(node);
        ir_node   *block   = get_nodes_block(node);
        int        offset  = get_ia32_am_offs_int(node);
        int        sc_sign = is_ia32_am_sc_sign(node);
        ir_entity *entity  = get_ia32_am_sc(node);
        ir_node   *res;

        res = new_rd_ia32_Immediate(NULL, irg, block, entity, sc_sign, offset);
        arch_set_irn_register(cg->arch_env, res, &ia32_gp_regs[REG_GP_NOREG]);
        return res;
}

static int is_am_one(const ir_node *node)
{
        int        offset  = get_ia32_am_offs_int(node);
        ir_entity *entity  = get_ia32_am_sc(node);

        return offset == 1 && entity == NULL;
}

static int is_am_minus_one(const ir_node *node)
{
        int        offset  = get_ia32_am_offs_int(node);
        ir_entity *entity  = get_ia32_am_sc(node);

        return offset == -1 && entity == NULL;
}

/**
 * Transforms a LEA into an Add or SHL if possible.
 */
static void peephole_ia32_Lea(ir_node *node)
{
        const arch_env_t      *arch_env = cg->arch_env;
        ir_graph              *irg      = current_ir_graph;
        ir_node               *base;
        ir_node               *index;
        const arch_register_t *base_reg;
        const arch_register_t *index_reg;
        const arch_register_t *out_reg;
        int                    scale;
        int                    has_immediates;
        ir_node               *op1;
        ir_node               *op2;
        dbg_info              *dbgi;
        ir_node               *block;
        ir_node               *res;
        ir_node               *noreg;
        ir_node               *nomem;

        assert(is_ia32_Lea(node));

        /* we can only do this if are allowed to globber the flags */
        if(be_peephole_get_value(CLASS_ia32_flags, REG_EFLAGS) != NULL)
                return;

        base  = get_irn_n(node, n_ia32_Lea_base);
        index = get_irn_n(node, n_ia32_Lea_index);

        if(is_noreg(cg, base)) {
                base     = NULL;
                base_reg = NULL;
        } else {
                base_reg = arch_get_irn_register(arch_env, base);
        }
        if(is_noreg(cg, index)) {
                index     = NULL;
                index_reg = NULL;
        } else {
                index_reg = arch_get_irn_register(arch_env, index);
        }

        if(base == NULL && index == NULL) {
                /* we shouldn't construct these in the first place... */
#ifdef DEBUG_libfirm
                ir_fprintf(stderr, "Optimisation warning: found immediate only lea\n");
#endif
                return;
        }

        out_reg = arch_get_irn_register(arch_env, node);
        scale   = get_ia32_am_scale(node);
        assert(!is_ia32_need_stackent(node) || get_ia32_frame_ent(node) != NULL);
        /* check if we have immediates values (frame entities should already be
         * expressed in the offsets) */
        if(get_ia32_am_offs_int(node) != 0 || get_ia32_am_sc(node) != NULL) {
                has_immediates = 1;
        } else {
                has_immediates = 0;
        }

        /* we can transform leas where the out register is the same as either the
         * base or index register back to an Add or Shl */
        if(out_reg == base_reg) {
                if(index == NULL) {
#ifdef DEBUG_libfirm
                        if(!has_immediates) {
                                ir_fprintf(stderr, "Optimisation warning: found lea which is "
                                           "just a copy\n");
                        }
#endif
                        op1 = base;
                        goto make_add_immediate;
                }
                if(scale == 0 && !has_immediates) {
                        op1 = base;
                        op2 = index;
                        goto make_add;
                }
                /* can't create an add */
                return;
        } else if(out_reg == index_reg) {
                if(base == NULL) {
                        if(has_immediates && scale == 0) {
                                op1 = index;
                                goto make_add_immediate;
                        } else if(!has_immediates && scale > 0) {
                                op1 = index;
                                op2 = create_immediate_from_int(cg, scale);
                                goto make_shl;
                        } else if(!has_immediates) {
#ifdef DEBUG_libfirm
                                ir_fprintf(stderr, "Optimisation warning: found lea which is "
                                           "just a copy\n");
#endif
                        }
                } else if(scale == 0 && !has_immediates) {
                        op1 = index;
                        op2 = base;
                        goto make_add;
                }
                /* can't create an add */
                return;
        } else {
                /* can't create an add */
                return;
        }

make_add_immediate:
        if(ia32_cg_config.use_incdec) {
                if(is_am_one(node)) {
                        dbgi  = get_irn_dbg_info(node);
                        block = get_nodes_block(node);
                        res   = new_rd_ia32_Inc(dbgi, irg, block, op1);
                        arch_set_irn_register(arch_env, res, out_reg);
                        goto exchange;
                }
                if(is_am_minus_one(node)) {
                        dbgi  = get_irn_dbg_info(node);
                        block = get_nodes_block(node);
                        res   = new_rd_ia32_Dec(dbgi, irg, block, op1);
                        arch_set_irn_register(arch_env, res, out_reg);
                        goto exchange;
                }
        }
        op2 = create_immediate_from_am(cg, node);

make_add:
        dbgi  = get_irn_dbg_info(node);
        block = get_nodes_block(node);
        noreg = ia32_new_NoReg_gp(cg);
        nomem = new_NoMem();
        res   = new_rd_ia32_Add(dbgi, irg, block, noreg, noreg, nomem, op1, op2);
        arch_set_irn_register(arch_env, res, out_reg);
        set_ia32_commutative(res);
        goto exchange;

make_shl:
        dbgi  = get_irn_dbg_info(node);
        block = get_nodes_block(node);
        noreg = ia32_new_NoReg_gp(cg);
        nomem = new_NoMem();
        res   = new_rd_ia32_Shl(dbgi, irg, block, op1, op2);
        arch_set_irn_register(arch_env, res, out_reg);
        goto exchange;

exchange:
        SET_IA32_ORIG_NODE(res, ia32_get_old_node_name(cg, node));

        /* add new ADD/SHL to schedule */
        DBG_OPT_LEA2ADD(node, res);

        /* exchange the Add and the LEA */
        sched_add_before(node, res);
        be_peephole_exchange(node, res);
}

/**
 * Split a Imul mem, imm into a Load mem and Imul reg, imm if possible.
 */
static void peephole_ia32_Imul_split(ir_node *imul) {
        const ir_node         *right = get_irn_n(imul, n_ia32_IMul_right);
        const arch_register_t *reg;
        ir_node               *load, *block, *base, *index, *mem, *res, *noreg;
        dbg_info              *dbgi;
        ir_graph              *irg;

        if (! is_ia32_Immediate(right) || get_ia32_op_type(imul) != ia32_AddrModeS) {
                /* no memory, imm form ignore */
                return;
        }
        /* we need a free register */
        reg = get_free_gp_reg();
        if (reg == NULL)
                return;

        /* fine, we can rebuild it */
        dbgi  = get_irn_dbg_info(imul);
        block = get_nodes_block(imul);
        irg   = current_ir_graph;
        base  = get_irn_n(imul, n_ia32_IMul_base);
        index = get_irn_n(imul, n_ia32_IMul_index);
        mem   = get_irn_n(imul, n_ia32_IMul_mem);
        load = new_rd_ia32_Load(dbgi, irg, block, base, index, mem);

        /* copy all attributes */
        set_irn_pinned(load, get_irn_pinned(imul));
        set_ia32_op_type(load, ia32_AddrModeS);
        set_ia32_ls_mode(load, get_ia32_ls_mode(imul));

        set_ia32_am_scale(load, get_ia32_am_scale(imul));
        set_ia32_am_sc(load, get_ia32_am_sc(imul));
        set_ia32_am_offs_int(load, get_ia32_am_offs_int(imul));
        if (is_ia32_am_sc_sign(imul))
                set_ia32_am_sc_sign(load);
        if (is_ia32_use_frame(imul))
                set_ia32_use_frame(load);
        set_ia32_frame_ent(load, get_ia32_frame_ent(imul));

        sched_add_before(imul, load);

        mem = new_rd_Proj(dbgi, irg, block, load, mode_M, pn_ia32_Load_M);
        res = new_rd_Proj(dbgi, irg, block, load, mode_Iu, pn_ia32_Load_res);

        arch_set_irn_register(arch_env, res, reg);
        be_peephole_new_node(res);

        set_irn_n(imul, n_ia32_IMul_mem, mem);
        noreg = get_irn_n(imul, n_ia32_IMul_left);
        set_irn_n(imul, n_ia32_IMul_left, res);
        set_ia32_op_type(imul, ia32_Normal);
}

/**
 * Replace xorps r,r and xorpd r,r by pxor r,r
 */
static void peephole_ia32_xZero(ir_node *xor) {
        set_irn_op(xor, op_ia32_xPzero);
}

/**
 * Register a peephole optimisation function.
 */
static void register_peephole_optimisation(ir_op *op, peephole_opt_func func) {
        assert(op->ops.generic == NULL);
        op->ops.generic = (op_func)func;
}

/* Perform peephole-optimizations. */
void ia32_peephole_optimization(ia32_code_gen_t *new_cg)
{
        cg       = new_cg;
        arch_env = cg->arch_env;

        /* register peephole optimisations */
        clear_irp_opcodes_generic_func();
        register_peephole_optimisation(op_ia32_Const, peephole_ia32_Const);
        register_peephole_optimisation(op_be_IncSP, peephole_be_IncSP);
        register_peephole_optimisation(op_ia32_Lea, peephole_ia32_Lea);
        register_peephole_optimisation(op_ia32_Test, peephole_ia32_Test);
        register_peephole_optimisation(op_ia32_Test8Bit, peephole_ia32_Test);
        register_peephole_optimisation(op_be_Return, peephole_ia32_Return);
        if (! ia32_cg_config.use_imul_mem_imm32)
                register_peephole_optimisation(op_ia32_IMul, peephole_ia32_Imul_split);
        if (ia32_cg_config.use_pxor)
                register_peephole_optimisation(op_ia32_xZero, peephole_ia32_xZero);

        be_peephole_opt(cg->birg);
}

/**
 * Removes node from schedule if it is not used anymore. If irn is a mode_T node
 * all it's Projs are removed as well.
 * @param irn  The irn to be removed from schedule
 */
static INLINE void try_kill(ir_node *node)
{
        if(get_irn_mode(node) == mode_T) {
                const ir_edge_t *edge, *next;
                foreach_out_edge_safe(node, edge, next) {
                        ir_node *proj = get_edge_src_irn(edge);
                        try_kill(proj);
                }
        }

        if(get_irn_n_edges(node) != 0)
                return;

        if (sched_is_scheduled(node)) {
                sched_remove(node);
        }

        kill_node(node);
}

static void optimize_conv_store(ir_node *node)
{
        ir_node *pred;
        ir_node *pred_proj;
        ir_mode *conv_mode;
        ir_mode *store_mode;

        if(!is_ia32_Store(node) && !is_ia32_Store8Bit(node))
                return;

        assert(n_ia32_Store_val == n_ia32_Store8Bit_val);
        pred_proj = get_irn_n(node, n_ia32_Store_val);
        if(is_Proj(pred_proj)) {
                pred = get_Proj_pred(pred_proj);
        } else {
                pred = pred_proj;
        }
        if(!is_ia32_Conv_I2I(pred) && !is_ia32_Conv_I2I8Bit(pred))
                return;
        if(get_ia32_op_type(pred) != ia32_Normal)
                return;

        /* the store only stores the lower bits, so we only need the conv
         * it it shrinks the mode */
        conv_mode  = get_ia32_ls_mode(pred);
        store_mode = get_ia32_ls_mode(node);
        if(get_mode_size_bits(conv_mode) < get_mode_size_bits(store_mode))
                return;

        set_irn_n(node, n_ia32_Store_val, get_irn_n(pred, n_ia32_Conv_I2I_val));
        if(get_irn_n_edges(pred_proj) == 0) {
                kill_node(pred_proj);
                if(pred != pred_proj)
                        kill_node(pred);
        }
}

static void optimize_load_conv(ir_node *node)
{
        ir_node *pred, *predpred;
        ir_mode *load_mode;
        ir_mode *conv_mode;

        if (!is_ia32_Conv_I2I(node) && !is_ia32_Conv_I2I8Bit(node))
                return;

        assert(n_ia32_Conv_I2I_val == n_ia32_Conv_I2I8Bit_val);
        pred = get_irn_n(node, n_ia32_Conv_I2I_val);
        if(!is_Proj(pred))
                return;

        predpred = get_Proj_pred(pred);
        if(!is_ia32_Load(predpred))
                return;

        /* the load is sign extending the upper bits, so we only need the conv
         * if it shrinks the mode */
        load_mode = get_ia32_ls_mode(predpred);
        conv_mode = get_ia32_ls_mode(node);
        if(get_mode_size_bits(conv_mode) < get_mode_size_bits(load_mode))
                return;

        if(get_mode_sign(conv_mode) != get_mode_sign(load_mode)) {
                /* change the load if it has only 1 user */
                if(get_irn_n_edges(pred) == 1) {
                        ir_mode *newmode;
                        if(get_mode_sign(conv_mode)) {
                                newmode = find_signed_mode(load_mode);
                        } else {
                                newmode = find_unsigned_mode(load_mode);
                        }
                        assert(newmode != NULL);
                        set_ia32_ls_mode(predpred, newmode);
                } else {
                        /* otherwise we have to keep the conv */
                        return;
                }
        }

        /* kill the conv */
        exchange(node, pred);
}

static void optimize_conv_conv(ir_node *node)
{
        ir_node *pred_proj, *pred, *result_conv;
        ir_mode *pred_mode, *conv_mode;
        int      conv_mode_bits;
        int      pred_mode_bits;

        if (!is_ia32_Conv_I2I(node) && !is_ia32_Conv_I2I8Bit(node))
                return;

        assert(n_ia32_Conv_I2I_val == n_ia32_Conv_I2I8Bit_val);
        pred_proj = get_irn_n(node, n_ia32_Conv_I2I_val);
        if(is_Proj(pred_proj))
                pred = get_Proj_pred(pred_proj);
        else
                pred = pred_proj;

        if(!is_ia32_Conv_I2I(pred) && !is_ia32_Conv_I2I8Bit(pred))
                return;

        /* we know that after a conv, the upper bits are sign extended
         * so we only need the 2nd conv if it shrinks the mode */
        conv_mode      = get_ia32_ls_mode(node);
        conv_mode_bits = get_mode_size_bits(conv_mode);
        pred_mode      = get_ia32_ls_mode(pred);
        pred_mode_bits = get_mode_size_bits(pred_mode);

        if(conv_mode_bits == pred_mode_bits
                        && get_mode_sign(conv_mode) == get_mode_sign(pred_mode)) {
                result_conv = pred_proj;
        } else if(conv_mode_bits <= pred_mode_bits) {
                /* if 2nd conv is smaller then first conv, then we can always take the
                 * 2nd conv */
                if(get_irn_n_edges(pred_proj) == 1) {
                        result_conv = pred_proj;
                        set_ia32_ls_mode(pred, conv_mode);

                        /* Argh:We must change the opcode to 8bit AND copy the register constraints */
                        if (get_mode_size_bits(conv_mode) == 8) {
                                set_irn_op(pred, op_ia32_Conv_I2I8Bit);
                                set_ia32_in_req_all(pred, get_ia32_in_req_all(node));
                        }
                } else {
                        /* we don't want to end up with 2 loads, so we better do nothing */
                        if(get_irn_mode(pred) == mode_T) {
                                return;
                        }

                        result_conv = exact_copy(pred);
                        set_ia32_ls_mode(result_conv, conv_mode);

                        /* Argh:We must change the opcode to 8bit AND copy the register constraints */
                        if (get_mode_size_bits(conv_mode) == 8) {
                                set_irn_op(result_conv, op_ia32_Conv_I2I8Bit);
                                set_ia32_in_req_all(result_conv, get_ia32_in_req_all(node));
                        }
                }
        } else {
                /* if both convs have the same sign, then we can take the smaller one */
                if(get_mode_sign(conv_mode) == get_mode_sign(pred_mode)) {
                        result_conv = pred_proj;
                } else {
                        /* no optimisation possible if smaller conv is sign-extend */
                        if(mode_is_signed(pred_mode)) {
                                return;
                        }
                        /* we can take the smaller conv if it is unsigned */
                        result_conv = pred_proj;
                }
        }

        /* kill the conv */
        exchange(node, result_conv);

        if(get_irn_n_edges(pred_proj) == 0) {
                kill_node(pred_proj);
                if(pred != pred_proj)
                        kill_node(pred);
        }
        optimize_conv_conv(result_conv);
}

static void optimize_node(ir_node *node, void *env)
{
        (void) env;

        optimize_load_conv(node);
        optimize_conv_store(node);
        optimize_conv_conv(node);
}

/**
 * Performs conv and address mode optimization.
 */
void ia32_optimize_graph(ia32_code_gen_t *cg)
{
        irg_walk_blkwise_graph(cg->irg, NULL, optimize_node, cg);

        if (cg->dump)
                be_dump(cg->irg, "-opt", dump_ir_block_graph_sched);
}

void ia32_init_optimize(void)
{
        FIRM_DBG_REGISTER(dbg, "firm.be.ia32.optimize");
}