[libfirm] / ir / opt / proc_cloning.c

/*
 * Project:     libFIRM
 * File name:   ir/opt/proc_cloning.c
 * Purpose:     procedure cloning
 * Author:      Beyhan Veliev
 * Created:
 * CVS-ID:      $Id$
 * Copyright:   (c) 1998-2005 Universität Karlsruhe
 * Licence:     This file protected by GPL -  GNU GENERAL PUBLIC LICENSE.
 */

/**
 * @file proc_cloning.c
 *
 * The purpose is first to find and analyze functions, that are called
 * with constant parameter(s).
 * The second step is to optimize the function that are found from our
 * analyze. Optimize mean to make a new function with parameters, that
 * aren't be constant. The constant parameters of the function are placed
 * in the function graph. They aren't be passed as parameters.
 *
 */
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#ifdef HAVE_MALLOC_H
#include <malloc.h>
#endif
#ifdef HAVE_ALLOCA_H
#include <alloca.h>
#endif
#ifdef HAVE_STRING_H
#include <string.h>
#endif

#include "tv.h"
#include "set.h"
#include "entity.h"
#include "irprog_t.h"
#include "hashptr.h"
#include "irgwalk.h"
#include "proc_cloning.h"
#include "analyze_irg_args.h"
#include "irprintf.h"
#include "ircons.h"
#include "irouts.h"
#include "mangle.h"
#include "irnode_t.h"
#include "irtools.h"
#include "irgmod.h"
#include "array.h"

/* A macro to iterate sets.*/
#define ITERATE_SET(set_entries, entry) for(entry = set_first(set_entries); entry; entry = set_next(set_entries))

/**
 * This struct contains the information quadruple for a Call, which we need to
 * decide if this function must be cloned.
 */
typedef struct quadruple {
  entity          *ent;     /**< The entity of our Call. */
  int             pos;      /**< Position of a constant argument of our Call. */
  tarval          *tv;      /**< The tarval of this argument if Const node. */
  ir_node         **calls;  /**< The list of all calls with the same characteristics */
} quad_t;

/**
 * The quadruplets are hold in a sorted list
 */
typedef struct entry {
  quad_t       q;      /**< the quadruple */
  float        weight; /**< its weight */
  struct entry *next;  /**< link to the next one */
} entry_t;

typedef struct q_set {
  struct obstack obst;        /**< an obstack containing all entries */
  pset           *map;        /**< a hash map containing the quadruples */
  entry_t        *heavy_uses; /**< the ordered list of heavy uses */
} q_set;

/**
 * Compare two quadruplets.
 *
 * @return zero if they are identically, non-zero else
 */
static int entry_cmp(const void *elt, const void *key)
{
  const entry_t *e1 = elt;
  const entry_t *e2 = key;

  return (e1->q.ent != e2->q.ent) || (e1->q.pos != e2->q.pos) || (e1->q.tv != e2->q.tv);
}

/**
 * Hash an element of type entry_t.
 *
 * @param entry  The element to be hashed.
 */
static int hash_entry(const entry_t *entry)
{
  return HASH_PTR(entry->q.ent) ^ HASH_PTR(entry->q.tv) ^ (entry->q.pos * 9);
}

/**
 * Free memory associated with a quadruplet.
 */
static void kill_entry(entry_t *entry) {
  if (entry->q.calls) {
    DEL_ARR_F(entry->q.calls);
    entry->q.calls = NULL;
  }
}

/**
 * Process a call node.
 *
 * @param call    A ir_node to be checked.
 * @param callee  The entity of the callee
 * @param hmap    The quadruple-set containing the calls with constant parameters
 */
static void process_call(ir_node *call, entity *callee, q_set *hmap)
{
  ir_type *mtp;
  entry_t *key, *entry;
  ir_node *call_param;
  int i, n_params;

  n_params = get_Call_n_params(call);

  /* Beware: we cannot clone variadic parameters as well as the
   * last non-variadic one, which might be needed for the va_start()
   * magic
   */
  mtp = get_Call_type(call);
  if (get_method_variadicity(mtp) != variadicity_non_variadic) {
    n_params = get_method_first_variadic_param_index(mtp) - 1;
  }

  /* In this for loop we collect the calls, that have
     an constant parameter. */
  for (i = n_params - 1; i >= 0; --i) {
    call_param = get_Call_param(call, i);
    if (is_Const(call_param)) {
      /* we have found a Call to collect and we save the informations,
         which we need.*/
      if (! hmap->map)
        hmap->map = new_pset(entry_cmp, 8);

      key = obstack_alloc(&hmap->obst, sizeof(*key));

      key->q.ent   = callee;
      key->q.pos   = i;
      key->q.tv    = get_Const_tarval(call_param);
      key->q.calls = NULL;
      key->weight  = 0.0F;
      key->next    = NULL;

      /* We insert our information in the set, where we collect the calls.*/
      entry = pset_insert(hmap->map, key, hash_entry(key));

      if (entry != key)
        obstack_free(&hmap->obst, key);

      /* add the call to the list */
      if (! entry->q.calls) {
        entry->q.calls = NEW_ARR_F(ir_node *, 1);
        entry->q.calls[0] = call;
      }
      else
        ARR_APP1(ir_node *, entry->q.calls, call);
    }
  }
}

/**
 * Collect all calls in a ir_graph to a set.
 *
 * @param call   A ir_node to be checked.
 * @param env   The quadruple-set containing the calls with constant parameters
 */
static void collect_irg_calls(ir_node *call, void *env)
{
  q_set *hmap = env;
  ir_node *call_ptr;
  entity *callee;

  /* We collect just "Call" nodes */
  if (is_Call(call)) {
    call_ptr = get_Call_ptr(call);

    /* Call pointer must be a SymConst*/
    if (op_SymConst != get_irn_op(call_ptr))
      return;
    /* Call pointer must be the address of an entity.*/
    if (get_SymConst_kind(call_ptr) != symconst_addr_ent)
      return;

    callee = get_SymConst_entity(call_ptr);

    /* we can only clone calls to existing entities */
    if (get_entity_visibility(callee) == visibility_external_allocated)
      return;

    process_call(call, callee, hmap);
  }
}

/**
 * Make a name for a clone. The clone name is
 * the name of the original method suffixed with "_cl_pos_nr".
 * pos is the pos from our quadruplet and nr is a counter.
 *
 * @param id  The ident of the cloned function.
 * @param pos The "pos" from our quadruplet.
 * @param nr  A counter for the clones.
 */
static ident *get_clone_ident(ident *id, int pos, unsigned nr)
{
  char clone_postfix[32];

  snprintf(clone_postfix, sizeof(clone_postfix), "_cl_%d_%u", pos, nr);

  return mangle(id, new_id_from_str(clone_postfix));
}

/**
 * Pre-Walker: Copies blocks and nodes from the original method graph
 * to the cloned graph. Fixes the argument projection numbers for
 * all arguments behind the removed one.
 *
 * @param irn  A node from the original method graph.
 * @param env  The clone graph.
 */
static void copy_nodes(ir_node *irn, void *env)
{
  ir_node *arg, *irg_args, *irn_copy;
  int proj_nr;
  ir_graph *clone_irg = env;

  arg      = get_irg_link(clone_irg);
  irg_args = get_Proj_pred(arg);

  /* Copy all nodes except the arg. */
  if (irn != arg)
    copy_irn_to_irg(irn, clone_irg);

  irn_copy = get_irn_link(irn);

  /* Fix argument numbers */
  if (is_Proj(irn) && get_Proj_pred(irn) == irg_args) {
    proj_nr = get_Proj_proj(irn);
    if (get_Proj_proj(arg) < proj_nr)
      set_Proj_proj(irn_copy, proj_nr - 1);
  }
}

/**
 * Post-walker: Set the predecessors of the copied nodes.
 * The copied nodes are set as link of their original nodes. The links of
 * "irn" predecessors are the predecessors of copied node.
 */
static void set_preds(ir_node *irn, void *env)
{
  int i;
  ir_node *irn_copy, *pred, *arg;
  ir_graph *clone_irg = env;

  arg = get_irg_link(clone_irg);
  /* Arg is the method argument, that we have replaced by a constant.*/
  if (arg == irn)
    return;

  irn_copy  = get_irn_link(irn);

  if (is_Block(irn)) {
    for (i = get_Block_n_cfgpreds(irn) - 1; i >= 0; i--) {
      pred = get_Block_cfgpred(irn, i);
      /* "End" block must be handled extra, because it is not matured.*/
      if (get_irg_end_block(current_ir_graph) == irn)
        add_immBlock_pred(get_irg_end_block(clone_irg), get_irn_link(pred));
      else
        set_Block_cfgpred(irn_copy, i, get_irn_link(pred));
    }
  }
  else {
    /* First we set the block our copy if it is not a block.*/
    set_nodes_block(irn_copy, get_irn_link(get_nodes_block(irn)));
    if (get_irn_op(irn) == op_End) {
      /* Handle the keep-alives. This must be done separately, because
         the End node was NOT copied */
      for (i = 0; i < get_End_n_keepalives(irn); ++i)
        add_End_keepalive(irn_copy, get_irn_link(get_End_keepalive(irn, i)));
    }
    else {
      for (i = get_irn_arity(irn) - 1; i >= 0; i--) {
        pred = get_irn_n(irn, i);
        set_irn_n(irn_copy, i, get_irn_link(pred));
      }
    }
  }
}

/**
 * Get the method argument at the position "pos".
 *
 * @param irg  irg that must be cloned.
 * @param pos  The position of the argument.
 */
static ir_node *get_irg_arg(ir_graph *irg, int pos)
{
  ir_node *irg_args = get_irg_args(irg), *arg = NULL;
  int i;

  /* Call algorithm that computes the out edges */
  if (get_irg_outs_state(irg) != outs_consistent)
    compute_irg_outs(irg);

  /* Search the argument with the number pos.*/
  for (i = get_irn_n_outs(irg_args) - 1; i >= 0; --i) {
    ir_node *proj = get_irn_out(irg_args, i);
    if (pos == get_Proj_proj(proj)) {
      if (arg) {
        /*
         * More than one arg node found:
         * We rely on the fact the only one arg exists, so do
         * a cheap CSE in this case.
         */
        set_irn_out(irg_args, i, arg);
        exchange(proj, arg);
      }
      else
        arg = proj;
    }
  }
  assert(arg && "Argument not found");
  return arg;
}

/**
 * Create a new graph for the clone of the method,
 * that we want to clone.
 *
 * @param ent The entity of the method that must be cloned.
 * @param q   Our quadruplet.
 */
static void create_clone_proc_irg(entity *ent, quad_t *q)
{
  ir_graph *method_irg, *clone_irg;
  ir_node *arg, *const_arg;

  method_irg = get_entity_irg(ent);

  /* We create the skeleton of the clone irg.*/
  clone_irg  = new_ir_graph(ent, 0);

  arg        = get_irg_arg(get_entity_irg(q->ent), q->pos);
  /* we will replace the argument in position "q->pos" by this constant. */
  const_arg  = new_r_Const_type(
    clone_irg, get_nodes_block(arg), get_irn_mode(arg), q->tv,
    get_method_param_type(get_entity_type(q->ent), q->pos));

  /* args copy in the cloned graph will be the const. */
  set_irn_link(arg, const_arg);

  /* Store the arg that will be replaced here, so we can easily detect it. */
  set_irg_link(clone_irg, arg);

  /* We copy the blocks and nodes, that must be in
     the clone graph and set their predecessors. */
  irg_walk_graph(method_irg, copy_nodes, set_preds, clone_irg);

  /* The "cloned" graph must be matured. */
  mature_immBlock(get_irg_end_block(clone_irg));
  irg_finalize_cons(clone_irg);
}

/**
 * The function create a new entity type
 * for our clone and set it to clone entity.
 *
 * @param q   Contains information for the method to clone.
 * @param ent The entity of the clone.
 * @param nr  A pointer to the counter of clones.
 **/
static void change_entity_type(quad_t *q, entity *ent, unsigned *nr)
{
  ir_type *mtp, *new_mtp, *tp;
  ident   *tp_name;
  int     i, j, n_params, n_ress;

  mtp      = get_entity_type(q->ent);
  tp_name  = get_clone_ident(get_type_ident(mtp), q->pos, (*nr)++);
  n_params = get_method_n_params(mtp);
  n_ress   = get_method_n_ress(mtp);

  /* Create the new type for our clone. It must have one parameter
     less then the original.*/
  new_mtp  = new_type_method(tp_name, n_params - 1, n_ress);

  /* We must set the type of the methods parameters.*/
  for (i = j = 0; i < n_params; ++i) {
    if (i == q->pos)
      /* This is the position of the argument, that we have
         replaced. */
      continue;

    tp = get_method_param_type(mtp, i);
    set_method_param_type(new_mtp, j++, tp);
  }
  /* Copy the methods result types. */
  for (i = 0; i < n_ress; ++i) {
    tp = get_method_res_type(mtp, i);
    set_method_res_type(new_mtp, i, tp);
  }
  set_entity_type(ent, new_mtp);
}

/**
 * Make a clone of a method.
 *
 * @param q   Contains information for the method to clone.
 */
static entity *clone_method(quad_t *q)
{
  entity *new_entity;
  ident *clone_ident;
  ir_graph *rem;
  symconst_symbol sym;
  /* A counter for the clones.*/
  static unsigned nr = 0;

  /* We get a new ident for our clone method.*/
  clone_ident = get_clone_ident(get_entity_ident(q->ent), q->pos, nr);
  /* We get our entity for the clone method. */
  new_entity  = copy_entity_name(q->ent, clone_ident);

  /* a cloned entity is always local */
  set_entity_visibility(new_entity, visibility_local);

  /* set a ld name here: Should we mangle this ? */
  set_entity_ld_ident(new_entity, get_entity_ident(new_entity));

  /* set a new type here. */
  change_entity_type(q, new_entity, &nr);

  /* We need now a new ir_graph for our clone method. */
  create_clone_proc_irg(new_entity, q);

  /* We must set the atomic value of our "new_entity". */
  sym.entity_p = new_entity;
  rem = current_ir_graph;
  current_ir_graph =  get_const_code_irg();
  new_entity->value = new_SymConst(sym, symconst_addr_ent);
  current_ir_graph = rem;

  /* The "new_entity" don't have this information. */
  new_entity->param_access = NULL;
  new_entity->param_weight = NULL;

  return new_entity;
}

/**
 * Creates a new "cloned" Call node and return it.
 *
 * @param call        The call that must be cloned.
 * @param new_entity  The entity of the cloned function.
 * @param pos         The position of the replaced parameter of this call.
 **/
static ir_node *new_cl_Call(ir_node *call, entity *new_entity, int pos)
{
  ir_node **in;
  ir_type *mtp;
  int i, n_params, new_params = 0;
  ir_node *callee;
  symconst_symbol sym;
  ir_graph *irg = get_irn_irg(call);
  ir_node *bl = get_nodes_block(call);

  sym.entity_p = new_entity;
  callee = new_r_SymConst(irg, bl, sym, symconst_addr_ent);

  mtp      = get_entity_type(new_entity);
  n_params = get_Call_n_params(call);
  NEW_ARR_A(ir_node *, in, n_params - 1);

  /* we save the parameters of the new call in the array "in" without the
   * parameter in position "pos", that is replaced with a constant.*/
  for (i = 0; i < n_params; i++){
    if (pos != i)
      in[new_params++] = get_Call_param(call, i);
  }
  /* Create and return the new Call. */
  return new_r_Call(irg, bl, get_Call_mem(call),
                    callee, n_params - 1, in, get_entity_type(new_entity));
}

/**
 * Exchange all Calls stored in the quadruplet to Calls of the cloned entity.
 *
 * @param q             The quadruple
 * @param cloned_ent    The entity of the new function that must be called
 *                      from the new Call.
 */
static void exchange_calls(quad_t *q, entity *cloned_ent)
{
  int pos = q->pos;
  ir_node *new_call, *call;
  int i;

  /* We iterate the list of the "call".*/
  for (i = 0; i < ARR_LEN(q->calls); ++i) {
    call = q->calls[i];

    /* A clone exist and the copy of "call" in this
     * clone graph must be exchanged with new one.*/
    new_call = new_cl_Call(call, cloned_ent, pos);
    exchange(call, new_call);
  }
}

/**
 * The weight formula:
 * We save one instruction in every caller and param_weight instructions
 * in the callee.
 */
static float calculate_weight(const entry_t *entry) {
  return ARR_LEN(entry->q.calls) *
    (get_method_param_weight(entry->q.ent, entry->q.pos) + 1);
}

/**
 * After we exchanged all calls, some entries on the list for
 * the next cloned entity may get invalid, so we have to check
 * them and may even update the list of heavy uses.
 */
static void reorder_weights(q_set *hmap, float threshold)
{
  entry_t **adr, *p, *entry;
  int i, len;
  entity *callee;

restart:
  entry = hmap->heavy_uses;
  if (! entry)
    return;

  len = ARR_LEN(entry->q.calls);
  for (i = 0; i < len; ++i) {
    ir_node *ptr, *call = entry->q.calls[i];

    /* might be exchanged, so skip Id nodes here. */
    call = skip_Id(call);

    /* we know, that a SymConst is here */
    ptr = get_Call_ptr(call);
    assert(get_irn_op(ptr) == op_SymConst);

    callee = get_SymConst_entity(ptr);
    if (callee != entry->q.ent) {
      /*
       * This call is already changed because of a previous
       * optimization. Remove it from the list.
       */
      --len;
      entry->q.calls[i] = entry->q.calls[len];
      entry->q.calls[len] = NULL;

      /* the new call should be processed */
      process_call(call, callee, hmap);
      --i;
    }
  }

  /* the length might be changed */
  ARR_SHRINKLEN(entry->q.calls, len);

  /* recalculate the weight and resort the heavy uses map */
  entry->weight = calculate_weight(entry);

  if (len <= 0 || entry->weight < threshold) {
    hmap->heavy_uses = entry->next;
    kill_entry(entry);

    /* we have changed the list, check the next one */
    goto restart;
  }

  adr = NULL;
  for (p = entry->next; p && entry->weight < p->weight; p = p->next) {
    adr = &p->next;
  }

  if (adr) {
    hmap->heavy_uses = entry->next;
    entry->next      = *adr;
    *adr             = entry;
    entry            = hmap->heavy_uses;

    /* we have changed the list, check the next one */
    goto restart;
  }
}

/*
 * Do the procedure cloning. Evaluate a heuristic weight for every
 * call(..., Const, ...). If the weight is bigger than threshold,
 * clone the entity and fix the calls.
 */
void proc_cloning(float threshold)
{
  entry_t *entry = NULL, *p;
  ir_graph *irg;
  int i;
  q_set hmap;

  obstack_init(&hmap.obst);
  hmap.map        = NULL;
  hmap.heavy_uses = NULL;

  /* initially fill our map by visiting all irgs */
  for (i = get_irp_n_irgs() - 1; i >= 0; --i) {
    irg = get_irp_irg(i);
    irg_walk_graph(irg, collect_irg_calls, NULL, &hmap);
  }

  /* We have the "Call" nodes to optimize in set "set_entries". Our algorithm
     replace one constant parameter and make a new "Call" node for all found "Calls". It exchange the
     old one with the new one and the algorithm is called with the new "Call".
     */
  while (hmap.map || hmap.heavy_uses) {
    /* We iterate the set and arrange the element of the set in a list.
       The elements are arranged dependent of their value descending.*/
    if (hmap.map) {
      for (entry = pset_first(hmap.map); entry; entry = pset_next(hmap.map)) {
        entry->weight = calculate_weight(entry);

        /*
         * Do not put entry with a weight < threshold in the list
         */
        if (entry->weight < threshold) {
          kill_entry(entry);
          continue;
        }

        /* put entry in the heavy uses list */
        entry->next = NULL;
        if (! hmap.heavy_uses)
          hmap.heavy_uses = entry;
        else {
          if (entry->weight >= hmap.heavy_uses->weight) {
            entry->next     = hmap.heavy_uses;
            hmap.heavy_uses = entry;
          }
          else {
            for (p = hmap.heavy_uses; p->next; p = p->next) {
              if (entry->weight >= p->next->weight) {
                entry->next = p->next;
                p->next     = entry;
                break;
              }
            }
            if (! p->next)
              p->next = entry;
          }
        }
      }
      del_pset(hmap.map);
      hmap.map = NULL;
    }

    /* Print some information about the list. */
    printf("-----------------\n");
    for (entry = hmap.heavy_uses; entry; entry = entry->next) {
      printf("\nweight: is %f\n", entry->weight);
      ir_printf("Call for Method %E\n", entry->q.ent);
      printf("Position %i\n", entry->q.pos);
      ir_printf("Value %T\n", entry->q.tv);
    }

    entry = hmap.heavy_uses;
    if (entry) {
      entity *ent = clone_method(&entry->q);

      hmap.heavy_uses = entry->next;

      /* We must exchange the copies of this call in all clones too.*/
      exchange_calls(&entry->q, ent);
      kill_entry(entry);

      /*
       * after we exchanged all calls, some entries on the list for
       * the next cloned entity may get invalid, so we have to check
       * them and may even update the list of heavy uses.
       */
      reorder_weights(&hmap, threshold);
    }
  }
  obstack_free(&hmap.obst, NULL);
}