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/* memory.c -- OpenRISC Custom Unit Compiler, memory optimization and scheduling
 *    Copyright (C) 2002 Marko Mlinar, markom@opencores.org
 *
 *    This file is part of OpenRISC 1000 Architectural Simulator.
 *
 *    This program is free software; you can redistribute it and/or modify
 *    it under the terms of the GNU General Public License as published by
 *    the Free Software Foundation; either version 2 of the License, or
 *    (at your option) any later version.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU General Public License for more details.
 *
 *    You should have received a copy of the GNU General Public License
 *    along with this program; if not, write to the Free Software
 *    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
 
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <assert.h>
#include "sim-config.h"
#include "cuc.h"
#include "insn.h"
 
/* Checks for memory conflicts between two instructions; returns 1 if detected
  0 - exact; 1 - strong; 2 - weak; 3 - none */
static int check_memory_conflict (cuc_func *f, cuc_insn *a, cuc_insn *b, int otype)
{
  switch (otype) {
    case MO_EXACT: /* exact */
    case MO_STRONG: /* strong */
      return 1;
    case MO_WEAK: /* weak */
      assert (a->type & IT_MEMORY);
      assert (b->type & IT_MEMORY);
      if ((a->opt[1] & OPT_REF) && f->INSN(a->op[1]).index == II_ADD
        &&(b->opt[1] & OPT_REF) && f->INSN(b->op[1]).index == II_ADD) {
        int aw, bw;
        assert ((aw = II_MEM_WIDTH (a->index)) >= 0);
        assert ((bw = II_MEM_WIDTH (b->index)) >= 0);
 
        a = &f->INSN(a->op[1]);
        b = &f->INSN(b->op[1]);
        if (a->opt[1] != b->opt[1] || a->op[1] != b->op[1]
         || a->opt[2] != OPT_CONST || b->opt[2] != OPT_CONST) return 1;
 
        /* Check if they overlap */
        if (a->op[2] >= b->op[2] && a->op[2] < b->op[2] + bw) return 1;
        if (b->op[2] >= a->op[2] && b->op[2] < a->op[2] + aw) return 1;
        return 0;
      } else return 1;
    case MO_NONE: /* none */
      return 0;
    default:
      assert (0);
  }
  return 1;
}
 
/* Adds memory dependencies based on ordering type:
  0 - exact; 1 - strong; 2 - weak;  3 - none */
void add_memory_dep (cuc_func *f, int otype)
{
  int b, i;
  dep_list *all_mem = NULL;
 
  for (b = 0; b < f->num_bb; b++) {
    cuc_insn *insn = f->bb[b].insn;
    for (i = 0; i < f->bb[b].ninsn; i++)
      if (insn[i].type & IT_MEMORY) {
        dep_list *tmp = all_mem;
        while (tmp) {
          //printf ("%x %x\n", REF (b,i), tmp->ref);
          if (check_memory_conflict (f, &insn[i], &f->INSN(tmp->ref), otype))
            add_dep (&insn[i].dep, tmp->ref);
          tmp = tmp->next;
        }
        add_dep (&all_mem, REF (b, i));
      }
  }
  dispose_list (&all_mem);
}
 
/* returns nonzero if a < b */
int mem_ordering_cmp (cuc_func *f, cuc_insn *a, cuc_insn *b)
{
  assert (a->type & IT_MEMORY);
  assert (b->type & IT_MEMORY);
  if ((a->opt[1] & OPT_REF) && f->INSN(a->op[1]).index == II_ADD
    &&(b->opt[1] & OPT_REF) && f->INSN(b->op[1]).index == II_ADD) {
    a = &f->INSN(a->op[1]);
    b = &f->INSN(b->op[1]);
    if (a->opt[1] != b->opt[1] || a->op[1] != b->op[1]
     || a->opt[2] != OPT_CONST || b->opt[2] != OPT_CONST) return 0;
 
    /* Order linearly, we can then join them to bursts */
    return a->op[2] < b->op[2];
  } else return 0;
}
 
/* Schedule memory accesses
  0 - exact; 1 - strong; 2 - weak;  3 - none */
void schedule_memory (cuc_func *f, int otype)
{
  int b, i, j;
  f->nmsched = 0;
 
  for (b = 0; b < f->num_bb; b++) {
    cuc_insn *insn = f->bb[b].insn;
    for (i = 0; i < f->bb[b].ninsn; i++)
      if (insn[i].type & IT_MEMORY) {
        f->msched[f->nmsched++] = REF (b, i);
        if (otype == MO_NONE || otype == MO_WEAK) insn[i].type |= IT_FLAG1; /* mark unscheduled */
      }
  }
#if 0
  for (i = 0; i < f->nmsched; i++)
    printf ("[%i]%i%c ", f->msched[i], f->mtype[i] & MT_WIDTH, (f->mtype[i] & MT_BURST) ? (f->mtype[i] & MT_BURSTE) ? 'E' : 'B' : ' ');
  printf ("\n");
#endif
 
  /* We can reorder just more loose types
     We assume, that memory accesses are currently in valid (but not neccesserly)
     optimal order */
  if (otype == MO_WEAK || otype == MO_NONE) {
    for (i = 0; i < f->nmsched; i++) {
      int best = i;
      int tmp;
      for (j = i + 1; j < f->nmsched; j++) if (REF_BB(f->msched[j]) == REF_BB(f->msched[best])) {
        if (mem_ordering_cmp (f, &f->INSN (f->msched[j]), &f->INSN(f->msched[best]))) {
          /* Check dependencies */
          dep_list *t = f->INSN(f->msched[j]).dep;
          while (t) {
            if (f->INSN(t->ref).type & IT_FLAG1) break;
            t = t->next;
          }
          if (!t) best = j; /* no conflicts -> ok */
        }
      }
 
      /* we have to shift instructions up, to maintain valid dependencies
         and make space for best candidate */
 
      /* make local copy */
      tmp = f->msched[best];
      for (j = best; j > i; j--) f->msched[j] = f->msched[j - 1];
      f->msched[i] = tmp;
      f->INSN(f->msched[i]).type &= ~IT_FLAG1; /* mark scheduled */
    }
  }
 
#if 0
  for (i = 0; i < f->nmsched; i++)
    printf ("[%i]%i%c ", f->msched[i], f->mtype[i] & MT_WIDTH, (f->mtype[i] & MT_BURST) ? (f->mtype[i] & MT_BURSTE) ? 'E' : 'B' : ' ');
  printf ("\n");
#endif
 
  /* Assign memory types */
  for (i = 0; i < f->nmsched; i++) {
    cuc_insn *a = &f->INSN(f->msched[i]);
    f->mtype[i] = !II_IS_LOAD(a->index) ? MT_WRITE : 0;
    f->mtype[i] |= II_MEM_WIDTH (a->index);
    if (a->type & IT_SIGNED) f->mtype[i] |= MT_SIGNED;
  }
 
  /* Check if they address the same location, so we can join them */
  if (otype == MO_WEAK || otype == MO_NONE) {
    for (i = 1, j = 1; i < f->nmsched; i++)
      /* Exclude memory stores and different memory types */
      if (f->mtype[i - 1] == f->mtype[i] && !(f->mtype[i] & MT_WRITE)) {
        cuc_insn *a = &f->INSN(f->msched[i - 1]);
        cuc_insn *b = &f->INSN(f->msched[i]);
        if ((a->opt[1] & OPT_REF) && f->INSN(a->op[1]).index == II_ADD
          &&(b->opt[1] & OPT_REF) && f->INSN(b->op[1]).index == II_ADD) {
          a = &f->INSN(a->op[1]);
          b = &f->INSN(b->op[1]);
          /* Not in usual form? */
          if (a->opt[1] != b->opt[1] || a->op[1] != b->op[1]
           || a->opt[2] != OPT_CONST || b->opt[2] != OPT_CONST) goto keep;
 
          //printf ("%i %i, ", a->op[2], b->op[2]);
 
          /* Check if they are the same => do not copy */
          if (a->op[2] == b->op[2]
            && REF_BB(f->msched[i - 1]) == REF_BB(f->msched[i])) {
            /* yes => remove actual instruction */
            int t1 = MIN (f->msched[i - 1], f->msched[i]);
            int t2 = MAX (f->msched[i - 1], f->msched[i]);
            int b, i, j;
            cucdebug (2, "Removing %x_%x and using %x_%x instead.\n",
              REF_BB(t2), REF_I(t2), REF_BB(t1), REF_I(t1));
            change_insn_type (&f->INSN(t2), II_NOP);
            /* Update references */
            for (b = 0; b < f->num_bb; b++)
              for (i = 0; i < f->bb[b].ninsn; i++)
                for (j = 0; j < MAX_OPERANDS; j++)
                  if (f->bb[b].insn[i].opt[j] & OPT_REF && f->bb[b].insn[i].op[j] == t2)
                    f->bb[b].insn[i].op[j] = t1;
 
          } else goto keep;
        }
      } else {
keep:
        f->msched[j] = f->msched[i];
        f->mtype[j++] = f->mtype[i];
      }
    f->nmsched = j;
  }
 
  if (config.cuc.enable_bursts) {
    //printf ("\n");
    for (i = 1; i < f->nmsched; i++) {
      cuc_insn *a = &f->INSN(f->msched[i - 1]);
      cuc_insn *b = &f->INSN(f->msched[i]);
      int aw = f->mtype[i - 1] & MT_WIDTH;
 
      if ((a->opt[1] & OPT_REF) && f->INSN(a->op[1]).index == II_ADD
        &&(b->opt[1] & OPT_REF) && f->INSN(b->op[1]).index == II_ADD) {
        a = &f->INSN(a->op[1]);
        b = &f->INSN(b->op[1]);
        /* Not in usual form? */
        if (a->opt[1] != b->opt[1] || a->op[1] != b->op[1]
         || a->opt[2] != OPT_CONST || b->opt[2] != OPT_CONST) continue; 
 
        //printf ("%i %i, ", a->op[2], b->op[2]);
 
        /* Check if they touch together */
        if (a->op[2] + aw == b->op[2]) {
          /* yes => do burst */
          f->mtype[i - 1] &= ~MT_BURSTE;
          f->mtype[i - 1] |= MT_BURST;
          f->mtype[i] |= MT_BURST | MT_BURSTE;
        }
      }
    }
  }
 
#if 0
  printf ("\n");
  for (i = 0; i < f->nmsched; i++)
    printf ("[%i]%i%c ", f->msched[i], f->mtype[i] & MT_WIDTH, (f->mtype[i] & MT_BURST) ? (f->mtype[i] & MT_BURSTE) ? 'E' : 'B' : ' ');
  printf ("\n");
#endif
 
  /* We don't need dependencies in non-memory instructions */
  for (b = 0; b < f->num_bb; b++) {
    cuc_insn *insn = f->bb[b].insn;
    for (i = 0; i < f->bb[b].ninsn; i++) if (!(insn[i].type & IT_MEMORY))
      dispose_list (&insn[i].dep);
  }
 
  /* Reduce number of dependecies, keeping just direct dependencies, based on memory schedule */
  {
    int lastl[2] = {-1, -1}, lasts[2] = {-1, -1};
    int last_load = -1, last_store = -1;
    for (i = 0; i < f->nmsched; i++) {
      int t = (f->mtype[i] & MT_WRITE) ? 1 : 0;
      int maxl = lastl[t];
      int maxs = lasts[t];
      dep_list *tmp = f->INSN(f->msched[i]).dep;
      while (tmp) {
        if (f->INSN(tmp->ref).type & IT_MEMORY && REF_BB(tmp->ref) == REF_BB(f->msched[i])) {
          /* Search for the reference */
          for (j = 0; j < f->nmsched; j++) if (f->msched[j] == tmp->ref) break;
          assert (j < f->nmsched);
          if (f->mtype[j] & MT_WRITE) {
            if (maxs < j) maxs = j;
          } else {
            if (maxl < j) maxl = j;
          }
        }
        tmp = tmp->next;
      }
      dispose_list (&f->INSN(f->msched[i]).dep);
      if (f->mtype[i] & MT_WRITE) {
        maxs = last_store;
        last_store = i;
      } else {
        maxl = last_load;
        last_load = i;
      }
 
      if (maxl > lastl[t]) {
        add_dep (&f->INSN(f->msched[i]).dep, f->msched[maxl]);
        lastl[t] = maxl;
      }
      if (maxs > lasts[t]) {
        add_dep (&f->INSN(f->msched[i]).dep, f->msched[maxs]);
        lasts[t] = maxs;
      }
      //printf ("%i(%i)> ml %i(%i) ms %i(%i) lastl %i %i lasts %i %i last_load %i last_store %i\n", i, f->msched[i], maxl, f->msched[maxl], maxs, f->msched[maxs], lastl[0], lastl[1], lasts[0], lasts[1], last_load, last_store);
 
      /* What we have to wait to finish this BB? */
      if (i + 1 >= f->nmsched || REF_BB(f->msched[i + 1]) != REF_BB(f->msched[i])) {
        if (last_load > lastl[t]) {
          add_dep (&f->bb[REF_BB(f->msched[i])].mdep, f->msched[last_load]);
          lastl[t] = last_load;
        }
        if (last_store > lasts[t]) {
          add_dep (&f->bb[REF_BB(f->msched[i])].mdep, f->msched[last_store]);
          lasts[t] = last_store;
        }
      }
    }
  }
}