sim-bpred.c

一个很有名的硬件模拟器。可以模拟CPU

/* sim-bpred.c - sample branch predictor simulator implementation */

/* SimpleScalar(TM) Tool Suite
 * Copyright (C) 1994-2003 by Todd M. Austin, Ph.D. and SimpleScalar, LLC.
 * All Rights Reserved. 
 * 
 * THIS IS A LEGAL DOCUMENT, BY USING SIMPLESCALAR,
 * YOU ARE AGREEING TO THESE TERMS AND CONDITIONS.
 * 
 * No portion of this work may be used by any commercial entity, or for any
 * commercial purpose, without the prior, written permission of SimpleScalar,
 * LLC ([e-mail]). Nonprofit and noncommercial use is permitted
 * as described below.
 * 
 * 1. SimpleScalar is provided AS IS, with no warranty of any kind, express
 * or implied. The user of the program accepts full responsibility for the
 * application of the program and the use of any results.
 * 
 * 2. Nonprofit and noncommercial use is encouraged. SimpleScalar may be
 * downloaded, compiled, executed, copied, and modified solely for nonprofit,
 * educational, noncommercial research, and noncommercial scholarship
 * purposes provided that this notice in its entirety accompanies all copies.
 * Copies of the modified software can be delivered to persons who use it
 * solely for nonprofit, educational, noncommercial research, and
 * noncommercial scholarship purposes provided that this notice in its
 * entirety accompanies all copies.
 * 
 * 3. ALL COMMERCIAL USE, AND ALL USE BY FOR PROFIT ENTITIES, IS EXPRESSLY
 * PROHIBITED WITHOUT A LICENSE FROM SIMPLESCALAR, LLC ([e-mail]).
 * 
 * 4. No nonprofit user may place any restrictions on the use of this software,
 * including as modified by the user, by any other authorized user.
 * 
 * 5. Noncommercial and nonprofit users may distribute copies of SimpleScalar
 * in compiled or executable form as set forth in Section 2, provided that
 * either: (A) it is accompanied by the corresponding machine-readable source
 * code, or (B) it is accompanied by a written offer, with no time limit, to
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 * must permit verbatim duplication by anyone, or (C) it is distributed by
 * someone who received only the executable form, and is accompanied by a
 * copy of the written offer of source code.
 * 
 * 6. SimpleScalar was developed by Todd M. Austin, Ph.D. The tool suite is
 * currently maintained by SimpleScalar LLC ([e-mail]). US Mail:
 * 2395 Timbercrest Court, Ann Arbor, MI 48105.
 * 
 * Copyright (C) 1994-2003 by Todd M. Austin, Ph.D. and SimpleScalar, LLC.
 */


#include <stdio.h>
#include <stdlib.h>
#include <math.h>

#include "host.h"
#include "misc.h"
#include "machine.h"
#include "regs.h"
#include "memory.h"
#include "loader.h"
#include "syscall.h"
#include "dlite.h"
#include "options.h"
#include "stats.h"
#include "bpred.h"
#include "sim.h"

/*
 * This file implements a branch predictor analyzer.
 */

/* simulated registers */
static struct regs_t regs;

/* simulated memory */
static struct mem_t *mem = NULL;

/* maximum number of inst's to execute */
static unsigned int max_insts;

/* branch predictor type {nottaken|taken|perfect|bimod|2lev} */
static char *pred_type;

/* bimodal predictor config (<table_size>) */
static int bimod_nelt = 1;
static int bimod_config[1] =
  { /* bimod tbl size */2048 };

/* 2-level predictor config (<l1size> <l2size> <hist_size> <xor>) */
static int twolev_nelt = 4;
static int twolev_config[4] =
  { /* l1size */1, /* l2size */1024, /* hist */8, /* xor */FALSE};

/* combining predictor config (<meta_table_size> */
static int comb_nelt = 1;
static int comb_config[1] =
  { /* meta_table_size */1024 };

/* return address stack (RAS) size */
static int ras_size = 8;

/* BTB predictor config (<num_sets> <associativity>) */
static int btb_nelt = 2;
static int btb_config[2] =
  { /* nsets */512, /* assoc */4 };

/* branch predictor */
static struct bpred_t *pred;

/* track number of insn and refs */
static counter_t sim_num_refs = 0;

/* total number of branches executed */
static counter_t sim_num_branches = 0;


/* register simulator-specific options */
void
sim_reg_options(struct opt_odb_t *odb)
{
  opt_reg_header(odb, 
"sim-bpred: This simulator implements a branch predictor analyzer.\n"
		 );

  /* branch predictor options */
  opt_reg_note(odb,
"  Branch predictor configuration examples for 2-level predictor:\n"
"    Configurations:   N, M, W, X\n"
"      N   # entries in first level (# of shift register(s))\n"
"      W   width of shift register(s)\n"
"      M   # entries in 2nd level (# of counters, or other FSM)\n"
"      X   (yes-1/no-0) xor history and address for 2nd level index\n"
"    Sample predictors:\n"
"      GAg     : 1, W, 2^W, 0\n"
"      GAp     : 1, W, M (M > 2^W), 0\n"
"      PAg     : N, W, 2^W, 0\n"
"      PAp     : N, W, M (M == 2^(N+W)), 0\n"
"      gshare  : 1, W, 2^W, 1\n"
"  Predictor `comb' combines a bimodal and a 2-level predictor.\n"
               );

  /* instruction limit */
  opt_reg_uint(odb, "-max:inst", "maximum number of inst's to execute",
	       &max_insts, /* default */0,
	       /* print */TRUE, /* format */NULL);

  opt_reg_string(odb, "-bpred",
		 "branch predictor type {nottaken|taken|bimod|2lev|comb}",
                 &pred_type, /* default */"bimod",
                 /* print */TRUE, /* format */NULL);

  opt_reg_int_list(odb, "-bpred:bimod",
		   "bimodal predictor config (<table size>)",
		   bimod_config, bimod_nelt, &bimod_nelt,
		   /* default */bimod_config,
		   /* print */TRUE, /* format */NULL, /* !accrue */FALSE);

  opt_reg_int_list(odb, "-bpred:2lev",
                   "2-level predictor config "
		   "(<l1size> <l2size> <hist_size> <xor>)",
                   twolev_config, twolev_nelt, &twolev_nelt,
		   /* default */twolev_config,
                   /* print */TRUE, /* format */NULL, /* !accrue */FALSE);

  opt_reg_int_list(odb, "-bpred:comb",
		   "combining predictor config (<meta_table_size>)",
		   comb_config, comb_nelt, &comb_nelt,
		   /* default */comb_config,
		   /* print */TRUE, /* format */NULL, /* !accrue */FALSE);

  opt_reg_int(odb, "-bpred:ras",
              "return address stack size (0 for no return stack)",
              &ras_size, /* default */ras_size,
              /* print */TRUE, /* format */NULL);

  opt_reg_int_list(odb, "-bpred:btb",
		   "BTB config (<num_sets> <associativity>)",
		   btb_config, btb_nelt, &btb_nelt,
		   /* default */btb_config,
		   /* print */TRUE, /* format */NULL, /* !accrue */FALSE);
}

/* check simulator-specific option values */
void
sim_check_options(struct opt_odb_t *odb, int argc, char **argv)
{
  if (!mystricmp(pred_type, "taken"))
    {
      /* static predictor, not taken */
      pred = bpred_create(BPredTaken, 0, 0, 0, 0, 0, 0, 0, 0, 0);
    }
  else if (!mystricmp(pred_type, "nottaken"))
    {
      /* static predictor, taken */
      pred = bpred_create(BPredNotTaken, 0, 0, 0, 0, 0, 0, 0, 0, 0);
    }
  else if (!mystricmp(pred_type, "bimod"))
    {
      if (bimod_nelt != 1)
	fatal("bad bimod predictor config (<table_size>)");
      if (btb_nelt != 2)
	fatal("bad btb config (<num_sets> <associativity>)");

      /* bimodal predictor, bpred_create() checks BTB_SIZE */
      pred = bpred_create(BPred2bit,
			  /* bimod table size */bimod_config[0],
			  /* 2lev l1 size */0,
			  /* 2lev l2 size */0,
			  /* meta table size */0,
			  /* history reg size */0,
			  /* history xor address */0,
			  /* btb sets */btb_config[0],
			  /* btb assoc */btb_config[1],
			  /* ret-addr stack size */ras_size);
    }
  else if (!mystricmp(pred_type, "2lev"))
    {
      /* 2-level adaptive predictor, bpred_create() checks args */
      if (twolev_nelt != 4)
	fatal("bad 2-level pred config (<l1size> <l2size> <hist_size> <xor>)");
      if (btb_nelt != 2)
	fatal("bad btb config (<num_sets> <associativity>)");

      pred = bpred_create(BPred2Level,
			  /* bimod table size */0,
			  /* 2lev l1 size */twolev_config[0],
			  /* 2lev l2 size */twolev_config[1],
			  /* meta table size */0,
			  /* history reg size */twolev_config[2],
			  /* history xor address */twolev_config[3],
			  /* btb sets */btb_config[0],
			  /* btb assoc */btb_config[1],
			  /* ret-addr stack size */ras_size);
    }
  else if (!mystricmp(pred_type, "comb"))
    {
      /* combining predictor, bpred_create() checks args */
      if (twolev_nelt != 4)
	fatal("bad 2-level pred config (<l1size> <l2size> <hist_size> <xor>)");
      if (bimod_nelt != 1)
	fatal("bad bimod predictor config (<table_size>)");
      if (comb_nelt != 1)
	fatal("bad combining predictor config (<meta_table_size>)");
      if (btb_nelt != 2)
	fatal("bad btb config (<num_sets> <associativity>)");

      pred = bpred_create(BPredComb,
			  /* bimod table size */bimod_config[0],
			  /* l1 size */twolev_config[0],
			  /* l2 size */twolev_config[1],
			  /* meta table size */comb_config[0],
			  /* history reg size */twolev_config[2],
			  /* history xor address */twolev_config[3],
			  /* btb sets */btb_config[0],
			  /* btb assoc */btb_config[1],
			  /* ret-addr stack size */ras_size);
    }
  else
    fatal("cannot parse predictor type `%s'", pred_type);
}

/* register simulator-specific statistics */
void
sim_reg_stats(struct stat_sdb_t *sdb)
{
  stat_reg_counter(sdb, "sim_num_insn",
		   "total number of instructions executed",
		   &sim_num_insn, sim_num_insn, NULL);
  stat_reg_counter(sdb, "sim_num_refs",
		   "total number of loads and stores executed",
		   &sim_num_refs, 0, NULL);
  stat_reg_int(sdb, "sim_elapsed_time",
	       "total simulation time in seconds",
	       &sim_elapsed_time, 0, NULL);
  stat_reg_formula(sdb, "sim_inst_rate",
		   "simulation speed (in insts/sec)",
		   "sim_num_insn / sim_elapsed_time", NULL);

  stat_reg_counter(sdb, "sim_num_branches",
                   "total number of branches executed",
                   &sim_num_branches, /* initial value */0, /* format */NULL);
  stat_reg_formula(sdb, "sim_IPB",