5c4714c1a9
SConscript: Include new files. arch/alpha/isa_desc: Make the eaCompPtr and memAccPtr non-const so that execute() can be called on them. arch/alpha/isa_traits.hh: Add enum for total number of data registers. arch/isa_parser.py: base/traceflags.py: Include new light-weight OoO CPU model. cpu/base_dyn_inst.cc: cpu/base_dyn_inst.hh: Changes to abstract more away from the base dyn inst class. cpu/beta_cpu/2bit_local_pred.cc: cpu/beta_cpu/2bit_local_pred.hh: cpu/beta_cpu/tournament_pred.cc: cpu/beta_cpu/tournament_pred.hh: Remove redundant SatCounter class. cpu/beta_cpu/alpha_dyn_inst.cc: cpu/beta_cpu/alpha_full_cpu.cc: cpu/beta_cpu/alpha_full_cpu.hh: cpu/beta_cpu/bpred_unit.cc: cpu/beta_cpu/inst_queue.cc: cpu/beta_cpu/mem_dep_unit.cc: cpu/beta_cpu/ras.cc: cpu/beta_cpu/rename_map.cc: cpu/beta_cpu/rename_map.hh: cpu/beta_cpu/rob.cc: Fix for gcc-3.4 cpu/beta_cpu/alpha_dyn_inst.hh: cpu/beta_cpu/alpha_dyn_inst_impl.hh: Fixes for gcc-3.4. Include more variables and functions that are specific to AlphaDynInst which were once in BaseDynInst. cpu/beta_cpu/alpha_full_cpu_builder.cc: Make params match the current params inherited from BaseCPU. cpu/beta_cpu/alpha_full_cpu_impl.hh: Fixes for gcc-3.4 cpu/beta_cpu/full_cpu.cc: Use new params pointer in BaseCPU. Fix for gcc-3.4. cpu/beta_cpu/full_cpu.hh: Use new params class from BaseCPU. cpu/beta_cpu/iew_impl.hh: Remove unused function. cpu/simple_cpu/simple_cpu.cc: Remove unused global variable. cpu/static_inst.hh: Include OoODynInst for new lightweight OoO CPU --HG-- extra : convert_revision : 34d9f2e64ca0313377391e0d059bf09c040286fa
229 lines
7.6 KiB
C++
229 lines
7.6 KiB
C++
#include "cpu/beta_cpu/tournament_pred.hh"
|
|
|
|
TournamentBP::TournamentBP(unsigned _local_predictor_size,
|
|
unsigned _local_ctr_bits,
|
|
unsigned _local_history_table_size,
|
|
unsigned _local_history_bits,
|
|
unsigned _global_predictor_size,
|
|
unsigned _global_ctr_bits,
|
|
unsigned _global_history_bits,
|
|
unsigned _choice_predictor_size,
|
|
unsigned _choice_ctr_bits,
|
|
unsigned _instShiftAmt)
|
|
: local_predictor_size(_local_predictor_size),
|
|
local_ctr_bits(_local_ctr_bits),
|
|
local_history_table_size(_local_history_table_size),
|
|
local_history_bits(_local_history_bits),
|
|
global_predictor_size(_global_predictor_size),
|
|
global_ctr_bits(_global_ctr_bits),
|
|
global_history_bits(_global_history_bits),
|
|
choice_predictor_size(_global_predictor_size),
|
|
choice_ctr_bits(_choice_ctr_bits),
|
|
instShiftAmt(_instShiftAmt)
|
|
{
|
|
//Should do checks here to make sure sizes are correct (powers of 2)
|
|
|
|
//Setup the array of counters for the local predictor
|
|
local_ctrs = new SatCounter[local_predictor_size];
|
|
|
|
for (int i = 0; i < local_predictor_size; ++i)
|
|
local_ctrs[i].setBits(local_ctr_bits);
|
|
|
|
//Setup the history table for the local table
|
|
local_history_table = new unsigned[local_history_table_size];
|
|
|
|
for (int i = 0; i < local_history_table_size; ++i)
|
|
local_history_table[i] = 0;
|
|
|
|
// Setup the local history mask
|
|
localHistoryMask = (1 << local_history_bits) - 1;
|
|
|
|
//Setup the array of counters for the global predictor
|
|
global_ctrs = new SatCounter[global_predictor_size];
|
|
|
|
for (int i = 0; i < global_predictor_size; ++i)
|
|
global_ctrs[i].setBits(global_ctr_bits);
|
|
|
|
//Clear the global history
|
|
global_history = 0;
|
|
// Setup the global history mask
|
|
globalHistoryMask = (1 << global_history_bits) - 1;
|
|
|
|
//Setup the array of counters for the choice predictor
|
|
choice_ctrs = new SatCounter[choice_predictor_size];
|
|
|
|
for (int i = 0; i < choice_predictor_size; ++i)
|
|
choice_ctrs[i].setBits(choice_ctr_bits);
|
|
|
|
threshold = (1 << (local_ctr_bits - 1)) - 1;
|
|
threshold = threshold / 2;
|
|
}
|
|
|
|
inline
|
|
unsigned
|
|
TournamentBP::calcLocHistIdx(Addr &branch_addr)
|
|
{
|
|
return (branch_addr >> instShiftAmt) & (local_history_table_size - 1);
|
|
}
|
|
|
|
inline
|
|
void
|
|
TournamentBP::updateHistoriesTaken(unsigned local_history_idx)
|
|
{
|
|
global_history = (global_history << 1) | 1;
|
|
global_history = global_history & globalHistoryMask;
|
|
|
|
local_history_table[local_history_idx] =
|
|
(local_history_table[local_history_idx] << 1) | 1;
|
|
}
|
|
|
|
inline
|
|
void
|
|
TournamentBP::updateHistoriesNotTaken(unsigned local_history_idx)
|
|
{
|
|
global_history = (global_history << 1);
|
|
global_history = global_history & globalHistoryMask;
|
|
|
|
local_history_table[local_history_idx] =
|
|
(local_history_table[local_history_idx] << 1);
|
|
}
|
|
|
|
bool
|
|
TournamentBP::lookup(Addr &branch_addr)
|
|
{
|
|
uint8_t local_prediction;
|
|
unsigned local_history_idx;
|
|
unsigned local_predictor_idx;
|
|
|
|
uint8_t global_prediction;
|
|
uint8_t choice_prediction;
|
|
|
|
//Lookup in the local predictor to get its branch prediction
|
|
local_history_idx = calcLocHistIdx(branch_addr);
|
|
local_predictor_idx = local_history_table[local_history_idx]
|
|
& localHistoryMask;
|
|
local_prediction = local_ctrs[local_predictor_idx].read();
|
|
|
|
//Lookup in the global predictor to get its branch prediction
|
|
global_prediction = global_ctrs[global_history].read();
|
|
|
|
//Lookup in the choice predictor to see which one to use
|
|
choice_prediction = choice_ctrs[global_history].read();
|
|
|
|
//@todo Put a threshold value in for the three predictors that can
|
|
// be set through the constructor (so this isn't hard coded).
|
|
//Also should put some of this code into functions.
|
|
if (choice_prediction > threshold) {
|
|
if (global_prediction > threshold) {
|
|
updateHistoriesTaken(local_history_idx);
|
|
|
|
assert(global_history < global_predictor_size &&
|
|
local_history_idx < local_predictor_size);
|
|
|
|
global_ctrs[global_history].increment();
|
|
local_ctrs[local_history_idx].increment();
|
|
|
|
return true;
|
|
} else {
|
|
updateHistoriesNotTaken(local_history_idx);
|
|
|
|
assert(global_history < global_predictor_size &&
|
|
local_history_idx < local_predictor_size);
|
|
|
|
global_ctrs[global_history].decrement();
|
|
local_ctrs[local_history_idx].decrement();
|
|
|
|
return false;
|
|
}
|
|
} else {
|
|
if (local_prediction > threshold) {
|
|
updateHistoriesTaken(local_history_idx);
|
|
|
|
assert(global_history < global_predictor_size &&
|
|
local_history_idx < local_predictor_size);
|
|
|
|
global_ctrs[global_history].increment();
|
|
local_ctrs[local_history_idx].increment();
|
|
|
|
return true;
|
|
} else {
|
|
updateHistoriesNotTaken(local_history_idx);
|
|
|
|
assert(global_history < global_predictor_size &&
|
|
local_history_idx < local_predictor_size);
|
|
|
|
global_ctrs[global_history].decrement();
|
|
local_ctrs[local_history_idx].decrement();
|
|
|
|
return false;
|
|
}
|
|
}
|
|
}
|
|
|
|
// Update the branch predictor if it predicted a branch wrong.
|
|
void
|
|
TournamentBP::update(Addr &branch_addr, unsigned correct_gh, bool taken)
|
|
{
|
|
|
|
uint8_t local_prediction;
|
|
unsigned local_history_idx;
|
|
unsigned local_predictor_idx;
|
|
bool local_pred_taken;
|
|
|
|
uint8_t global_prediction;
|
|
bool global_pred_taken;
|
|
|
|
// Load the correct global history into the register.
|
|
global_history = correct_gh;
|
|
|
|
// Get the local predictor's current prediction, remove the incorrect
|
|
// update, and update the local predictor
|
|
local_history_idx = calcLocHistIdx(branch_addr);
|
|
local_predictor_idx = local_history_table[local_history_idx];
|
|
local_predictor_idx = (local_predictor_idx >> 1) & localHistoryMask;
|
|
|
|
local_prediction = local_ctrs[local_predictor_idx].read();
|
|
local_pred_taken = local_prediction > threshold;
|
|
|
|
//Get the global predictor's current prediction, and update the
|
|
//global predictor
|
|
global_prediction = global_ctrs[global_history].read();
|
|
global_pred_taken = global_prediction > threshold;
|
|
|
|
//Update the choice predictor to tell it which one was correct
|
|
if (local_pred_taken != global_pred_taken) {
|
|
//If the local prediction matches the actual outcome, decerement
|
|
//the counter. Otherwise increment the counter.
|
|
if (local_pred_taken == taken) {
|
|
choice_ctrs[global_history].decrement();
|
|
} else {
|
|
choice_ctrs[global_history].increment();
|
|
}
|
|
}
|
|
|
|
if (taken) {
|
|
assert(global_history < global_predictor_size &&
|
|
local_predictor_idx < local_predictor_size);
|
|
|
|
local_ctrs[local_predictor_idx].increment();
|
|
global_ctrs[global_history].increment();
|
|
|
|
global_history = (global_history << 1) | 1;
|
|
global_history = global_history & globalHistoryMask;
|
|
|
|
local_history_table[local_history_idx] |= 1;
|
|
}
|
|
else {
|
|
assert(global_history < global_predictor_size &&
|
|
local_predictor_idx < local_predictor_size);
|
|
|
|
local_ctrs[local_predictor_idx].decrement();
|
|
global_ctrs[global_history].decrement();
|
|
|
|
global_history = (global_history << 1);
|
|
global_history = global_history & globalHistoryMask;
|
|
|
|
local_history_table[local_history_idx] &= ~1;
|
|
}
|
|
}
|