ExecutableMove.cc

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/**
 * @file ExecutableMove.cc
 *
 * Definition of ExecutableMove class.
 *
 * @author Jussi Nykänen 2005 (nykanen-no.spam-cs.tut.fi)
 * @author Pekka Jääskeläinen 2005 (pjaaskel-no.spam-cs.tut.fi)
 * @note rating: red
 */
 
#include "ExecutableMove.hh"
#include "ReadableState.hh"
#include "WritableState.hh"
#include "BusState.hh"
#include "SimValue.hh"
 
// This should be defined if guards block bus writes, that is, in case
// guard definition evaluates to false, even the bus is not written.
// At least this is the case in MOVE, therefore this needs to be defined
// to be able to compare bus traces between MOVE and TCE easily.
const bool GUARD_BLOCKS_BUS_WRITE = true;
 
/**
 * Constructor.
 *
 * @param src Source of the move.
 * @param bus Bus of the move.
 * @param dst Destination of the move.
 */
ExecutableMove::ExecutableMove(
    const ReadableState& src,
    BusState& bus,
    WritableState& dst) : 
    src_(&src), bus_(&bus), dst_(&dst), 
    guardReg_(NULL), guarded_(false), negated_(false), 
    executionCount_(0), squashed_(false),
    inlineImmediate_(NULL) {
}
 
/**
 * Constructor.
 *
 * @param src Source of the move.
 * @param bus Bus of the move.
 * @param dst Destination of the move.
 * @param guardReg Guard register.
 * @param negated True if guard is reversed.
 */
ExecutableMove::ExecutableMove(
    const ReadableState& src,
    BusState& bus,
    WritableState& dst,
    const ReadableState& guardReg,
    bool negated) : 
    src_(&src), bus_(&bus), dst_(&dst), guardReg_(&guardReg),
    guarded_(true), negated_(negated), 
    executionCount_(0), squashed_(false),
    inlineImmediate_(NULL) {
}
 
/**
 * Constructor.
 *
 * Used to construct a move that has an inline immediate as the source.
 * The inline immediate becomes property of the created ExecutableMove
 * and is deleted by it.
 *
 * @param immediateSource The inline immediate source of the move.
 * @param bus Bus of the move.
 * @param dst Destination of the move.
 * @param guardReg Guard register.
 * @param negated True if guard is reversed.
 */
ExecutableMove::ExecutableMove(
    InlineImmediateValue* immediateSource,
    BusState& bus,
    WritableState& dst,
    const ReadableState& guardReg,
    bool negated) : 
    src_(immediateSource), bus_(&bus), dst_(&dst), guardReg_(&guardReg),
    guarded_(true), negated_(negated), 
    executionCount_(0), squashed_(false),
    inlineImmediate_(immediateSource) {
}
 
/**
 * Constructor.
 *
 * Used to construct a move that has an inline immediate as the source.
 * The inline immediate becomes property of the created ExecutableMove
 * and is deleted by it.
 *
 * @param immediateSource The inline immediate source of the move.
 * @param bus Bus of the move.
 * @param dst Destination of the move.
 * @param guardReg Guard register.
 * @param negated True if guard is reversed.
 */
ExecutableMove::ExecutableMove(
    InlineImmediateValue* immediateSource,
    BusState& bus,
    WritableState& dst) : 
    src_(immediateSource), bus_(&bus), dst_(&dst), 
    guardReg_(NULL), guarded_(false), negated_(false),
    executionCount_(0), squashed_(false),
    inlineImmediate_(immediateSource) {
}
 
 
/**
 * Destructor.
 */
ExecutableMove::~ExecutableMove() {
    delete inlineImmediate_;
    inlineImmediate_ = NULL;
}
 
/**
 * Evaluates the possible guard of the move, i.e., decides whether the
 * move is squashed at the simulated cycle or not.
 *
 * This must be called by the ExecutableInstruction before any 
 * executeRead()/executeWrite() is called in order not to overwrite 
 * the old guard value in case of the default 1-latency guards.
 */
void
ExecutableMove::evaluateGuard() {
    if (guarded_) {
        const SimValue& regValue = guardReg_->value();
        const bool guardTerm = (regValue.sIntWordValue() & 1) == 1;
        squashed_ = !((!negated_ &&  guardTerm) ||
                      ( negated_ && !guardTerm));
        bus_->setSquashed(squashed_);
    } else {
        bus_->setSquashed(false);
    }
}
 
/**
 * Copies the value of the move source to the transport bus.
 */
void
ExecutableMove::executeRead() {
 
    if (guarded_ && GUARD_BLOCKS_BUS_WRITE && squashed_) 
        return;
    bus_->setValueInlined(src_->value());
}
 
/**
 * Writes the value of the bus to the destination.
 *
 * If the move is guarded, the value is written to destination only if guard 
 * expression is true.
 *
 */
void
ExecutableMove::executeWrite() {
 
    if (guarded_ && squashed_) 
        return;
 
    dst_->setValue(bus_->value());
    executionCount_++;
}
 
/**
 * Resets the execution counter of this move.
 */
void
ExecutableMove::resetExecutionCount() {
    executionCount_ = 0;
}
 
/**
 * Returns the count of executions of this move.
 *
 * This count does not include squashed executions.
 *
 * @return Count of executions of this move.
 */
ClockCycleCount 
ExecutableMove::executionCount() const {
    return executionCount_;
}
 
/**
 * Returns true in case move with the move was squashed the last time
 * the instruction was executed.
 *
 * Being squashed means that the move is guarded and the guard expression
 * evaluated to false.
 *
 * @return True in case move was squashed last time its instruction was 
 *              executed.
 */
inline bool 
ExecutableMove::squashed() const {
    return squashed_;
}
 
/**
 * A dummy constructor for being used with DummyExecutableMove
 */
ExecutableMove::ExecutableMove() :
    src_(0),
    bus_(&NullBusState::instance()), 
    dst_(0),
    guarded_(false), 
    negated_(false) {
    inlineImmediate_ = NULL;
} 
        
 
 
/**
 * Constructor for SimpleExecutableMove that sets the execution count
 * 
 * @param executionCount the execution count
 */
DummyExecutableMove::DummyExecutableMove(ClockCycleCount executionCount) {
    executionCount_ = executionCount;
}