timing_expr.cc

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/*
 * Copyright (c) 2013-2014 ARM Limited
 * All rights reserved.
 *
 * The license below extends only to copyright in the software and shall
 * not be construed as granting a license to any other intellectual
 * property including but not limited to intellectual property relating
 * to a hardware implementation of the functionality of the software
 * licensed hereunder.  You may use the software subject to the license
 * terms below provided that you ensure that this notice is replicated
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 * modified or unmodified, in source code or in binary form.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met: redistributions of source code must retain the above copyright
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 * redistributions in binary form must reproduce the above copyright
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 * this software without specific prior written permission.
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 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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 */
 
#include "cpu/timing_expr.hh"
 
#include "base/intmath.hh"
 
namespace gem5
{
 
TimingExprEvalContext::TimingExprEvalContext(const StaticInstPtr &inst_,
    ThreadContext *thread_, TimingExprLet *let_) :
    inst(inst_), thread(thread_), let(let_)
{
    /* Reserve space to hold the results of evaluating the
     *  let expressions */
    if (let) {
        unsigned int num_defns = let->defns.size();
 
        results.resize(num_defns, 0);
        resultAvailable.resize(num_defns, false);
    }
}
 
uint64_t
TimingExprSrcReg::eval(TimingExprEvalContext &context)
{
    return context.inst->srcRegIdx(index).index();
}
 
uint64_t
TimingExprReadIntReg::eval(TimingExprEvalContext &context)
{
    return context.thread->readIntReg(reg->eval(context));
}
 
uint64_t
TimingExprLet::eval(TimingExprEvalContext &context)
{
    TimingExprEvalContext new_context(context.inst, context.thread, this);
 
    return expr->eval(new_context);
}
 
uint64_t
TimingExprRef::eval(TimingExprEvalContext &context)
{
    /* Lookup the result, evaluating if necessary.  @todo, this
     *  should have more error checking */
    if (!context.resultAvailable[index]) {
        context.results[index] = context.let->defns[index]->eval(context);
        context.resultAvailable[index] = true;
    }
 
    return context.results[index];
}
 
uint64_t
TimingExprUn::eval(TimingExprEvalContext &context)
{
    uint64_t arg_value = arg->eval(context);
    uint64_t ret = 0;
 
    switch (op) {
      case enums::timingExprSizeInBits:
        if (arg_value == 0)
            ret = 0;
        else
            ret = ceilLog2(arg_value);
        break;
      case enums::timingExprNot:
        ret = arg_value != 0;
        break;
      case enums::timingExprInvert:
        ret = ~arg_value;
        break;
      case enums::timingExprSignExtend32To64:
        ret = static_cast<int64_t>(
            static_cast<int32_t>(arg_value));
        break;
      case enums::timingExprAbs:
        if (static_cast<int64_t>(arg_value) < 0)
            ret = -arg_value;
        else
            ret = arg_value;
        break;
      default:
        break;
    }
 
    return ret;
}
 
uint64_t
TimingExprBin::eval(TimingExprEvalContext &context)
{
    uint64_t left_value = left->eval(context);
    uint64_t right_value = right->eval(context);
    uint64_t ret = 0;
 
    switch (op) {
      case enums::timingExprAdd:
        ret = left_value + right_value;
        break;
      case enums::timingExprSub:
        ret = left_value - right_value;
        break;
      case enums::timingExprUMul:
        ret = left_value * right_value;
        break;
      case enums::timingExprUDiv:
        if (right_value != 0) {
            ret = left_value / right_value;
        }
        break;
      case enums::timingExprUCeilDiv:
        if (right_value != 0) {
            ret = (left_value + (right_value - 1)) / right_value;
        }
        break;
      case enums::timingExprSMul:
        ret = static_cast<int64_t>(left_value) *
            static_cast<int64_t>(right_value);
        break;
      case enums::timingExprSDiv:
        if (right_value != 0) {
            ret = static_cast<int64_t>(left_value) /
                static_cast<int64_t>(right_value);
        }
        break;
      case enums::timingExprEqual:
        ret = left_value == right_value;
        break;
      case enums::timingExprNotEqual:
        ret = left_value != right_value;
        break;
      case enums::timingExprULessThan:
        ret = left_value < right_value;
        break;
      case enums::timingExprUGreaterThan:
        ret = left_value > right_value;
        break;
      case enums::timingExprSLessThan:
        ret = static_cast<int64_t>(left_value) <
            static_cast<int64_t>(right_value);
        break;
      case enums::timingExprSGreaterThan:
        ret = static_cast<int64_t>(left_value) >
            static_cast<int64_t>(right_value);
        break;
      case enums::timingExprAnd:
        ret = (left_value != 0) && (right_value != 0);
        break;
      case enums::timingExprOr:
        ret = (left_value != 0) || (right_value != 0);
        break;
      default:
        break;
    }
 
    return ret;
}
 
uint64_t
TimingExprIf::eval(TimingExprEvalContext &context)
{
    uint64_t cond_value = cond->eval(context);
 
    if (cond_value != 0)
        return trueExpr->eval(context);
    else
        return falseExpr->eval(context);
}
 
} // namespace gem5