ConstantAliasAnalyzer.cc

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/*
    Copyright (c) 2002-2009 Tampere University.
 
    This file is part of TTA-Based Codesign Environment (TCE).
 
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/**
 * @file ConstantAliasAnalyzer.cc
 *
 * Implementation of ConstantAliasAnalyzer class.
 * 
 * This class does simple alias analysis between memove addresses
 * that come directly from immediates.
 *
 * @author Heikki Kultala 2007 (heikki.kultala-no.spam-tut.fi)
 * @note rating: red
 */
 
#include "ConstantAliasAnalyzer.hh"
 
#include "MoveNode.hh"
#include "Move.hh"
#include "DataDependenceGraph.hh"
#include "Terminal.hh"
#include "Operation.hh"
#include "MoveNodeSet.hh"
 
using namespace TTAProgram;
using namespace TTAMachine;
 
 
 
bool ConstantAliasAnalyzer::getConstantAddress(
    DataDependenceGraph& ddg, const ProgramOperation& po,
    long& addr, long& loopIncrement) {
    const MoveNode* mn = addressOperandMove(po);
    addr = 0;
    while (mn != NULL && mn->isMove()) {
        if (mn->isSourceVariable()) {
            MoveNode* prevSrc = ddg.onlyRegisterRawSource(*mn,2,2);
            MoveNode* loopSrc = ddg.onlyRegisterRawSource(*mn,2,1);
            if (prevSrc == NULL) {
                break;
            }
            if (loopSrc) {
                if (!findIncrement(*loopSrc, loopIncrement)) {
                    return false;
                }
            }
            mn = prevSrc;
        } else {
            if (mn->isSourceOperation()) {
                const MoveNode* incrementInput = findIncrement(*mn, addr);
                if (incrementInput != NULL) {
                    mn = incrementInput;
                } else {
                    mn = searchLoopIndexBasedIncrement(ddg, *mn, loopIncrement);
                }
            } else {
                if (mn->isMove()) {
                    const Move& move = mn->move();
                    if (!move.isFunctionCall()) {
                        const Terminal& src = move.source();
                        if (src.isImmediate()) {
                            addr += src.value().unsignedValue();
                            return true;
                        }
                    }
                }
                return false;
            }
        }
    }
    return false;
}
 
bool
ConstantAliasAnalyzer::isAddressTraceable(
    DataDependenceGraph& ddg, const ProgramOperation& po) {
    long tmp;
    long tmp2 = 0;
    return getConstantAddress(ddg, po, tmp, tmp2);
}
 
// TODO: does not handle unaligned 64-bit memory operations well.
MemoryAliasAnalyzer::AliasingResult
ConstantAliasAnalyzer::analyze(
    DataDependenceGraph& ddg, 
    const ProgramOperation& pop1, 
    const ProgramOperation& pop2, 
    MoveNodeUse::BBRelation bbRel) {
 
    long addr1, addr2;
    long inc1 = 0, inc2 = 0;
 
    if (!getConstantAddress(ddg, pop1, addr1, inc1) ||
        !getConstantAddress(ddg, pop2, addr2, inc2)) {
        return ALIAS_UNKNOWN;
    }
 
    // if updated different amount, may overlap?
    if (inc1 != inc2) {
        return ALIAS_UNKNOWN;
    }
 
    if (bbRel != MoveNodeUse::LOOP) {
        return compareIndeces(addr1, addr2, pop1, pop2);
    } else {
        return compareIndeces(addr1, addr2+inc2, pop1, pop2);
    }
}
 
ConstantAliasAnalyzer::~ConstantAliasAnalyzer() {}