AirReportUsedRegisters.cpp   [plain text]

/*
 * Copyright (C) 2015-2016 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
 */

#include "config.h"
#include "AirReportUsedRegisters.h"

#if ENABLE(B3_JIT)

#include "AirArgInlines.h"
#include "AirCode.h"
#include "AirInstInlines.h"
#include "AirLiveness.h"
#include "AirPhaseScope.h"

namespace JSC { namespace B3 { namespace Air {

void reportUsedRegisters(Code& code)
{
    PhaseScope phaseScope(code, "reportUsedRegisters");

    RegLiveness liveness(code);

    for (BasicBlock* block : code) {
        RegLiveness::LocalCalc localCalc(liveness, block);

        for (unsigned instIndex = block->size(); instIndex--;) {
            Inst& inst = block->at(instIndex);

            // Kill dead assignments to registers. For simplicity we say that a store is killable if
            // it has only late defs and those late defs are to registers that are dead right now.
            if (!inst.hasNonArgEffects()) {
                bool canDelete = true;
                inst.forEachArg(
                    [&] (Arg& arg, Arg::Role role, Arg::Type, Arg::Width) {
                        if (Arg::isEarlyDef(role)) {
                            canDelete = false;
                            return;
                        }
                        if (!Arg::isLateDef(role))
                            return;
                        if (!arg.isReg()) {
                            canDelete = false;
                            return;
                        }
                        if (localCalc.isLive(arg.reg())) {
                            canDelete = false;
                            return;
                        }
                    });
                if (canDelete)
                    inst = Inst();
            }
            
            if (inst.opcode == Patch) {
                RegisterSet registerSet;
                for (Reg reg : localCalc.live())
                    registerSet.set(reg);
                inst.reportUsedRegisters(registerSet);
            }
            localCalc.execute(instIndex);
        }
        
        block->insts().removeAllMatching(
            [&] (const Inst& inst) -> bool {
                return !inst;
            });
    }
}

} } } // namespace JSC::B3::Air

#endif // ENABLE(B3_JIT)