Source/JavaScriptCore/b3/air/AirHandleCalleeSaves.cpp

/*
 * Copyright (C) 2015-2017 Apple Inc. All rights reserved.
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 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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#include "config.h"
#include "AirHandleCalleeSaves.h"

#if ENABLE(B3_JIT)

#include "AirCode.h"
#include "AirInstInlines.h"

namespace JSC { namespace B3 { namespace Air {

void handleCalleeSaves(Code& code)
{
    RegisterSet usedCalleeSaves;

    for (BasicBlock* block : code) {
        for (Inst& inst : *block) {
            inst.forEachTmpFast(
                [&] (Tmp& tmp) {
                    // At first we just record all used regs.
                    usedCalleeSaves.set(tmp.reg());
                });

            if (inst.kind.opcode == Patch)
                usedCalleeSaves.merge(inst.extraClobberedRegs());
        }
    }

    // Now we filter to really get the callee saves.
    usedCalleeSaves.filter(RegisterSet::calleeSaveRegisters());
    usedCalleeSaves.filter(code.mutableRegs());
    usedCalleeSaves.exclude(RegisterSet::stackRegisters()); // We don't need to save FP here.

    if (!usedCalleeSaves.numberOfSetRegisters())
        return;

    RegisterAtOffsetList calleeSaveRegisters = RegisterAtOffsetList(usedCalleeSaves);

    size_t byteSize = 0;
    for (const RegisterAtOffset& entry : calleeSaveRegisters)
        byteSize = std::max(static_cast<size_t>(-entry.offset()), byteSize);

    code.setCalleeSaveRegisterAtOffsetList(
        WTFMove(calleeSaveRegisters),
        code.addStackSlot(byteSize, StackSlotKind::Locked));
}

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

#endif // ENABLE(B3_JIT)