ChangeLog

2015-02-04  Filip Pizlo  <fpizlo@apple.com>

        Remove BytecodeGenerator::preserveLastVar() and replace it with a more robust mechanism for preserving non-temporary registers

        https://bugs.webkit.org/show_bug.cgi?id=141211

        Reviewed by NOBODY (OOPS!).

        Previously, the way non-temporary registers were preserved (i.e. not reclaimed anytime

        we did newTemporary()) by calling preserveLastVar() after all non-temps are created. It

        would raise the refcount on the last (highest-numbered) variable created, and rely on

        the fact that register reclamation started at higher-numbered registers and worked its

        way down. So any retained register would block any lower-numbered registers from being

        reclaimed.

        Also, preserveLastVar() sets a thing called m_firstConstantIndex. It's unused.

        This removes preserveLastVar() and makes addVar() retain each register it creates. This

        is more explicit, since addVar() is the mechanism for creating non-temporary registers.

        To make this work I had to remove an assertion that Register::setIndex() can only be

        called when the refcount is zero. This method might be called after a var is created to

        change its index. This previously worked because preserveLastVar() would be called after

        we had already made all index changes, so the vars would still have refcount zero. Now

        they have refcount 1. I think it's OK to lose this assertion; I can't remember this

        assertion ever firing in a way that alerted me to a serious issue.

        * bytecompiler/BytecodeGenerator.cpp:

        (JSC::BytecodeGenerator::BytecodeGenerator):

        (JSC::BytecodeGenerator::preserveLastVar): Deleted.

        * bytecompiler/BytecodeGenerator.h:

        (JSC::BytecodeGenerator::addVar):

        * bytecompiler/RegisterID.h:

        (JSC::RegisterID::setIndex):

2015-02-03  Filip Pizlo  <fpizlo@apple.com>

        Reviewed by NOBODY (OOPS!).

        Also removes the localArgumentsRegister local variable in BytecodeGenerator's

        constructor. It's not used.

        * bytecompiler/BytecodeGenerator.cpp:

        (JSC::BytecodeGenerator::BytecodeGenerator):

        (JSC::BytecodeGenerator::preserveLastVar): Deleted.

        * bytecompiler/BytecodeGenerator.h:

        (JSC::BytecodeGenerator::addVar):

2015-02-04  Chris Dumez  <cdumez@apple.com>

        Add removeFirst(value) / removeAll(value) methods to WTF::Vector

179602

Source/JavaScriptCore/bytecompiler/BytecodeGenerator.cpp

@@bool BytecodeGenerator::addVar(

    return true;

}

void BytecodeGenerator::preserveLastVar()

{

    if ((m_firstConstantIndex = m_calleeRegisters.size()) != 0)

        m_lastVar = &m_calleeRegisters.last();

}

BytecodeGenerator::BytecodeGenerator(VM& vm, ProgramNode* programNode, UnlinkedProgramCodeBlock* codeBlock, DebuggerMode debuggerMode, ProfilerMode profilerMode)

    : m_shouldEmitDebugHooks(Options::forceDebuggerBytecodeGeneration() || debuggerMode == DebuggerOn)

    , m_shouldEmitProfileHooks(Options::forceProfilerBytecodeGeneration() || profilerMode == ProfilerOn)

@@BytecodeGenerator::BytecodeGenerator(VM&

        }

        addParameter(simpleParameter->boundProperty(), index);

    }

431 preserveLastVar();

    // We declare the callee's name last because it should lose to a var, function, and/or parameter declaration.

    addCallee(functionNode, calleeRegister);

@@BytecodeGenerator::BytecodeGenerator(VM&

        variables.append(varStack[i].first);

    }

    codeBlock->adoptVariables(variables);

496 preserveLastVar();

}

BytecodeGenerator::~BytecodeGenerator()

179533

Source/JavaScriptCore/bytecompiler/BytecodeGenerator.h

@@namespace JSC {

        RegisterID* addVar()

        {

            ++m_codeBlock->m_numVars;

633 return newRegister();

            RegisterID* result = newRegister();

            ASSERT(VirtualRegister(result->index()).toLocal() == m_codeBlock->m_numVars - 1);

            result->ref(); // We should never free this slot.

            return result;

        }

        // Returns the index of the added var.

@@namespace JSC {

        SegmentedVector<RegisterID, 32> m_parameters;

        SegmentedVector<Label, 32> m_labels;

        LabelScopeStore m_labelScopes;

780 RefPtr<RegisterID> m_lastVar;

        int m_finallyDepth;

        int m_localScopeDepth;

        CodeType m_codeType;

@@namespace JSC {

        Vector<TryRange> m_tryRanges;

        SegmentedVector<TryData, 8> m_tryData;

794 int m_firstConstantIndex;

        int m_nextConstantOffset;

        int m_firstLazyFunction;

179533

Source/JavaScriptCore/ChangeLog

Source/JavaScriptCore/bytecompiler/BytecodeGenerator.cpp

Source/JavaScriptCore/bytecompiler/BytecodeGenerator.h

Source/JavaScriptCore/bytecompiler/RegisterID.h