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authorLorry Tar Creator <lorry-tar-importer@lorry>2015-05-20 09:56:07 +0000
committerLorry Tar Creator <lorry-tar-importer@lorry>2015-05-20 09:56:07 +0000
commit41386e9cb918eed93b3f13648cbef387e371e451 (patch)
treea97f9d7bd1d9d091833286085f72da9d83fd0606 /Source/JavaScriptCore/dfg/DFGStructureAbstractValue.cpp
parente15dd966d523731101f70ccf768bba12435a0208 (diff)
downloadWebKitGtk-tarball-41386e9cb918eed93b3f13648cbef387e371e451.tar.gz
webkitgtk-2.4.9webkitgtk-2.4.9
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diff --git a/Source/JavaScriptCore/dfg/DFGStructureAbstractValue.cpp b/Source/JavaScriptCore/dfg/DFGStructureAbstractValue.cpp
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-/*
- * Copyright (C) 2014, 2015 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 "DFGStructureAbstractValue.h"
-
-#if ENABLE(DFG_JIT)
-
-#include "DFGGraph.h"
-
-namespace JSC { namespace DFG {
-
-// Comment out the empty SAMPLE() definition, and uncomment the one that uses SamplingRegion, if
-// you want extremely fine-grained profiling in this code.
-#define SAMPLE(name)
-//#define SAMPLE(name) SamplingRegion samplingRegion(name)
-
-#if !ASSERT_DISABLED
-void StructureAbstractValue::assertIsRegistered(Graph& graph) const
-{
- SAMPLE("StructureAbstractValue assertIsRegistered");
-
- if (isTop())
- return;
-
- for (unsigned i = size(); i--;)
- graph.assertIsRegistered(at(i));
-}
-#endif // !ASSERT_DISABLED
-
-void StructureAbstractValue::clobber()
-{
- SAMPLE("StructureAbstractValue clobber");
-
- // The premise of this approach to clobbering is that anytime we introduce
- // a watchable structure into an abstract value, we watchpoint it. You can assert
- // that this holds by calling assertIsWatched().
-
- if (isTop())
- return;
-
- setClobbered(true);
-
- if (m_set.isThin()) {
- if (!m_set.singleEntry())
- return;
- if (!m_set.singleEntry()->dfgShouldWatch())
- makeTopWhenThin();
- return;
- }
-
- StructureSet::OutOfLineList* list = m_set.list();
- for (unsigned i = list->m_length; i--;) {
- if (!list->list()[i]->dfgShouldWatch()) {
- makeTop();
- return;
- }
- }
-}
-
-void StructureAbstractValue::observeTransition(Structure* from, Structure* to)
-{
- SAMPLE("StructureAbstractValue observeTransition");
-
- ASSERT(!from->dfgShouldWatch());
-
- if (isTop())
- return;
-
- if (!m_set.contains(from))
- return;
-
- if (!m_set.add(to))
- return;
-
- if (m_set.size() > polymorphismLimit)
- makeTop();
-}
-
-void StructureAbstractValue::observeTransitions(const TransitionVector& vector)
-{
- SAMPLE("StructureAbstractValue observeTransitions");
-
- if (isTop())
- return;
-
- StructureSet newStructures;
- for (unsigned i = vector.size(); i--;) {
- ASSERT(!vector[i].previous->dfgShouldWatch());
-
- if (!m_set.contains(vector[i].previous))
- continue;
-
- newStructures.add(vector[i].next);
- }
-
- if (!m_set.merge(newStructures))
- return;
-
- if (m_set.size() > polymorphismLimit)
- makeTop();
-}
-
-bool StructureAbstractValue::add(Structure* structure)
-{
- SAMPLE("StructureAbstractValue add");
-
- if (isTop())
- return false;
-
- if (!m_set.add(structure))
- return false;
-
- if (m_set.size() > polymorphismLimit)
- makeTop();
-
- return true;
-}
-
-bool StructureAbstractValue::merge(const StructureSet& other)
-{
- SAMPLE("StructureAbstractValue merge set");
-
- if (isTop())
- return false;
-
- return mergeNotTop(other);
-}
-
-bool StructureAbstractValue::mergeSlow(const StructureAbstractValue& other)
-{
- SAMPLE("StructureAbstractValue merge value slow");
-
- // It isn't immediately obvious that the code below is doing the right thing, so let's go
- // through it.
- //
- // This not clobbered, other not clobbered: Clearly, we don't want to make anything clobbered
- // since we just have two sets and we are merging them. mergeNotTop() can handle this just
- // fine.
- //
- // This clobbered, other clobbered: Clobbered means that we have a set of things, plus we
- // temporarily have the set of all things but the latter will go away once we hit the next
- // invalidation point. This allows us to merge two clobbered sets the natural way. For now
- // the set will still be TOP (and so we keep the clobbered bit set), but we know that after
- // invalidation, we will have the union of the this and other.
- //
- // This clobbered, other not clobbered: It's safe to merge in other for both before and after
- // invalidation, so long as we leave the clobbered bit set. Before invalidation this has no
- // effect since the set will still appear to have all things in it. The way to think about
- // what invalidation would do is imagine if we had a set A that was clobbered and a set B
- // that wasn't and we considered the following two cases. Note that we expect A to be the
- // same at the end in both cases:
- //
- // A.merge(B) InvalidationPoint
- // InvalidationPoint A.merge(B)
- //
- // The fact that we expect A to be the same in both cases means that we want to merge other
- // into this but keep the clobbered bit.
- //
- // This not clobbered, other clobbered: This is just the converse of the previous case. We
- // want to merge other into this and set the clobbered bit.
-
- bool changed = false;
-
- if (!isClobbered() && other.isClobbered()) {
- setClobbered(true);
- changed = true;
- }
-
- changed |= mergeNotTop(other.m_set);
-
- return changed;
-}
-
-bool StructureAbstractValue::mergeNotTop(const StructureSet& other)
-{
- SAMPLE("StructureAbstractValue merge not top");
-
- if (!m_set.merge(other))
- return false;
-
- if (m_set.size() > polymorphismLimit)
- makeTop();
-
- return true;
-}
-
-void StructureAbstractValue::filter(const StructureSet& other)
-{
- SAMPLE("StructureAbstractValue filter set");
-
- if (isTop()) {
- m_set = other;
- return;
- }
-
- if (isClobbered()) {
- // We have two choices here:
- //
- // Do nothing: It's legal to keep our set intact, which would essentially mean that for
- // now, our set would behave like TOP but after the next invalidation point it wold be
- // a finite set again. This may be a good choice if 'other' is much bigger than our
- // m_set.
- //
- // Replace m_set with other and clear the clobber bit: This is also legal, and means that
- // we're no longer clobbered. This is usually better because it immediately gives us a
- // smaller set.
- //
- // This scenario should come up rarely. We usually don't do anything to an abstract value
- // after it is clobbered. But we apply some heuristics.
-
- if (other.size() > m_set.size() + clobberedSupremacyThreshold)
- return; // Keep the clobbered set.
-
- m_set = other;
- setClobbered(false);
- return;
- }
-
- m_set.filter(other);
-}
-
-void StructureAbstractValue::filter(const StructureAbstractValue& other)
-{
- SAMPLE("StructureAbstractValue filter value");
-
- if (other.isTop())
- return;
-
- if (other.isClobbered()) {
- if (isTop())
- return;
-
- if (!isClobbered()) {
- // See justification in filter(const StructureSet&), above. An unclobbered set is
- // almost always better.
- if (m_set.size() > other.m_set.size() + clobberedSupremacyThreshold)
- *this = other; // Keep the clobbered set.
- return;
- }
-
- m_set.filter(other.m_set);
- return;
- }
-
- filter(other.m_set);
-}
-
-void StructureAbstractValue::filterSlow(SpeculatedType type)
-{
- SAMPLE("StructureAbstractValue filter type slow");
-
- if (!(type & SpecCell)) {
- clear();
- return;
- }
-
- ASSERT(!isTop());
-
- m_set.genericFilter(
- [&] (Structure* structure) {
- return !!(speculationFromStructure(structure) & type);
- });
-}
-
-bool StructureAbstractValue::contains(Structure* structure) const
-{
- SAMPLE("StructureAbstractValue contains");
-
- if (isInfinite())
- return true;
-
- return m_set.contains(structure);
-}
-
-bool StructureAbstractValue::isSubsetOf(const StructureSet& other) const
-{
- SAMPLE("StructureAbstractValue isSubsetOf set");
-
- if (isInfinite())
- return false;
-
- return m_set.isSubsetOf(other);
-}
-
-bool StructureAbstractValue::isSubsetOf(const StructureAbstractValue& other) const
-{
- SAMPLE("StructureAbstractValue isSubsetOf value");
-
- if (isTop())
- return false;
-
- if (other.isTop())
- return true;
-
- if (isClobbered() == other.isClobbered())
- return m_set.isSubsetOf(other.m_set);
-
- // Here it gets tricky. If in doubt, return false!
-
- if (isClobbered())
- return false; // A clobbered set is never a subset of an unclobbered set.
-
- // An unclobbered set is currently a subset of a clobbered set, but it may not be so after
- // invalidation.
- return m_set.isSubsetOf(other.m_set);
-}
-
-bool StructureAbstractValue::isSupersetOf(const StructureSet& other) const
-{
- SAMPLE("StructureAbstractValue isSupersetOf set");
-
- if (isInfinite())
- return true;
-
- return m_set.isSupersetOf(other);
-}
-
-bool StructureAbstractValue::overlaps(const StructureSet& other) const
-{
- SAMPLE("StructureAbstractValue overlaps set");
-
- if (isInfinite())
- return true;
-
- return m_set.overlaps(other);
-}
-
-bool StructureAbstractValue::overlaps(const StructureAbstractValue& other) const
-{
- SAMPLE("StructureAbstractValue overlaps value");
-
- if (other.isInfinite())
- return true;
-
- return overlaps(other.m_set);
-}
-
-bool StructureAbstractValue::equalsSlow(const StructureAbstractValue& other) const
-{
- SAMPLE("StructureAbstractValue equalsSlow");
-
- ASSERT(m_set.m_pointer != other.m_set.m_pointer);
- ASSERT(!isTop());
- ASSERT(!other.isTop());
-
- return m_set == other.m_set
- && isClobbered() == other.isClobbered();
-}
-
-void StructureAbstractValue::dumpInContext(PrintStream& out, DumpContext* context) const
-{
- if (isClobbered())
- out.print("Clobbered:");
-
- if (isTop())
- out.print("TOP");
- else
- out.print(inContext(m_set, context));
-}
-
-void StructureAbstractValue::dump(PrintStream& out) const
-{
- dumpInContext(out, 0);
-}
-
-void StructureAbstractValue::validateReferences(const TrackedReferences& trackedReferences) const
-{
- if (isTop())
- return;
- m_set.validateReferences(trackedReferences);
-}
-
-} } // namespace JSC::DFG
-
-#endif // ENABLE(DFG_JIT)
-