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/*
* Copyright (C) 2013-2018 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 "DFGAbstractValue.h"
#if ENABLE(DFG_JIT)
#include "DFGGraph.h"
#include "JSCJSValueInlines.h"
#include "TrackedReferences.h"
namespace JSC { namespace DFG {
void AbstractValue::observeTransitions(const TransitionVector& vector)
{
if (m_type & SpecCell) {
m_structure.observeTransitions(vector);
ArrayModes newModes = 0;
for (unsigned i = vector.size(); i--;) {
if (m_arrayModes & arrayModesFromStructure(vector[i].previous.get()))
newModes |= arrayModesFromStructure(vector[i].next.get());
}
m_arrayModes |= newModes;
}
checkConsistency();
}
void AbstractValue::set(Graph& graph, const FrozenValue& value, StructureClobberState clobberState)
{
if (!!value && value.value().isCell()) {
Structure* structure = value.structure();
StructureRegistrationResult result;
RegisteredStructure registeredStructure = graph.registerStructure(structure, result);
if (result == StructureRegisteredAndWatched) {
m_structure = registeredStructure;
if (clobberState == StructuresAreClobbered) {
m_arrayModes = ALL_ARRAY_MODES;
m_structure.clobber();
} else
m_arrayModes = arrayModesFromStructure(structure);
} else {
m_structure.makeTop();
m_arrayModes = ALL_ARRAY_MODES;
}
} else {
m_structure.clear();
m_arrayModes = 0;
}
m_type = speculationFromValue(value.value());
m_value = value.value();
checkConsistency();
assertIsRegistered(graph);
}
void AbstractValue::set(Graph& graph, Structure* structure)
{
set(graph, graph.registerStructure(structure));
}
void AbstractValue::set(Graph& graph, RegisteredStructure structure)
{
RELEASE_ASSERT(structure);
m_structure = structure;
m_arrayModes = arrayModesFromStructure(structure.get());
m_type = speculationFromStructure(structure.get());
m_value = JSValue();
checkConsistency();
assertIsRegistered(graph);
}
void AbstractValue::set(Graph& graph, const RegisteredStructureSet& set)
{
m_structure = set;
m_arrayModes = set.arrayModesFromStructures();
m_type = set.speculationFromStructures();
m_value = JSValue();
checkConsistency();
assertIsRegistered(graph);
}
void AbstractValue::setType(Graph& graph, SpeculatedType type)
{
SpeculatedType cellType = type & SpecCell;
if (cellType) {
if (!(cellType & ~SpecString))
m_structure = graph.stringStructure;
else if (isSymbolSpeculation(cellType))
m_structure = graph.symbolStructure;
else
m_structure.makeTop();
m_arrayModes = ALL_ARRAY_MODES;
} else {
m_structure.clear();
m_arrayModes = 0;
}
m_type = type;
m_value = JSValue();
checkConsistency();
}
void AbstractValue::fixTypeForRepresentation(Graph& graph, NodeFlags representation, Node* node)
{
if (representation == NodeResultDouble) {
if (m_value) {
DFG_ASSERT(graph, node, m_value.isNumber());
if (m_value.isInt32())
m_value = jsDoubleNumber(m_value.asNumber());
}
if (m_type & SpecIntAnyFormat) {
m_type &= ~SpecIntAnyFormat;
m_type |= SpecAnyIntAsDouble;
}
if (m_type & ~SpecFullDouble)
DFG_CRASH(graph, node, toCString("Abstract value ", *this, " for double node has type outside SpecFullDouble.\n").data());
} else if (representation == NodeResultInt52) {
if (m_type & SpecAnyIntAsDouble) {
// AnyIntAsDouble can produce i32 or i52. SpecAnyIntAsDouble doesn't bound the magnitude of the value.
m_type &= ~SpecAnyIntAsDouble;
m_type |= SpecInt52Any;
}
if (m_type & SpecInt32Only) {
m_type &= ~SpecInt32Only;
m_type |= SpecInt32AsInt52;
}
if (m_type & ~SpecInt52Any)
DFG_CRASH(graph, node, toCString("Abstract value ", *this, " for int52 node has type outside SpecInt52Any.\n").data());
if (m_value) {
DFG_ASSERT(graph, node, m_value.isAnyInt());
m_type = int52AwareSpeculationFromValue(m_value);
}
} else {
if (m_type & SpecInt32AsInt52) {
m_type &= ~SpecInt32AsInt52;
m_type |= SpecInt32Only;
}
if (m_type & SpecNonInt32AsInt52) {
m_type &= ~SpecNonInt32AsInt52;
m_type |= SpecAnyIntAsDouble;
}
if (m_type & ~SpecBytecodeTop)
DFG_CRASH(graph, node, toCString("Abstract value ", *this, " for value node has type outside SpecBytecodeTop.\n").data());
}
checkConsistency();
}
void AbstractValue::fixTypeForRepresentation(Graph& graph, Node* node)
{
fixTypeForRepresentation(graph, node->result(), node);
}
bool AbstractValue::mergeOSREntryValue(Graph& graph, JSValue value, VariableAccessData* variable, Node* node)
{
FlushFormat flushFormat = variable->flushFormat();
{
if (flushFormat == FlushedDouble && value.isNumber())
value = jsDoubleNumber(value.asNumber());
SpeculatedType incomingType = resultFor(flushFormat) == NodeResultInt52 ? int52AwareSpeculationFromValue(value) : speculationFromValue(value);
SpeculatedType requiredType = typeFilterFor(flushFormat);
if (incomingType & ~requiredType)
return false;
}
AbstractValue oldMe = *this;
if (isClear()) {
FrozenValue* frozenValue = graph.freeze(value);
if (frozenValue->pointsToHeap()) {
m_structure = graph.registerStructure(frozenValue->structure());
m_arrayModes = arrayModesFromStructure(frozenValue->structure());
} else {
m_structure.clear();
m_arrayModes = 0;
}
m_type = speculationFromValue(value);
m_value = value;
} else {
mergeSpeculation(m_type, speculationFromValue(value));
if (!!value && value.isCell()) {
RegisteredStructure structure = graph.registerStructure(value.asCell()->structure(graph.m_vm));
mergeArrayModes(m_arrayModes, arrayModesFromStructure(structure.get()));
m_structure.merge(RegisteredStructureSet(structure));
}
if (m_value != value)
m_value = JSValue();
}
assertIsRegistered(graph);
fixTypeForRepresentation(graph, resultFor(flushFormat), node);
checkConsistency();
return oldMe != *this;
}
FiltrationResult AbstractValue::filter(
Graph& graph, const RegisteredStructureSet& other, SpeculatedType admittedTypes)
{
ASSERT(!(admittedTypes & SpecCell));
if (isClear())
return FiltrationOK;
// FIXME: This could be optimized for the common case of m_type not
// having structures, array modes, or a specific value.
// https://bugs.webkit.org/show_bug.cgi?id=109663
m_type &= other.speculationFromStructures() | admittedTypes;
m_arrayModes &= other.arrayModesFromStructures();
m_structure.filter(other);
// It's possible that prior to the above two statements we had (Foo, TOP), where
// Foo is a SpeculatedType that is disjoint with the passed RegisteredStructureSet. In that
// case, we will now have (None, [someStructure]). In general, we need to make
// sure that new information gleaned from the SpeculatedType needs to be fed back
// into the information gleaned from the RegisteredStructureSet.
m_structure.filter(m_type);
filterArrayModesByType();
filterValueByType();
return normalizeClarity(graph);
}
FiltrationResult AbstractValue::changeStructure(Graph& graph, const RegisteredStructureSet& other)
{
m_type &= other.speculationFromStructures();
m_arrayModes = other.arrayModesFromStructures();
m_structure = other;
filterValueByType();
return normalizeClarity(graph);
}
FiltrationResult AbstractValue::filterArrayModes(ArrayModes arrayModes, SpeculatedType admittedTypes)
{
ASSERT(arrayModes);
ASSERT(!(admittedTypes & SpecCell));
if (isClear())
return FiltrationOK;
m_type &= SpecCell | admittedTypes;
m_arrayModes &= arrayModes;
return normalizeClarity();
}
FiltrationResult AbstractValue::filterClassInfo(Graph& graph, const ClassInfo* classInfo)
{
// FIXME: AI should track ClassInfo to leverage hierarchical class information.
// https://bugs.webkit.org/show_bug.cgi?id=162989
if (isClear())
return FiltrationOK;
m_type &= speculationFromClassInfoInheritance(classInfo);
m_structure.filterClassInfo(classInfo);
m_structure.filter(m_type);
filterArrayModesByType();
filterValueByType();
return normalizeClarity(graph);
}
FiltrationResult AbstractValue::filterSlow(SpeculatedType type)
{
m_type &= type;
// It's possible that prior to this filter() call we had, say, (Final, TOP), and
// the passed type is Array. At this point we'll have (None, TOP). The best way
// to ensure that the structure filtering does the right thing is to filter on
// the new type (None) rather than the one passed (Array).
m_structure.filter(m_type);
filterArrayModesByType();
filterValueByType();
return normalizeClarity();
}
FiltrationResult AbstractValue::fastForwardToAndFilterSlow(AbstractValueClobberEpoch newEpoch, SpeculatedType type)
{
if (newEpoch != m_effectEpoch)
fastForwardToSlow(newEpoch);
return filterSlow(type);
}
FiltrationResult AbstractValue::filterByValue(const FrozenValue& value)
{
FiltrationResult result = filter(speculationFromValue(value.value()));
if (m_type) {
m_value = value.value();
// It is possible that SpeculatedType from value is broader than original m_type.
// The filter operation can only keep m_type as is or make it narrower.
// As a result, the SpeculatedType from m_value can become broader than m_type. This breaks an invariant.
// When setting m_value after filtering, we should filter m_value with m_type.
filterValueByType();
}
checkConsistency();
return result;
}
bool AbstractValue::contains(RegisteredStructure structure) const
{
return couldBeType(speculationFromStructure(structure.get()))
&& (m_arrayModes & arrayModesFromStructure(structure.get()))
&& m_structure.contains(structure);
}
FiltrationResult AbstractValue::filter(const AbstractValue& other)
{
m_type &= other.m_type;
m_structure.filter(other.m_structure);
m_arrayModes &= other.m_arrayModes;
m_structure.filter(m_type);
filterArrayModesByType();
filterValueByType();
if (normalizeClarity() == Contradiction)
return Contradiction;
if (m_value == other.m_value)
return FiltrationOK;
// Neither of us are BOTTOM, so an empty value means TOP.
if (!m_value) {
// We previously didn't prove a value but now we have done so.
m_value = other.m_value;
// It is possible that SpeculatedType from other.m_value is broader than original m_type.
// The filter operation can only keep m_type as is or make it narrower.
// As a result, the SpeculatedType from m_value can become broader than m_type. This breaks an invariant.
// When setting m_value after filtering, we should filter m_value with m_type.
filterValueByType();
return FiltrationOK;
}
if (!other.m_value) {
// We had proved a value but the other guy hadn't, so keep our proof.
return FiltrationOK;
}
// We both proved there to be a specific value but they are different.
clear();
return Contradiction;
}
void AbstractValue::filterValueByType()
{
// We could go further, and ensure that if the futurePossibleStructure contravenes
// the value, then we could clear both of those things. But that's unlikely to help
// in any realistic scenario, so we don't do it. Simpler is better.
if (!m_value)
return;
if (validateTypeAcceptingBoxedInt52(m_value))
return;
// We assume that the constant value can produce a narrower type at
// some point. For example, rope JSString produces SpecString, but
// it produces SpecStringIdent once it is resolved to AtomStringImpl.
// We do not make this AbstractValue cleared, but clear the constant
// value if validation fails currently.
m_value = JSValue();
}
void AbstractValue::filterArrayModesByType()
{
if (!(m_type & SpecCell))
m_arrayModes = 0;
else if (!(m_type & ~SpecArray))
m_arrayModes &= ALL_ARRAY_ARRAY_MODES;
// NOTE: If m_type doesn't have SpecArray set, that doesn't mean that the
// array modes have to be a subset of ALL_NON_ARRAY_ARRAY_MODES, since
// in the speculated type type-system, RegExpMatchesArry and ArrayPrototype
// are Otherobj (since they are not *exactly* JSArray) but in the ArrayModes
// type system they are arrays (since they expose the magical length
// property and are otherwise allocated using array allocation). Hence the
// following would be wrong:
//
// if (!(m_type & SpecArray))
// m_arrayModes &= ALL_NON_ARRAY_ARRAY_MODES;
}
bool AbstractValue::shouldBeClear() const
{
if (m_type == SpecNone)
return true;
if (!(m_type & ~SpecCell)
&& (!m_arrayModes || m_structure.isClear()))
return true;
return false;
}
FiltrationResult AbstractValue::normalizeClarity()
{
// It's useful to be able to quickly check if an abstract value is clear.
// This normalizes everything to make that easy.
FiltrationResult result;
if (shouldBeClear()) {
clear();
result = Contradiction;
} else
result = FiltrationOK;
checkConsistency();
return result;
}
FiltrationResult AbstractValue::normalizeClarity(Graph& graph)
{
FiltrationResult result = normalizeClarity();
assertIsRegistered(graph);
return result;
}
#if ASSERT_ENABLED
void AbstractValue::checkConsistency() const
{
if (!(m_type & SpecCell)) {
RELEASE_ASSERT(m_structure.isClear());
RELEASE_ASSERT(!m_arrayModes);
}
if (isClear())
RELEASE_ASSERT(!m_value);
if (!!m_value)
RELEASE_ASSERT(validateTypeAcceptingBoxedInt52(m_value));
// Note that it's possible for a prediction like (Final, []). This really means that
// the value is bottom and that any code that uses the value is unreachable. But
// we don't want to get pedantic about this as it would only increase the computational
// complexity of the code.
}
void AbstractValue::assertIsRegistered(Graph& graph) const
{
m_structure.assertIsRegistered(graph);
}
#endif // ASSERT_ENABLED
ResultType AbstractValue::resultType() const
{
ASSERT(isType(SpecBytecodeTop));
if (isType(SpecBoolean))
return ResultType::booleanType();
if (isType(SpecInt32Only))
return ResultType::numberTypeIsInt32();
if (isType(SpecBytecodeNumber))
return ResultType::numberType();
if (isType(SpecString))
return ResultType::stringType();
if (isType(SpecString | SpecBytecodeNumber))
return ResultType::stringOrNumberType();
return ResultType::unknownType();
}
void AbstractValue::dump(PrintStream& out) const
{
dumpInContext(out, nullptr);
}
void AbstractValue::dumpInContext(PrintStream& out, DumpContext* context) const
{
out.print("(", SpeculationDump(m_type));
if (m_type & SpecCell) {
out.print(
", ", ArrayModesDump(m_arrayModes), ", ",
inContext(m_structure, context));
}
if (!!m_value)
out.print(", ", inContext(m_value, context));
out.print(", ", m_effectEpoch);
out.print(")");
}
void AbstractValue::validateReferences(const TrackedReferences& trackedReferences)
{
trackedReferences.check(m_value);
m_structure.validateReferences(trackedReferences);
}
#if USE(JSVALUE64) && !defined(NDEBUG)
void AbstractValue::ensureCanInitializeWithZeros()
{
std::aligned_storage<sizeof(AbstractValue), alignof(AbstractValue)>::type zeroFilledStorage;
memset(static_cast<void*>(&zeroFilledStorage), 0, sizeof(AbstractValue));
ASSERT(*this == *static_cast<AbstractValue*>(static_cast<void*>(&zeroFilledStorage)));
}
#endif
void AbstractValue::fastForwardToSlow(AbstractValueClobberEpoch newEpoch)
{
ASSERT(newEpoch != m_effectEpoch);
if (newEpoch.clobberEpoch() != m_effectEpoch.clobberEpoch())
clobberStructures();
if (newEpoch.structureClobberState() == StructuresAreWatched)
m_structure.observeInvalidationPoint();
m_effectEpoch = newEpoch;
checkConsistency();
}
} } // namespace JSC::DFG
#endif // ENABLE(DFG_JIT)