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/*
* Copyright (C) 2013 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.
*/
#ifndef DFGInPlaceAbstractState_h
#define DFGInPlaceAbstractState_h
#if ENABLE(DFG_JIT)
#include "DFGAbstractValue.h"
#include "DFGBranchDirection.h"
#include "DFGGraph.h"
#include "DFGNode.h"
namespace JSC { namespace DFG {
class InPlaceAbstractState {
WTF_MAKE_FAST_ALLOCATED;
public:
InPlaceAbstractState(Graph&);
~InPlaceAbstractState();
void createValueForNode(Node*) { }
AbstractValue& forNode(Node* node)
{
return node->value;
}
AbstractValue& forNode(Edge edge)
{
return forNode(edge.node());
}
Operands<AbstractValue>& variables()
{
return m_variables;
}
// Call this before beginning CFA to initialize the abstract values of
// arguments, and to indicate which blocks should be listed for CFA
// execution.
void initialize();
// Start abstractly executing the given basic block. Initializes the
// notion of abstract state to what we believe it to be at the head
// of the basic block, according to the basic block's data structures.
// This method also sets cfaShouldRevisit to false.
void beginBasicBlock(BasicBlock*);
BasicBlock* block() const { return m_block; }
// Finish abstractly executing a basic block. If MergeToTail or
// MergeToSuccessors is passed, then this merges everything we have
// learned about how the state changes during this block's execution into
// the block's data structures.
//
// Returns true if the state of the block at the tail was changed,
// and, if the state at the heads of successors was changed.
// A true return means that you must revisit (at least) the successor
// blocks. This also sets cfaShouldRevisit to true for basic blocks
// that must be visited next.
bool endBasicBlock();
// Reset the AbstractState. This throws away any results, and at this point
// you can safely call beginBasicBlock() on any basic block.
void reset();
// Did the last executed node clobber the world?
bool didClobber() const { return m_didClobber; }
// Are structures currently clobbered?
StructureClobberState structureClobberState() const { return m_structureClobberState; }
// Is the execution state still valid? This will be false if execute() has
// returned false previously.
bool isValid() const { return m_isValid; }
// Merge the abstract state stored at the first block's tail into the second
// block's head. Returns true if the second block's state changed. If so,
// that block must be abstractly interpreted again. This also sets
// to->cfaShouldRevisit to true, if it returns true, or if to has not been
// visited yet.
bool merge(BasicBlock* from, BasicBlock* to);
// Merge the abstract state stored at the block's tail into all of its
// successors. Returns true if any of the successors' states changed. Note
// that this is automatically called in endBasicBlock() if MergeMode is
// MergeToSuccessors.
bool mergeToSuccessors(BasicBlock*);
// Methods intended to be called from AbstractInterpreter.
void setDidClobber(bool didClobber) { m_didClobber = didClobber; }
void setStructureClobberState(StructureClobberState value) { m_structureClobberState = value; }
void setIsValid(bool isValid) { m_isValid = isValid; }
void setBranchDirection(BranchDirection branchDirection) { m_branchDirection = branchDirection; }
// This method is evil - it causes a huge maintenance headache and there is a gross amount of
// code devoted to it. It would be much nicer to just always run the constant folder on each
// block. But, the last time we did it, it was a 1% SunSpider regression:
// https://bugs.webkit.org/show_bug.cgi?id=133947
// So, we should probably keep this method.
void setFoundConstants(bool foundConstants) { m_foundConstants = foundConstants; }
private:
bool mergeStateAtTail(AbstractValue& destination, AbstractValue& inVariable, Node*);
static bool mergeVariableBetweenBlocks(AbstractValue& destination, AbstractValue& source, Node* destinationNode, Node* sourceNode);
Graph& m_graph;
Operands<AbstractValue> m_variables;
BasicBlock* m_block;
bool m_foundConstants;
bool m_isValid;
bool m_didClobber;
StructureClobberState m_structureClobberState;
BranchDirection m_branchDirection; // This is only set for blocks that end in Branch and that execute to completion (i.e. m_isValid == true).
};
} } // namespace JSC::DFG
#endif // ENABLE(DFG_JIT)
#endif // DFGInPlaceAbstractState_h
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