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/*
* Copyright (C) 2015-2024 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 "DFGCombinedLiveness.h"
#if ENABLE(DFG_JIT)
#include "DFGAvailabilityMap.h"
#include "DFGBlockMapInlines.h"
#include "JSCJSValueInlines.h"
namespace JSC { namespace DFG {
static void addBytecodeLiveness(Graph& graph, AvailabilityMap& availabilityMap, NodeSet& seen, Node* node)
{
graph.forAllLiveInBytecode(
node->origin.forExit,
[&] (Operand reg) {
availabilityMap.closeStartingWithLocal(
reg,
[&] (Node* node) -> bool {
return seen.contains(node);
},
[&] (Node* node) -> bool {
return seen.add(node).isNewEntry;
});
});
}
NodeSet liveNodesAtHead(Graph& graph, BasicBlock* block)
{
NodeSet seen;
for (NodeFlowProjection node : block->ssa->liveAtHead) {
if (node.kind() == NodeFlowProjection::Primary)
seen.addVoid(node.node());
}
addBytecodeLiveness(graph, block->ssa->availabilityAtHead, seen, block->at(0));
return seen;
}
CombinedLiveness::CombinedLiveness(Graph& graph)
: liveAtHead(graph)
, liveAtTail(graph)
{
// First compute
// - The liveAtHead for each block.
// - The liveAtTail for blocks that won't properly propagate
// the information based on their empty successor list.
for (BasicBlock* block : graph.blocksInNaturalOrder()) {
liveAtHead[block] = liveNodesAtHead(graph, block);
// If we don't have successors, we can't rely on the propagation below. This doesn't usually
// do anything for terminal blocks, since the last node is usually a return, so nothing is live
// after it. However, we may also have the end of the basic block be:
//
// ForceOSRExit
// Unreachable
//
// And things may definitely be live in bytecode at that point in the program.
if (!block->numSuccessors()) {
NodeSet seen;
addBytecodeLiveness(graph, block->ssa->availabilityAtTail, seen, block->last());
liveAtTail[block] = seen;
}
}
// Now compute the liveAtTail by unifying the liveAtHead of the successors.
for (BasicBlock* block : graph.blocksInNaturalOrder()) {
for (BasicBlock* successor : block->successors()) {
for (Node* node : liveAtHead[successor])
liveAtTail[block].addVoid(node);
}
}
}
} } // namespace JSC::DFG
#endif // ENABLE(DFG_JIT)
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