| /* |
| * Copyright (C) 2015-2019 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 "DFGVarargsForwardingPhase.h" |
| |
| #if ENABLE(DFG_JIT) |
| |
| #include "ClonedArguments.h" |
| #include "DFGArgumentsUtilities.h" |
| #include "DFGClobberize.h" |
| #include "DFGForAllKills.h" |
| #include "DFGGraph.h" |
| #include "DFGPhase.h" |
| #include "JSCInlines.h" |
| #include <wtf/ListDump.h> |
| |
| namespace JSC { namespace DFG { |
| |
| namespace { |
| |
| |
| class VarargsForwardingPhase : public Phase { |
| static constexpr bool verbose = false; |
| public: |
| VarargsForwardingPhase(Graph& graph) |
| : Phase(graph, "varargs forwarding") |
| { |
| } |
| |
| bool run() |
| { |
| DFG_ASSERT(m_graph, nullptr, m_graph.m_form != SSA); |
| |
| if (verbose) { |
| dataLog("Graph before varargs forwarding:\n"); |
| m_graph.dump(); |
| } |
| |
| m_changed = false; |
| for (BasicBlock* block : m_graph.blocksInNaturalOrder()) |
| handleBlock(block); |
| return m_changed; |
| } |
| |
| private: |
| void handleBlock(BasicBlock* block) |
| { |
| for (unsigned nodeIndex = 0; nodeIndex < block->size(); ++nodeIndex) { |
| Node* node = block->at(nodeIndex); |
| switch (node->op()) { |
| case CreateDirectArguments: |
| case CreateClonedArguments: |
| handleCandidate(block, nodeIndex); |
| break; |
| default: |
| break; |
| } |
| } |
| } |
| |
| void handleCandidate(BasicBlock* block, unsigned candidateNodeIndex) |
| { |
| // We expect calls into this function to be rare. So, this is written in a simple O(n) manner. |
| |
| Node* candidate = block->at(candidateNodeIndex); |
| if (verbose) |
| dataLog("Handling candidate ", candidate, "\n"); |
| |
| // We eliminate GetButterfly over CreateClonedArguments if the butterfly is only |
| // used by a GetByOffset that loads the CreateClonedArguments's length. We also |
| // eliminate it if the GetButterfly node is totally unused. |
| Vector<Node*, 1> candidateButterflies; |
| |
| // Find the index of the last node in this block to use the candidate, and look for escaping |
| // sites. |
| unsigned lastUserIndex = candidateNodeIndex; |
| Vector<VirtualRegister, 2> relevantLocals; // This is a set. We expect it to be a small set. |
| for (unsigned nodeIndex = candidateNodeIndex + 1; nodeIndex < block->size(); ++nodeIndex) { |
| Node* node = block->at(nodeIndex); |
| |
| auto defaultEscape = [&] { |
| if (m_graph.uses(node, candidate)) { |
| if (verbose) |
| dataLog(" Escape at ", node, "\n"); |
| return true; |
| } |
| return false; |
| }; |
| |
| bool validGetByOffset = false; |
| switch (node->op()) { |
| case MovHint: |
| if (node->child1() != candidate) |
| break; |
| ASSERT_WITH_MESSAGE(!node->unlinkedOperand().isTmp(), "We don't currently support a tmp referring to an arguments object."); |
| lastUserIndex = nodeIndex; |
| if (!relevantLocals.contains(node->unlinkedOperand().virtualRegister())) |
| relevantLocals.append(node->unlinkedOperand().virtualRegister()); |
| break; |
| |
| case CheckVarargs: |
| case Check: { |
| bool sawEscape = false; |
| m_graph.doToChildren( |
| node, |
| [&] (Edge edge) { |
| if (edge == candidate) |
| lastUserIndex = nodeIndex; |
| |
| if (edge.willNotHaveCheck()) |
| return; |
| |
| if (alreadyChecked(edge.useKind(), SpecObject)) |
| return; |
| |
| sawEscape = true; |
| }); |
| if (sawEscape) { |
| if (verbose) |
| dataLog(" Escape at ", node, "\n"); |
| return; |
| } |
| break; |
| } |
| |
| case VarargsLength: |
| case LoadVarargs: |
| if (m_graph.uses(node, candidate)) |
| lastUserIndex = nodeIndex; |
| break; |
| |
| case CallVarargs: |
| case ConstructVarargs: |
| case TailCallVarargs: |
| case TailCallVarargsInlinedCaller: |
| if (node->child1() == candidate || node->child2() == candidate) { |
| if (verbose) |
| dataLog(" Escape at ", node, "\n"); |
| return; |
| } |
| if (node->child2() == candidate) |
| lastUserIndex = nodeIndex; |
| break; |
| |
| case SetLocal: |
| if (node->child1() == candidate && node->variableAccessData()->isLoadedFrom()) { |
| if (verbose) |
| dataLog(" Escape at ", node, "\n"); |
| return; |
| } |
| break; |
| |
| case GetArrayLength: { |
| if (node->arrayMode().type() == Array::DirectArguments && node->child1() == candidate && node->child1()->op() == CreateDirectArguments) { |
| lastUserIndex = nodeIndex; |
| break; |
| } |
| if (defaultEscape()) |
| return; |
| break; |
| } |
| |
| case GetButterfly: { |
| if (node->child1() == candidate && candidate->op() == CreateClonedArguments) { |
| lastUserIndex = nodeIndex; |
| candidateButterflies.append(node); |
| break; |
| } |
| if (defaultEscape()) |
| return; |
| break; |
| } |
| |
| case FilterGetByStatus: |
| case FilterPutByIdStatus: |
| case FilterCallLinkStatus: |
| case FilterInByIdStatus: |
| break; |
| |
| case GetByOffset: { |
| if (node->child1()->op() == GetButterfly |
| && candidateButterflies.contains(node->child1().node()) |
| && node->child2() == candidate |
| && node->storageAccessData().offset == clonedArgumentsLengthPropertyOffset) { |
| ASSERT(node->child1()->child1() == candidate); |
| ASSERT(isOutOfLineOffset(clonedArgumentsLengthPropertyOffset)); |
| // We're good to go. This is getting the length of the arguments. |
| lastUserIndex = nodeIndex; |
| validGetByOffset = true; |
| break; |
| } |
| if (defaultEscape()) |
| return; |
| break; |
| } |
| |
| default: |
| if (defaultEscape()) |
| return; |
| break; |
| } |
| |
| if (!validGetByOffset) { |
| for (Node* butterfly : candidateButterflies) { |
| if (m_graph.uses(node, butterfly)) { |
| if (verbose) |
| dataLog(" Butterfly escaped at ", node, "\n"); |
| return; |
| } |
| } |
| } |
| |
| forAllKilledOperands( |
| m_graph, node, block->tryAt(nodeIndex + 1), |
| [&] (Operand operand) { |
| if (verbose) |
| dataLog(" Killing ", operand, " while we are interested in ", listDump(relevantLocals), "\n"); |
| for (unsigned i = 0; i < relevantLocals.size(); ++i) { |
| if (operand == relevantLocals[i]) { |
| relevantLocals[i--] = relevantLocals.last(); |
| relevantLocals.removeLast(); |
| lastUserIndex = nodeIndex; |
| } |
| } |
| }); |
| } |
| if (verbose) |
| dataLog("Selected lastUserIndex = ", lastUserIndex, ", ", block->at(lastUserIndex), "\n"); |
| |
| // We're still in business. Determine if between the candidate and the last user there is any |
| // effect that could interfere with sinking. |
| for (unsigned nodeIndex = candidateNodeIndex + 1; nodeIndex <= lastUserIndex; ++nodeIndex) { |
| Node* node = block->at(nodeIndex); |
| |
| // We have our own custom switch to detect some interferences that clobberize() wouldn't know |
| // about, and also some of the common ones, too. In particular, clobberize() doesn't know |
| // that Flush, MovHint, ZombieHint, and KillStack are bad because it's not worried about |
| // what gets read on OSR exit. |
| switch (node->op()) { |
| case MovHint: |
| case ZombieHint: |
| case KillStack: |
| if (argumentsInvolveStackSlot(candidate, node->unlinkedOperand())) { |
| if (verbose) |
| dataLog(" Interference at ", node, "\n"); |
| return; |
| } |
| break; |
| |
| case PutStack: |
| if (argumentsInvolveStackSlot(candidate, node->stackAccessData()->operand)) { |
| if (verbose) |
| dataLog(" Interference at ", node, "\n"); |
| return; |
| } |
| break; |
| |
| case SetLocal: |
| case Flush: |
| if (argumentsInvolveStackSlot(candidate, node->operand())) { |
| if (verbose) |
| dataLog(" Interference at ", node, "\n"); |
| return; |
| } |
| break; |
| |
| default: { |
| bool doesInterfere = false; |
| clobberize( |
| m_graph, node, NoOpClobberize(), |
| [&] (AbstractHeap heap) { |
| if (heap.kind() != Stack) { |
| ASSERT(!heap.overlaps(Stack)); |
| return; |
| } |
| ASSERT(!heap.payload().isTop()); |
| if (argumentsInvolveStackSlot(candidate, heap.operand())) |
| doesInterfere = true; |
| }, |
| NoOpClobberize()); |
| if (doesInterfere) { |
| if (verbose) |
| dataLog(" Interference at ", node, "\n"); |
| return; |
| } |
| } } |
| } |
| |
| // We can make this work. |
| if (verbose) |
| dataLog(" Will do forwarding!\n"); |
| m_changed = true; |
| |
| // Transform the program. |
| switch (candidate->op()) { |
| case CreateDirectArguments: |
| candidate->setOpAndDefaultFlags(PhantomDirectArguments); |
| break; |
| |
| case CreateClonedArguments: |
| candidate->setOpAndDefaultFlags(PhantomClonedArguments); |
| break; |
| |
| default: |
| DFG_CRASH(m_graph, candidate, "bad node type"); |
| break; |
| } |
| |
| InsertionSet insertionSet(m_graph); |
| for (unsigned nodeIndex = candidateNodeIndex + 1; nodeIndex <= lastUserIndex; ++nodeIndex) { |
| Node* node = block->at(nodeIndex); |
| switch (node->op()) { |
| case Check: |
| case CheckVarargs: |
| case MovHint: |
| case PutHint: |
| // We don't need to change anything with these. |
| break; |
| |
| case VarargsLength: { |
| if (node->argumentsChild() != candidate) |
| break; |
| |
| node->convertToIdentityOn(emitCodeToGetArgumentsArrayLength(insertionSet, candidate, nodeIndex, node->origin, /* addThis = */ true)); |
| break; |
| } |
| |
| case LoadVarargs: |
| if (node->argumentsChild() != candidate) |
| break; |
| node->setOpAndDefaultFlags(ForwardVarargs); |
| break; |
| |
| case CallVarargs: |
| if (node->child3() != candidate) |
| break; |
| node->setOpAndDefaultFlags(CallForwardVarargs); |
| break; |
| |
| case ConstructVarargs: |
| if (node->child3() != candidate) |
| break; |
| node->setOpAndDefaultFlags(ConstructForwardVarargs); |
| break; |
| |
| case TailCallVarargs: |
| if (node->child3() != candidate) |
| break; |
| node->setOpAndDefaultFlags(TailCallForwardVarargs); |
| break; |
| |
| case TailCallVarargsInlinedCaller: |
| if (node->child3() != candidate) |
| break; |
| node->setOpAndDefaultFlags(TailCallForwardVarargsInlinedCaller); |
| break; |
| |
| case SetLocal: |
| // This is super odd. We don't have to do anything here, since in DFG IR, the phantom |
| // arguments nodes do produce a JSValue. Also, we know that if this SetLocal referenecs a |
| // candidate then the SetLocal - along with all of its references - will die off pretty |
| // soon, since it has no real users. DCE will surely kill it. If we make it to SSA, then |
| // SSA conversion will kill it. |
| break; |
| |
| case GetButterfly: { |
| if (node->child1().node() == candidate) { |
| ASSERT(candidateButterflies.contains(node)); |
| node->child1() = Edge(); |
| node->remove(m_graph); |
| } |
| break; |
| } |
| |
| case FilterGetByStatus: |
| case FilterPutByIdStatus: |
| case FilterCallLinkStatus: |
| case FilterInByIdStatus: |
| if (node->child1().node() == candidate) |
| node->remove(m_graph); |
| break; |
| |
| case GetByOffset: { |
| if (node->child2() == candidate) { |
| ASSERT(candidateButterflies.contains(node->child1().node())); // It's no longer a GetButterfly node, but it should've been a candidate butterfly. |
| ASSERT(node->storageAccessData().offset == clonedArgumentsLengthPropertyOffset); |
| node->convertToIdentityOn( |
| emitCodeToGetArgumentsArrayLength(insertionSet, candidate, nodeIndex, node->origin)); |
| } |
| break; |
| } |
| |
| case GetArrayLength: |
| if (node->arrayMode().type() == Array::DirectArguments && node->child1() == candidate) { |
| node->convertToIdentityOn( |
| emitCodeToGetArgumentsArrayLength(insertionSet, candidate, nodeIndex, node->origin)); |
| } |
| break; |
| |
| default: |
| if (!ASSERT_ENABLED) |
| break; |
| m_graph.doToChildren( |
| node, |
| [&] (Edge edge) { |
| DFG_ASSERT(m_graph, node, edge != candidate); |
| }); |
| break; |
| } |
| } |
| |
| insertionSet.execute(block); |
| } |
| |
| bool m_changed; |
| }; |
| |
| } // anonymous namespace |
| |
| bool performVarargsForwarding(Graph& graph) |
| { |
| return runPhase<VarargsForwardingPhase>(graph); |
| } |
| |
| } } // namespace JSC::DFG |
| |
| #endif // ENABLE(DFG_JIT) |
| |
