--- /dev/null
+/*
+ * Copyright (C) 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 "DFGVarargsForwardingPhase.h"
+
+#if ENABLE(DFG_JIT)
+
+#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 {
+
+bool verbose = false;
+
+class VarargsForwardingPhase : public Phase {
+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");
+
+ // 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);
+
+ switch (node->op()) {
+ case MovHint:
+ if (node->child1() != candidate)
+ break;
+ lastUserIndex = nodeIndex;
+ if (!relevantLocals.contains(node->unlinkedLocal()))
+ relevantLocals.append(node->unlinkedLocal());
+ break;
+
+ 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 LoadVarargs:
+ if (m_graph.uses(node, candidate))
+ lastUserIndex = nodeIndex;
+ break;
+
+ case CallVarargs:
+ case ConstructVarargs:
+ if (node->child1() == candidate || node->child3() == 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;
+
+ default:
+ if (m_graph.uses(node, candidate)) {
+ if (verbose)
+ dataLog(" Escape at ", node, "\n");
+ return;
+ }
+ }
+
+ forAllKilledOperands(
+ m_graph, node, block->tryAt(nodeIndex + 1),
+ [&] (VirtualRegister reg) {
+ if (verbose)
+ dataLog(" Killing ", reg, " while we are interested in ", listDump(relevantLocals), "\n");
+ for (unsigned i = 0; i < relevantLocals.size(); ++i) {
+ if (relevantLocals[i] == reg) {
+ 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->unlinkedLocal())) {
+ if (verbose)
+ dataLog(" Interference at ", node, "\n");
+ return;
+ }
+ break;
+
+ case PutStack:
+ if (argumentsInvolveStackSlot(candidate, node->stackAccessData()->local)) {
+ if (verbose)
+ dataLog(" Interference at ", node, "\n");
+ return;
+ }
+ break;
+
+ case SetLocal:
+ case Flush:
+ if (argumentsInvolveStackSlot(candidate, node->local())) {
+ 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());
+ VirtualRegister reg(heap.payload().value32());
+ if (argumentsInvolveStackSlot(candidate, reg))
+ 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;
+ }
+ for (unsigned nodeIndex = candidateNodeIndex + 1; nodeIndex <= lastUserIndex; ++nodeIndex) {
+ Node* node = block->at(nodeIndex);
+ switch (node->op()) {
+ case Check:
+ case MovHint:
+ case PutHint:
+ // We don't need to change anything with these.
+ break;
+
+ case LoadVarargs:
+ if (node->child1() != candidate)
+ break;
+ node->setOpAndDefaultFlags(ForwardVarargs);
+ break;
+
+ case CallVarargs:
+ if (node->child2() != candidate)
+ break;
+ node->setOpAndDefaultFlags(CallForwardVarargs);
+ break;
+
+ case ConstructVarargs:
+ if (node->child2() != candidate)
+ break;
+ node->setOpAndDefaultFlags(ConstructForwardVarargs);
+ 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;
+
+ default:
+ if (ASSERT_DISABLED)
+ break;
+ m_graph.doToChildren(
+ node,
+ [&] (Edge edge) {
+ DFG_ASSERT(m_graph, node, edge != candidate);
+ });
+ break;
+ }
+ }
+ }
+
+ bool m_changed;
+};
+
+} // anonymous namespace
+
+bool performVarargsForwarding(Graph& graph)
+{
+ SamplingRegion samplingRegion("DFG Varargs Forwarding Phase");
+ return runPhase<VarargsForwardingPhase>(graph);
+}
+
+} } // namespace JSC::DFG
+
+#endif // ENABLE(DFG_JIT)
+
projects / apple / javascriptcore.git / blobdiff