1 files changed, 159 insertions, 0 deletions
diff --git a/Source/JavaScriptCore/dfg/DFGMaximalFlushInsertionPhase.cpp b/Source/JavaScriptCore/dfg/DFGMaximalFlushInsertionPhase.cpp
new file mode 100644
index 000000000..a63442781
--- /dev/null
+++ b/Source/JavaScriptCore/dfg/DFGMaximalFlushInsertionPhase.cpp
@@ -0,0 +1,159 @@
+/*
+ * 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 "DFGMaximalFlushInsertionPhase.h"
+
+#if ENABLE(DFG_JIT)
+
+#include "DFGBasicBlockInlines.h"
+#include "DFGGraph.h"
+#include "DFGInsertionSet.h"
+#include "DFGPhase.h"
+#include "JSCInlines.h"
+
+namespace JSC { namespace DFG {
+
+class MaximalFlushInsertionPhase : public Phase {
+public:
+    MaximalFlushInsertionPhase(Graph& graph)
+        : Phase(graph, "maximal flush insertion phase")
+    {
+    }
+    
+    bool run()
+    {
+        DFG_ASSERT(m_graph, nullptr, m_graph.m_form == LoadStore);
+
+        InsertionSet insertionSet(m_graph);
+        for (BasicBlock* block : m_graph.blocksInNaturalOrder()) {
+            treatRegularBlock(block, insertionSet);
+            insertionSet.execute(block);
+        }
+
+        treatRootBlock(m_graph.block(0), insertionSet);
+        insertionSet.execute(m_graph.block(0));
+
+        return true;
+    }
+
+    void treatRegularBlock(BasicBlock* block, InsertionSet& insertionSet)
+    {
+        Operands<VariableAccessData*> currentBlockAccessData(block->variablesAtTail.numberOfArguments(), block->variablesAtTail.numberOfLocals(), nullptr);
+        // Insert a Flush before every SetLocal to properly pattern the graph such that 
+        // any range between SetLocal and Flush has access to the local on the stack.
+        {
+            for (unsigned i = 0; i < block->size(); i++) {
+                Node* node = block->at(i);
+                bool isPrimordialSetArgument = node->op() == SetArgument && node->local().isArgument() && node == m_graph.m_arguments[node->local().toArgument()];
+                if (node->op() == SetLocal || (node->op() == SetArgument && !isPrimordialSetArgument)) {
+                    VirtualRegister operand = node->local();
+                    VariableAccessData* flushAccessData = currentBlockAccessData.operand(operand);
+                    if (!flushAccessData)
+                        flushAccessData = newVariableAccessData(operand);
+
+                    insertionSet.insertNode(i, SpecNone, 
+                        Flush, node->origin, OpInfo(flushAccessData));
+                }
+
+                if (node->hasVariableAccessData(m_graph))
+                    currentBlockAccessData.operand(node->local()) = node->variableAccessData();
+            }
+        }
+
+        // Flush everything at the end of the block.
+        {
+            NodeOrigin origin = block->at(block->size() - 1)->origin;
+            auto insertFlushAtEnd = [&] (VirtualRegister operand) {
+                VariableAccessData* accessData = currentBlockAccessData.operand(operand);
+                if (!accessData)
+                    accessData = newVariableAccessData(operand);
+
+                currentBlockAccessData.operand(operand) = accessData;
+
+                insertionSet.insertNode(block->size(), SpecNone, 
+                    Flush, origin, OpInfo(accessData));
+            };
+
+            for (unsigned i = 0; i < block->variablesAtTail.numberOfLocals(); i++)
+                insertFlushAtEnd(virtualRegisterForLocal(i));
+            for (unsigned i = 0; i < block->variablesAtTail.numberOfArguments(); i++)
+                insertFlushAtEnd(virtualRegisterForArgument(i));
+        }
+    }
+
+    void treatRootBlock(BasicBlock* block, InsertionSet& insertionSet)
+    {
+        Operands<VariableAccessData*> initialAccessData(block->variablesAtTail.numberOfArguments(), block->variablesAtTail.numberOfLocals(), nullptr);
+        Operands<Node*> initialAccessNodes(block->variablesAtTail.numberOfArguments(), block->variablesAtTail.numberOfLocals(), nullptr);
+        for (unsigned i = 0; i < block->size(); i++) {
+            Node* node = block->at(i);
+            if (!node->hasVariableAccessData(m_graph))
+                continue;
+
+            VirtualRegister operand = node->local();
+            if (initialAccessData.operand(operand))
+                continue;
+
+            DFG_ASSERT(m_graph, node, node->op() != SetLocal); // We should have inserted a Flush before this!
+            initialAccessData.operand(operand) = node->variableAccessData();
+            initialAccessNodes.operand(operand) = node;
+        }
+
+        // We want every Flush to be able to reach backwards to
+        // a SetLocal. Doing this in the root block achieves this goal.
+        NodeOrigin origin = block->at(0)->origin;
+        Node* undefined = insertionSet.insertConstant(0, origin, jsUndefined());
+
+        for (unsigned i = 0; i < block->variablesAtTail.numberOfLocals(); i++) {
+            VirtualRegister operand = virtualRegisterForLocal(i);
+            VariableAccessData* accessData;
+            DFG_ASSERT(m_graph, nullptr, initialAccessNodes.operand(operand)->op() == Flush); // We should have inserted a Flush before any SetLocal/SetArgument for the local that we are analyzing now.
+            accessData = initialAccessData.operand(operand);
+            DFG_ASSERT(m_graph, nullptr, accessData);
+            insertionSet.insertNode(0, SpecNone, 
+                SetLocal, origin, OpInfo(accessData), Edge(undefined));
+        }
+    }
+
+
+    VariableAccessData* newVariableAccessData(VirtualRegister operand)
+    {
+        ASSERT(!operand.isConstant());
+        
+        m_graph.m_variableAccessData.append(VariableAccessData(operand));
+        return &m_graph.m_variableAccessData.last();
+    }
+};
+
+bool performMaximalFlushInsertion(Graph& graph)
+{
+    SamplingRegion samplingRegion("DFG Flush Everything Insertion Phase");
+    return runPhase<MaximalFlushInsertionPhase>(graph);
+}
+
+} } // namespace JSC::DFG
+
+#endif // ENABLE(DFG_JIT)