Imported WebKit commit eb5c1b8fe4d4b1b90b5137433fc58a91da0e6878 (http://svn.webkit.org/repository/webkit/trunk@118516)

1 files changed, 120 insertions, 0 deletions

diff --git a/Source/JavaScriptCore/dfg/DFGConstantFoldingPhase.cpp b/Source/JavaScriptCore/dfg/DFGConstantFoldingPhase.cpp
new file mode 100644
index 000000000..b2b74ba04
--- /dev/null
+++ b/Source/JavaScriptCore/dfg/DFGConstantFoldingPhase.cpp
@@ -0,0 +1,120 @@
+/*
+ * Copyright (C) 2012 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 "DFGConstantFoldingPhase.h"
+
+#if ENABLE(DFG_JIT)
+
+#include "DFGAbstractState.h"
+#include "DFGBasicBlock.h"
+#include "DFGGraph.h"
+#include "DFGInsertionSet.h"
+#include "DFGPhase.h"
+
+namespace JSC { namespace DFG {
+
+class ConstantFoldingPhase : public Phase {
+public:
+    ConstantFoldingPhase(Graph& graph)
+        : Phase(graph, "constant folding")
+    {
+    }
+    
+    bool run()
+    {
+        bool changed = false;
+        
+        AbstractState state(m_graph);
+        InsertionSet<NodeIndex> insertionSet;
+        
+        for (BlockIndex blockIndex = 0; blockIndex < m_graph.m_blocks.size(); ++blockIndex) {
+            BasicBlock* block = m_graph.m_blocks[blockIndex].get();
+            if (!block)
+                continue;
+            if (!block->cfaFoundConstants)
+                continue;
+            state.beginBasicBlock(block);
+            for (unsigned indexInBlock = 0; indexInBlock < block->size(); ++indexInBlock) {
+                if (!state.isValid())
+                    break;
+                state.execute(indexInBlock);
+                NodeIndex nodeIndex = block->at(indexInBlock);
+                Node& node = m_graph[nodeIndex];
+                if (!node.shouldGenerate()
+                    || m_graph.clobbersWorld(node)
+                    || node.hasConstant())
+                    continue;
+                JSValue value = state.forNode(nodeIndex).value();
+                if (!value)
+                    continue;
+                
+                Node phantom(Phantom, node.codeOrigin);
+                
+                if (node.op() == GetLocal) {
+                    ASSERT(m_graph[node.child1()].op() == Phi);
+                    ASSERT(!m_graph[node.child1()].hasResult());
+                    
+                    ASSERT(block->variablesAtHead.operand(node.local()) == nodeIndex);
+                    ASSERT(block->isInPhis(node.child1().index()));
+                    block->variablesAtHead.operand(node.local()) = node.child1().index();
+                    
+                    NodeIndex tailNodeIndex = block->variablesAtTail.operand(node.local());
+                    if (tailNodeIndex == nodeIndex)
+                        block->variablesAtTail.operand(node.local()) = node.child1().index();
+                    else {
+                        ASSERT(m_graph[tailNodeIndex].op() == Flush
+                               || m_graph[tailNodeIndex].op() == SetLocal);
+                    }
+                }
+                
+                phantom.children = node.children;
+                phantom.ref();
+                
+                m_graph.convertToConstant(nodeIndex, value);
+                NodeIndex phantomNodeIndex = m_graph.size();
+                m_graph.append(phantom);
+                insertionSet.append(indexInBlock, phantomNodeIndex);
+                
+                changed = true;
+            }
+            insertionSet.execute(*block);
+            state.reset();
+        }
+        
+        return changed;
+    }
+};
+
+bool performConstantFolding(Graph& graph)
+{
+    return runPhase<ConstantFoldingPhase>(graph);
+}
+
+} } // namespace JSC::DFG
+
+#endif // ENABLE(DFG_JIT)
+
+