Bug 58696 - DFG JIT split handling of vars/temporaries

Gavin Barraclough · Gavin Barraclough · commit e3a890c86b9a · 2011-04-15T21:45:42.000Z
Reviewed by Sam Weinig. Presently all callee registers are treated as having single block scope, since the DFG JIT can only compile single block functions. In order to expand the JIT to support control flow we will need to change to retaining locals (but not temporaries) across basic block boundaries. * dfg/DFGByteCodeParser.cpp: (JSC::DFG::ByteCodeParser::ByteCodeParser): (JSC::DFG::ByteCodeParser::get): (JSC::DFG::ByteCodeParser::set): (JSC::DFG::ByteCodeParser::getVariable): (JSC::DFG::ByteCodeParser::setVariable): (JSC::DFG::ByteCodeParser::getTemporary): (JSC::DFG::ByteCodeParser::setTemporary): (JSC::DFG::ByteCodeParser::getArgument): (JSC::DFG::ByteCodeParser::getInt32Constant): (JSC::DFG::ByteCodeParser::getDoubleConstant): (JSC::DFG::ByteCodeParser::getJSConstant): (JSC::DFG::ByteCodeParser::constantUndefined): (JSC::DFG::ByteCodeParser::constantNull): (JSC::DFG::ByteCodeParser::one): (JSC::DFG::ByteCodeParser::parseBlock): (JSC::DFG::ByteCodeParser::parse): (JSC::DFG::parse): * dfg/DFGNode.h: * dfg/DFGScoreBoard.h: (JSC::DFG::ScoreBoard::ScoreBoard): (JSC::DFG::ScoreBoard::~ScoreBoard): (JSC::DFG::ScoreBoard::allocate): (JSC::DFG::ScoreBoard::use): Canonical link: https://commits.webkit.org/73779@main git-svn-id: https://svn.webkit.org/repository/webkit/trunk@84037 268f45cc-cd09-0410-ab3c-d52691b4dbfc
diff --git a/Source/JavaScriptCore/ChangeLog b/Source/JavaScriptCore/ChangeLog
@@ -1,3 +1,39 @@
+2011-04-15  Gavin Barraclough  <barraclough@apple.com>
+
+        Reviewed by Sam Weinig.
+
+        Bug 58696 - DFG JIT split handling of vars/temporaries
+
+        Presently all callee registers are treated as having single block scope,
+        since the DFG JIT can only compile single block functions. In order to
+        expand the JIT to support control flow we will need to change to retaining
+        locals (but not temporaries) across basic block boundaries.
+
+        * dfg/DFGByteCodeParser.cpp:
+        (JSC::DFG::ByteCodeParser::ByteCodeParser):
+        (JSC::DFG::ByteCodeParser::get):
+        (JSC::DFG::ByteCodeParser::set):
+        (JSC::DFG::ByteCodeParser::getVariable):
+        (JSC::DFG::ByteCodeParser::setVariable):
+        (JSC::DFG::ByteCodeParser::getTemporary):
+        (JSC::DFG::ByteCodeParser::setTemporary):
+        (JSC::DFG::ByteCodeParser::getArgument):
+        (JSC::DFG::ByteCodeParser::getInt32Constant):
+        (JSC::DFG::ByteCodeParser::getDoubleConstant):
+        (JSC::DFG::ByteCodeParser::getJSConstant):
+        (JSC::DFG::ByteCodeParser::constantUndefined):
+        (JSC::DFG::ByteCodeParser::constantNull):
+        (JSC::DFG::ByteCodeParser::one):
+        (JSC::DFG::ByteCodeParser::parseBlock):
+        (JSC::DFG::ByteCodeParser::parse):
+        (JSC::DFG::parse):
+        * dfg/DFGNode.h:
+        * dfg/DFGScoreBoard.h:
+        (JSC::DFG::ScoreBoard::ScoreBoard):
+        (JSC::DFG::ScoreBoard::~ScoreBoard):
+        (JSC::DFG::ScoreBoard::allocate):
+        (JSC::DFG::ScoreBoard::use):
+
 2011-04-15  Michael Saboff  <msaboff@apple.com>
 
         Reviewed by Oliver Hunt.
diff --git a/Source/JavaScriptCore/dfg/DFGByteCodeParser.cpp b/Source/JavaScriptCore/dfg/DFGByteCodeParser.cpp
@@ -55,31 +55,33 @@ class ByteCodeParser {
         , m_constantUndefined(UINT_MAX)
         , m_constantNull(UINT_MAX)
         , m_constant1(UINT_MAX)
+        , m_constants(codeBlock->numberOfConstantRegisters())
+        , m_arguments(codeBlock->m_numParameters)
+        , m_variables(codeBlock->m_numVars)
+        , m_temporaries(codeBlock->m_numCalleeRegisters - codeBlock->m_numVars)
     {
-        unsigned numberOfConstants = codeBlock->numberOfConstantRegisters();
-        m_constantRecords.grow(numberOfConstants);
-
-        unsigned numberOfParameters = codeBlock->m_numParameters;
-        m_arguments.grow(numberOfParameters);
-        for (unsigned i = 0; i < numberOfParameters; ++i)
+        for (unsigned i = 0; i < m_arguments.size(); ++i)
             m_arguments[i] = NoNode;
-
-        unsigned numberOfRegisters = codeBlock->m_numCalleeRegisters;
-        m_calleeRegisters.grow(numberOfRegisters);
-        for (unsigned i = 0; i < numberOfRegisters; ++i)
-            m_calleeRegisters[i] = NoNode;
+        for (unsigned i = 0; i < m_variables.size(); ++i)
+            m_variables[i] = NoNode;
+        for (unsigned i = 0; i < m_temporaries.size(); ++i)
+            m_temporaries[i] = NoNode;
     }
 
+    // Parse a full CodeBlock of bytecode.
     bool parse();
 
 private:
+    // Parse a single basic block of bytecode instructions.
+    bool parseBlock();
+
     // Get/Set the operands/result of a bytecode instruction.
     NodeIndex get(int operand)
     {
         // Is this a constant?
         if (operand >= FirstConstantRegisterIndex) {
             unsigned constant = operand - FirstConstantRegisterIndex;
-            ASSERT(constant < m_constantRecords.size());
+            ASSERT(constant < m_constants.size());
             return getJSConstant(constant);
         }
 
@@ -90,9 +92,15 @@ class ByteCodeParser {
             return getArgument(argument);
         }
 
-        // Must be a local or temporary.
-        ASSERT((unsigned)operand < m_calleeRegisters.size());
-        return getRegister((unsigned)operand);
+        // Is this a variable?
+        unsigned numVariables = m_variables.size();
+        if ((unsigned)operand < numVariables)
+            return getVariable((unsigned)operand);
+        
+        // Must be a temporary.
+        unsigned temporary = (unsigned)operand - numVariables;
+        ASSERT(temporary < m_temporaries.size());
+        return getTemporary(temporary);
     }
     void set(int operand, NodeIndex value)
     {
@@ -103,15 +111,23 @@ class ByteCodeParser {
             return setArgument(argument, value);
         }
 
-        // Must be a local or temporary.
-        ASSERT((unsigned)operand < m_calleeRegisters.size());
-        return setRegister((unsigned)operand, value);
+        // Is this a variable?
+        unsigned numVariables = m_variables.size();
+        if ((unsigned)operand < numVariables) {
+            setVariable((unsigned)operand, value);
+            return;
+        }
+        
+        // Must be a temporary.
+        unsigned temporary = (unsigned)operand - numVariables;
+        ASSERT(temporary < m_temporaries.size());
+        setTemporary(temporary, value);
     }
 
-    // Used in implementing get/set, above, where the operand is a local or temporary.
-    NodeIndex getRegister(unsigned operand)
+    // Used in implementing get/set, above, where the operand is a local variable.
+    NodeIndex getVariable(unsigned operand)
     {
-        NodeIndex index = m_calleeRegisters[operand];
+        NodeIndex index = m_variables[operand];
         if (index != NoNode)
             return index;
         // We have not yet seen a definition for this value in this block.
@@ -121,9 +137,25 @@ class ByteCodeParser {
         //     function f() { var x; return x; }
         return constantUndefined();
     }
-    void setRegister(int operand, NodeIndex value)
+    void setVariable(int operand, NodeIndex value)
     {
-        m_calleeRegisters[operand] = value;
+        m_variables[operand] = value;
+    }
+
+    // Used in implementing get/set, above, where the operand is a temporary.
+    NodeIndex getTemporary(unsigned operand)
+    {
+        NodeIndex index = m_temporaries[operand];
+        if (index != NoNode)
+            return index;
+        
+        // Detect a read of an temporary that is not a yet defined within this block (e.g. use of ?:).
+        m_parseFailed = true;
+        return constantUndefined();
+    }
+    void setTemporary(int operand, NodeIndex value)
+    {
+        m_temporaries[operand] = value;
     }
 
     // Used in implementing get/set, above, where the operand is an argument.
@@ -132,8 +164,7 @@ class ByteCodeParser {
         NodeIndex index = m_arguments[argument];
         if (index != NoNode)
             return index;
-        NodeIndex resultIndex = (NodeIndex)m_graph.size();
-        m_graph.append(Node(Argument, m_currentIndex, OpInfo(argument)));
+        NodeIndex resultIndex = addToGraph(Argument, OpInfo(argument));
         return m_arguments[argument] = resultIndex;
     }
     void setArgument(int operand, NodeIndex value)
@@ -237,35 +268,32 @@ class ByteCodeParser {
     // Used in implementing get, above, where the operand is a constant.
     NodeIndex getInt32Constant(int32_t value, unsigned constant)
     {
-        NodeIndex index = m_constantRecords[constant].asInt32;
+        NodeIndex index = m_constants[constant].asInt32;
         if (index != NoNode)
             return index;
-        NodeIndex resultIndex = (NodeIndex)m_graph.size();
-        m_graph.append(Node(Int32Constant, m_currentIndex, OpInfo(constant)));
+        NodeIndex resultIndex = addToGraph(Int32Constant, OpInfo(constant));
         m_graph[resultIndex].setInt32Constant(value);
-        m_constantRecords[constant].asInt32 = resultIndex;
+        m_constants[constant].asInt32 = resultIndex;
         return resultIndex;
     }
     NodeIndex getDoubleConstant(double value, unsigned constant)
     {
-        NodeIndex index = m_constantRecords[constant].asNumeric;
+        NodeIndex index = m_constants[constant].asNumeric;
         if (index != NoNode)
             return index;
-        NodeIndex resultIndex = (NodeIndex)m_graph.size();
-        m_graph.append(Node(DoubleConstant, m_currentIndex, OpInfo(constant)));
+        NodeIndex resultIndex = addToGraph(DoubleConstant, OpInfo(constant));
         m_graph[resultIndex].setDoubleConstant(value);
-        m_constantRecords[constant].asNumeric = resultIndex;
+        m_constants[constant].asNumeric = resultIndex;
         return resultIndex;
     }
     NodeIndex getJSConstant(unsigned constant)
     {
-        NodeIndex index = m_constantRecords[constant].asJSValue;
+        NodeIndex index = m_constants[constant].asJSValue;
         if (index != NoNode)
             return index;
 
-        NodeIndex resultIndex = (NodeIndex)m_graph.size();
-        m_graph.append(Node(JSConstant, m_currentIndex, OpInfo(constant)));
-        m_constantRecords[constant].asJSValue = resultIndex;
+        NodeIndex resultIndex = addToGraph(JSConstant, OpInfo(constant));
+        m_constants[constant].asJSValue = resultIndex;
         return resultIndex;
     }
 
@@ -323,11 +351,11 @@ class ByteCodeParser {
                     return getJSConstant(m_constantUndefined);
             }
 
-            // Add undefined to the CodeBlock's constants, and add a corresponding slot in m_constantRecords.
-            ASSERT(m_constantRecords.size() == numberOfConstants);
+            // Add undefined to the CodeBlock's constants, and add a corresponding slot in m_constants.
+            ASSERT(m_constants.size() == numberOfConstants);
             m_codeBlock->addConstant(jsUndefined());
-            m_constantRecords.append(ConstantRecord());
-            ASSERT(m_constantRecords.size() == m_codeBlock->numberOfConstantRegisters());
+            m_constants.append(ConstantRecord());
+            ASSERT(m_constants.size() == m_codeBlock->numberOfConstantRegisters());
         }
 
         // m_constantUndefined must refer to an entry in the CodeBlock's constant pool that has the value 'undefined'.
@@ -348,11 +376,11 @@ class ByteCodeParser {
                     return getJSConstant(m_constantNull);
             }
 
-            // Add null to the CodeBlock's constants, and add a corresponding slot in m_constantRecords.
-            ASSERT(m_constantRecords.size() == numberOfConstants);
+            // Add null to the CodeBlock's constants, and add a corresponding slot in m_constants.
+            ASSERT(m_constants.size() == numberOfConstants);
             m_codeBlock->addConstant(jsNull());
-            m_constantRecords.append(ConstantRecord());
-            ASSERT(m_constantRecords.size() == m_codeBlock->numberOfConstantRegisters());
+            m_constants.append(ConstantRecord());
+            ASSERT(m_constants.size() == m_codeBlock->numberOfConstantRegisters());
         }
 
         // m_constantNull must refer to an entry in the CodeBlock's constant pool that has the value 'null'.
@@ -373,11 +401,11 @@ class ByteCodeParser {
                     return getDoubleConstant(1, m_constant1);
             }
 
-            // Add the value 1 to the CodeBlock's constants, and add a corresponding slot in m_constantRecords.
-            ASSERT(m_constantRecords.size() == numberOfConstants);
+            // Add the value 1 to the CodeBlock's constants, and add a corresponding slot in m_constants.
+            ASSERT(m_constants.size() == numberOfConstants);
             m_codeBlock->addConstant(jsNumber(1));
-            m_constantRecords.append(ConstantRecord());
-            ASSERT(m_constantRecords.size() == m_codeBlock->numberOfConstantRegisters());
+            m_constants.append(ConstantRecord());
+            ASSERT(m_constants.size() == m_codeBlock->numberOfConstantRegisters());
         }
 
         // m_constant1 must refer to an entry in the CodeBlock's constant pool that has the integer value 1.
@@ -441,12 +469,13 @@ class ByteCodeParser {
         NodeIndex asNumeric;
         NodeIndex asJSValue;
     };
-    Vector <ConstantRecord, 32> m_constantRecords;
+    Vector <ConstantRecord, 32> m_constants;
 
     // Track the index of the node whose result is the current value for every
     // register value in the bytecode - argument, local, and temporary.
     Vector <NodeIndex, 32> m_arguments;
-    Vector <NodeIndex, 32> m_calleeRegisters;
+    Vector <NodeIndex, 32> m_variables;
+    Vector <NodeIndex, 32> m_temporaries;
 
     // These maps are used to unique ToNumber and ToInt32 operations.
     typedef HashMap<NodeIndex, NodeIndex> UnaryOpMap;
@@ -462,7 +491,7 @@ class ByteCodeParser {
     m_currentIndex += OPCODE_LENGTH(name); \
     return !m_parseFailed
 
-bool ByteCodeParser::parse()
+bool ByteCodeParser::parseBlock()
 {
     AliasTracker aliases(m_graph);
 
@@ -799,17 +828,15 @@ bool ByteCodeParser::parse()
     }
 }
 
-bool parse(Graph& graph, JSGlobalData* globalData, CodeBlock* codeBlock)
+bool ByteCodeParser::parse()
 {
-    // Call ByteCodeParser::parse to build the dataflow for the basic block at 'startIndex'.
-    ByteCodeParser state(globalData, codeBlock, graph);
-    if (!state.parse())
+    if (!parseBlock())
         return false;
 
     // Assign VirtualRegisters.
-    ScoreBoard scoreBoard(graph);
-    Node* nodes = graph.begin();
-    size_t size = graph.size();
+    ScoreBoard scoreBoard(m_graph, m_variables.size());
+    Node* nodes = m_graph.begin();
+    size_t size = m_graph.size();
     for (size_t i = 0; i < size; ++i) {
         Node& node = nodes[i];
         if (node.refCount) {
@@ -831,15 +858,29 @@ bool parse(Graph& graph, JSGlobalData* globalData, CodeBlock* codeBlock)
     // 'm_numCalleeRegisters' is the number of locals and temporaries allocated
     // for the function (and checked for on entry). Since we perform a new and
     // different allocation of temporaries, more registers may now be required.
-    if ((unsigned)codeBlock->m_numCalleeRegisters < scoreBoard.allocatedCount())
-        codeBlock->m_numCalleeRegisters = scoreBoard.allocatedCount();
+    unsigned calleeRegisters = scoreBoard.allocatedCount() + m_variables.size();
+    if ((unsigned)m_codeBlock->m_numCalleeRegisters < calleeRegisters)
+        m_codeBlock->m_numCalleeRegisters = calleeRegisters;
 
 #if DFG_DEBUG_VERBOSE
-    graph.dump(codeBlock);
+    m_graph.dump(m_codeBlock);
 #endif
+
     return true;
 }
 
+bool parse(Graph& graph, JSGlobalData* globalData, CodeBlock* codeBlock)
+{
+#if DFG_DEBUG_LOCAL_DISBALE
+    UNUSED_PARAM(graph);
+    UNUSED_PARAM(globalData);
+    UNUSED_PARAM(codeBlock);
+    return false;
+#else
+    return ByteCodeParser(globalData, codeBlock, graph).parse();
+#endif
+}
+
 } } // namespace JSC::DFG
 
 #endif
diff --git a/Source/JavaScriptCore/dfg/DFGNode.h b/Source/JavaScriptCore/dfg/DFGNode.h
@@ -38,6 +38,8 @@
 #define DFG_CONSISTENCY_CHECK 0
 // Emit a breakpoint into the head of every generated function, to aid debugging in GDB.
 #define DFG_JIT_BREAK_ON_ENTRY 0
+// Disable the DFG JIT without having to touch Platform.h!
+#define DFG_DEBUG_LOCAL_DISBALE 0
 
 
 namespace JSC { namespace DFG {
diff --git a/Source/JavaScriptCore/dfg/DFGScoreBoard.h b/Source/JavaScriptCore/dfg/DFGScoreBoard.h
