Imported WebKit commit 356d83016b090995d08ad568f2d2c243aa55e831 (http://svn.webkit.org/repository/webkit/trunk@126147)

New snapshot including various build fixes for newer Qt 5

1 files changed, 60 insertions, 27 deletions

diff --git a/Source/JavaScriptCore/dfg/DFGAbstractState.cpp b/Source/JavaScriptCore/dfg/DFGAbstractState.cpp
index 4f02ee793..5c53f6d78 100644
--- a/Source/JavaScriptCore/dfg/DFGAbstractState.cpp
+++ b/Source/JavaScriptCore/dfg/DFGAbstractState.cpp
@@ -62,13 +62,13 @@ void AbstractState::beginBasicBlock(BasicBlock* basicBlock)
     m_variables = basicBlock->valuesAtHead;
     m_haveStructures = false;
     for (size_t i = 0; i < m_variables.numberOfArguments(); ++i) {
-        if (m_variables.argument(i).m_structure.isNeitherClearNorTop()) {
+        if (m_variables.argument(i).m_currentKnownStructure.isNeitherClearNorTop()) {
             m_haveStructures = true;
             break;
         }
     }
     for (size_t i = 0; i < m_variables.numberOfLocals(); ++i) {
-        if (m_variables.local(i).m_structure.isNeitherClearNorTop()) {
+        if (m_variables.local(i).m_currentKnownStructure.isNeitherClearNorTop()) {
             m_haveStructures = true;
             break;
         }
@@ -106,8 +106,6 @@ void AbstractState::initialize(Graph& graph)
         SpeculatedType prediction = node.variableAccessData()->prediction();
         if (isInt32Speculation(prediction))
             root->valuesAtHead.argument(i).set(SpecInt32);
-        else if (isArraySpeculation(prediction))
-            root->valuesAtHead.argument(i).set(SpecArray);
         else if (isBooleanSpeculation(prediction))
             root->valuesAtHead.argument(i).set(SpecBoolean);
         else if (isInt8ArraySpeculation(prediction))
@@ -160,6 +158,16 @@ void AbstractState::initialize(Graph& graph)
             block->valuesAtHead.local(i).clear();
             block->valuesAtTail.local(i).clear();
         }
+        if (!block->isOSRTarget)
+            continue;
+        if (block->bytecodeBegin != graph.m_osrEntryBytecodeIndex)
+            continue;
+        for (size_t i = 0; i < graph.m_mustHandleValues.size(); ++i) {
+            AbstractValue value;
+            value.setMostSpecific(graph.m_mustHandleValues[i]);
+            block->valuesAtHead.operand(graph.m_mustHandleValues.operandForIndex(i)).merge(value);
+        }
+        block->cfaShouldRevisit = true;
     }
 }
 
@@ -290,10 +298,7 @@ bool AbstractState::execute(unsigned indexInBlock)
         SpeculatedType predictedType = node.variableAccessData()->argumentAwarePrediction();
         if (isInt32Speculation(predictedType))
             speculateInt32Unary(node);
-        else if (isArraySpeculation(predictedType)) {
-            node.setCanExit(!isArraySpeculation(forNode(node.child1()).m_type));
-            forNode(node.child1()).filter(SpecArray);
-        } else if (isCellSpeculation(predictedType)) {
+        else if (isCellSpeculation(predictedType)) {
             node.setCanExit(!isCellSpeculation(forNode(node.child1()).m_type));
             forNode(node.child1()).filter(SpecCell);
         } else if (isBooleanSpeculation(predictedType))
@@ -867,7 +872,7 @@ bool AbstractState::execute(unsigned indexInBlock)
             m_isValid = false;
             break;
         }
-        if (!isActionableArraySpeculation(m_graph[node.child1()].prediction()) || !m_graph[node.child2()].shouldSpeculateInteger()) {
+        if (!m_graph[node.child2()].shouldSpeculateInteger() || (!node.child3() && !m_graph[node.child1()].shouldSpeculateArguments())) {
             clobberWorld(node.codeOrigin, indexInBlock);
             forNode(nodeIndex).makeTop();
             break;
@@ -942,8 +947,7 @@ bool AbstractState::execute(unsigned indexInBlock)
             forNode(nodeIndex).set(SpecDouble);
             break;
         }
-        ASSERT(m_graph[node.child1()].shouldSpeculateArray());
-        forNode(node.child1()).filter(SpecArray);
+        forNode(node.child1()).filter(SpecCell);
         forNode(node.child2()).filter(SpecInt32);
         forNode(nodeIndex).makeTop();
         break;
@@ -962,7 +966,7 @@ bool AbstractState::execute(unsigned indexInBlock)
             m_isValid = false;
             break;
         }
-        if (!m_graph[child2].shouldSpeculateInteger() || !isActionableMutableArraySpeculation(m_graph[child1].prediction())
+        if (!m_graph[child2].shouldSpeculateInteger()
 #if USE(JSVALUE32_64)
             || m_graph[child1].shouldSpeculateArguments()
 #endif
@@ -1053,8 +1057,7 @@ bool AbstractState::execute(unsigned indexInBlock)
             forNode(child3).filter(SpecNumber);
             break;
         }
-        ASSERT(m_graph[child1].shouldSpeculateArray());
-        forNode(child1).filter(SpecArray);
+        forNode(child1).filter(SpecCell);
         forNode(child2).filter(SpecInt32);
         if (node.op() == PutByValSafe)
             clobberWorld(node.codeOrigin, indexInBlock);
@@ -1063,13 +1066,13 @@ bool AbstractState::execute(unsigned indexInBlock)
             
     case ArrayPush:
         node.setCanExit(true);
-        forNode(node.child1()).filter(SpecArray);
+        forNode(node.child1()).filter(SpecCell);
         forNode(nodeIndex).set(SpecNumber);
         break;
             
     case ArrayPop:
         node.setCanExit(true);
-        forNode(node.child1()).filter(SpecArray);
+        forNode(node.child1()).filter(SpecCell);
         forNode(nodeIndex).makeTop();
         break;
             
@@ -1354,7 +1357,7 @@ bool AbstractState::execute(unsigned indexInBlock)
             
     case GetArrayLength:
         node.setCanExit(true);
-        forNode(node.child1()).filter(SpecArray);
+        forNode(node.child1()).filter(SpecCell);
         forNode(nodeIndex).set(SpecInt32);
         break;
 
@@ -1420,19 +1423,52 @@ bool AbstractState::execute(unsigned indexInBlock)
     case ForwardCheckStructure: {
         // FIXME: We should be able to propagate the structure sets of constants (i.e. prototypes).
         AbstractValue& value = forNode(node.child1());
+        // If this structure check is attempting to prove knowledge already held in
+        // the futurePossibleStructure set then the constant folding phase should
+        // turn this into a watchpoint instead.
+        StructureSet& set = node.structureSet();
+        if (value.m_futurePossibleStructure.isSubsetOf(set))
+            m_foundConstants = true;
         node.setCanExit(
-            !value.m_structure.isSubsetOf(node.structureSet())
+            !value.m_currentKnownStructure.isSubsetOf(set)
             || !isCellSpeculation(value.m_type));
-        value.filter(node.structureSet());
+        value.filter(set);
+        // This is likely to be unnecessary, but it's conservative, and that's a good thing.
+        // This is trying to avoid situations where the CFA proves that this structure check
+        // must fail due to a future structure proof. We have two options at that point. We
+        // can either compile all subsequent code as we would otherwise, or we can ensure
+        // that the subsequent code is never reachable. The former is correct because the
+        // Proof Is Infallible (TM) -- hence even if we don't force the subsequent code to
+        // be unreachable, it must be unreachable nonetheless. But imagine what would happen
+        // if the proof was borked. In the former case, we'd get really bizarre bugs where
+        // we assumed that the structure of this object was known even though it wasn't. In
+        // the latter case, we'd have a slight performance pathology because this would be
+        // turned into an OSR exit unnecessarily. Which would you rather have?
+        if (value.m_currentKnownStructure.isClear()
+            || value.m_futurePossibleStructure.isClear())
+            m_isValid = false;
         m_haveStructures = true;
         break;
     }
         
-    case StructureTransitionWatchpoint: {
-        // FIXME: Turn CheckStructure into StructureTransitionWatchpoint when possible!
+    case StructureTransitionWatchpoint:
+    case ForwardStructureTransitionWatchpoint: {
         AbstractValue& value = forNode(node.child1());
+
+        // It's only valid to issue a structure transition watchpoint if we already
+        // know that the watchpoint covers a superset of the structures known to
+        // belong to the set of future structures that this value may have.
+        // Currently, we only issue singleton watchpoints (that check one structure)
+        // and our futurePossibleStructure set can only contain zero, one, or an
+        // infinity of structures.
+        ASSERT(value.m_futurePossibleStructure.isSubsetOf(StructureSet(node.structure())));
+        
         ASSERT(value.isClear() || isCellSpeculation(value.m_type)); // Value could be clear if we've proven must-exit due to a speculation statically known to be bad.
         value.filter(node.structure());
+        // See comment in CheckStructure for why this is here.
+        if (value.m_currentKnownStructure.isClear()
+            || value.m_futurePossibleStructure.isClear())
+            m_isValid = false;
         m_haveStructures = true;
         node.setCanExit(true);
         break;
@@ -1453,12 +1489,9 @@ bool AbstractState::execute(unsigned indexInBlock)
         forNode(nodeIndex).clear(); // The result is not a JS value.
         break;
     case GetIndexedPropertyStorage: {
+        ASSERT(m_graph[node.child1()].prediction());
+        ASSERT(m_graph[node.child2()].shouldSpeculateInteger());
         node.setCanExit(true); // Lies, but this is (almost) always followed by GetByVal, which does exit. So no point in trying to be more precise.
-        SpeculatedType basePrediction = m_graph[node.child2()].prediction();
-        if (!(basePrediction & SpecInt32) && basePrediction) {
-            forNode(nodeIndex).clear();
-            break;
-        }
         if (m_graph[node.child1()].shouldSpeculateArguments()) {
             ASSERT_NOT_REACHED();
             break;
@@ -1514,7 +1547,7 @@ bool AbstractState::execute(unsigned indexInBlock)
             forNode(nodeIndex).clear();
             break;
         }
-        forNode(node.child1()).filter(SpecArray);
+        forNode(node.child1()).filter(SpecCell);
         forNode(nodeIndex).clear();
         break; 
     }