Imported QtWebKit TP3 (git b57bc6801f1876c3220d5a4bfea33d620d477443)

Change-Id: I3b1d8a2808782c9f34d50240000e20cb38d3680f
Reviewed-by: Konstantin Tokarev <annulen@yandex.ru>

1 files changed, 222 insertions, 0 deletions

diff --git a/Source/JavaScriptCore/dfg/DFGVariableAccessData.cpp b/Source/JavaScriptCore/dfg/DFGVariableAccessData.cpp
new file mode 100644
index 000000000..bd1ba87ee
--- /dev/null
+++ b/Source/JavaScriptCore/dfg/DFGVariableAccessData.cpp
@@ -0,0 +1,222 @@
+/*
+ * Copyright (C) 2014, 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 "DFGVariableAccessData.h"
+
+#if ENABLE(DFG_JIT)
+
+namespace JSC { namespace DFG {
+
+VariableAccessData::VariableAccessData()
+    : m_local(static_cast<VirtualRegister>(std::numeric_limits<int>::min()))
+    , m_prediction(SpecNone)
+    , m_argumentAwarePrediction(SpecNone)
+    , m_flags(0)
+    , m_shouldNeverUnbox(false)
+    , m_structureCheckHoistingFailed(false)
+    , m_checkArrayHoistingFailed(false)
+    , m_isProfitableToUnbox(false)
+    , m_isLoadedFrom(false)
+    , m_doubleFormatState(EmptyDoubleFormatState)
+{
+    clearVotes();
+}
+
+VariableAccessData::VariableAccessData(VirtualRegister local)
+    : m_local(local)
+    , m_prediction(SpecNone)
+    , m_argumentAwarePrediction(SpecNone)
+    , m_flags(0)
+    , m_shouldNeverUnbox(false)
+    , m_structureCheckHoistingFailed(false)
+    , m_checkArrayHoistingFailed(false)
+    , m_isProfitableToUnbox(false)
+    , m_isLoadedFrom(false)
+    , m_doubleFormatState(EmptyDoubleFormatState)
+{
+    clearVotes();
+}
+
+bool VariableAccessData::mergeShouldNeverUnbox(bool shouldNeverUnbox)
+{
+    bool newShouldNeverUnbox = m_shouldNeverUnbox | shouldNeverUnbox;
+    if (newShouldNeverUnbox == m_shouldNeverUnbox)
+        return false;
+    m_shouldNeverUnbox = newShouldNeverUnbox;
+    return true;
+}
+
+bool VariableAccessData::predict(SpeculatedType prediction)
+{
+    VariableAccessData* self = find();
+    bool result = mergeSpeculation(self->m_prediction, prediction);
+    if (result)
+        mergeSpeculation(m_argumentAwarePrediction, m_prediction);
+    return result;
+}
+
+bool VariableAccessData::mergeArgumentAwarePrediction(SpeculatedType prediction)
+{
+    return mergeSpeculation(find()->m_argumentAwarePrediction, prediction);
+}
+
+bool VariableAccessData::shouldUseDoubleFormatAccordingToVote()
+{
+    // We don't support this facility for arguments, yet.
+    // FIXME: make this work for arguments.
+    if (local().isArgument())
+        return false;
+        
+    // If the variable is not a number prediction, then this doesn't
+    // make any sense.
+    if (!isFullNumberSpeculation(prediction())) {
+        // FIXME: we may end up forcing a local in inlined argument position to be a double even
+        // if it is sometimes not even numeric, since this never signals the fact that it doesn't
+        // want doubles. https://bugs.webkit.org/show_bug.cgi?id=109511
+        return false;
+    }
+        
+    // If the variable is predicted to hold only doubles, then it's a
+    // no-brainer: it should be formatted as a double.
+    if (isDoubleSpeculation(prediction()))
+        return true;
+        
+    // If the variable is known to be used as an integer, then be safe -
+    // don't force it to be a double.
+    if (flags() & NodeBytecodeUsesAsInt)
+        return false;
+        
+    // If the variable has been voted to become a double, then make it a
+    // double.
+    if (voteRatio() >= Options::doubleVoteRatioForDoubleFormat())
+        return true;
+        
+    return false;
+}
+
+bool VariableAccessData::tallyVotesForShouldUseDoubleFormat()
+{
+    ASSERT(isRoot());
+        
+    if (local().isArgument() || shouldNeverUnbox()
+        || (flags() & NodeBytecodeUsesAsArrayIndex))
+        return DFG::mergeDoubleFormatState(m_doubleFormatState, NotUsingDoubleFormat);
+    
+    if (m_doubleFormatState == CantUseDoubleFormat)
+        return false;
+        
+    bool newValueOfShouldUseDoubleFormat = shouldUseDoubleFormatAccordingToVote();
+    if (!newValueOfShouldUseDoubleFormat) {
+        // We monotonically convert to double. Hence, if the fixpoint leads us to conclude that we should
+        // switch back to int, we instead ignore this and stick with double.
+        return false;
+    }
+        
+    if (m_doubleFormatState == UsingDoubleFormat)
+        return false;
+        
+    return DFG::mergeDoubleFormatState(m_doubleFormatState, UsingDoubleFormat);
+}
+
+bool VariableAccessData::mergeDoubleFormatState(DoubleFormatState doubleFormatState)
+{
+    return DFG::mergeDoubleFormatState(find()->m_doubleFormatState, doubleFormatState);
+}
+
+bool VariableAccessData::makePredictionForDoubleFormat()
+{
+    ASSERT(isRoot());
+    
+    if (m_doubleFormatState != UsingDoubleFormat)
+        return false;
+    
+    SpeculatedType type = m_prediction;
+    if (type & ~SpecBytecodeNumber)
+        type |= SpecDoublePureNaN;
+    if (type & SpecMachineInt)
+        type |= SpecInt52AsDouble;
+    return checkAndSet(m_prediction, type);
+}
+
+bool VariableAccessData::couldRepresentInt52()
+{
+    if (shouldNeverUnbox())
+        return false;
+    
+    return couldRepresentInt52Impl();
+}
+
+bool VariableAccessData::couldRepresentInt52Impl()
+{
+    // The hardware has to support it.
+    if (!enableInt52())
+        return false;
+    
+    // We punt for machine arguments.
+    if (m_local.isArgument())
+        return false;
+    
+    // The argument-aware prediction -- which merges all of an (inlined or machine)
+    // argument's variable access datas' predictions -- must possibly be MachineInt.
+    return !(argumentAwarePrediction() & ~SpecMachineInt);
+}
+
+FlushFormat VariableAccessData::flushFormat()
+{
+    ASSERT(find() == this);
+    
+    if (!shouldUnboxIfPossible())
+        return FlushedJSValue;
+    
+    if (shouldUseDoubleFormat())
+        return FlushedDouble;
+    
+    SpeculatedType prediction = argumentAwarePrediction();
+    
+    // This guard is here to protect the call to couldRepresentInt52(), which will return
+    // true for !prediction.
+    if (!prediction)
+        return FlushedJSValue;
+    
+    if (isInt32Speculation(prediction))
+        return FlushedInt32;
+    
+    if (couldRepresentInt52Impl())
+        return FlushedInt52;
+    
+    if (isCellSpeculation(prediction))
+        return FlushedCell;
+    
+    if (isBooleanSpeculation(prediction))
+        return FlushedBoolean;
+    
+    return FlushedJSValue;
+}
+
+} } // namespace JSC::DFG
+
+#endif // ENABLE(DFG_JIT)
+