From ee4c86d1990a9e26277a6948e7027ad8d525ebfa Mon Sep 17 00:00:00 2001
From: Simon Hausmann <simon.hausmann@digia.com>
Date: Thu, 18 Oct 2012 10:55:06 +0200
Subject: Imported WebKit commit 795dcd25a9649fccaf1c9b685f6e2ffedaf7e620
 (http://svn.webkit.org/repository/webkit/trunk@131718)

New snapshot that includes the return of -fkeep-memory at link time
to reduce memory pressure as well as modularized documentation
---
 .../bytecompiler/BytecodeGenerator.cpp             | 97 ++++++++++++++++++++--
 .../bytecompiler/BytecodeGenerator.h               | 20 ++++-
 .../JavaScriptCore/bytecompiler/NodesCodegen.cpp   | 36 ++++----
 3 files changed, 130 insertions(+), 23 deletions(-)

(limited to 'Source/JavaScriptCore/bytecompiler')

diff --git a/Source/JavaScriptCore/bytecompiler/BytecodeGenerator.cpp b/Source/JavaScriptCore/bytecompiler/BytecodeGenerator.cpp
index 4308148b3..1160a1888 100644
--- a/Source/JavaScriptCore/bytecompiler/BytecodeGenerator.cpp
+++ b/Source/JavaScriptCore/bytecompiler/BytecodeGenerator.cpp
@@ -2013,9 +2013,9 @@ RegisterID* BytecodeGenerator::emitNewFunctionExpression(RegisterID* r0, FuncExp
     return r0;
 }
 
-RegisterID* BytecodeGenerator::emitCall(RegisterID* dst, RegisterID* func, CallArguments& callArguments, unsigned divot, unsigned startOffset, unsigned endOffset)
+RegisterID* BytecodeGenerator::emitCall(RegisterID* dst, RegisterID* func, ExpectedFunction expectedFunction, CallArguments& callArguments, unsigned divot, unsigned startOffset, unsigned endOffset)
 {
-    return emitCall(op_call, dst, func, callArguments, divot, startOffset, endOffset);
+    return emitCall(op_call, dst, func, expectedFunction, callArguments, divot, startOffset, endOffset);
 }
 
 void BytecodeGenerator::createArgumentsIfNecessary()
@@ -2048,10 +2048,85 @@ void BytecodeGenerator::createActivationIfNecessary()
 
 RegisterID* BytecodeGenerator::emitCallEval(RegisterID* dst, RegisterID* func, CallArguments& callArguments, unsigned divot, unsigned startOffset, unsigned endOffset)
 {
-    return emitCall(op_call_eval, dst, func, callArguments, divot, startOffset, endOffset);
+    return emitCall(op_call_eval, dst, func, NoExpectedFunction, callArguments, divot, startOffset, endOffset);
 }
 
-RegisterID* BytecodeGenerator::emitCall(OpcodeID opcodeID, RegisterID* dst, RegisterID* func, CallArguments& callArguments, unsigned divot, unsigned startOffset, unsigned endOffset)
+ExpectedFunction BytecodeGenerator::expectedFunctionForIdentifier(const Identifier& identifier)
+{
+    if (identifier == m_globalData->propertyNames->Object)
+        return ExpectObjectConstructor;
+    if (identifier == m_globalData->propertyNames->Array)
+        return ExpectArrayConstructor;
+    return NoExpectedFunction;
+}
+
+ExpectedFunction BytecodeGenerator::emitExpectedFunctionSnippet(RegisterID* dst, RegisterID* func, ExpectedFunction expectedFunction, CallArguments& callArguments, Label* done)
+{
+    RefPtr<Label> realCall = newLabel();
+    switch (expectedFunction) {
+    case ExpectObjectConstructor: {
+        // If the number of arguments is non-zero, then we can't do anything interesting.
+        if (callArguments.argumentCountIncludingThis() >= 2)
+            return NoExpectedFunction;
+        
+        size_t begin = instructions().size();
+        emitOpcode(op_jneq_ptr);
+        instructions().append(func->index());
+        instructions().append(Special::ObjectConstructor);
+        instructions().append(realCall->bind(begin, instructions().size()));
+        
+        if (dst != ignoredResult()) {
+            emitOpcode(op_new_object);
+            instructions().append(dst->index());
+        }
+        break;
+    }
+        
+    case ExpectArrayConstructor: {
+        // If you're doing anything other than "new Array()" or "new Array(foo)" then we
+        // don't do inline it, for now. The only reason is that call arguments are in
+        // the opposite order of what op_new_array expects, so we'd either need to change
+        // how op_new_array works or we'd need an op_new_array_reverse. Neither of these
+        // things sounds like it's worth it.
+        if (callArguments.argumentCountIncludingThis() > 2)
+            return NoExpectedFunction;
+        
+        size_t begin = instructions().size();
+        emitOpcode(op_jneq_ptr);
+        instructions().append(func->index());
+        instructions().append(Special::ArrayConstructor);
+        instructions().append(realCall->bind(begin, instructions().size()));
+        
+        if (dst != ignoredResult()) {
+            if (callArguments.argumentCountIncludingThis() == 2) {
+                emitOpcode(op_new_array_with_size);
+                instructions().append(dst->index());
+                instructions().append(callArguments.argumentRegister(0)->index());
+            } else {
+                ASSERT(callArguments.argumentCountIncludingThis() == 1);
+                emitOpcode(op_new_array);
+                instructions().append(dst->index());
+                instructions().append(0);
+                instructions().append(0);
+            }
+        }
+        break;
+    }
+        
+    default:
+        ASSERT(expectedFunction == NoExpectedFunction);
+        return NoExpectedFunction;
+    }
+    
+    size_t begin = instructions().size();
+    emitOpcode(op_jmp);
+    instructions().append(done->bind(begin, instructions().size()));
+    emitLabel(realCall.get());
+    
+    return expectedFunction;
+}
+
+RegisterID* BytecodeGenerator::emitCall(OpcodeID opcodeID, RegisterID* dst, RegisterID* func, ExpectedFunction expectedFunction, CallArguments& callArguments, unsigned divot, unsigned startOffset, unsigned endOffset)
 {
     ASSERT(opcodeID == op_call || opcodeID == op_call_eval);
     ASSERT(func->refCount());
@@ -2076,6 +2151,9 @@ RegisterID* BytecodeGenerator::emitCall(OpcodeID opcodeID, RegisterID* dst, Regi
 
     emitExpressionInfo(divot, startOffset, endOffset);
 
+    RefPtr<Label> done = newLabel();
+    expectedFunction = emitExpectedFunctionSnippet(dst, func, expectedFunction, callArguments, done.get());
+    
     // Emit call.
     ArrayProfile* arrayProfile = newArrayProfile();
     emitOpcode(opcodeID);
@@ -2093,6 +2171,9 @@ RegisterID* BytecodeGenerator::emitCall(OpcodeID opcodeID, RegisterID* dst, Regi
         instructions().append(dst->index()); // dst
         instructions().append(profile);
     }
+    
+    if (expectedFunction != NoExpectedFunction)
+        emitLabel(done.get());
 
     if (m_shouldEmitProfileHooks) {
         emitOpcode(op_profile_did_call);
@@ -2162,7 +2243,7 @@ RegisterID* BytecodeGenerator::emitUnaryNoDstOp(OpcodeID opcodeID, RegisterID* s
     return src;
 }
 
-RegisterID* BytecodeGenerator::emitConstruct(RegisterID* dst, RegisterID* func, CallArguments& callArguments, unsigned divot, unsigned startOffset, unsigned endOffset)
+RegisterID* BytecodeGenerator::emitConstruct(RegisterID* dst, RegisterID* func, ExpectedFunction expectedFunction, CallArguments& callArguments, unsigned divot, unsigned startOffset, unsigned endOffset)
 {
     ASSERT(func->refCount());
 
@@ -2187,6 +2268,9 @@ RegisterID* BytecodeGenerator::emitConstruct(RegisterID* dst, RegisterID* func,
         callFrame.append(newTemporary());
 
     emitExpressionInfo(divot, startOffset, endOffset);
+    
+    RefPtr<Label> done = newLabel();
+    expectedFunction = emitExpectedFunctionSnippet(dst, func, expectedFunction, callArguments, done.get());
 
     emitOpcode(op_construct);
     instructions().append(func->index()); // func
@@ -2204,6 +2288,9 @@ RegisterID* BytecodeGenerator::emitConstruct(RegisterID* dst, RegisterID* func,
         instructions().append(profile);
     }
 
+    if (expectedFunction != NoExpectedFunction)
+        emitLabel(done.get());
+
     if (m_shouldEmitProfileHooks) {
         emitOpcode(op_profile_did_call);
         instructions().append(callArguments.profileHookRegister()->index());
diff --git a/Source/JavaScriptCore/bytecompiler/BytecodeGenerator.h b/Source/JavaScriptCore/bytecompiler/BytecodeGenerator.h
index a429c710e..ae79a13ae 100644
--- a/Source/JavaScriptCore/bytecompiler/BytecodeGenerator.h
+++ b/Source/JavaScriptCore/bytecompiler/BytecodeGenerator.h
@@ -51,6 +51,12 @@ namespace JSC {
     class Label;
     class JSScope;
 
+    enum ExpectedFunction {
+        NoExpectedFunction,
+        ExpectObjectConstructor,
+        ExpectArrayConstructor
+    };
+
     class CallArguments {
     public:
         CallArguments(BytecodeGenerator& generator, ArgumentsNode* argumentsNode);
@@ -483,8 +489,9 @@ namespace JSC {
         RegisterID* emitDeleteByVal(RegisterID* dst, RegisterID* base, RegisterID* property);
         RegisterID* emitPutByIndex(RegisterID* base, unsigned index, RegisterID* value);
         void emitPutGetterSetter(RegisterID* base, const Identifier& property, RegisterID* getter, RegisterID* setter);
-
-        RegisterID* emitCall(RegisterID* dst, RegisterID* func, CallArguments&, unsigned divot, unsigned startOffset, unsigned endOffset);
+        
+        ExpectedFunction expectedFunctionForIdentifier(const Identifier&);
+        RegisterID* emitCall(RegisterID* dst, RegisterID* func, ExpectedFunction, CallArguments&, unsigned divot, unsigned startOffset, unsigned endOffset);
         RegisterID* emitCallEval(RegisterID* dst, RegisterID* func, CallArguments&, unsigned divot, unsigned startOffset, unsigned endOffset);
         RegisterID* emitCallVarargs(RegisterID* dst, RegisterID* func, RegisterID* thisRegister, RegisterID* arguments, RegisterID* firstFreeRegister, RegisterID* profileHookRegister, unsigned divot, unsigned startOffset, unsigned endOffset);
         RegisterID* emitLoadVarargs(RegisterID* argCountDst, RegisterID* thisRegister, RegisterID* args);
@@ -492,7 +499,7 @@ namespace JSC {
         RegisterID* emitReturn(RegisterID* src);
         RegisterID* emitEnd(RegisterID* src) { return emitUnaryNoDstOp(op_end, src); }
 
-        RegisterID* emitConstruct(RegisterID* dst, RegisterID* func, CallArguments&, unsigned divot, unsigned startOffset, unsigned endOffset);
+        RegisterID* emitConstruct(RegisterID* dst, RegisterID* func, ExpectedFunction, CallArguments&, unsigned divot, unsigned startOffset, unsigned endOffset);
         RegisterID* emitStrcat(RegisterID* dst, RegisterID* src, int count);
         void emitToPrimitive(RegisterID* dst, RegisterID* src);
 
@@ -590,7 +597,12 @@ namespace JSC {
         typedef HashMap<double, JSValue> NumberMap;
         typedef HashMap<StringImpl*, JSString*, IdentifierRepHash> IdentifierStringMap;
         
-        RegisterID* emitCall(OpcodeID, RegisterID* dst, RegisterID* func, CallArguments&, unsigned divot, unsigned startOffset, unsigned endOffset);
+        // Helper for emitCall() and emitConstruct(). This works because the set of
+        // expected functions have identical behavior for both call and construct
+        // (i.e. "Object()" is identical to "new Object()").
+        ExpectedFunction emitExpectedFunctionSnippet(RegisterID* dst, RegisterID* func, ExpectedFunction, CallArguments&, Label* done);
+        
+        RegisterID* emitCall(OpcodeID, RegisterID* dst, RegisterID* func, ExpectedFunction, CallArguments&, unsigned divot, unsigned startOffset, unsigned endOffset);
 
         RegisterID* newRegister();
 
diff --git a/Source/JavaScriptCore/bytecompiler/NodesCodegen.cpp b/Source/JavaScriptCore/bytecompiler/NodesCodegen.cpp
index 0ac4149b6..10a873d1c 100644
--- a/Source/JavaScriptCore/bytecompiler/NodesCodegen.cpp
+++ b/Source/JavaScriptCore/bytecompiler/NodesCodegen.cpp
@@ -366,9 +366,14 @@ RegisterID* ArgumentListNode::emitBytecode(BytecodeGenerator& generator, Registe
 
 RegisterID* NewExprNode::emitBytecode(BytecodeGenerator& generator, RegisterID* dst)
 {
+    ExpectedFunction expectedFunction;
+    if (m_expr->isResolveNode())
+        expectedFunction = generator.expectedFunctionForIdentifier(static_cast<ResolveNode*>(m_expr)->identifier());
+    else
+        expectedFunction = NoExpectedFunction;
     RefPtr<RegisterID> func = generator.emitNode(m_expr);
     CallArguments callArguments(generator, m_args);
-    return generator.emitConstruct(generator.finalDestinationOrIgnored(dst), func.get(), callArguments, divot(), startOffset(), endOffset());
+    return generator.emitConstruct(generator.finalDestinationOrIgnored(dst), func.get(), expectedFunction, callArguments, divot(), startOffset(), endOffset());
 }
 
 inline CallArguments::CallArguments(BytecodeGenerator& generator, ArgumentsNode* argumentsNode)
@@ -415,20 +420,23 @@ RegisterID* FunctionCallValueNode::emitBytecode(BytecodeGenerator& generator, Re
     RefPtr<RegisterID> func = generator.emitNode(m_expr);
     CallArguments callArguments(generator, m_args);
     generator.emitLoad(callArguments.thisRegister(), jsUndefined());
-    return generator.emitCall(generator.finalDestinationOrIgnored(dst, func.get()), func.get(), callArguments, divot(), startOffset(), endOffset());
+    return generator.emitCall(generator.finalDestinationOrIgnored(dst, func.get()), func.get(), NoExpectedFunction, callArguments, divot(), startOffset(), endOffset());
 }
 
 // ------------------------------ FunctionCallResolveNode ----------------------------------
 
 RegisterID* FunctionCallResolveNode::emitBytecode(BytecodeGenerator& generator, RegisterID* dst)
 {
+    ExpectedFunction expectedFunction = generator.expectedFunctionForIdentifier(m_ident);
     ResolveResult resolveResult = generator.resolve(m_ident);
 
     if (RegisterID* local = resolveResult.local()) {
         RefPtr<RegisterID> func = generator.emitMove(generator.tempDestination(dst), local);
         CallArguments callArguments(generator, m_args);
         generator.emitLoad(callArguments.thisRegister(), jsUndefined());
-        return generator.emitCall(generator.finalDestinationOrIgnored(dst, callArguments.thisRegister()), func.get(), callArguments, divot(), startOffset(), endOffset());
+        // This passes NoExpectedFunction because we expect that if the function is in a
+        // local variable, then it's not one of our built-in constructors.
+        return generator.emitCall(generator.finalDestinationOrIgnored(dst, callArguments.thisRegister()), func.get(), NoExpectedFunction, callArguments, divot(), startOffset(), endOffset());
     }
 
     if (resolveResult.isStatic()) {
@@ -436,7 +444,7 @@ RegisterID* FunctionCallResolveNode::emitBytecode(BytecodeGenerator& generator,
         CallArguments callArguments(generator, m_args);
         generator.emitGetStaticVar(func.get(), resolveResult, m_ident);
         generator.emitLoad(callArguments.thisRegister(), jsUndefined());
-        return generator.emitCall(generator.finalDestinationOrIgnored(dst, func.get()), func.get(), callArguments, divot(), startOffset(), endOffset());
+        return generator.emitCall(generator.finalDestinationOrIgnored(dst, func.get()), func.get(), expectedFunction, callArguments, divot(), startOffset(), endOffset());
     }
 
     RefPtr<RegisterID> func = generator.newTemporary();
@@ -445,7 +453,7 @@ RegisterID* FunctionCallResolveNode::emitBytecode(BytecodeGenerator& generator,
 
     generator.emitExpressionInfo(identifierStart + m_ident.length(), m_ident.length(), 0);
     generator.emitResolveWithThis(callArguments.thisRegister(), func.get(), resolveResult, m_ident);
-    return generator.emitCall(generator.finalDestinationOrIgnored(dst, func.get()), func.get(), callArguments, divot(), startOffset(), endOffset());
+    return generator.emitCall(generator.finalDestinationOrIgnored(dst, func.get()), func.get(), expectedFunction, callArguments, divot(), startOffset(), endOffset());
 }
 
 // ------------------------------ FunctionCallBracketNode ----------------------------------
@@ -458,7 +466,7 @@ RegisterID* FunctionCallBracketNode::emitBytecode(BytecodeGenerator& generator,
     RefPtr<RegisterID> function = generator.emitGetByVal(generator.tempDestination(dst), base.get(), property);
     CallArguments callArguments(generator, m_args);
     generator.emitMove(callArguments.thisRegister(), base.get());
-    return generator.emitCall(generator.finalDestinationOrIgnored(dst, function.get()), function.get(), callArguments, divot(), startOffset(), endOffset());
+    return generator.emitCall(generator.finalDestinationOrIgnored(dst, function.get()), function.get(), NoExpectedFunction, callArguments, divot(), startOffset(), endOffset());
 }
 
 // ------------------------------ FunctionCallDotNode ----------------------------------
@@ -471,7 +479,7 @@ RegisterID* FunctionCallDotNode::emitBytecode(BytecodeGenerator& generator, Regi
     generator.emitExpressionInfo(divot() - m_subexpressionDivotOffset, startOffset() - m_subexpressionDivotOffset, m_subexpressionEndOffset);
     generator.emitMethodCheck();
     generator.emitGetById(function.get(), callArguments.thisRegister(), m_ident);
-    return generator.emitCall(generator.finalDestinationOrIgnored(dst, function.get()), function.get(), callArguments, divot(), startOffset(), endOffset());
+    return generator.emitCall(generator.finalDestinationOrIgnored(dst, function.get()), function.get(), NoExpectedFunction, callArguments, divot(), startOffset(), endOffset());
 }
 
 RegisterID* CallFunctionCallDotNode::emitBytecode(BytecodeGenerator& generator, RegisterID* dst)
@@ -491,7 +499,7 @@ RegisterID* CallFunctionCallDotNode::emitBytecode(BytecodeGenerator& generator,
             RefPtr<RegisterID> realFunction = generator.emitMove(generator.tempDestination(dst), base.get());
             CallArguments callArguments(generator, m_args);
             generator.emitNode(callArguments.thisRegister(), oldList->m_expr);
-            generator.emitCall(finalDestinationOrIgnored.get(), realFunction.get(), callArguments, divot(), startOffset(), endOffset());
+            generator.emitCall(finalDestinationOrIgnored.get(), realFunction.get(), NoExpectedFunction, callArguments, divot(), startOffset(), endOffset());
             generator.emitJump(end.get());
 
             m_args->m_listNode = oldList;
@@ -499,7 +507,7 @@ RegisterID* CallFunctionCallDotNode::emitBytecode(BytecodeGenerator& generator,
             RefPtr<RegisterID> realFunction = generator.emitMove(generator.tempDestination(dst), base.get());
             CallArguments callArguments(generator, m_args);
             generator.emitLoad(callArguments.thisRegister(), jsUndefined());
-            generator.emitCall(finalDestinationOrIgnored.get(), realFunction.get(), callArguments, divot(), startOffset(), endOffset());
+            generator.emitCall(finalDestinationOrIgnored.get(), realFunction.get(), NoExpectedFunction, callArguments, divot(), startOffset(), endOffset());
             generator.emitJump(end.get());
         }
     }
@@ -507,7 +515,7 @@ RegisterID* CallFunctionCallDotNode::emitBytecode(BytecodeGenerator& generator,
     {
         CallArguments callArguments(generator, m_args);
         generator.emitMove(callArguments.thisRegister(), base.get());
-        generator.emitCall(finalDestinationOrIgnored.get(), function.get(), callArguments, divot(), startOffset(), endOffset());
+        generator.emitCall(finalDestinationOrIgnored.get(), function.get(), NoExpectedFunction, callArguments, divot(), startOffset(), endOffset());
     }
     generator.emitLabel(end.get());
     return finalDestinationOrIgnored.get();
@@ -544,20 +552,20 @@ RegisterID* ApplyFunctionCallDotNode::emitBytecode(BytecodeGenerator& generator,
                     RefPtr<RegisterID> realFunction = generator.emitMove(generator.tempDestination(dst), base.get());
                     CallArguments callArguments(generator, m_args);
                     generator.emitNode(callArguments.thisRegister(), oldList->m_expr);
-                    generator.emitCall(finalDestinationOrIgnored.get(), realFunction.get(), callArguments, divot(), startOffset(), endOffset());
+                    generator.emitCall(finalDestinationOrIgnored.get(), realFunction.get(), NoExpectedFunction, callArguments, divot(), startOffset(), endOffset());
                 } else {
                     m_args->m_listNode = m_args->m_listNode->m_next;
                     RefPtr<RegisterID> realFunction = generator.emitMove(generator.tempDestination(dst), base.get());
                     CallArguments callArguments(generator, m_args);
                     generator.emitNode(callArguments.thisRegister(), oldList->m_expr);
-                    generator.emitCall(finalDestinationOrIgnored.get(), realFunction.get(), callArguments, divot(), startOffset(), endOffset());
+                    generator.emitCall(finalDestinationOrIgnored.get(), realFunction.get(), NoExpectedFunction, callArguments, divot(), startOffset(), endOffset());
                 }
                 m_args->m_listNode = oldList;
             } else {
                 RefPtr<RegisterID> realFunction = generator.emitMove(generator.tempDestination(dst), base.get());
                 CallArguments callArguments(generator, m_args);
                 generator.emitLoad(callArguments.thisRegister(), jsUndefined());
-                generator.emitCall(finalDestinationOrIgnored.get(), realFunction.get(), callArguments, divot(), startOffset(), endOffset());
+                generator.emitCall(finalDestinationOrIgnored.get(), realFunction.get(), NoExpectedFunction, callArguments, divot(), startOffset(), endOffset());
             }
         } else {
             ASSERT(m_args->m_listNode && m_args->m_listNode->m_next);
@@ -586,7 +594,7 @@ RegisterID* ApplyFunctionCallDotNode::emitBytecode(BytecodeGenerator& generator,
     {
         CallArguments callArguments(generator, m_args);
         generator.emitMove(callArguments.thisRegister(), base.get());
-        generator.emitCall(finalDestinationOrIgnored.get(), function.get(), callArguments, divot(), startOffset(), endOffset());
+        generator.emitCall(finalDestinationOrIgnored.get(), function.get(), NoExpectedFunction, callArguments, divot(), startOffset(), endOffset());
     }
     generator.emitLabel(end.get());
     return finalDestinationOrIgnored.get();
-- 
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