Fix endianness in constant handling

When running on a big-endian system, we need to convert the constant values
into big-endian once and then it's possible to access them directly.

Change-Id: I655bad7b7734e3b95e79e5f688f0b4041d0c41c4
Reviewed-by: Erik Verbruggen <erik.verbruggen@qt.io>

src/qml/compiler/qv4compileddata.cpp

@@ -161,6 +161,16 @@ QV4::Function *CompilationUnit::linkToEngine(ExecutionEngine *engine)
         }
     }
 
+#if Q_BYTE_ORDER == Q_BIG_ENDIAN
+    Value *bigEndianConstants = new Value[data->constantTableSize];
+    const LEUInt64 *littleEndianConstants = data->constants();
+    for (uint i = 0; i < data->constantTableSize; ++i)
+        bigEndianConstants[i] = Value::fromReturnedValue(littleEndianConstants[i]);
+    constants = bigEndianConstants;
+#else
+    constants = reinterpret_cast<const Value*>(data->constants());
+#endif
+
     linkBackendToEngine(engine);
 
     if (data->indexOfRootFunction != -1)
@@ -203,6 +213,9 @@ void CompilationUnit::unlink()
     runtimeClasses = 0;
     qDeleteAll(runtimeFunctions);
     runtimeFunctions.clear();
+#if Q_BYTE_ORDER == Q_BIG_ENDIAN
+    delete [] constants;
+#endif
 }
 
 void CompilationUnit::markObjects(QV4::ExecutionEngine *e)

src/qml/compiler/qv4compileddata_p.h

@@ -691,8 +691,8 @@ struct Unit
     const RegExp *regexpAt(int index) const {
         return reinterpret_cast<const RegExp*>(reinterpret_cast<const char *>(this) + offsetToRegexpTable + index * sizeof(RegExp));
     }
-    const QV4::Value *constants() const {
-        return reinterpret_cast<const QV4::Value*>(reinterpret_cast<const char *>(this) + offsetToConstantTable);
+    const LEUInt64 *constants() const {
+        return reinterpret_cast<const LEUInt64*>(reinterpret_cast<const char *>(this) + offsetToConstantTable);
     }
 
     const JSClassMember *jsClassAt(int idx, int *nMembers) const {
@@ -853,6 +853,9 @@ struct Q_QML_PRIVATE_EXPORT CompilationUnit : public QQmlRefCount
     QHash<int, IdentifierHash<int>> namedObjectsPerComponentCache;
     IdentifierHash<int> namedObjectsPerComponent(int componentObjectIndex);
 
+    // pointers either to data->constants() or little-endian memory copy.
+    const Value* constants;
+
     void finalize(QQmlEnginePrivate *engine);
 
     int totalBindingsCount; // Number of bindings used in this type

src/qml/compiler/qv4compiler.cpp

@@ -248,8 +248,14 @@ QV4::CompiledData::Unit *QV4::Compiler::JSUnitGenerator::generateUnit(GeneratorO
     CompiledData::RegExp *regexpTable = reinterpret_cast<CompiledData::RegExp *>(dataPtr + unit->offsetToRegexpTable);
     memcpy(regexpTable, regexps.constData(), regexps.size() * sizeof(*regexpTable));
 
+#if Q_BYTE_ORDER == Q_LITTLE_ENDIAN
     ReturnedValue *constantTable = reinterpret_cast<ReturnedValue *>(dataPtr + unit->offsetToConstantTable);
     memcpy(constantTable, constants.constData(), constants.size() * sizeof(ReturnedValue));
+#else
+    CompiledData::LEUInt64 *constantTable = reinterpret_cast<CompiledData::LEUInt64 *>(dataPtr + unit->offsetToConstantTable);
+    for (int i = 0; i < constants.count(); ++i)
+        constantTable[i] = constants.at(i);
+#endif
 
     {
         memcpy(dataPtr + jsClassDataOffset, jsClassData.constData(), jsClassData.size());

src/qml/jsruntime/qv4context.cpp

@@ -73,7 +73,7 @@ Heap::CallContext *ExecutionContext::newCallContext(const FunctionObject *functi
 
     c->compilationUnit = function->function()->compilationUnit;
     c->lookups = c->compilationUnit->runtimeLookups;
-    c->constantTable = c->compilationUnit->data->constants();
+    c->constantTable = c->compilationUnit->constants;
     c->locals = (Value *)((quintptr(c + 1) + 7) & ~7);
 
     const CompiledData::Function *compiledFunction = function->function()->compiledFunction;

src/qml/jsruntime/qv4functionobject.cpp

@@ -535,7 +535,7 @@ void SimpleScriptFunction::construct(const Managed *that, Scope &scope, CallData
     ctx.function = f->d();
     ctx.compilationUnit = f->function()->compilationUnit;
     ctx.lookups = ctx.compilationUnit->runtimeLookups;
-    ctx.constantTable = ctx.compilationUnit->data->constants();
+    ctx.constantTable = ctx.compilationUnit->constants;
     ctx.outer = f->scope();
     ctx.locals = scope.alloc(f->varCount());
     for (int i = callData->argc; i < (int)f->formalParameterCount(); ++i)
@@ -573,7 +573,7 @@ void SimpleScriptFunction::call(const Managed *that, Scope &scope, CallData *cal
     ctx.function = f->d();
     ctx.compilationUnit = f->function()->compilationUnit;
     ctx.lookups = ctx.compilationUnit->runtimeLookups;
-    ctx.constantTable = ctx.compilationUnit->data->constants();
+    ctx.constantTable = ctx.compilationUnit->constants;
     ctx.outer = f->scope();
     ctx.locals = scope.alloc(f->varCount());
     for (int i = callData->argc; i < (int)f->formalParameterCount(); ++i)

src/qml/jsruntime/qv4script.cpp

@@ -222,7 +222,7 @@ ReturnedValue Script::run()
         ContextStateSaver stateSaver(valueScope, scope);
         scope->d()->strictMode = vmFunction->isStrict();
         scope->d()->lookups = vmFunction->compilationUnit->runtimeLookups;
-        scope->d()->constantTable = vmFunction->compilationUnit->data->constants();
+        scope->d()->constantTable = vmFunction->compilationUnit->constants;
         scope->d()->compilationUnit = vmFunction->compilationUnit;
 
         return Q_V4_PROFILE(engine, vmFunction);

src/qml/jsruntime/qv4vme_moth.cpp

@@ -402,7 +402,7 @@ QV4::ReturnedValue VME::run(ExecutionEngine *engine, const uchar *code
 
     QV4::Value **scopes = static_cast<QV4::Value **>(alloca(sizeof(QV4::Value *)*(2 + 2*scopeDepth)));
     {
-        scopes[0] = const_cast<QV4::Value *>(context->d()->compilationUnit->data->constants());
+        scopes[0] = const_cast<QV4::Value *>(context->d()->compilationUnit->constants);
         // stack gets setup in push instruction
         scopes[1] = 0;
         QV4::Heap::ExecutionContext *scope = context->d();