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/*
* Copyright (C) 2012-2017 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.
*/
#pragma once
#include "UnlinkedGlobalCodeBlock.h"
namespace JSC {
class Decoder;
class CachedModuleCodeBlock;
class UnlinkedModuleProgramCodeBlock final : public UnlinkedGlobalCodeBlock {
public:
typedef UnlinkedGlobalCodeBlock Base;
static const unsigned StructureFlags = Base::StructureFlags | StructureIsImmortal;
static UnlinkedModuleProgramCodeBlock* create(VM* vm, const ExecutableInfo& info, OptionSet<CodeGenerationMode> codeGenerationMode)
{
UnlinkedModuleProgramCodeBlock* instance = new (NotNull, allocateCell<UnlinkedModuleProgramCodeBlock>(vm->heap)) UnlinkedModuleProgramCodeBlock(vm, vm->unlinkedModuleProgramCodeBlockStructure.get(), info, codeGenerationMode);
instance->finishCreation(*vm);
return instance;
}
static void destroy(JSCell*);
// This offset represents the constant register offset to the stored symbol table that represents the layout of the
// module environment. This symbol table is created by the byte code generator since the module environment includes
// the top-most lexical captured variables inside the module code. This means that, once the module environment is
// allocated and instantiated from this symbol table, it is titely coupled with the specific unlinked module program
// code block and the stored symbol table. So before executing the module code, we should not clear the unlinked module
// program code block in the module executable. This requirement is met because the garbage collector only clears
// unlinked code in (1) unmarked executables and (2) function executables.
//
// Since the function code may be executed repeatedly and the environment of each function execution is different,
// the function code need to allocate and instantiate the environment in the prologue of the function code. On the
// other hand, the module code is executed only once. So we can instantiate the module environment outside the module
// code. At that time, we construct the module environment by using the symbol table that is held by the module executable.
// The symbol table held by the executable is the cloned one from one in the unlinked code block. Instantiating the module
// environment before executing and linking the module code is required to link the imported bindings between the modules.
//
// The unlinked module program code block only holds the pre-cloned symbol table in its constant register pool. It does
// not hold the instantiated module environment. So while the module environment requires the specific unlinked module
// program code block, the unlinked module code block can be used for the module environment instantiated from this
// unlinked code block. There is 1:N relation between the unlinked module code block and the module environments. So the
// unlinked module program code block can be cached.
//
// On the other hand, the linked code block for the module environment includes the resolved references to the imported
// bindings. The imported binding references the other module environment, so the linked code block is titly coupled
// with the specific set of the module environments. Thus, the linked code block should not be cached.
int moduleEnvironmentSymbolTableConstantRegisterOffset() { return m_moduleEnvironmentSymbolTableConstantRegisterOffset; }
void setModuleEnvironmentSymbolTableConstantRegisterOffset(int offset)
{
m_moduleEnvironmentSymbolTableConstantRegisterOffset = offset;
}
private:
friend CachedModuleCodeBlock;
UnlinkedModuleProgramCodeBlock(VM* vm, Structure* structure, const ExecutableInfo& info, OptionSet<CodeGenerationMode> codeGenerationMode)
: Base(vm, structure, ModuleCode, info, codeGenerationMode)
{
}
UnlinkedModuleProgramCodeBlock(Decoder&, const CachedModuleCodeBlock&);
int m_moduleEnvironmentSymbolTableConstantRegisterOffset { 0 };
public:
static Structure* createStructure(VM& vm, JSGlobalObject* globalObject, JSValue proto)
{
return Structure::create(vm, globalObject, proto, TypeInfo(UnlinkedModuleProgramCodeBlockType, StructureFlags), info());
}
DECLARE_INFO;
};
}