• oliver@apple.com's avatar
    Reduce parser overhead in JSC · f0c01b8e
    oliver@apple.com authored
    https://bugs.webkit.org/show_bug.cgi?id=101127
    
    Reviewed by Filip Pizlo.
    
    An exciting journey into the world of architecture in which our hero
    adds yet another layer to JSC codegeneration.
    
    This patch adds a marginally more compact form of bytecode that is
    free from any data specific to a given execution context, and that
    does store any data structures necessary for execution.  To actually
    execute this UnlinkedBytecode we still need to instantiate a real
    CodeBlock, but this is a much faster linear time operation than any
    of the earlier parsing or code generation passes.
    
    As the unlinked code is context free we can then simply use a cache
    from source to unlinked code mapping to completely avoid all of the
    old parser overhead.  The cache is currently very simple and memory
    heavy, using the complete source text as a key (rather than SourceCode
    or equivalent), and a random eviction policy.
    
    This seems to produce a substantial win when loading identical content
    in different contexts.
    
    * API/tests/testapi.c:
    (main):
    * CMakeLists.txt:
    * GNUmakefile.list.am:
    * JavaScriptCore.vcproj/JavaScriptCore/JavaScriptCore.vcproj:
    * JavaScriptCore.xcodeproj/project.pbxproj:
    * bytecode/CodeBlock.cpp:
    * bytecode/CodeBlock.h:
        Moved a number of fields, and a bunch of logic to UnlinkedCodeBlock.h/cpp
    * bytecode/Opcode.h:
        Added a global const init no op instruction needed to get correct
        behaviour without any associated semantics.
    * bytecode/UnlinkedCodeBlock.cpp: Added.
    * bytecode/UnlinkedCodeBlock.h: Added.
        A fairly shallow, GC allocated version of the old CodeBlock
        classes with a 32bit instruction size, and just metadata
        size tracking.
    * bytecompiler/BytecodeGenerator.cpp:
    * bytecompiler/BytecodeGenerator.h:
        Replace direct access to m_symbolTable with access through
        symbolTable().  ProgramCode no longer has a symbol table at
        all so some previously unconditional (and pointless) uses
        of symbolTable get null checks.
        A few other changes to deal with type changes due to us generating
        unlinked code (eg. pointer free, so profile indices rather than
        pointers).
    * dfg/DFGByteCodeParser.cpp:
    * dfg/DFGCapabilities.h:
        Support global_init_nop
    * interpreter/Interpreter.cpp:
        Now get the ProgramExecutable to initialise new global properties
        before starting execution.
    * jit/JIT.cpp:
    * jit/JITDriver.h:
    * jit/JITStubs.cpp:
    * llint/LLIntData.cpp:
    * llint/LLIntSlowPaths.cpp:
    * llint/LowLevelInterpreter.asm:
    * llint/LowLevelInterpreter32_64.asm:
    * llint/LowLevelInterpreter64.asm:
        Adding init_global_const_nop everywhere else
    * parser/Parser.h:
    * parser/ParserModes.h: Added.
    * parser/ParserTokens.h:
        Parser no longer needs a global object or callframe to function
    * runtime/CodeCache.cpp: Added.
    * runtime/CodeCache.h: Added.
        A simple, random eviction, Source->UnlinkedCode cache
    * runtime/Executable.cpp:
    * runtime/Executable.h:
        Executables now reference their unlinked counterparts, and
        request code specifically for the target global object.
    * runtime/JSGlobalData.cpp:
    * runtime/JSGlobalData.h:
        GlobalData now owns a CodeCache and a set of new structures
        for the unlinked code types.
    * runtime/JSGlobalObject.cpp:
    * runtime/JSGlobalObject.h:
        Utility functions used by executables to perform compilation
    
    * runtime/JSType.h:
      Add new JSTypes for unlinked code
    
    git-svn-id: http://svn.webkit.org/repository/webkit/trunk@133688 268f45cc-cd09-0410-ab3c-d52691b4dbfc
    f0c01b8e
CodeCache.cpp 9.03 KB