1. 06 Nov, 2012 1 commit
    • oliver@apple.com's avatar
      Reduce parser overhead in JSC · f0c01b8e
      oliver@apple.com authored
      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:
      * 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
      * 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