程式者的胡言亂語 : 一個程式者的胡言亂語

程式者的胡言亂語 : 一個程式者的胡言亂語

• Bytecode - Wikipedia, the free encyclopedi
  

  Bytecode is a binary representation of an executable program designed to be executed by a virtual machine rather than by dedicated hardware. Since it is processed by software, it is usually more abstract than machine code.
  After compiling to bytecode, the resulting output may be used as the input of a compiler targeting machine code, or executed directly on a virtual machine.
  bytecodes encode the results of semantic analysis such as the scope of each variable access (that is, whether the variable is global or local). Thus, performance is usually better than interpretation of source code.
  Some systems, called dynamic translators, or "just-in-time" (JIT) compilers, translate bytecode into machine language as necessary at runtime.
  For example, Java and C# code is typically stored in bytecoded format, which then uses a JIT compiler to translate the bytecode to machine code before execution. This introduces a delay before a program is run, when bytecode is compiled to native machine code, but improves execution speed considerably compared to interpretation - normally by several times.



• Common Language Infrastructure - Wikipedia, the free encyclopedia


• Common Intermediate Language - Wikipedia, the free encyclopedia


• Just-in-time compilation - Wikipedia, the free encyclopedia
  

  just-in-time compilation (JIT), is a technique for improving the runtime performance of a computer program. It converts, at runtime, code from one format into another, for example bytecode into native machine code. The performance improvement originates from caching the results of translating blocks of code, and not simply evaluating each line or operand separately.
  The goal is to combine many of the advantages of native and bytecode compilation: Much of the "heavy lifting" of parsing the original source code and performing basic optimization is handled at compile time, prior to deployment: compilation from bytecode to machine code is much faster than from source.
  However, JIT may have a drawback by causing a slight delay in initial execution of an application, due to the time taken to compile the bytecode. Sometimes this delay is called "startup time delay".
  JIT compilation is considered advantageous in many scenarios because of its portability, flexibility and performance. The only major drawback probably is the startup time delay.



• Universal binary - Wikipedia, the free encyclopedia
  

  Universal binaries typically include both PowerPC and x86 versions of a compiled application. The operating system detects a universal binary by its header, and executes the appropriate section depending on the architecture in use. This allows the application to run natively on any supported architecture, with no performance impact.



• Managed code - Wikipedia, the free encyclopedia
  

  
  In Microsoft Windows terminology, managed code is computer instructions — that is, "code" — executed by a CLI-compliant virtual machine, such as Microsoft's .NET Framework Common Language Runtime, or other CLI implementations from The Mono Project or the DotGNU Project.
  Before the code is run, the Intermediate Language is compiled into native machine code. Since this compilation happens by the managed execution environment's own runtime-aware compiler, the managed execution environment can guarantee what the code is going to do. It can insert garbage collection hooks, exception handling, type safety, array bounds, index checking, etc.
  

  
  
• Java 相關的編譯技術