reads a single source code instruction, translates it into CPU instructions or a DLL call, and executes the instructions or DLL call immediately, before the next program statement is read.
The process you are referring to is called just-in-time (JIT) compilation. JIT compilation is a technique commonly used by modern programming languages and runtime environments to improve performance by dynamically translating code instructions into machine code at runtime.
Here is a simplified overview of the steps involved in JIT compilation:
1. Source Code: The original program's source code is written using a high-level programming language, such as C#, Java, or Python.
2. Parsing: The source code is parsed and converted into an intermediate representation (IR), which is a platform-independent representation of the code.
3. JIT Compilation: The JIT compiler translates the IR into machine code specific to the target CPU architecture, also known as native code. This translation typically happens on a per-function or per-basic-block basis.
4. DLL Call: If the source code instruction is calling a function in a dynamically linked library (DLL), the JIT compiler generates the appropriate machine code instructions to invoke the DLL function.
5. Execution: The generated machine code or DLL call is executed immediately, potentially inline with the rest of the program's execution, without waiting for the full program to be compiled.
6. Continuation: Once the translated code or DLL call is executed, the program proceeds to read the next statement and repeats the JIT compilation process for subsequent instructions if necessary.
By translating code to machine code just before execution, JIT compilation eliminates the need for static compilation or interpretation. This approach takes advantage of runtime information, such as profiling data and optimization opportunities, to generate highly optimized code tailored specifically to the current execution context.
JIT compilation is commonly used in virtual machines, such as the Java Virtual Machine (JVM) or the .NET Common Language Runtime (CLR), where it provides the performance benefits of compiled code with the flexibility of a runtime environment.