Copy-and-Patch: A Copy-and-Patch Tutorial
10 hours ago
- #copy-and-patch
- #runtime code generation
- #JIT compilation
- Copy-and-patch compilation is a method for constructing a baseline JIT that allows fast runtime compilation with minimal assembly knowledge.
- The process involves writing stencils in C, compiling them into native code, and then copying and patching these stencils at runtime to form executable code.
- A practical example demonstrates creating a JIT function to compute 1 + 2 by breaking it down into bytecode operations and using stencils for each operation.
- Stencils are defined with relocation holes for constants and addresses, which are patched at runtime to specialize the generated code.
- The tutorial includes steps to compile stencils, generate a library of copy and patch functions, and use them to build a runtime-specialized adder.
- Advanced techniques are introduced for handling more complex operations with multiple relocation holes, demonstrating the flexibility of the copy-and-patch approach.