CPSC 323: Object Code Generation

Object Code Generation

• Compiler phase where intermediate code (typically three-address code, 3AC) is translated into the machine/assembly language of a specific target architecture. It bridges the gap between abstract, high-level program representation and concrete, executable instructions

• Goal: Produce correct, efficient, and minimal assembly that respects hardware constraints, especially the very limited number of registers available on real machines.

How does object code generation avoid redundancy?

Naive translation emits many loads/stores that are never actually needed.

Goals of Object Code Generation

• Correctness

• Minimal Instructions

• Efficient Register Use

• Minimize Memory Traffic

• Preserve Semantics

• Portability(Target Constranints)

Challenges in Object Code Generation

• Limited CPU registers

• Frequent loads and stores

• Selecting efficient instructions

• Handling temporaries

• Balancing correctness and performance

• Target diversity

Target Machine Model

• Simple abstract machine for studying code generation

• 
  

Memory ←→ Register

• One of the families of instructions a generator emits

R1 =

4R2