How does Rust’s compiler pipeline (AST → HIR → MIR → LLVM IR) work?

Rust compiles code through multiple intermediate representations: AST, HIR, MIR, and LLVM IR before machine code generation.

Rust first parses code into an Abstract Syntax Tree (AST), then lowers it into High-level IR (HIR) for name resolution. MIR (Mid-level IR) is where borrow checking and lifetime analysis occur. Finally, LLVM IR is generated for optimization and machine code generation. Each stage reduces abstraction while increasing semantic precision.