Rust Compiler for 20-Year-Old Macs: A Technical Marvel

I Built a Rust Compiler for a 20-Year-Old Mac (Borrow Checker and All)

AutoJanitor has built a custom Rust-to-PowerPC compiler, allowing modern Rust code to run on 20-year-old Macs. The compiler, written in C, features a working borrow checker with Non-Lexical Lifetimes (NLL) and generates AltiVec SIMD code.

Why This Matters

The technical reality is that modern Rust does not compile for PowerPC Mac OS X Tiger, and the official Rust compiler has never targeted this platform. The ideal model would be to have a compiler that can generate efficient code for vintage hardware, but the cost of maintaining such a compiler is high. The failure to provide a working compiler for PowerPC Macs would mean that millions of these machines would be unable to run modern software, leading to a significant loss of functional hardware.

Key Insights

• The compiler features a working borrow checker with NLL, allowing for more efficient memory management (Source: AutoJanitor’s GitHub repository)
• The use of AltiVec SIMD instructions provides a significant performance boost for certain operations (Example: Float operations can be vectorized, resulting in a 4x throughput increase)
• The compiler is written in C and generates native PowerPC assembly code (Tool: GCC 4.0.1, used to compile the compiler)

Working Examples

Example usage of the Rust compiler

$ ./rustc_ppc hello.rs > hello.s
$ as -o hello.o hello.s
$ gcc -o hello hello.o
$ ./hello
Hello from Rust on PowerPC G4!

Practical Applications

• Company: Elyan Labs, Behavior: Using the Rust compiler to build a minimal Firefox browser for PowerPC Macs
• Pitfall: Using the wrong compiler flags can result in inefficient code generation, consequence: Significant performance degradation

References:

• https://dev.to/scottcjn/i-built-a-rust-compiler-for-a-20-year-old-mac-borrow-checker-and-all-37n7
• https://github.com/Scottcjn/rust-ppc-tiger