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I heard that GCC supports more architectures than LLVM. Perhaps Rust having a C backend would make sense? On the other hand, I have no idea how tightly coupled

by d33 9y ago

I heard that GCC supports more architectures than LLVM. Perhaps Rust having a C backend would make sense? On the other hand, I have no idea how tightly coupled to LLVM it is.

adrianN 9y ago
LLVM is used for optimizations in Rust. LLVM is more than just a nice way to target multiple backends, it's a very sophisticated set of building blocks for compilers.
Rusky 9y ago
The language itself isn't coupled to LLVM outside of some underspecified details around things like unsafe and the memory model, which will eventually be better-defined. The compiler has historically been fairly strongly tied to LLVM. This is changing for several reasons as the compiler is refactored, which should enable alternative backends like directly generating C or even plugging directly into GCC. There is also an LLVM backend for generating C, at various levels of maintenance, that might be made to work.
- pjmlp 9y ago
  A very long term project could be to eventually make the Rust compiler full Rust based. However that would not make much sense from engineering point of view, too many years of optimization algorithms, tooling and supported architectures have been spent into gcc and LLVM backends just to thrown them away in name of purity.
  - Rusky 9y ago
    There actually is work going on in that direction. The Cretonne code generator is written in Rust, and designed to support WebAssembly. It would also work as a fast rustc backend for debug builds on the few platforms it supports.
    - pjmlp 9y ago
      Interesting, thanks for point it out.
__s 9y ago
Rust has tried to not couple its design to LLVM For awhile LLVM could target C
- cpeterso 9y ago
  There is some discussion of supporting Mozilla's experimental Cretonne compiler (initially designed to be a new Firefox wasm JIT) as an alternative backend for rustc. Cretonne could be handy for developers wanting faster compile times during development with the cost of less code optimization. https://internals.rust-lang.org/t/possible-alternative-compiler-backend-cretonne/ https://internals.rust-lang.org/t/possible-alternative-compi...

by d33 9y ago

I heard that GCC supports more architectures than LLVM. Perhaps Rust having a C backend would make sense? On the other hand, I have no idea how tightly coupled to LLVM it is.

adrianN 9y ago

LLVM is used for optimizations in Rust. LLVM is more than just a nice way to target multiple backends, it's a very sophisticated set of building blocks for compilers.

Rusky 9y ago

The language itself isn't coupled to LLVM outside of some underspecified details around things like unsafe and the memory model, which will eventually be better-defined. The compiler has historically been fairly strongly tied to LLVM. This is changing for several reasons as the compiler is refactored, which should enable alternative backends like directly generating C or even plugging directly into GCC. There is also an LLVM backend for generating C, at various levels of maintenance, that might be made to work.

pjmlp 9y ago
A very long term project could be to eventually make the Rust compiler full Rust based. However that would not make much sense from engineering point of view, too many years of optimization algorithms, tooling and supported architectures have been spent into gcc and LLVM backends just to thrown them away in name of purity.
- Rusky 9y ago
  There actually is work going on in that direction. The Cretonne code generator is written in Rust, and designed to support WebAssembly. It would also work as a fast rustc backend for debug builds on the few platforms it supports.
  - pjmlp 9y ago
    Interesting, thanks for point it out.

__s 9y ago

Rust has tried to not couple its design to LLVM For awhile LLVM could target C

cpeterso 9y ago
There is some discussion of supporting Mozilla's experimental Cretonne compiler (initially designed to be a new Firefox wasm JIT) as an alternative backend for rustc. Cretonne could be handy for developers wanting faster compile times during development with the cost of less code optimization. https://internals.rust-lang.org/t/possible-alternative-compiler-backend-cretonne/ https://internals.rust-lang.org/t/possible-alternative-compi...