GCC-Rust: Rust frontend for GCC

Re:GCC-Rust: Rust frontend for GCC by jeltz on Sunday December 08, 2019 @07:04AM (#21735491)

GCC does some things better than LLVM. It supports more architectures, has a not broken implentation of restrict (which should be useful for Rust), and optimizes some code better. They both have their own pros and cons.

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Re:GCC-Rust: Rust frontend for GCC by cesarb on Sunday December 08, 2019 @08:22AM (#21735760)

> has a not broken implementation of restrict (which should be useful for Rust)

The most recent restrict bug the rustc developers found (which made they disable restrict again) was found in both LLVM and GCC (they made a C reproducer, so they could test in both). See: https://github.com/rust-lang/rust/issues/54878 (rustc) https://bugs.llvm.org/show_bug.cgi?id=39282 (LLVM) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87609 (GCC).

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Re:GCC-Rust: Rust frontend for GCC by cwzwarich on Sunday December 08, 2019 @09:25AM (#21736008)

The interiteration issue with LLVM's noalias has been known for years:

https://reviews.llvm.org/D9375

I even filed a version of it myself:

https://bugs.llvm.org/show_bug.cgi?id=27955

I'm actually surprised that Rust enabled noalias usage with this known outstanding issue. When I worked on Rust years ago, it was definitely common knowledge on the compiler "team" that this was broken.

I'm equally surprised that GCC had that bug, since their pointer aliasing model is equipped to correctly handle this situation (and is why they were able to fix it quickly).

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Re:GCC-Rust: Rust frontend for GCC by sanxiyn on Sunday December 08, 2019 @09:06AM (#21735927)

Note that GCC bug is now fixed. LLVM bug isn't.

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