# Plan to test parallel rustc

**URL:** https://internals.rust-lang.org/t/plan-to-test-parallel-rustc/11487
**Category:** announcements
**Created:** [December 16, 2019, 9:08pm UTC](https://internals.rust-lang.org/t/plan-to-test-parallel-rustc/11487 "2019-12-16T21:08:56Z")
**Posts on this page:** 1
**Showing post:** 28

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### Author: ![est31](https://sea2.discourse-cdn.com/flex002/user_avatar/internals.rust-lang.org/est31/32/2551_2.png) [@est31](https://internals.rust-lang.org/u/est31)
#### Post date: [December 19, 2019, 4:26pm UTC](https://internals.rust-lang.org/t/plan-to-test-parallel-rustc/11487/28 "2019-12-19T16:26:49Z")

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This reminds me of the discussion to add a nightly-alt channel to rustup: [Add support for a nightly-alt toolchain · Issue #1099 · rust-lang/rustup · GitHub](https://github.com/rust-lang/rustup/issues/1099)

> [@Disabling LLVM assertions in Nightly builds?](https://internals.rust-lang.org/t/disabling-llvm-assertions-in-nightly-builds/5388):
>
> Building rustc (usually) involves building LLVM. One of LLVM’s compile-time configuration is whether to enable assertions. Currently, in rust-lang’s official builds, LLVM assertions are enabled in the Nightly channel, and disabled on Beta and Stable. I imagine that these assertions help catch some rustc bugs, but they also have a compiler performance cost. In [one particular benchmark](https://github.com/servo/servo/pull/15559#issuecomment-280003926), they added 16% to Servo’s compilation time in debug mode and 53% in release mode. “Rust should have a pleasant…

The proposal didn't materialize as the LLVM assertions were disabled unconditionally.

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_[View the full topic](https://internals.rust-lang.org/t/plan-to-test-parallel-rustc/11487)._