[llvm-dev] Details on JavaScriptCore's new B3 JIT, replacing their LLVM JIT

[Philip Reames via llvm-dev]

FYI, Sanjoy just started a discussion on what a "check"-like construct 
might look like in LLVM over in the thread "RFC: Add guard intrinsics to 
LLVM".  To avoid confusion, it's worth calling out that the predicate is 
reversed in Sanjoy's proposal from how it's described in the b3 post.

Philip

On 02/15/2016 08:02 AM, Alex Bradbury via llvm-dev wrote:
> A great blog post has just gone up about JavascriptCore's new B3 JIT.
> https://webkit.org/blog/5852/introducing-the-b3-jit-compiler/
>
> This replaces LLVM as the low-level optimisation layer of the FTL JIT.
> They currently achieve roughly 5x faster compile time than LLVM while
> achieving roughly the same generated code quality for their workloads.
>
> I'm sharing as I thought some parts of the design may be interesting
> to other LLVM devs, including the use of Check opcodes ("like a
> marriage between a Branch and a Patchpoint")  and the backwards greedy
> pattern matching for lowering from B3 to Air.
>
> Alex
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