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XLS: Accelerated HW Synthesis

google.github.io

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Re: XLS: Accelerated HW Synthesis

#11

Post by est31 »

tlack wrote: post #4
jashmenn wrote: post #2

I've been programming for 20 years and yet I have no idea what this does. Can someone ELI5?

You feed in Rust (a flavor called DSLX) or C++ and it generates code for your FPGA (in Verilog). You then upload this compiled "bitstream" to your FPGA and now you have something akin to a custom microprocessor, but running just your program.

It looks really quite similar to Rust: https://github.com/google/xls/blob/main/xls/examples/dslx_in...

Note that there are differences though: Seems no type inferrence, for .. in, different array syntax, match arms delimitered by ";" instead of ",".

But it has a lot of the cool stuff from Rust: pattern matching, expression orientedness (let ... = match { ... }), etc.

Also other syntax is similar: fn foo() -> Type syntax, although something similar to that can be achieved in C++ as well.

Re: XLS: Accelerated HW Synthesis

#15

Post by typon »

jeffreyrogers wrote: post #10

This is interesting. Overall I'm bearish on high-level synthesis for anything requiring high performance, since you typically need to think about how your code will be mapped to hardware if you want it to perform well, and adding abstractions interferes with that. I would like to know more about how Google uses this, since it doesn't seem like a good fit for the type of stuff I work on.

This doesn't seem like HLS, more like a new HDL that's based on Rust. This has been done many times before with other functional languages (Clash, Chisel, Spinal, hardcaml and others). These projects never take off because hardware designers are inherently conservative and they won't let go of their horrible language (Verilog or SystemVeriog) no matter what.

I'm sure Google will use XLS for their internal digital design work, but I don't expect this to ever gain widespread support. (not because HLS is inherently bad, but because of the culture)

Re: XLS: Accelerated HW Synthesis

#18

Post by dirtypersian »

simonw wrote: post #17

XLS as an acronym for Accelerated HW Synthesis is a bit of a stretch!

I believe it might come from the fact that this process of going from high level programming language to hardware is called "high level synthesis". I think the "X" is meant to make it more generic, i.e. X level synthesis.
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