[PATCH] D88390: [M68k] (Patch 4/8) MC layer and object file support

Fri Jan 29 09:34:10 PST 2021

myhsu added a comment.

In D88390#2530647 <https://reviews.llvm.org/D88390#2530647>, @rengolin wrote:

> In D88390#2529089 <https://reviews.llvm.org/D88390#2529089>, @myhsu wrote:
>
>> We don't have AsmParser and disassembler right now. We're using MIR as input to test our integrated assembler, so you're right, we can't test MC layer without CodeGen. But why would that will be a hard blocker?
>
> The real requirement is being able to produce code at the end. If that relies on (free, accessible) third-party tools, then it should be find for the first import. Some production targets have (free) proprietary tools that are required to continue the code generation (ex. NVPTX). Other targets have assemblers but can be tested (no available hardware). Having specific hard requirements would make it really hard for LLVM to have new backends.

Agree.

> What we need for the first batch is to know that the target can be used to generate correct code. It's less relevant if that can be shown with an integrated assembler or other tools at the end.

That is also what I'm thinking: it's true that the current work need to use external assembler (GNU AS) to deal with cases like inline assembly, but at the same time it can handle common cases with integrated assembler just fine. We also have test cases on testing that part.

> It would be important, however, to know if the m86k community intends to upstream the assembler before moving to production or if the target requires use of third-party closed source tools to work. This will help guide this and other reviews after the first merge, into production.

Speaking of that. Few days ago there is a (draft) PR sent to our GitHub repo: https://github.com/M680x0/M680x0-mono-repo/pull/20
Author of that PR is working on the AsmParser and disassembler (that PR is just a placeholder to inform us in order to prevent overlapping works). I'm pretty excited and looking forward to seeing it appearing upstream before becoming an official backend.

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