RFR: 8253757: Add LLVM-based backend for hsdis

[Ludovic Henry]

On Fri, 18 Feb 2022 11:44:04 GMT, Magnus Ihse Bursie <ihse at openjdk.org> wrote:

> Third time's a charm! After the two previous closed PRs for this issue, I think this functionality is finally ready to enter mainline. :)
> 
> This code is at it's core the same as the previous PR. The main C++ hsdis implementation is still the one @luhenry wrote, with some changes. As in the previous PR, I extracted the LLVM-specific part into a separate file. In addition to the last PR, I have also fixed a warning, and added a patch inspired by @nick-arm for getting past instructions unknown to LLVM.
> 
> Thanks to the prototype written by @JornVernee (and his graciously providing me with a working version of LLVM build for Windows), this PR now has full support for LLVM on Windows (as well as Linux and macOS).
> 
> Finally, I have cleaned up the integration in autoconf and Hsdis.gmk, and written a thorough guide in the README on how to build witth LLVM, on Windows and on saner platforms. :)
> 
> I'm pretty sure this means that all comments and criticism in the previous PR has been addressed.
> 
> Huge thanks to everyone who has helped me with getting this PR in place. I have a hard time remember a feature that has been so tricky to get in place, for something to seemingly simple...

Marked as reviewed by luhenry (Author).

Thanks again for pushing that forward! It's always good to have an alternative especially for porting to new platforms and architectures.

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PR: https://git.openjdk.java.net/jdk/pull/7531