RFR: 8253757: Add LLVM-based backend for hsdis

[Erik Joelsson]

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...

Build changes look good. I can't comment on the hsdis implementation.

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Marked as reviewed by erikj (Reviewer).

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