Cherrypick DMD PR #6582.

[JohanEngelen]

Fix dlang Issue 17237 - Wrong alignment for 256-bit vectors.

https://forum.dlang.org/post/dehxjddmuyzoyqkbdzwn@forum.dlang.org
https://issues.dlang.org/show_bug.cgi?id=17237

[kinke]

Please wait before merging this, I asked Iain for more details upstream (dlang/dmd#6582).

[dnadlinger]

Not important, but: "Fast-forward"? Do you mean "cherry-pick"?

[kinke]

Looks like I messed up something when merging the front-end - we have 2 Target::alignsize() implementations (ddmd/target.d and gen/target.cpp), and no linker complains. :(

The target.d diff is just the !IN_LLVM block. ;)

[dnadlinger]

Isn't there a "header-only" LDC version in ddmd/target.d?

[JohanEngelen]

I thought to fully apply the diff, even if we don't use some code of it. But perhaps you prefer to not artificially add to the diff with the "based-upon dlang version"?

[dnadlinger]

@JohanEngelen: Agreed – I was just responding to @kinke's concerns about duplication.

[JohanEngelen]

Fixed.

[dnadlinger]

Huh, why did you change away from using the full DMD diff? And could you please add the DMD commit hash in the commit description? It's less ambiguous/reliant on GitHub's online data (e.g. when working on a plane).

[dnadlinger]

(Feel free to merge then.)

[JohanEngelen]

Ah lol. Confusion :)
I thought you wanted not the full diff. I have no preference, let me know. I'll add the git commit hash too then.

[dnadlinger]

I was agreeing with you, ie. keep the full diff. Confusion indeed.