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[Bug target/70119] AArch64 should take advantage of implicit truncation of variable shift amount without defining SHIFT_COUNT_TRUNCATED
- From: "rguenth at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Mon, 07 Mar 2016 12:46:30 +0000
- Subject: [Bug target/70119] AArch64 should take advantage of implicit truncation of variable shift amount without defining SHIFT_COUNT_TRUNCATED
- Auto-submitted: auto-generated
- References: <bug-70119-4 at http dot gcc dot gnu dot org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70119
--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to ktkachov from comment #3)
> Right, I see we have the same issue on aarch64 as on x86.
> So what would be the accepted solution here?
> I've been playing with a patch to simplify-rtx to move the subreg inside the
> AND and transform the AND into a QImode operation, but there were concerns
> on it pessimising other code
I think adding some special support to combine itself might be better.