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[Bug middle-end/82479] missing popcount builtin detection
- From: "wdijkstr at arm dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Mon, 09 Oct 2017 08:07:03 +0000
- Subject: [Bug middle-end/82479] missing popcount builtin detection
- Auto-submitted: auto-generated
- References: <bug-82479-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82479
Wilco <wdijkstr at arm dot com> changed:
What |Removed |Added
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CC| |wdijkstr at arm dot com
--- Comment #6 from Wilco <wdijkstr at arm dot com> ---
(In reply to Andrew Pinski from comment #5)
> Was added to LLVM back in 2012:
> http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20121119/156272.html
>
> Again I don't know how useful it is compared to the compile time that it
> would take.
I'd be more worried that the LLVM sequence isn't better in common usage. Given
it has a fixed high latency, you need quite a few set bits before it's faster.