From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga01.intel.com ([192.55.52.88]:33033 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751071AbaBHUV1 (ORCPT ); Sat, 8 Feb 2014 15:21:27 -0500 Date: Sat, 8 Feb 2014 12:21:24 -0800 From: Andi Kleen Subject: Re: [PATCH 02/17] x86, lto: Disable fancy hweight optimizations for LTO v2 Message-ID: <20140208202124.GK12219@tassilo.jf.intel.com> References: <1391846481-31491-1-git-send-email-ak@linux.intel.com> <1391846481-31491-2-git-send-email-ak@linux.intel.com> <52F67CD7.5090609@zytor.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <52F67CD7.5090609@zytor.com> Sender: linux-kbuild-owner@vger.kernel.org List-ID: To: "H. Peter Anvin" Cc: linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org, x86@kernel.org On Sat, Feb 08, 2014 at 10:52:07AM -0800, H. Peter Anvin wrote: > On 02/08/2014 12:01 AM, Andi Kleen wrote: > > The fancy x86 hweight uses different compiler options for the > > hweight file. This does not work with LTO. Just disable the optimization > > with LTO > > No, I'm going to NAK this. This means not using the POPCNT instruction > if LTO is enabled, and that really isn't an acceptable option. I thought the use was obscure? Ok, suppose can just disable LTO for the file. The only drawback is that the functions will not be optimized away when not used, as they'll need to be __visible. -Andi -- ak@linux.intel.com -- Speaking for myself only