From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH] of_mdio: merge branch tails in of_phy_register_fixed_link() Date: Sun, 13 Aug 2017 20:09:08 -0700 (PDT) Message-ID: <20170813.200908.1426365653542179792.davem@davemloft.net> References: <20170812210321.520045884@cogentembedded.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20170812210321.520045884@cogentembedded.com> Sender: netdev-owner@vger.kernel.org To: sergei.shtylyov@cogentembedded.com Cc: andrew@lunn.ch, f.fainelli@gmail.com, robh+dt@kernel.org, frowand.list@gmail.com, netdev@vger.kernel.org, devicetree@vger.kernel.org List-Id: devicetree@vger.kernel.org From: Sergei Shtylyov Date: Sun, 13 Aug 2017 00:03:06 +0300 > Looks like gcc isn't always able to figure out that 3 *if* branches in > of_phy_register_fixed_link() calling fixed_phy_register() at their ends > are similar enough and thus can be merged. The "manual" merge saves 40 > bytes of the object code (AArch64 gcc 4.8.5), and still saves 12 bytes > even if gcc was able to merge the branch tails (ARM gcc 4.8.5)... > > Signed-off-by: Sergei Shtylyov Applied, but if two instances of the "same" compiler just with different targets changes the optimization, it could be because of a tradeoff which is specific to parameters expressed in that target's backend. So in the future we should probably back away from trying to "help" the compiler in this way.