From: David Miller <davem@davemloft.net>
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
Subject: Re: [PATCH] of_mdio: merge branch tails in of_phy_register_fixed_link()
Date: Sun, 13 Aug 2017 20:09:08 -0700 (PDT) [thread overview]
Message-ID: <20170813.200908.1426365653542179792.davem@davemloft.net> (raw)
In-Reply-To: <20170812210321.520045884@cogentembedded.com>
From: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
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 <sergei.shtylyov@cogentembedded.com>
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.
next prev parent reply other threads:[~2017-08-14 3:09 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-12 21:03 [PATCH] of_mdio: merge branch tails in of_phy_register_fixed_link() Sergei Shtylyov
2017-08-14 3:09 ` David Miller [this message]
[not found] ` <20170813.200908.1426365653542179792.davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>
2017-08-15 11:18 ` David Laight
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