From: Andrew Haley <aph@redhat.com>
To: Carrot Wei <carrot@google.com>
Cc: gcc@gcc.gnu.org, Richard Earnshaw <rearnsha@arm.com>,
Paul Brook <paul@codesourcery.com>,
nickc@redhat.com
Subject: Re: Where can I put the optimization of got for arm back end at?
Date: Thu, 01 Apr 2010 18:11:00 -0000 [thread overview]
Message-ID: <4BB4E1A1.4050000@redhat.com> (raw)
In-Reply-To: <7587b291003280745o651a9c61ia1abae6707832526@mail.gmail.com>
On 28/03/10 15:45, Carrot Wei wrote:
> Hi
>
> The detailed description of the optimization is at
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43129. This is an ARM
> specific optimization.
>
> This optimization uses one less register (the register hold the GOT
> base), to get this beneficial the ideal place for it should be before
> register allocation.
>
> Usually expand pass generates instructions to load global variable's
> address from GOT entry for each access of the global variable. Later
> cse/gcse passes can remove many of them. In order to precisely model
> the cost, this optimization should be put after some cse/gcse passes.
>
> So what is the best place for this optimization? Is there any existed
> pass can be enhanced with this optimization? Or should I add a new
> pass?
The obvious place is machine-dependent reorg, which is a very late pass.
Andrew.
next prev parent reply other threads:[~2010-04-01 18:11 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-28 21:00 Carrot Wei
2010-04-01 18:11 ` Andrew Haley [this message]
2010-04-01 20:31 ` Steven Bosscher
2010-04-02 4:06 ` Carrot Wei
[not found] ` <l2z5885251a1004050624h1237ec10z2a0bf34b7ba91d2c@mail.gmail.com>
2010-04-06 13:38 ` Carrot Wei
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