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From: Carrot Wei <carrot@google.com>
To: gcc@gcc.gnu.org, Richard Earnshaw <rearnsha@arm.com>,
	        Paul Brook <paul@codesourcery.com>,
	nickc@redhat.com
Subject: Where can I put the optimization of got for arm back end at?
Date: Sun, 28 Mar 2010 21:00:00 -0000	[thread overview]
Message-ID: <7587b291003280745o651a9c61ia1abae6707832526@mail.gmail.com> (raw)

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?

thanks
Guozhi

             reply	other threads:[~2010-03-28 14:45 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-03-28 21:00 Carrot Wei [this message]
2010-04-01 18:11 ` Andrew Haley
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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