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From: kum <a.kumaresh@gmail.com>
To: gcc-help@gcc.gnu.org
Subject: DSO: pc relative symbol address
Date: Fri, 19 Mar 2010 09:48:00 -0000	[thread overview]
Message-ID: <302c6e641003190237t51b81746ob43db174f2d08bab@mail.gmail.com> (raw)

Hi,
Consider the scrap of code

  static int my_foo1(int i)
    {...}

  int (*my_foo)(int) = my_foo1;
  ...

The compiler emits code like this (excerpt from .s)
...
	lw	$2,%got(my_foo1)($28)
...

There are no direct invocation of my_foo1. What prevents the compiler
from emitting a PC relative address to store in my_foo? Something like
  lw $2, PC - <offset>

I guess that this offset is compile-time known quantity. Kindly enlighten me.

If this is possible what compile option(s) turns it on? Is it possible
to do this optimization while building (elf) shared objects too?

Thanks for clearing my ignorance,
kumaresh

             reply	other threads:[~2010-03-19  9:38 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-03-19  9:48 kum [this message]
2010-03-19 18:15 ` Ian Lance Taylor
2010-03-22  4:38   ` kum

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