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From: "ramana.radhakrishnan at arm dot com" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug target/43129] Simplify global variable's address loading with option -fpic
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43129

--- Comment #9 from ramana.radhakrishnan at arm dot com <ramana.radhakrishnan at arm dot com> 2010-10-14 16:39:26 UTC ---
On Thu, 2010-10-14 at 16:33 +0000, stephen.clarke at st dot com wrote:
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43129
> 
> Stephen Clarke <stephen.clarke at st dot com> changed:
> 
>            What    |Removed                     |Added
> ----------------------------------------------------------------------------
>                  CC|                            |stephen.clarke at st dot
>                    |                            |com
> 
> --- Comment #8 from Stephen Clarke <stephen.clarke at st dot com> 2010-10-14 16:32:56 UTC ---
> For arm instruction set, could you fold pc into the indexing
> to save an instruction?
> 
> foo:
>         ldr     r3, .L2        // C
> .LPIC0:
>         ldr     r3, [r3,pc]    // C


You'll find that the ARM-ARM thinks that PC in any of the 3 locations in this
instruction form is *unpredictable*. Thus this form of the instruction should
not be used. 

cheers
Ramana