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Subject: Re: [boost] ARM thumb support in spinlock_gcc_arm.hpp
From: Jerry Napoli (jnapoli_at_[hidden])
Date: 2008-09-05 15:26:00

Hi Michael,

Yes, the sdk forces thumb under the covers. All of the objects provided
with the sdk are built with thumb.


Michael Marcin wrote:
> Jerry Napoli wrote:
>> I'm trying to compile using boost 1_36_0 for ARMv6 Thumb for iPhone
>> development. The compiler used is gcc 4.0.x supplied with the iphone
>> sdk.
>> I run into issues with the inline assembly inside
>> boost/detail/spinlock_gcc_arm.hpp. It generates a SWP instruction
>> which (AFAIK) is not supported in thumb mode. The gnu arm assembler
>> gives me a 'bad instruction ...' error. I'm able to work around it by
>> modifying spinlock.hpp to include spinlock_sp.hpp instead. But has
>> anyone addressed spinlock support for armv6 thumb?
> Sorry this is not an answer but why are you using thumb?
> Does the iphone sdk force it?
> While working on armv5 cell phone projects I found that in practice arm
> was smaller and faster than thumb because many arm instructions took
> more than 2 thumb instructions to emulate.
> Thanks,
> Michael Marcin
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