Re: [boost] ARM thumb support in spinlock_gcc_arm.hpp

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.

Thanks,
Jerry

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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