Re: ARM EABI version 5 and bpabi.o

[Sebastian Huber <sebastian dot huber at embedded-brains dot de>]

On 03/14/2011 03:14 PM, Andrew Haley wrote:
> On 03/14/2011 12:02 PM, Sebastian Huber wrote:
>> Hello,
>>
>> the object file bpabi.o is part of libgcc.  It is compiled with the option
>> -fexceptions.  Does anyone know why we need exceptions here?
> 
> __divdi3 can throw an exception.  I don't know whether it does on ARM,
> but it does on other processors.
> 
> Andrew.

Thanks for the hint.  How can an assembler or C function throw an exception?  I
am absolutely not sure how this low-level stuff works in detail, but it seems
to me from a look at libgcc/Makefile.in that this -fexceptions is used for all
targets?  I currently try to prepare a RTEMS GCC for ARM to use the ARM EABI
version 5.  Now I have the problem that an innocent looking

int64_t f(int64_t a, int64_t b)
{
	return a / b;
}

will pull in the hole unwind mechanic that accounts for 10kByte of Thumb code.
 This might be a problem for small target systems.

-- 
Sebastian Huber, embedded brains GmbH

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