Re: [boost] [context] Floating Point Exception

Subject: Re: [boost] [context] Floating Point Exception
From: Oliver Kowalke (oliver.kowalke_at_[hidden])
Date: 2011-07-02 14:12:05

Am 02.07.2011 18:17, schrieb Daniel Larimer:
>
> 	Your new code still has the invalid Unknown pseudo-op: .type.
>
.type tells the compile which kind of symbol is encountered -> function

I need some assembler genereated by gcc to see how the meta infos look 
like on MacOS X (I've no installation)

>>> 3) Compiled with:
>>>    gcc-4.5.0   -o fcontext_x86_64_sysv_macho_gas.S.o   -c
>>> fcontext_x86_64_sysv_macho_gas.S
>> could you write a little helloworld-app and compile it with -S and send me the generated assembler?
>>
> 	Sure.  Do you want it to use your context or just want to see int main( ) { printf( "hello world"); return 0; } ?
>

yes - at best you generated a shared library with position-independed 
code (-fPIC) and link the test app.
The assembler (gcc -S) file should tell me how functions are addresses 
in pic on MacOSX/Mach-O.
The meta infos (see above -> .type) are provided too.

>> fixed missing fp x87 word initialisation
>>
> 	Seems to have fixed things.  Asm version is 2x as fast as ucontext for my use case.
>
how do you test it? I get a spped-up factor of 10x on Linux/x86.
boost.context contains a subfolder 'performance' with code measuring the 
CPU cycles

>>> I noticed that none of the examples test for floating point ops.  You might
>>> want to include that as part of your standard testing.
> 	I saw you added these tests to git...  did it work on other platforms, or did you have to change multiple asm files?

I've modified the asm files for x86 platform (added missing fp-register 
initialisation) and I've added an example and a test for floating point 
ops too (which should work on all platforms)