May 21, 2008
The subject pretty much says it all. I'd like to use one (or if possible, two) of these registers in some assmbly code and want to know if I need to preserve them or if D will just ignore them and leave them untouched between callbacks into the assembler code?

Thanks, b.
-- 

May 21, 2008
Me Here wrote:
> The subject pretty much says it all. I'd like to use one (or if possible, two)
> of these registers in some assmbly code and want to know if I need to preserve
> them or if D will just ignore them and leave them untouched between callbacks
> into the assembler code?

ES is used by certain instructions the compiler generates (movs & friends, IIRC)
Windows exception handling uses FS.
I'm not sure about GS (nor FS on Linux, but you specified Windows so you don't care).
May 21, 2008
Me Here wrote:
> The subject pretty much says it all. I'd like to use one (or if possible, two)
> of these registers in some assmbly code and want to know if I need to preserve
> them or if D will just ignore them and leave them untouched between callbacks
> into the assembler code?

I recommend save/restoring them. GS, for example, is used in Linux for thread local storage. FS is used for exception handling. ES is used for string instructions.
May 21, 2008
== Quote from Walter Bright (newshound1@digitalmars.com)'s article
> Me Here wrote:
> > The subject pretty much says it all. I'd like to use one (or if possible, two) of these registers in some assmbly code and want to know if I need to preserve them or if D will just ignore them and leave them untouched between callbacks into the assembler code?
> I recommend save/restoring them. GS, for example, is used in Linux for thread local storage. FS is used for exception handling. ES is used for string instructions.

In general, I think following the x86 C ABI is the best approach insofar as register allocation and such is concerned.  I don't have the link handy, but I believe it was published by Sun.  If I remember correctly, the only scratch registers are EAX and EDX.


Sean
May 22, 2008
Sean Kelly wrote:

> In general, I think following the x86 C ABI is the best approach insofar as register allocation and such is concerned.  I don't have the link handy, but I believe it was published by Sun.

I don't suppose I could impose on you for a few more clues as to what you are remembering?

Every search I've done looking for x86 ABI (with or without C and/or Sun) is
turning up the
AMD64 ABI...which doesn't seem to applicable to what I'm trying to do.

(It may in the future if I ever try to code for 64-bit, but what I'm working on is so machine wordsize specific that everything will have to change anyway).

Thanks for any and all latent memory pointers you can provide :)

b.
-- 

May 22, 2008
Me Here wrote:
> Thanks for any and all latent memory pointers you can provide :)

On windows and linux, you can modify EAX, ECX and EDX. The rest must be preserved.
May 26, 2008
Me Here wrote:
> Sean Kelly wrote:
> 
>> In general, I think following the x86 C ABI is the best approach insofar as
>> register allocation and such is concerned.  I don't have the link handy, but
>> I believe it was published by Sun.
> 
> I don't suppose I could impose on you for a few more clues as to what you are
> remembering?
> 
> Every search I've done looking for x86 ABI (with or without C and/or Sun) is
> turning up the
> AMD64 ABI...which doesn't seem to applicable to what I'm trying to do. 
> 
> (It may in the future if I ever try to code for 64-bit, but what I'm working on is so machine wordsize specific that everything will have to change anyway).
> 
> Thanks for any and all latent memory pointers you can provide :)

I think this is the one I was referring to:

http://www.sco.com/developers/devspecs/abi386-4.pdf


Sean
May 26, 2008
Sean Kelly wrote:

> Me Here wrote:
> > Sean Kelly wrote:
> > 
> > > In general, I think following the x86 C ABI is the best approach insofar as register allocation and such is concerned.  I don't have the link handy, but I believe it was published by Sun.

> > Thanks for any and all latent memory pointers you can provide :)
> 
> I think this is the one I was referring to:
> 
> http://www.sco.com/developers/devspecs/abi386-4.pdf
> 
> 
> Sean

Many thanks. That is very useful.
b.
-- 

Top | Discussion index | About this forum | D home