Re: [RFC] Port libitm to powerpc

[Iain Sandoe <developer at sandoe-acoustics dot co dot uk>]

Hi Richard,

On 2 Dec 2011, at 23:36, Iain Sandoe wrote:

> On 2 Dec 2011, at 22:59, Richard Henderson wrote:
>
> > I personally think the whole thing would be much easier to read  
> > without relying on the redzone.  Aside from that, there's actually  
> > very little real difference in the two files.  Essentially, you're  
> > storing the registers in a different order because the prologue  
> > does, just so you can make use of the redzone.
>
> OK -  I guess I got carried away with thinking that I might be able  
> to re-use the save_world () routine - but that doesn't look feasible  
> after all so....
>
> > The aix abi saves r2; darwin 32-bit saves r13.  One extra register  
> > in both cases, which could use the same slot.
>
> ... will take another look tomorrow....
> .... although we still have some syntax issues that might make  
> sharing the original code somewhat ugly....

Two versions attached, both of which produce working code on darwin  
(although the attached modification to yours will be broken on  
assemblers needing % in front of reg names).

version 1 is a tidied up red-zone implementation.

===

version 2 is a modification of your original:

a)  -FRAME+BASE(r1) cannot be guaranteed to be vec-aligned in general  
(it isn't on m32 darwin)

... so I've taken the liberty of rounding the gtm_buffer object and  
then pointing r4 at  original_sp-rounded_size, which is what we want  
for the call to GTM_begin_transaction anyway.

b) I've added the CR etc. wrapped in  __MACH__ ifdefs.

c) ";" is a comment introducer for Darwin's asm .. so I unwrapped  
those lines ...

d) I put in the logic for handling __USER_LABEL_PREFIX__ .

===

e) The real problem is finding a non-horrible way of dealing with the  
%r <=> r issue - and I've not done that so far...

... pending your opinion on the best way forward....

cheers
Iain

Attachment: 181968-ppc-darwin-libitm-redzone-version-diff.txt
Description: Text document

Attachment: 181968-ppc-darwin-libitm-norz.txt
Description: Text document