Re: in ccio_io_pdir_entry(),BUG_ON() seems to break gcc-4.2 optimization?

[Joel Soete <soete.joel@scarlet.be>]

Grant Grundler wrote:
> On Mon, Jun 30, 2008 at 06:28:36PM +0000, Joel Soete wrote:
> ...
>> Taken also into account of David remarks, here is the latest stuff tested 
>> with success:
>>
>>         __asm__ __volatile__ (
>>         "lci    %%r0(%%sr1, %2), %0\n"
>>         "\textru        %0,19,12,%0\n"
>>         "\tdepw         %0,15,12,%1\n"
>>         : "=r" (ci), "=r" (pa)
>>         : "r" (vba)
>>         );
> 
> So can you remind me (and Kyle) why this is better than what is
> there now?
> 
mmm may be because gcc consider it now as only 1 'volatile' instruction:

in <ccio_map_sg>
-----------< Original code > --------------+------------< New stuff >-----------------
200: 06 80 53 13  lci r0(sr1,r20),r19      |  200: 08 1a 02 54  copy r26,r20
204: d2 73 1a 74  extrw,u r19,19,12,r19    |  204: 06 a0 53 14  lci r0(sr1,r21),r20
208: 08 1a 02 5c  copy r26,ret0            |  208: d2 94 1a 74  extrw,u r20,19,12,r20
20c: d7 93 0e 14  depw r19,15,12,ret0      |  20c: d7 94 0e 14  depw r20,15,12,ret0
210: 0e dc 12 80  stw ret0,0(r22)             210: 0e dc 12 80  stw ret0,0(r22)
214: 06 c0 12 80  fdc r0(r22)                 214: 06 c0 12 80  fdc r0(r22)
218: 00 00 04 00  sync                        218: 00 00 04 00  sync

thought?

>> Tx to all for kind comments, they learn me a lot ;-)
> 
> welcome! :)
> 
> grant
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