[patch] tuning gcc for Intel Core2

Vladimir Makarov vmakarov@redhat.com
Mon Nov 13 18:28:00 GMT 2006


Andi Kleen wrote:

>Vladimir Makarov <vmakarov@redhat.com> writes:
>
>  
>
>>+const int x86_accumulate_outgoing_args = m_ATHLON_K8 | m_CORE2 | m_PENT4 | m_NOCONA | m_PPRO | m_GENERIC;
>>+const int x86_prologue_using_move = m_ATHLON_K8 | m_PPRO | m_CORE2 | m_GENERIC;
>>+const int x86_epilogue_using_move = m_ATHLON_K8 | m_PPRO | m_CORE2 | m_GENERIC;
>>    
>>
>
>Are you sure this is correct? Using moves in epilogue/prolgue
>generates much bigger code and AFAIK Core2 has special hardware
>to avoid any dependencies on the stack pointer, so shorter push/pop
>should be as fast here and use less icache.
>
>  
>
I tried these parameters and got better results (although I don't 
remeber exact numbers).  Actually I've tried all parameters.  I started 
the work when intel's guide was not public so I had to try all parameters.

Even if Core2 has special hardware to decrease problem of dependencies 
on stack pointer, it does not mean that usage of push/pop will be better.



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