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Re: PowerPC : GCC2 optimises better than GCC4???
On Mon, Jan 04, 2010 at 04:08:17PM +0000, Andrew Haley wrote:
> On 01/04/2010 12:07 PM, Jakub Jelinek wrote:
> > IMHO we really should have some late tree pass that converts adjacent
> > bitfield operations into integral operations on non-bitfields (likely with
> > alias set of the whole containing aggregate), as at the RTL level many cases
> > are simply too many instructions for combine etc. to optimize them properly,
> > while at the tree level it could be simpler.
>
> Yabbut, how come RTL cse can handle it in x86_64, but PPC not?
Probably because the RTL on x86_64 uses and's and ior's, but PPC uses
set's of zero_extract's (insvsi).
-Nathan