This is the mail archive of the gcc@gcc.gnu.org mailing list for the GCC project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]

Re: Inefficient bitfield code generation


>>>>> degger  writes:

Daniel> Actually the rs6000 port of gcc is really bad when it
Daniel> comes to using the blazingly powerful rotate and mask
Daniel> instructions of the powerpc. 

Daniel> I see several different approaches to cure this performance
Daniel> penalty:
Daniel> - Consider such instructions while optimising in RTL
Daniel> - Have better RTL->insn generators and splitters
Daniel> - Have good peephole definitions

	The rs6000 backend has the rotate and mask instructions
well-described, but GCC does not generate the relevant RTL for enough
instances.

David


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]