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Re: [patch] rfa: fix problem with reassociating pointer additions


On Mon, 2004-10-04 at 20:57, Daniel Jacobowitz wrote:
> On Mon, Oct 04, 2004 at 11:27:02PM -0400, David Edelsohn wrote:
> > 	GCC does not do it very intelligently, but reassociation can be an
> > important optimization when one is trying to create address
> > sub-expressions that match the offset addressing modes and auto-increments
> > of a target architecture.  I am concerned about disabling this type of
> > transformation instead of trying to make it smarter.
> 
> It sounds like we need to carry around the address-arithmetic-may-trap
> property...  Why is MIPS using the trapping address operations anyway?
> I think it has non-trapping versions of everything we'd need.

You'd think that, but the problem is in 64-bit processors with 32-bit
addressing in kernel mode.

I kid you not.

MIPS64TM Architecture For Programmers Volume III, Section 4.9.

-eric

-- 
Eric Christopher <echristo@redhat.com>


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