[trunk<-vta] Re: [vta] stabilize loop-unroll across insn uid variations

[Alexandre Oliva]

On Oct  7, 2008, Alexandre Oliva <aoliva@redhat.com> wrote:

> compare-debug detected some differences causes by RTL loop unrolling,
> because debug insns changed the insn uids it uses as hashes.  Because
> of this change, insns were walked in different orders, and different
> decisions were made.

> I couldn't find a simple way to stabilize the uids or compute good and
> stable hashes without using them.  This is the only place AFAICT that
> uses them as hashes, so I came up with a solution that will waste a
> bit of memory, but that will ensure we walk the insns in a consistent
> order, regardless of changes to insn uids.  To make up for the
> (little) additional memory, we should get a slight speedup when
> walking the lists with type-safe inlinable calls, rather than walking
> every entry of a hashtable that's designed to be about half empty,
> with a type-unsafe non-inlinable callback.

Ok for trunk?

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Alexandre Oliva, freedom fighter    http://FSFLA.org/~lxoliva/
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