Re: LuaJIT on solaris 64

  • From: Mike Pall <mike-1206@xxxxxxxxxx>
  • To: luajit@xxxxxxxxxxxxx
  • Date: Thu, 21 Jun 2012 20:57:58 +0200

Florian Weimer wrote:
> What about scaled, zero-based pointers?  Would that work?

Scaling would be difficult. The low bits are used in some cases,
e.g. in frame links.

Ok, so this would allow for more memory. But it still requires a
special allocator that only allocates in the low 32 GB (4GB * 8)
region, which is equivalent to the original problem.

> (Hotspot more or less assumes that scaling is zero-cost, and I
> couldn't disprove it in my benchmarks.)

Maybe on x64, but it's not free on other architectures. And only
if the operations don't already have a scaled operand, which is
quite common in LuaJIT with all of the base+idx*8 TValue indexing.

--Mike

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