Re: Tuning numerical computations for LuaJIT (was Re: [ANN] Sci-1.0-beta1)
- From: Geoff Leyland <geoff_leyland@xxxxxxxxxxx>
- To: luajit@xxxxxxxxxxxxx
- Date: Fri, 21 Sep 2012 07:28:18 +1200
On 21/09/2012, at 12:28 AM, Mike Pall wrote:
> * Do not try to second-guess the JIT compiler.
> - It's perfectly ok to write 'z = x[a+b] + y[a+b]'.
> - Do not try CSE by hand, e.g. 'local c = a+b'.
Could you expand on this a little? I asks because sometimes "hand-made CSE"
improves readability, so:
- Is it actually detrimental to do the above, or just pointless as a speed
optimization?
- Does this only apply to index expressions? (I suspect not, but all your
examples involved indexes)
- Does this only apply to relatively simple expressions, if so, can you say
roughly how simple?
Geoff
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