[squeak-dev] The Trunk: Collections-cmm.1016.mcz

Chris Muller asqueaker at gmail.com
Wed Jul 13 20:39:12 UTC 2022

Hi Christoph,

Thanks for the review and excellent suggestions.  Please see
Collections-cmm.1019, and let me know if you see anything else.

> Regarding the implementation: Did you run any benchmarks and how massive
> is the slowdown? The previous implementation used #basicAt: to avoid
> comparing characters (which is not fast on all platforms) and sending
> messages to them (in favor of inlining). I'm curious whether this could be
> avoided in the new implementation as well and how much performance could be
> won with that. #numberOrValue also looks very slow. Maybe it would be
> worth providing two alternative branches depending on the type of the
> collection argument?
I tend to weigh toward a system defined tersely in terms of its own
messages, and letting performance emanate from the _design_, as opposed to
chasing an extra 5% of execution performance improvement at the expense of
expressivity of the code.  If the point of that 5% is to "save time", it
seems reasonable to consider the time of future readers of the code.

The method, #isAlphanumeric, is a prime example.  Originally, its
implementation beautifully matched its definition.
        "Answer whether the receiver is a letter or a digit."
        ^self isLetter or: [self isDigit]

Compare that to now, a complex, copy-and-pasted "implementation" which is a
lot harder to understand and maintain, but only 10% faster in execution.
IMO, that seems past the point of diminishing returns of what a user of
Smalltalk would expect.

Having said that, Squeak's speed is sweet, I can appreciate the desire to
hyper-optimize at the bytecode level.  Here's Marcel's benchmark with the
['Hello {1}!' format: { 'Squeak' }] bench.

 '3,450,000 per second. 290 nanoseconds per run. 1.35946 % GC time.'   <---
 '3,820,000 per second. 262 nanoseconds per run. 4.22 % GC time.'     <---

3450.0/3820   0.9031413612565445

Looks like about a 10% hit for this example.  Maybe it could be improved,
but I doubt by very much.  Unfortunately using #basicAt: isn't convenient
when alphanumeric tokens are possible.

If this is still too much, let me know, I'll take it back to the original
numerals-only version.

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