Re: Speed comparison: compare:, methodForSelector: & CFNumberCompare()
Re: Speed comparison: compare:, methodForSelector: & CFNumberCompare()
- Subject: Re: Speed comparison: compare:, methodForSelector: & CFNumberCompare()
- From: Sailor Quasar <email@hidden>
- Date: Mon, 23 Feb 2004 02:09:27 -0500
On Feb 22, 2004, at 10:33 PM, Allan Odgaard wrote:
There is discussion of the merits and relative performance of using
function pointers. There is discussion of the implementation of
message sending. There is description of profiling to find out for
sure where the time is being spent instead of guessing. There is
discussion of the specific issues having to do with Foundation
classes and class clusters such as NSNumber.
Sorry, but I am aware of all these things, and I do not think they
shed light on why compare:, when invoked using a function pointer (in
a concrete subclass), is that much slower than CFNumberCompare.
I could follow the example of the page you link to and disassemble
compare:, I don't know if that was your intent? if so, I guess there
is little reason for this mailing-list if the answer is that I should
go look at the assembler source for things I do not understand! ;)
Well this isn't quite a matter of understanding of the APIs and their
effects, which is what this list is for. You're now talking about
in-depth optimizations while still retaining Objective-C (-ish) code,
and optimizing Objective-C means knowing what messages are being thrown
all over the place; since we don't have Foundation or AppKit source
code, we have to make do with assembly. Aside from the author's lack of
comprehension of dyld stubs (which, if I understood the Mach-O book
correctly, have to do with the way shared libraries are implemented in
Darwin), I found the page in question to be extremely informative and
very well written, if dated a bit far back relative to now.
-- Sailor Quasar, just another player in The World
"Come with me in the twilight of the summer night for awhile"
Email: email@hidden
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