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A good choice of data structures is critical.
For example, when constructing a sequence in a loop, it is better to push elements onto a vector with push
and push-all
than it is to use suffix
or append
, since the latter copy the head of the sequence.
When taking sequences apart, using slices instead of subsequence operations can yield a performance boost. For example, calling rest
on a one-million-element array will allocate a new array with 999,999 elements, whereas calling rest-slice
will allocate a slice which is a very efficient operation.
The first step when optimizing Factor code is to ensure that it is compiled with the Optimizing compiler. A word will be optimized if and only if it has a static stack effect. To check this,
[ my-word ] infer.
You can define unit tests which assert this is true,
\ my-word must-infer
To see how the high level optimizer treats a word, you can use the following tool:
USE: compiler.tree.debugger \ foo optimized.
You will be able to see if generic dispatch has been eliminated, and if generic arithmetic has been converted to machine arithmetic, and which words have been inlined.
You can also pass a quotation to optimized.
:
[ 100 [ ] times ] optimized.
The high level compiler can be given hints and inline declarations which affects the output of the above.
Big picture: The optimizing compiler works on single words. Gather code using inline
into those words. Give the optimizing compiler assistance in figuring out what types things are. It's does well when it knows, but often lacks for information.
To see how the low level optimizer treats a word,
USE: compiler.cfg.debugger \ foo test-optimizer cfgs.
To see the final code generated for a word, use the disassemble
word.
Disassembling words is accomplished using libudis86
on x86, and gdb
on PowerPC.
Note that udis
needs to be compiled with the --enable-shared
option:
extra/benchmark/
directory. These programs are extremely optimized, but also written in a high-level style.case
combinator, and so on, are highly-optimized, and might be faster than something you'd cook up on your own. For example, case
with integer keys turns into a jump table, member?
with a literal sequence becomes a hashed dispatch or a bit array lookup, generic word dispatch scales very well with a large number of methods, and so on.fixnum+
, and so on. Given the right set of inline
ing declarations and HINTS
, the compiler can eliminate generic arithmetic, and the result will be safer and more readable than if you attempt these transformations by hand. See also TYPED
, and dangerous declare
.map
, reduce
, or something like that instead, since they already use unsafe operations under the hood.Xa uyihlobisa ikhaya lakho okokuqala, likhethekileyo. Ukuhlawula indawo yakho yokuhlala kuthetha ukuba ufikelele kwigumbi ngalinye kunye nezilenge zodonga, izicwangciso zombala Jual Kursi Kantor kunye nefenitshala efanayo. Ukuthanda kwakho kuphila emva kokuba ukhethe ngokucophelela iqatha elilodwa lokugxininisa. Kodwa xa uhamba nale nkqubo, ufuna ukuwugqiba ukwazi indawo yakho ibonakalisa ubuntu bakho obukhethekileyo kunye nezinto ezikhethiweyo. Ufuna ifenitshala yenkcubeko engabikho mntu. Kwinkcubeko yempahla eveliswa ngobuninzi, ngaba unako ukufumana isiqwengathi ngokungafani nabanye? Ifenitshala eyenziwe ngesandla eyenziwe ngabasebenzi abanezakhono yimarike abaninzi Jual Meja Kantor abayifumayo.
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This revision created on Tue, 4 Jun 2019 08:06:48 by widya (Adding additional info)