Feature #12172
closedArray#max and Array#min
Description
I propose to define Array#max
. It is 10+ times faster than Enumerable#max
since it skips a call to #each
.
a = [*1..10000]; 100000.times { a.max }
- no patch: 22.424s
- Array#max defined: 1.740s
I don't think it is a good idea to copy all Enumerable methods to Array. But there are two reasons why max
is special:
- It is one of the most basic operations for big data processing.
- We often use an idiom
[a, b].max
because of the lack ofMath.max(a, b)
.
I think the latter is particularly important. The idiom is concise but unsuitable in a hotspot since it creates a temporal array. If Array#max
is defined, we can easily optimize the idiom by introducing a special instruction like opt_newarray_max
.
x, y = 1, 2; 10000000.times { [x, y].max }
- no patch: 2.799s
- Array#max defined: 1.224s
- opt_newarray_max: 0.555s
$ ./miniruby --dump=insns -e 'x, y = 1, 2; [x, y].max'
== disasm: #<ISeq:<main>@-e>============================================
local table (size: 3, argc: 0 [opts: 0, rest: -1, post: 0, block: -1, kw: -1@-1, kwrest: -1])
[ 3] x [ 2] y
0000 trace 1 ( 1)
0002 putobject_OP_INT2FIX_O_1_C_
0003 putobject 2
0005 setlocal_OP__WC__0 2
0007 setlocal_OP__WC__0 3
0009 getlocal_OP__WC__0 3
0011 getlocal_OP__WC__0 2
0013 opt_newarray_max 2
0015 leave
The patches are attached. (0001 is a preparation. 0002 introduces Array#max
. 0003 introduces a special instruction.)
Of course, we can say the same for Array#min
. The patches include Array#min
too.
What do you think?
Files
Updated by mame (Yusuke Endoh) almost 9 years ago
- Description updated (diff)
Updated by mame (Yusuke Endoh) over 8 years ago
- Status changed from Open to Assigned
- Assignee set to mame (Yusuke Endoh)
Matz and ko1 accepted this proposal. I'll commit.
Updated by mame (Yusuke Endoh) over 8 years ago
- Status changed from Assigned to Closed
Applied in changeset r54150.
-
array.c (rb_ary_max, rb_ary_min): Array#max and Array#min added.
[Feature #12172] -
internal.h (OPTIMIZED_CMP): moved from enum.c so that array.c can
use it. -
test/ruby/test_array.rb (test_max, test_min): tests for Array#max
and Array#min. -
test/ruby/test_enum.rb (test_max, test_min): revised a bit to test
Enumerable#max and #min explicitly.