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Improve performance of some Time & Rational methods 

rational.c (i_gcd): replace GCD algorithm from Euclidean algorithm to Stein
    algorithm (https://en.wikipedia.org/wiki/Binary_GCD_algorithm).

    Some Time methods will call internal quov() function and it calls
    Rational#quo -> f_muldiv() -> i_gcd() in rational.c
    And some Rational methods also call i_gcd().

    The implementation of Euclidean algorithm spent a long time at modulo
    operation (ie "x = y % x;").
    The Stein algorithm will replace with shift operation which is faster
    than modulo.

    Time#subsec -> 36 % up
    Time#to_r   -> 26 % up
    Rational#+  -> 14 % up
    Rational#-  -> 15 % up
    Rational#*  -> 13 % up

    [ruby-core:80843] [Bug #13503] [Fix GH-1596]

### Before
         Time#subsec      2.142M (± 9.8%) i/s -     10.659M in   5.022659s
           Time#to_r      2.003M (± 9.1%) i/s -      9.959M in   5.012445s
          Rational#+      3.843M (± 0.9%) i/s -     19.274M in   5.016254s
          Rational#-      3.820M (± 1.3%) i/s -     19.149M in   5.014137s
          Rational#*      5.198M (± 1.4%) i/s -     26.016M in   5.005664s
* After
         Time#subsec      2.902M (± 2.9%) i/s -     14.505M in   5.001815s
           Time#to_r      2.503M (± 4.8%) i/s -     12.512M in   5.011454s
          Rational#+      4.390M (± 1.2%) i/s -     22.001M in   5.012413s
          Rational#-      4.391M (± 1.2%) i/s -     22.013M in   5.014584s
          Rational#*      5.872M (± 2.2%) i/s -     29.369M in   5.003666s

* Test code
require 'benchmark/ips'

Benchmark.ips do |x|
  x.report "Time#subsec" do |t|
    time = Time.now
    t.times { time.subsec }
  end

  x.report "Time#to_r" do |t|
    time = Time.now
    t.times { time.to_r }
  end

  x.report "Rational#+" do |t|
    rat1 = 1/2r
    rat2 = 1/3r
    t.times { rat1 + rat2 }
  end

  x.report "Rational#-" do |t|
    rat1 = 1/3r
    rat2 = 1/2r
    t.times { rat1 - rat2 }
  end

  x.report "Rational#*" do |t|
    rat1 = 1/3r
    rat2 = 1/2r
    t.times { rat1 * rat2 }
  end
end

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@58922 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
This commit is contained in:
watson1978 2017-05-27 05:41:02 +00:00
parent 6fcb76ed80
commit b0accd9b13
1 changed files with 25 additions and 5 deletions
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30
rational.c
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@ -280,6 +280,9 @@ rb_gcd_gmp(VALUE x, VALUE y)
inline static long
i_gcd(long x, long y)
{
unsigned long u, v, t;
int shift;
if (x < 0)
x = -x;
if (y < 0)
@ -290,12 +293,29 @@ i_gcd(long x, long y)
if (y == 0)
return x;
while (x > 0) {
long t = x;
x = y % x;
y = t;
u = (unsigned long)x;
v = (unsigned long)y;
for (shift = 0; ((u | v) & 1) == 0; ++shift) {
u >>= 1;
v >>= 1;
}
return y;
while ((u & 1) == 0)
u >>= 1;
do {
while ((v & 1) == 0)
v >>= 1;
if (u > v) {
t = v;
v = u;
u = t;
}
v = v - u;
} while (v != 0);
return (long)(u << shift);
}
inline static VALUE