From: Charles Oliver Nutter <charles.nutter@...>
Date: 2008-10-11T01:14:47+09:00
Subject: [ruby-core:19285] Re: performance of C function calls in 1.8 vs 1.9

Charles Oliver Nutter wrote:
> Unexpectedly, 'times' and 'each' are faster for 1.8.6 than 'for'.

The "fasterness" of 1.8.6 appears to be because the original bench did 
not have a variable assignment in the times/each blocks (where the 'for' 
does). Adding that:

~/projects/jruby ��� ruby test.rb
                           user     system      total        real
times                 1.760000   0.010000   1.770000 (  1.773225)
for                   1.220000   0.010000   1.230000 (  1.239431)
each                  1.790000   0.010000   1.800000 (  1.805276)

~/projects/jruby ��� ../ruby1.9/ruby -I ../ruby1.9/lib test.rb
                           user     system      total        real
times                 1.090000   0.020000   1.110000 (  1.110330)
for                   5.320000   0.030000   5.350000 (  5.372634)
each                  1.040000   0.010000   1.050000 (  1.041633)

~/projects/jruby ��� jruby --server test.rb
                           user     system      total        real
times                 1.511000   0.000000   1.511000 (  1.510814)
for                   1.113000   0.000000   1.113000 (  1.112858)
each                  1.347000   0.000000   1.347000 (  1.346819)

So at least that's one mystery solved; 1.8.6 must have some peephole 
optimization for empty blocks with no var assignment (i.e. completely 
empty).

- Charlie