From: "charliesome (Charlie Somerville)" <charliesome@...>
Date: 2013-08-31T22:27:52+09:00
Subject: [ruby-core:56939] [ruby-trunk - Bug #8847] opt_regexpmatch2 does	not use method caching


Issue #8847 has been updated by charliesome (Charlie Somerville).


nagachika: There's no incorrect behaviour that r42742 fixes - it is merely a performance improvement.

You can use the following benchmark script as a test:

    require "benchmark"

    puts Benchmark.measure {
      1_000_000.times do
        1 =~ //
        1 =~ //
        1 =~ //
        1 =~ //
        1 =~ //
        1 =~ //
        1 =~ //
        1 =~ //
      end
    }

Before my commit, I get this result:

      0.330000   0.000000   0.330000 (  0.332941)

After my commit, I get:

      0.240000   0.000000   0.240000 (  0.241248)

You can probably do something similar to verify your backport is correct.
----------------------------------------
Bug #8847: opt_regexpmatch2 does not use method caching
https://bugs.ruby-lang.org/issues/8847#change-41497

Author: charliesome (Charlie Somerville)
Status: Closed
Priority: Normal
Assignee: charliesome (Charlie Somerville)
Category: 
Target version: 
ruby -v: ruby 2.1.0dev (2013-08-31 trunk 42741) [x86_64-darwin12.4.0]
Backport: 1.9.3: UNKNOWN, 2.0.0: REQUIRED


The opt_regexpmatch2 instruction does not use method caching, instead it uses rb_funcall internally.

opt_regexpmatch2 is emitted by the compiler when a literal regexp is on the right hand side of the =~ operator.

This means a full method lookup must be performed every time the receiver of the =~ method call is not a String.


-- 
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