From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS4713 221.184.0.0/13 X-Spam-Status: No, score=-2.6 required=3.0 tests=AWL,BAYES_00, DKIM_ADSP_CUSTOM_MED,FORGED_GMAIL_RCVD,FREEMAIL_FORGED_FROMDOMAIN, FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED,SPF_HELO_NONE,T_SPF_TEMPERROR shortcircuit=no autolearn=no autolearn_force=no version=3.4.2 Received: from neon.ruby-lang.org (neon.ruby-lang.org [221.186.184.75]) by dcvr.yhbt.net (Postfix) with ESMTP id 5BD0D1F463 for ; Wed, 27 Nov 2019 16:00:01 +0000 (UTC) Received: from neon.ruby-lang.org (localhost [IPv6:::1]) by neon.ruby-lang.org (Postfix) with ESMTP id 9EE09120AFD; Thu, 28 Nov 2019 00:59:50 +0900 (JST) Received: from o1678948x4.outbound-mail.sendgrid.net (o1678948x4.outbound-mail.sendgrid.net [167.89.48.4]) by neon.ruby-lang.org (Postfix) with ESMTPS id F3D41120AFC for ; Thu, 28 Nov 2019 00:59:47 +0900 (JST) Received: by filter0078p3iad2.sendgrid.net with SMTP id filter0078p3iad2-1960-5DDE9D76-32 2019-11-27 15:59:50.81609512 +0000 UTC m=+663021.297789864 Received: from herokuapp.com (unknown [3.87.7.191]) by ismtpd0052p1iad1.sendgrid.net (SG) with ESMTP id 1noBttTDS8Slpxn6DVg54A for ; Wed, 27 Nov 2019 15:59:50.699 +0000 (UTC) Date: Wed, 27 Nov 2019 15:59:50 +0000 (UTC) From: eregontp@gmail.com Message-ID: References: Mime-Version: 1.0 X-Redmine-MailingListIntegration-Message-Ids: 71623 X-Redmine-Project: ruby-trunk X-Redmine-Issue-Id: 16188 X-Redmine-Issue-Author: Eregon X-Redmine-Issue-Assignee: jeremyevans0 X-Redmine-Sender: Eregon X-Mailer: Redmine X-Redmine-Host: bugs.ruby-lang.org X-Redmine-Site: Ruby Issue Tracking System X-Auto-Response-Suppress: All Auto-Submitted: auto-generated X-SG-EID: =?us-ascii?Q?KippOI8ZHtTweq7XfQzW93937kJ4QNWwSBuHnaMEcr3uqlHZtVUZKJMUNZuIpj?= =?us-ascii?Q?mnZv1fhOD=2FM2U5IWJt6PqrT6vbjI1Lkuw1btwVg?= =?us-ascii?Q?iFFMBv80JREP8enyBa7n8DsLX8gFsWFZYr+Sw8x?= =?us-ascii?Q?SQtWp761ypfGtlyVtHO69OV4heG668HrAG78DDE?= =?us-ascii?Q?u8tWds80bX5YuGhDtAKQa7wOMncaHP7gDCg=3D=3D?= To: ruby-core@ruby-lang.org X-ML-Name: ruby-core X-Mail-Count: 95989 Subject: [ruby-core:95989] [Ruby master Misc#16188] What are the performance implications of the new keyword arguments in 2.7 and 3.0? X-BeenThere: ruby-core@ruby-lang.org X-Mailman-Version: 2.1.15 Precedence: list Reply-To: Ruby developers List-Id: Ruby developers List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: ruby-core-bounces@ruby-lang.org Sender: "ruby-core" Issue #16188 has been updated by Eregon (Benoit Daloze). jeremyevans0 (Jeremy Evans) wrote: > Do all non-`ruby2_keywords` tests still pass with that? If so, what are the benchmark results with the patch? Yes, all specs pass and test-all has just 2 expected failures: ``` 1) Failure: TestKeywordArguments#test_ruby2_keywords [/home/eregon/code/ruby/test/ruby/test_keyword.rb:2794]: <[[{:a=>1}], {}]> expected but was <[[], {:a=>1}]>. [ 92/226] TestSyntax#test_argument_forwarding = 0.00 s 2) Failure: TestSyntax#test_argument_forwarding [/home/eregon/code/ruby/test/ruby/test_syntax.rb:1515]: --- expected +++ actual @@ -1 +1,4 @@ -"" +"/home/eregon/code/ruby/test/ruby/test_syntax.rb:1485: warning: The last argument is used as the keyword parameter +" + +"/home/eregon/code/ruby/test/ruby/test_syntax.rb:1478: warning: for `bar' defined here +" 20722 tests, 2699145 assertions, 2 failures, 0 errors, 114 skips ``` ---------------------------------------- Misc #16188: What are the performance implications of the new keyword arguments in 2.7 and 3.0? https://bugs.ruby-lang.org/issues/16188#change-82822 * Author: Eregon (Benoit Daloze) * Status: Open * Priority: Normal * Assignee: jeremyevans0 (Jeremy Evans) ---------------------------------------- In #14183, keyword arguments became further separated from positional arguments. Contrary to the original design though, keyword and positional arguments are not fully separated for methods not accepting keyword arguments. Example: `foo(key: :value)` will `def foo(hash)` will pass a positional argument. This is of course better for compatibility, but I wonder what are the performance implications. The block argument is completely separate in all versions, so no need to concern ourselves about that. In Ruby <= 2.6: * The caller never needs to know about the callee's arguments, it can just take all arguments and pass them as an array. The last argument might be used to extract keyword, but this is all done at the callee side. * Splitting kwargs composed of Symbol and non-Symbol keys can be fairly expensive, but it is a rare occurrence. If inlining the callee and kwargs are all passed as a literal Hash at the call site, there shouldn't be any overhead compared to positional arguments once JIT'ed. In Ruby 2.7: * The caller needs to pass positional and keyword arguments separately, at least when calling a method accepting kwargs. But, if it calls a methods not accepting kwargs, then the "kwargs" (e.g. `foo(key: :value)`) should be treated just like a final Hash positional argument. * (If we had complete separation, then we could always pass positional and keyword arguments separately, so the caller could once again ignore the callee) How is the logic implemented in MRI for 2.7? Specializing the caller for a given callee is a well-known technique. However, it becomes more difficult if different methods are called from the same callsite (polymorphic call), especially if one accepts kwargs and another does not. In that case, I think we will see a performance cost to this approach, by having to pass arguments differently based on the method to be called. What about delegation using `ruby2_keywords`? Which checks does that add (compared to 2.6) in the merged approach with the Hash flag? -- https://bugs.ruby-lang.org/