{"action":"created","issue":{"url":"https://api.github.com/repos/dotnet/coreclr/issues/8101","repository_url":"https://api.github.com/repos/dotnet/coreclr","labels_url":"https://api.github.com/repos/dotnet/coreclr/issues/8101/labels{/name}","comments_url":"https://api.github.com/repos/dotnet/coreclr/issues/8101/comments","events_url":"https://api.github.com/repos/dotnet/coreclr/issues/8101/events","html_url":"https://github.com/dotnet/coreclr/pull/8101","id":188880913,"number":8101,"title":"Generate \"inc/dec [mem]\" instead of \"add/sub [mem], 1\" for Read-Modify-Write (RMW) operations.","user":{"login":"sivarv","id":11184808,"avatar_url":"https://avatars.githubusercontent.com/u/11184808?v=3","gravatar_id":"","url":"https://api.github.com/users/sivarv","html_url":"https://github.com/sivarv","followers_url":"https://api.github.com/users/sivarv/followers","following_url":"https://api.github.com/users/sivarv/following{/other_user}","gists_url":"https://api.github.com/users/sivarv/gists{/gist_id}","starred_url":"https://api.github.com/users/sivarv/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/sivarv/subscriptions","organizations_url":"https://api.github.com/users/sivarv/orgs","repos_url":"https://api.github.com/users/sivarv/repos","events_url":"https://api.github.com/users/sivarv/events{/privacy}","received_events_url":"https://api.github.com/users/sivarv/received_events","type":"User","site_admin":false},"labels":[{"id":197462704,"url":"https://api.github.com/repos/dotnet/coreclr/labels/cla-already-signed","name":"cla-already-signed","color":"009800","default":false},{"id":196940911,"url":"https://api.github.com/repos/dotnet/coreclr/labels/CodeGen","name":"CodeGen","color":"d4c5f9","default":false},{"id":190283555,"url":"https://api.github.com/repos/dotnet/coreclr/labels/optimization","name":"optimization","color":"0052cc","default":false}],"state":"open","locked":false,"assignee":{"login":"sivarv","id":11184808,"avatar_url":"https://avatars.githubusercontent.com/u/11184808?v=3","gravatar_id":"","url":"https://api.github.com/users/sivarv","html_url":"https://github.com/sivarv","followers_url":"https://api.github.com/users/sivarv/followers","following_url":"https://api.github.com/users/sivarv/following{/other_user}","gists_url":"https://api.github.com/users/sivarv/gists{/gist_id}","starred_url":"https://api.github.com/users/sivarv/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/sivarv/subscriptions","organizations_url":"https://api.github.com/users/sivarv/orgs","repos_url":"https://api.github.com/users/sivarv/repos","events_url":"https://api.github.com/users/sivarv/events{/privacy}","received_events_url":"https://api.github.com/users/sivarv/received_events","type":"User","site_admin":false},"assignees":[{"login":"sivarv","id":11184808,"avatar_url":"https://avatars.githubusercontent.com/u/11184808?v=3","gravatar_id":"","url":"https://api.github.com/users/sivarv","html_url":"https://github.com/sivarv","followers_url":"https://api.github.com/users/sivarv/followers","following_url":"https://api.github.com/users/sivarv/following{/other_user}","gists_url":"https://api.github.com/users/sivarv/gists{/gist_id}","starred_url":"https://api.github.com/users/sivarv/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/sivarv/subscriptions","organizations_url":"https://api.github.com/users/sivarv/orgs","repos_url":"https://api.github.com/users/sivarv/repos","events_url":"https://api.github.com/users/sivarv/events{/privacy}","received_events_url":"https://api.github.com/users/sivarv/received_events","type":"User","site_admin":false}],"milestone":null,"comments":1,"created_at":"2016-11-12T00:50:31Z","updated_at":"2016-11-12T01:23:42Z","closed_at":null,"pull_request":{"url":"https://api.github.com/repos/dotnet/coreclr/pulls/8101","html_url":"https://github.com/dotnet/coreclr/pull/8101","diff_url":"https://github.com/dotnet/coreclr/pull/8101.diff","patch_url":"https://github.com/dotnet/coreclr/pull/8101.patch"},"body":"Happened to observe the below code sequence while analyzing method \r\n`System.Collections.Generic.HashSet`1[__Canon][System.__Canon]:AddIfNotPresent(ref):bool:this`\r\n\r\n```\r\nIN0074: 0001CD add      dword ptr [rsi+40], 1\r\nIN0075: 0001D1 add      dword ptr [rsi+52], 1\r\n```\r\nThe above instructions are generated for RMW operations.  Preferring inc/dec would result in a smaller instruction.\r\n\r\nSuperPMI asm diffs: 3KB of code size win across all desktop fx assemblies\r\n```\r\n00.71:         <filename>                                            baseline        diff improvement  %improvement    #funcs\r\n00.71:         CQ_PERF_Clean_Thin_Unique_all.dasm                      202538      201889         649          0.32       347\r\n04.46:         All_FX_Clean_Thin_Unique_all.dasm                      1165984     1162171        3813          0.33      2677\r\n```\r\n\r\n"},"comment":{"url":"https://api.github.com/repos/dotnet/coreclr/issues/comments/260091744","html_url":"https://github.com/dotnet/coreclr/pull/8101#issuecomment-260091744","issue_url":"https://api.github.com/repos/dotnet/coreclr/issues/8101","id":260091744,"user":{"login":"sivarv","id":11184808,"avatar_url":"https://avatars.githubusercontent.com/u/11184808?v=3","gravatar_id":"","url":"https://api.github.com/users/sivarv","html_url":"https://github.com/sivarv","followers_url":"https://api.github.com/users/sivarv/followers","following_url":"https://api.github.com/users/sivarv/following{/other_user}","gists_url":"https://api.github.com/users/sivarv/gists{/gist_id}","starred_url":"https://api.github.com/users/sivarv/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/sivarv/subscriptions","organizations_url":"https://api.github.com/users/sivarv/orgs","repos_url":"https://api.github.com/users/sivarv/repos","events_url":"https://api.github.com/users/sivarv/events{/privacy}","received_events_url":"https://api.github.com/users/sivarv/received_events","type":"User","site_admin":false},"created_at":"2016-11-12T01:23:42Z","updated_at":"2016-11-12T01:23:42Z","body":"@dotnet/jit-contrib - Please review this."}}
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