224589 2021-04-14 19:16:46 -0700 Avoid indirect load in ContainerNode::hasOneChild() 2021-04-14 20:35:15 -0700 1 1 1 Unclassified WebKit DOM WebKit Nightly Build Unspecified Unspecified RESOLVED FIXED InRadar P2 Normal --- 1 rniwa rniwa cdumez darin esprehn+autocc ews-watchlist kangil.han webkit-bug-importer ysuzuki oldest_to_newest 1750446 0 rniwa 2021-04-14 19:16:46 -0700 Getting nextSibling() will involve loading the first child into the register. Avoid that and just check m_firstChild and m_lastChild instead to avoid this extra memory load. 1750452 1 426070 rniwa 2021-04-14 19:43:00 -0700 Created attachment 426070 Patch 1750454 2 426070 cdumez 2021-04-14 19:47:33 -0700 Comment on attachment 426070 Patch If you say this is more efficient, I believe you. R=me. The new code definitely still is correct. 1750455 3 rniwa 2021-04-14 19:52:44 -0700 (In reply to Chris Dumez from comment #2) > Comment on attachment 426070 [details] > Patch > > If you say this is more efficient, I believe you. R=me. The new code > definitely still is correct. Yeah because m_firstChild and m_lastChild are both in the same object whereas m_firstChild isn't. CPU needs to load the content of m_firstChild and then retrieve m_nextSibling, which is an indirect load that CPU will have a hard time predicting so whilst prefetched would detect this and will fetch it, it can still result in either TLB hit miss and/or L2/L3 cache misses, which would be horrifyingly expensive. 1750466 4 426070 rniwa 2021-04-14 20:34:17 -0700 Comment on attachment 426070 Patch Clearing flags on attachment: 426070 Committed r275997 (236549@main): <https://commits.webkit.org/236549@main> 1750467 5 rniwa 2021-04-14 20:34:19 -0700 All reviewed patches have been landed. Closing bug. 1750468 6 webkit-bug-importer 2021-04-14 20:35:15 -0700 <rdar://problem/76682121> 426070 2021-04-14 19:43:00 -0700 2021-04-14 20:34:17 -0700 Patch fix224589.patch text/plain 1658 rniwa ZGlmZiAtLWdpdCBhL1NvdXJjZS9XZWJDb3JlL0NoYW5nZUxvZyBiL1NvdXJjZS9XZWJDb3JlL0No YW5nZUxvZwppbmRleCA4ODM4MTU2NDRlY2IuLjk2MThlNzJlZWY3MiAxMDA2NDQKLS0tIGEvU291 cmNlL1dlYkNvcmUvQ2hhbmdlTG9nCisrKyBiL1NvdXJjZS9XZWJDb3JlL0NoYW5nZUxvZwpAQCAt MSwzICsxLDE2IEBACisyMDIxLTA0LTE0ICBSeW9zdWtlIE5pd2EgIDxybml3YUB3ZWJraXQub3Jn PgorCisgICAgICAgIEF2b2lkIGluZGlyZWN0IGxvYWQgaW4gQ29udGFpbmVyTm9kZTo6aGFzT25l Q2hpbGQoKQorICAgICAgICBodHRwczovL2J1Z3Mud2Via2l0Lm9yZy9zaG93X2J1Zy5jZ2k/aWQ9 MjI0NTg5CisKKyAgICAgICAgUmV2aWV3ZWQgYnkgTk9CT0RZIChPT1BTISkuCisKKyAgICAgICAg R2V0dGluZyBuZXh0U2libGluZygpIHdpbGwgaW52b2x2ZSBsb2FkaW5nIHRoZSBmaXJzdCBjaGls ZCBpbnRvIHRoZSByZWdpc3Rlci4KKyAgICAgICAgQXZvaWQgdGhhdCBhbmQganVzdCBjaGVjayBt X2ZpcnN0Q2hpbGQgYW5kIG1fbGFzdENoaWxkIGluc3RlYWQgdG8gYXZvaWQgdGhpcyBleHRyYSBt ZW1vcnkgbG9hZC4KKworICAgICAgICAqIGRvbS9Db250YWluZXJOb2RlLmg6CisgICAgICAgIChX ZWJDb3JlOjpDb250YWluZXJOb2RlOjpoYXNPbmVDaGlsZCBjb25zdCk6CisKIDIwMjEtMDQtMTQg IEFudHRpIEtvaXZpc3RvICA8YW50dGlAYXBwbGUuY29tPgogCiAgICAgICAgIFJ1bkl0ZXJhdG9y Ojp0cmF2ZXJzZU5leHQvUHJldmlvdXNPbkxpbmVJZ25vcmluZ0xpbmVCcmVhayBzaG91bGQgc2tp cCBvdmVyIFdCUnMKZGlmZiAtLWdpdCBhL1NvdXJjZS9XZWJDb3JlL2RvbS9Db250YWluZXJOb2Rl LmggYi9Tb3VyY2UvV2ViQ29yZS9kb20vQ29udGFpbmVyTm9kZS5oCmluZGV4IDk5NzM0NWM1MGE1 ZC4uZjY2ZjZlMzZkYzNlIDEwMDY0NAotLS0gYS9Tb3VyY2UvV2ViQ29yZS9kb20vQ29udGFpbmVy Tm9kZS5oCisrKyBiL1NvdXJjZS9XZWJDb3JlL2RvbS9Db250YWluZXJOb2RlLmgKQEAgLTQ1LDcg KzQ1LDcgQEAgcHVibGljOgogICAgIE5vZGUqIGxhc3RDaGlsZCgpIGNvbnN0IHsgcmV0dXJuIG1f bGFzdENoaWxkOyB9CiAgICAgc3RhdGljIHB0cmRpZmZfdCBsYXN0Q2hpbGRNZW1vcnlPZmZzZXQo KSB7IHJldHVybiBPQkpFQ1RfT0ZGU0VUT0YoQ29udGFpbmVyTm9kZSwgbV9sYXN0Q2hpbGQpOyB9 CiAgICAgYm9vbCBoYXNDaGlsZE5vZGVzKCkgY29uc3QgeyByZXR1cm4gbV9maXJzdENoaWxkOyB9 Ci0gICAgYm9vbCBoYXNPbmVDaGlsZCgpIGNvbnN0IHsgcmV0dXJuIG1fZmlyc3RDaGlsZCAmJiAh bV9maXJzdENoaWxkLT5uZXh0U2libGluZygpOyB9CisgICAgYm9vbCBoYXNPbmVDaGlsZCgpIGNv bnN0IHsgcmV0dXJuIG1fZmlyc3RDaGlsZCAmJiBtX2ZpcnN0Q2hpbGQgPT0gbV9sYXN0Q2hpbGQ7 IH0KIAogICAgIGJvb2wgZGlyZWN0Q2hpbGROZWVkc1N0eWxlUmVjYWxjKCkgY29uc3QgeyByZXR1 cm4gaGFzU3R5bGVGbGFnKE5vZGVTdHlsZUZsYWc6OkRpcmVjdENoaWxkTmVlZHNTdHlsZVJlc29s dXRpb24pOyB9CiAgICAgdm9pZCBzZXREaXJlY3RDaGlsZE5lZWRzU3R5bGVSZWNhbGMoKSB7IHNl dFN0eWxlRmxhZyhOb2RlU3R5bGVGbGFnOjpEaXJlY3RDaGlsZE5lZWRzU3R5bGVSZXNvbHV0aW9u KTsgfQo=