199291 2019-06-27 15:13:20 -0700 FTL keepAlive()'s patchpoint should also declare that it reads HeapRange::top(). 2019-06-27 17:31:35 -0700 1 1 1 Unclassified WebKit JavaScriptCore WebKit Nightly Build Unspecified Unspecified RESOLVED FIXED InRadar P2 Normal --- 1 mark.lam mark.lam fpizlo justin_michaud keith_miller msaboff rmorisset saam tzagallo webkit-bug-importer ysuzuki oldest_to_newest 1548632 0 mark.lam 2019-06-27 15:13:20 -0700 The main purpose of keepAlive() is to communicate to B3 that an LValue needs to be kept alive pass the last opportunity for a GC. The only way we can get a GC is via a function call. Hence, what keepAlive() really needs to communicate is that the LValue needs to be kept alive pass the last function call. Function calls read and write HeapRange::top(). Currently, B3 does not shuffle writes. Hence, simply inserting the keepAlive() after the calls that can GC is sufficient. But to be strictly correct, keepAlive() should also declare that it reads HeapRange::top(). This will guarantee that the keepAlive patchpoint won't ever be moved before the function call should B3 gain the ability to shuffle writes in the future. 1548633 1 373057 mark.lam 2019-06-27 15:19:04 -0700 Created attachment 373057 proposed patch. 1548634 2 373057 ysuzuki 2019-06-27 15:23:42 -0700 Comment on attachment 373057 proposed patch. r=me 1548647 3 373057 fpizlo 2019-06-27 16:00:05 -0700 Comment on attachment 373057 proposed patch. R=me too. 1548674 4 mark.lam 2019-06-27 17:27:23 -0700 Thanks for the reviews. Landed in r246910: <http://trac.webkit.org/r246910>. 1548677 5 webkit-bug-importer 2019-06-27 17:31:35 -0700 <rdar://problem/52296737> 373057 2019-06-27 15:19:04 -0700 2019-06-27 15:23:42 -0700 proposed patch. bug-199291.patch text/plain 2127 mark.lam SW5kZXg6IFNvdXJjZS9KYXZhU2NyaXB0Q29yZS9DaGFuZ2VMb2cKPT09PT09PT09PT09PT09PT09 PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PQotLS0gU291 cmNlL0phdmFTY3JpcHRDb3JlL0NoYW5nZUxvZwkocmV2aXNpb24gMjQ2OTA2KQorKysgU291cmNl L0phdmFTY3JpcHRDb3JlL0NoYW5nZUxvZwkod29ya2luZyBjb3B5KQpAQCAtMSwzICsxLDI2IEBA CisyMDE5LTA2LTI3ICBNYXJrIExhbSAgPG1hcmsubGFtQGFwcGxlLmNvbT4KKworICAgICAgICBG VEwga2VlcEFsaXZlKCkncyBwYXRjaHBvaW50IHNob3VsZCBhbHNvIGRlY2xhcmUgdGhhdCBpdCBy ZWFkcyBIZWFwUmFuZ2U6OnRvcCgpLgorICAgICAgICBodHRwczovL2J1Z3Mud2Via2l0Lm9yZy9z aG93X2J1Zy5jZ2k/aWQ9MTk5MjkxCisKKyAgICAgICAgUmV2aWV3ZWQgYnkgTk9CT0RZIChPT1BT ISkuCisKKyAgICAgICAgVGhlIHNvbGUgcHVycG9zZSBvZiBrZWVwQWxpdmUoKSBpcyB0byBjb21t dW5pY2F0ZSB0byBCMyB0aGF0IGFuIExWYWx1ZQorICAgICAgICBuZWVkcyB0byBiZSBrZXB0IGFs aXZlIHBhc3MgdGhlIGxhc3Qgb3Bwb3J0dW5pdHkgZm9yIGEgR0MuICBUaGUgb25seSB3YXkKKyAg ICAgICAgd2UgY2FuIGdldCBhIEdDIGlzIHZpYSBhIGZ1bmN0aW9uIGNhbGwuICBIZW5jZSwgd2hh dCBrZWVwQWxpdmUoKSByZWFsbHkKKyAgICAgICAgbmVlZHMgdG8gY29tbXVuaWNhdGUgaXMgdGhh dCB0aGUgTFZhbHVlIG5lZWRzIHRvIGJlIGtlcHQgYWxpdmUgcGFzcyB0aGUKKyAgICAgICAgbGFz dCBmdW5jdGlvbiBjYWxsLiAgRnVuY3Rpb24gY2FsbHMgcmVhZCBhbmQgd3JpdGUgSGVhcFJhbmdl Ojp0b3AoKS4KKyAgICAgICAgQ3VycmVudGx5LCBCMyBkb2VzIG5vdCBzaHVmZmxlIHdyaXRlcy4g IEhlbmNlLCBzaW1wbHkgaW5zZXJ0aW5nIHRoZQorICAgICAgICBrZWVwQWxpdmUoKSBhZnRlciB0 aGUgY2FsbHMgdGhhdCBjYW4gR0MgaXMgc3VmZmljaWVudC4KKworICAgICAgICBCdXQgdG8gYmUg c3RyaWN0bHkgY29ycmVjdCwga2VlcEFsaXZlKCkgc2hvdWxkIGFsc28gZGVjbGFyZSB0aGF0IGl0 IHJlYWRzCisgICAgICAgIEhlYXBSYW5nZTo6dG9wKCkuICBUaGlzIHdpbGwgZ3VhcmFudGVlIHRo YXQgdGhlIGtlZXBBbGl2ZSBwYXRjaHBvaW50IHdvbid0CisgICAgICAgIGV2ZXIgYmUgbW92ZWQg YmVmb3JlIHRoZSBmdW5jdGlvbiBjYWxsIHNob3VsZCBCMyBnYWluIHRoZSBhYmlsaXR5IHRvIHNo dWZmbGUKKyAgICAgICAgd3JpdGVzIGluIHRoZSBmdXR1cmUuCisKKyAgICAgICAgKiBmdGwvRlRM TG93ZXJERkdUb0IzLmNwcDoKKyAgICAgICAgKEpTQzo6RlRMOjpERkc6Okxvd2VyREZHVG9CMzo6 a2VlcEFsaXZlKToKKwogMjAxOS0wNi0yNyAgQmV0aCBEYWtpbiAgPGJkYWtpbkBhcHBsZS5jb20+ CiAKICAgICAgICAgVXBzdHJlYW0gdXNlIG9mIE1BQ0NBVEFMWVNUCkluZGV4OiBTb3VyY2UvSmF2 YVNjcmlwdENvcmUvZnRsL0ZUTExvd2VyREZHVG9CMy5jcHAKPT09PT09PT09PT09PT09PT09PT09 PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PQotLS0gU291cmNl L0phdmFTY3JpcHRDb3JlL2Z0bC9GVExMb3dlckRGR1RvQjMuY3BwCShyZXZpc2lvbiAyNDY5MDYp CisrKyBTb3VyY2UvSmF2YVNjcmlwdENvcmUvZnRsL0ZUTExvd2VyREZHVG9CMy5jcHAJKHdvcmtp bmcgY29weSkKQEAgLTE3Mjg0LDYgKzE3Mjg0LDcgQEAgcHJpdmF0ZToKICAgICAgICAgUGF0Y2hw b2ludFZhbHVlKiBwYXRjaHBvaW50ID0gbV9vdXQucGF0Y2hwb2ludChWb2lkKTsKICAgICAgICAg cGF0Y2hwb2ludC0+ZWZmZWN0cyA9IEVmZmVjdHM6Om5vbmUoKTsKICAgICAgICAgcGF0Y2hwb2lu dC0+ZWZmZWN0cy53cml0ZXNMb2NhbFN0YXRlID0gdHJ1ZTsKKyAgICAgICAgcGF0Y2hwb2ludC0+ ZWZmZWN0cy5yZWFkcyA9IEhlYXBSYW5nZTo6dG9wKCk7CiAgICAgICAgIHBhdGNocG9pbnQtPmFw cGVuZCh2YWx1ZSwgVmFsdWVSZXA6OkNvbGRBbnkpOwogICAgICAgICBwYXRjaHBvaW50LT5zZXRH ZW5lcmF0b3IoWz1dIChDQ2FsbEhlbHBlcnMmLCBjb25zdCBTdGFja21hcEdlbmVyYXRpb25QYXJh bXMmKSB7IH0pOwogICAgIH0K