152162 2015-12-10 18:55:27 -0800 B3 should be able to sink values into checks 2016-02-28 17:50:43 -0800 1 1 1 Unclassified WebKit JavaScriptCore WebKit Nightly Build All All NEW P2 Normal --- 152224 152968 152106 1 fpizlo webkit-unassigned oldest_to_newest 1148391 0 fpizlo 2015-12-10 18:55:27 -0800 B3 should sink sinkable operations to the lowest dominating point in the CFG. In case an operation's output is only used for the stackmap of Check, we should turn this: @a = Foo(...) Check(@p, @a) into this: Branch(@p, #exit, #continuation) exit: @a = Foo(...) Check(false, @a) contination: ... This will help with the useless Shr that we will see on some array bounds checks from asm.js code. 1148392 1 fpizlo 2015-12-10 18:56:11 -0800 (In reply to comment #0) > B3 should sink sinkable operations to the lowest dominating point in the > CFG. In case an operation's output is only used for the stackmap of Check, > we should turn this: > > @a = Foo(...) > Check(@p, @a) > > into this: > > Branch(@p, #exit, #continuation) > > exit: > @a = Foo(...) > Check(false, @a) > > contination: > ... > > This will help with the useless Shr that we will see on some array bounds > checks from asm.js code. It's worth saying that usually, https://bugs.webkit.org/show_bug.cgi?id=152160 will obviate the need for this. But things may leak past that optimization. This optimization is more general, but it has a compile time cost due to the introduction of control flow. 1148786 2 fpizlo 2015-12-12 22:26:22 -0800 The priority right now is sinking into checks, not general sinking. 1169052 3 fpizlo 2016-02-28 17:50:43 -0800 Note that we could sink anything that the CSE can reason about. For example, we could sink stores into checks!