112836 2013-03-20 13:41:02 -0700 JSC should be a quadruple-tier VM 2014-04-29 15:08:36 -0700 1 1 1 Unclassified WebKit JavaScriptCore 528+ (Nightly build) All All RESOLVED FIXED P2 Normal --- 112838 112839 112840 115464 115465 115466 116556 116557 116561 116630 116633 116748 1 fpizlo fpizlo abucur barraclough galpeter ggaren mark.lam mhahnenberg msaboff oliver ossy rgabor sam syoichi zherczeg oldest_to_newest 859672 0 fpizlo 2013-03-20 13:41:02 -0700 Our existing DFG optimizing compiler is pretty good, but not as good as it could be. In fact, we've even gone so far as de-tuned it to do fewer optimizations. This is because we care about compile times, and we want the DFG to be able to give profit to even very-short-running functions. Right now it can produce significant speed-ups even for things that only run for ~2ms or less, and even in cases where the relevant functions are relatively complex. But this approach also means that for longer-running code, we get less win. This can be fixed by having an alternate, more powerful, but longer-compiling, tier of the DFG. This would be the fourth tier of JSC. Here's the wishlist for this tier: 1) Bring back the optimization fixpoint to allow CFG simplification to feed back into things like CSE. 2) Run the compiler on a separate thread. 3) Use a proper compiler backend that does global register allocation, GVN, PRE, LICM, etc. 859687 1 fpizlo 2013-03-20 13:48:00 -0700 Branched for this work in http://trac.webkit.org/changeset/146384 859725 2 sam 2013-03-20 14:17:28 -0700 Why not 5 onion.com/bWBRid ? 859729 3 fpizlo 2013-03-20 14:19:26 -0700 (In reply to comment #2) > Why not 5 onion.com/bWBRid ? Assign that bug to Gavin. He was saying something about doing AST interpretation for really simple code. 864856 4 fpizlo 2013-03-27 14:25:16 -0700 (In reply to comment #1) > Branched for this work in http://trac.webkit.org/changeset/146384 The branch is called "fourthTier". I'm prefixing all bugs that are intended to land on this branch with "fourthTier: ". 1005151 5 fpizlo 2014-04-29 15:08:36 -0700 Aaaannnnnd we're done.