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github.com/moarvm/moarvm | IRC logs at colabti.org/irclogger/irclogger_logs/moarvm Set by AlexDaniel on 12 June 2018. |
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| nwc10 | good *, #moarvm | 09:33 | |
| jnthn | o/ | 10:08 | |
| nwc10 | \o | 10:09 | |
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| nine | quiet day it seems | 20:23 | |
| MasterDuke | i've been distracted from debugging remove_spesh_candidate by --profile-compiling the rakudo build | 20:26 | |
| don't think there's anything particularly new or exciting though in the output though | 20:27 | ||
| nine | so at least no negative surprise | 20:28 | |
| MasterDuke | don't think so | 20:29 | |
| lots of complaints in a spesh log about missing templates for (bind|get)attrs?_(i|n|s|o) github.com/MoarVM/MoarVM/blob/mast...1985-L2172 any reason they couldn't be templated? | 20:35 | ||
| jnthn has a sore arm (trapped nerve, happens now and then), so hasn't had the most productive of days... | |||
| nine | jnthn: ouch | ||
| jnthn | Though it's less bad now than it was in the morning, so hopefully it clears up soon. | ||
| nwc10 | this is good. And my (sorry rather) flippant comment is "But with the new coffee machine, as it's push button, you don't even have to pump your beverage" | 20:36 | |
| nine | MasterDuke: the reason we don't do that is because those ought to be optimized to spesh variants (which then are JITed) | ||
| MasterDuke: so for the best result we should figure out why they aren't | |||
| jnthn | nwc10: It's certainly lower effort than what it replaced, yes | 20:37 | |
| It eats the ground coffee rather faster, however. On the upside, that means I'll be feeding it beans soon... | |||
| MasterDuke | i see a bunch of `JIT: not devirtualized (type unknown)` near bindattr_os in the spesh log | 20:38 | |
| jnthn | And then it's even less effort (the ground type has to be put in per cup, the beans it can probably hold enough for a week or more) | ||
| MasterDuke | that message is the `else` of this `if` github.com/MoarVM/MoarVM/blob/mast...#L886-L887 | 20:42 | |
| jnthn | MasterDuke: What are the facts on the invocant? | 20:43 | |
| MasterDuke | jnthn: is the invocant the first r123(4) thing right after the op name in the log? | 20:44 | |
| jnthn | Yes | 20:45 | |
| For bindattr, anyway | |||
| For getattr the second thing | 20:46 | ||
| ('cus the first is the result register) | |||
| MasterDuke | `r127(2): usages=1, flags=0` | ||
| jnthn | Oh. So it knows nothing about its type | 20:48 | |
| MasterDuke | `getattr_o r129(2), r127(2), r128(2), lits($!dispatch_cache), liti16(13) # [261] JIT: not devirtualized (type unknown)` is the gettattr_o i was just looking at. i see `$!dispatch_cache` in there, is this going to change with new-disp? | ||
| jnthn | Ye | ||
| *yes | |||
| MasterDuke | oh, nm, i see lots of other things referenced too | ||
| jnthn | But "type unknown" is the case there too | ||
| The $!dispatch_cache attr will go away | 20:49 | ||
| MasterDuke | lots of $bstack, $cstack, @!named_names, $!type, @!post_constraints, etc | 20:50 | |
| jnthn | Hm, the first two are a bit annoying, since they could be quite hot in the regex engine | 20:51 | |
| MasterDuke | `r51(11): usages=1, deopt=71, flags=0` for one of the $bstack ones | ||
| `r9(12): usages=1, deopt=22, flags=0` for a $cstack | 20:52 | ||
| jnthn | Yeah, means it knows pretty much nothing about them | 20:53 | |
| There's many potential reasons, including being in a branch that was never taken, so there's no type stats recorded | |||
| Though if that's the case then it's also not a very important miss | 20:54 | ||
| MasterDuke | any way to find important misses? | ||
| jnthn | Hm, not sure. I mean, one can try and match up the instructions to the HLL code and see if it looks reasonable that it'd not be executed much | 20:55 | |
| Can also see if you can trace back where that value comes from | 20:56 | ||
| That is, which instruction writes the register | |||
| MasterDuke | github.com/Raku/nqp/blob/master/sr...#L422-L447 | 20:58 | |
| $!shared, $!braid, $!regexsub, $!restart, $!from, $!pos, $!to, $!cstack, $!bstack all get some `JIT: not devirtualized (type unknown)` for bindattr_o, bindattr_i, getattr_o, etc | 21:03 | ||
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| jnthn | Can you find the instruction that goes with: | 21:04 | |
| my $new := nqp::create(self); | |||
| MasterDuke | !cursor_start is called 397,825 times, but it is 99.9% jit according to moarperf | ||
| jnthn | What are the facts on both the result and the type? | ||
| MasterDuke | `create r1(2), r3(2)` | 21:05 | |
| jnthn | I think the message didn't say JIT failed, so much as expr JIT failed? | ||
| MasterDuke | `r1(2): usages=14, deopt=37,36,35,34,33,32,31,29,28,27,25,24,22,21,20,19,18,17,16,14,13,12,10,11,6,5,4,3,1, flags=8 Concr` | ||
| `r3(2): usages=1, deopt=0, flags=0` | 21:06 | ||
| jnthn | Hmmm, so it doesn't know the type of self. Does it say if it's a certain specialization or an observed type specialization? | ||
| I guess it may have specialized it in a bunch of ways and then decided there were too many and gone for a generic one | |||
| MasterDuke | Certain specialization of '!cursor_start' (cuid: 82, file: gen/moar/stage2/QRegex.nqp:1485) | 21:07 | |
| The specialization is for the callsite: | |||
| jnthn | Aha, that explains it | ||
| MasterDuke | Callsite 0x7f3afd04a840 (1 args, 1 pos) | ||
| Positional flags: obj | |||
| It was planned due to the callsite receiving 572 hits. | |||
| The maximum stack depth is 102. | |||
| jnthn | Hm, can you trace back to the stats before it? Did it think it was too morphic? | 21:08 | |
| (Stats it used should be just before the plan) | |||
| well, the list of plans | |||
| I guess the other thing to look back and check is if it did other specializations in the past | 21:09 | ||
| I guess there can be quite a few types of cursor (main language, regex language, various quote languages) | |||
| MasterDuke | i don't see the word morphic | 21:10 | |
| there are 4 type tuples | |||
| jnthn | oh, it won't appear; I mean are there lots of type tuples that are about balanced in appearance, or one that dominates, or? | 21:11 | |
| MasterDuke | Hits: 227, Hits: 15, Hits: 91, Hits: 172, Hits: 69 | 21:12 | |
| oh, 0-based counting. there are 5 type tuples | |||
| jnthn | Hm, yeah, quite distributed | ||
| There's a percentage threshold somewhere (I think it's 25%) that controls if it considers something worth a specialization | |||
| gotta afk a bit | 21:13 | ||
| MasterDuke | hm, so if spesh is legitimately not able to do anything with these, does that make creating templates worthwhile? | 21:15 | |
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| jnthn | Well, it's the same trade-off either way: do we want to use more memory for more speed? | 23:29 | |
| We can pick a lower percentage for "worthwhile". We could also make it conditional on absolute number of hits. | 23:30 | ||
| Although in this case we aren't seeing them be much over the baseline threshold, iirc | |||