Currently, when compiling Ion code, we start compiling the script, and abort if we hit a try/finally. Likewise, when inlining a script in Ion, we start inlining and abort if we hit a try/catch, since we can't inline try/catch yet. There are numerous situations where we will start compiling an outer script, and then abort midway through. This is worse when we start inlining a script, and then abort the entire compilation because we ran into a try/catch in the inlined script. These cases should be checked eagerly and compilation/inlining disabled.

Bug 939614 part 3 will fix this for the non-inlineable cases, but it would be good to do this for other aborts as well.

This was an unexpectedly significant win on octane. Here are the average octane scores across 20 runs (pre-patch first, post-patch second). All averaged scores are posted at the end of the comment. No regressions that I can see, and some improvments. Here are the improved scores: Splay: 15614.10 Splay: 16154.00 SplayLatency: 7654.75 SplayLatency: 8543.25 Crypto: 21464.60 Crypto: 21642.25 Gameboy: 30509.85 Gameboy: 30676.35 MandreelLatency: 14208.65 MandreelLatency: 14368.80 PdfJS: 11034.45 PdfJS: 11108.20 Score 13729.75 Score 13895.95 Splay and SplayLatency are the biggest take-homes, with ~500 points gained on Splay and ~900 points gained on SplayLatency. Overall score improves by about 160 points, or 1.2%. All averaged scores: Box2D: 7371.10 Box2D: 7305.70 CodeLoad: 18426.25 CodeLoad: 18405.00 Crypto: 21464.60 Crypto: 21642.25 DeltaBlue: 18182.20 DeltaBlue: 18193.00 EarleyBoyer: 18856.10 EarleyBoyer: 18833.75 Gameboy: 30509.85 Gameboy: 30676.35 Mandreel: 5986.95 Mandreel: 6003.95 MandreelLatency: 14208.65 MandreelLatency: 14368.80 NavierStokes: 25953.40 NavierStokes: 25949.85 PdfJS: 11034.45 PdfJS: 11108.20 RayTrace: 20185.55 RayTrace: 20135.35 RegExp: 1555.55 RegExp: 1572.35 Richards: 21272.20 Richards: 21268.85 Splay: 15614.10 Splay: 16154.00 SplayLatency: 7654.75 SplayLatency: 8543.25 Typescript: 7677.50 Typescript: 7694.05 zlib: 51406.05 zlib: 51437.25 Score 13729.75 Score 13895.95

Comment on attachment 8342626 [details] [diff] [review] eager-avoid-compiling-try-catch-finally.patch Review of attachment 8342626 [details] [diff] [review]: ----------------------------------------------------------------- try-catch and try-finally are two cases that we can't compile or inline, but there are others: Ion also doesn't compile JSOP_ENTERBLOCK for instance and we'll have the same problem there: start a compilation and then find out we have to abort. There's also an abort in jsop_setarg (in some cases) if we are inlining. It'd be nice if we could turn the abort() in IonBuilder::inspectOpcode into a MOZ_ASSUME_UNREACHABLE. I think the approach in bug 939614 part 3 is simpler: it's trivial for baseline or the bytecode analysis to set script->ion to ION_DISABLED_SCRIPT or script->uninlineable to true, without needing any extra bits/state or checks.

Fair enough. Looking forward to that landing. If these results are any indication, it should have a pretty significant impact on our scores. I'll mark this bug as a dup.