173908 2017-06-27 23:47:26 -0700 WebAssembly: don't tier up when out of executable memory 2017-06-28 00:50:35 -0700 1 1 1 Unclassified WebKit JavaScriptCore WebKit Nightly Build Unspecified Unspecified NEW P2 Normal --- 171537 1 jfbastien webkit-unassigned fpizlo jfbastien keith_miller mark.lam msaboff saam oldest_to_newest 1323457 0 jfbastien 2017-06-27 23:47:26 -0700 In https://bugs.webkit.org/show_bug.cgi?id=171537 I made our implementation throw when instantiating a new module fails because there isn't enough executable memory. I also made it abort the installation of a tiered up function if we run out of executable memory. I now want to make sure that the second case (tier up fail) doesn't end up in infinite recompile. A few ideas: - Before compiling for tier up, check that at least $SOMETHING executable memory is available, where $SOMETHING is a heuristic we pick (percentage of total?). - Before compiling for tier up, check that at least $MULTIPLE * (end - start) executable memory is available, where (end - start) refer to the original binary, and $SOMETHING is a number we can measure from compiling existing code (average or max of what we typically see). - Connect with the GC better, maybe we can clean things up and find more executable memory (similar to what I did to WebAssembly.Memory + GC?). We can do all or some of these, and base tier up backoff on these heuristics. 1323473 1 saam 2017-06-28 00:50:35 -0700 We won’t infinite loop today. We’ll only compile something once. That said, it might be worth avoiding a compilation all together if we don’t have X memory. That said, this scenario is pretty unlikely, so whatever we do there will mostly be untested code.