2020-09-21 Triage Log
This was the first week of semi-automated perf triage, and thank goodness: There was a lot going on. Most regressions are either quite small or already have a fix published.
#72412 is probably the most interesting case. It fixes a pathological problem involving nested closures by adding cycle detection to what seems to be a relatively hot part of the code. As a result, most users will see a slight compile-time regression for their crates.
Triage done by @ecstaticmorse. Revision range: dbb73f8f79ab176a897d5a95e696adb71b957cbe..b01326ab033e41986d4a5c8b96ce4f40f3b38e30
2 Regressions, 5 Improvements, 4 Mixed, 1 of them in rollups
#76575 compare generic constants using AbstractConsts
full builds of inflate-check)#74040 fix unification of const variables
incr-full builds of coercions-debug)#76656 Don't query stability data when staged_api is off
incr-unchanged builds of many-assoc-items-check)#76311 Split core::slice to smaller mods
full builds of html5ever-opt)#76880 Update cc crate to 1.0.60 to understand aarch64-apple-darwin with clang
incr-patched: Compiler new builds of regex-opt)#76975 Rollup of 15 pull requests
encoding-check (-2.0% on incr-full builds)#76680 Make ensure_sufficient_stack() non-generic, using cargo-llvm-lines
incr-full builds of coercions-debug)#76244 Removing the def_id field from hot ParamEnv to make it smaller
full builds of unicode_normalization-check)full builds of ctfe-stress-4-check)#72412 Issue 72408 nested closures exponential
incr-unchanged builds of deeply-nested-closures-opt)full builds of coercions-check)#74949 Validate constants during const_eval_raw
incr-unchanged builds of ctfe-stress-4-check)incr-patched: add static arr item builds of coercions-check)#75119 New MIR optimization pass to reduce branches on match of tuples of enums
full builds of style-servo-opt)full builds of wf-projection-stress-65510-check)