rust/compiler/rustc_infer
bors 45198456be Auto merge of #76913 - vandenheuvel:performance_debug, r=lcnr
Fixing the performance regression of #76244

Issue https://github.com/rust-lang/rust/issues/74865 suggested that removing the `def_id` field from `ParamEnv` would improve performance. PR https://github.com/rust-lang/rust/pull/76244 implemented this change.

Generally, [results](https://perf.rust-lang.org/compare.html?start=80fc9b0ecb29050d45b17c64af004200afd3cfc2&end=5ef250dd2ad618ee339f165e9b711a1b4746887d) were as expected: an instruction count decrease of about a percent. The instruction count for the unicode crates increased by about 3%, which `@nnethercote` speculated to be caused by a quirk of inlining or codegen. As the results were generally positive, and for chalk integration, this was also a step in the right direction, the PR was r+'d regardless.

However, [wall-time performance results](https://perf.rust-lang.org/compare.html?start=a055c5a1bd95e029e9b31891db63b6dc8258b472&end=7402a394471a6738a40fea7d4f1891666e5a80c5&stat=task-clock) show a much larger performance degradation: 25%, as [mentioned](https://github.com/rust-lang/rust/pull/76244#issuecomment-694459840) by `@Mark-Simulacrum.`

This PR, for now, reverts #76244 and attempts to find out, which change caused the regression.
2020-09-22 00:22:24 +00:00
..
src Auto merge of #76913 - vandenheuvel:performance_debug, r=lcnr 2020-09-22 00:22:24 +00:00
Cargo.toml Intorduced MiniMap - a tiny small storage optimized map implementation 2020-09-17 20:44:11 -05:00