forked from OSchip/llvm-project
e3e25b5112
In a CGSCC pass manager, we may visit the same function multiple times due to SCC mutations. In the inliner pipeline, this results in running the function simplification pipeline on a function multiple times even if it hasn't been changed since the last function simplification pipeline run. We use a newly introduced analysis to keep track of whether or not a function has changed since the last time the function simplification pipeline has run on it. If we see this analysis available for a function in a CGSCCToFunctionPassAdaptor, we skip running the function passes on the function. The analysis is queried at the end of the function passes so that it's available after the first time the function simplification pipeline runs on a function. This is a per-adaptor option so it doesn't apply to every adaptor. The goal of this is to improve compile times. However, currently we can't turn this on by default at least for the higher optimization levels since the function simplification pipeline is not robust enough to be idempotent in many cases, resulting in performance regressions if we stop running the function simplification pipeline on a function multiple times. We may be able to turn this on for -O1 in the near future, but turning this on for higher optimization levels would require more investment in the function simplification pipeline. Heavily inspired by D98103. Example compile time improvements with flag turned on: https://llvm-compile-time-tracker.com/compare.php?from=998dc4a5d3491d2ae8cbe742d2e13bc1b0cacc5f&to=5c27c913687d3d5559ef3ab42b5a3d513531d61c&stat=instructions Reviewed By: asbirlea, nikic Differential Revision: https://reviews.llvm.org/D113947 |
||
|---|---|---|
| .. | ||
| CMakeLists.txt | ||
| OptimizationLevel.cpp | ||
| PassBuilder.cpp | ||
| PassBuilderBindings.cpp | ||
| PassBuilderPipelines.cpp | ||
| PassPlugin.cpp | ||
| PassRegistry.def | ||
| StandardInstrumentations.cpp | ||