This patch makes it so that onEviction actually gets called when the model ends up selecting the candidate to evict. Where we were handling this previously ended up being dead code as we would return earlier with MCRegister::NoRegister. Fixes #129841.
Similar to #117309. The advisor and logger are accessed through the provider, which is served by the new PM. Legacy PM forwards calls to the provider. New PM is a machine function analysis that lazily initializes the provider.
Legacy pass used to provide the advisor, so this extracts that logic into a provider class used by both analysis passes. All three (Default, Release, Development) legacy passes `*AdvisorAnalysis` are basically renamed to `*AdvisorProvider`, so the actual legacy wrapper passes are `*AdvisorAnalysisLegacy`. There is only one NPM analysis `RegAllocEvictionAnalysis` that switches between the three providers in the `::run` method, to be cached by the NPM. Also adds `RequireAnalysis<RegAllocEvictionAnalysis>` to the optimized target reg alloc codegen builder.
This reverts commit aa65f93b71dee8cacb22be1957673c8be6a3ec24. This relands commit 8cc83b66e20e72cdb3bb5fbd549c941797b0e0c9. It looks like this was a transitive include issue.
This reverts commit 8cc83b66e20e72cdb3bb5fbd549c941797b0e0c9. This was causing builbot failures. https://lab.llvm.org/buildbot/#/builders/90/builds/4198 https://lab.llvm.org/buildbot/#/builders/110/builds/3616
This patch adjusts the mlregalloc-max-cascade flag (renaming it to mlregalloc-max-eviction-count) to actually count evictions rather than just looking at the cascade number. The cascade number is not very representative of how many times a LR has been evicted, which can lead to some problems in certain cases, where we might end up with many eviction problems where we have now masked off all the interferences and are forced to evict the candidate. This is probably what I should've done in the first place. No test case as this only shows up in quite large functions post ThinLTO and it would be hard to construct something that would serve as a nice regression test without being super brittle. I've tested this on the pathological cases that we have come across so far and it works. Fixes #122829
A previous PR introduced a threshold where we would mask out a LR that had been evicted a certain number of times to combat pathological compile time cases with a somewhat adversarial model. However, this patch did not take into account urgent LRs which led to compilation failures when greedy would expect us to provide an eviction and we could not due to the newly introduced logic.
This patch adds a threshold flag, -mlregalloc-max-cascade, to prevent live ranges from being evicted more than is necessary. After deploying a new regalloc model, we ran into some pathological cases where the model decided it wanted to ping-pong evictions, taking up a large amount of compile time. This threshold is mostly a stop gap while we continue to investigate other solutions and work on minimizing/constructing test cases.