[PATCH] D50311: [WIP!][DomTreeUpdater/Auto[3]] A new Auto UpdateStrategy candidate

[Chijun Sima via Phabricator via llvm-commits]

NutshellySima created this revision.
NutshellySima added a reviewer: kuhar.
Herald added a subscriber: llvm-commits.

> This patch is a work-in-process and I don't intend to commit it. If you are automatically subscribed to this patch, please ignore it.

This patch is the most promising one of the Auto UpdateStrategy implementations.

This patch is an approach to solve the problems in the current `DomTreeUpdater` and `JumpThreading` pass. (We need to figure out the previous state of the CFG when we call `applyUpdates()/insertEdge()/deleteEdge()` or we need to concern about the internal state of the `DomTreeUpdater`). It shows a similar performance on bitcode files with the current `DomTreeUpdater` working under Lazy UpdateStrategy after converting `CorrelatedValuePropagation/RewriteStatepointsForGC/JumpThreading` and testing under the `-O3` pipeline.
This patch implements the Auto UpdateStrategy by getting a snapshot of the single from point if it didn't get one when user calls `DTU.isAboutToChange()`. Then use the information submitted by users (especially the From points) to narrow down the changes needs to be applied. When a flush() happens, it diffs the narrowed down range of points, thus it shows a rather good performance in line with the current one.


Repository:
  rL LLVM

https://reviews.llvm.org/D50311

Files:
  include/llvm/IR/DomTreeUpdater.h
  lib/IR/DomTreeUpdater.cpp
  unittests/IR/DomTreeUpdaterTest.cpp

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