Summary:
This patch refines the logic of `recalculate()` in the `DomTreeUpdater` in the following two aspects:
1. Previously, `recalculate()` tests whether there are pending updates/BBs awaiting deletion and then do recalculation under Lazy UpdateStrategy; and do recalculation immediately under Eager UpdateStrategy. (The former behavior is inherited from the `DeferredDominance` class). This is an inconsistency between two strategies and there is no obvious reason to do this. So the behavior is changed to always recalculate available trees when calling `recalculate()`.
2. Fix the issue of when DTU under Lazy UpdateStrategy holds nothing but with BBs awaiting deletion, after calling `recalculate()`, BBs awaiting deletion aren't flushed. An additional unittest is added to cover this case.
Reviewers: kuhar, dmgreen, brzycki, grosser, davide
Reviewed By: kuhar
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D50173
llvm-svn: 338822
Summary:
Previously, passes use
```
DomTreeUpdater DTU(DT, DomTreeUpdater::UpdateStrategy::Lazy);
DTU.deleteBB(DelBB);
```
to delete a BasicBlock.
But passes which don't have the ability to update DomTree (e.g. tailcallelim, simplifyCFG) cannot recognize a DelBB awaiting deletion and will continue to process this DelBB.
This is a simple approach to notify devs of passes which may use DTU in the future to deal with deleted BasicBlocks under Lazy Strategy correctly.
Reviewers: kuhar, brzycki, dmgreen
Reviewed By: kuhar
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D49731
llvm-svn: 337891
Summary:
Previously, when both DT and PDT are nullptrs and the UpdateStrategy is Lazy, DomTreeUpdater still pends updates inside.
After this patch, DomTreeUpdater will ignore all updates from(`applyUpdates()/insertEdge*()/deleteEdge*()`) in this case. (call `delBB()` still pends BasicBlock deletion until a flush event according to the doc).
The behavior of DomTreeUpdater previously documented won't change after the patch.
Reviewers: dmgreen, davide, kuhar, brzycki, grosser
Reviewed By: kuhar
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D48974
llvm-svn: 336968
Summary:
This patch is the first in a series of patches related to the [[ http://lists.llvm.org/pipermail/llvm-dev/2018-June/123883.html | RFC - A new dominator tree updater for LLVM ]].
This patch introduces the DomTreeUpdater class, which provides a cleaner API to perform updates on available dominator trees (none, only DomTree, only PostDomTree, both) using different update strategies (eagerly or lazily) to simplify the updating process.
—Prior to the patch—
- Directly calling update functions of DominatorTree updates the data structure eagerly while DeferredDominance does updates lazily.
- DeferredDominance class cannot be used when a PostDominatorTree also needs to be updated.
- Functions receiving DT/DDT need to branch a lot which is currently necessary.
- Functions using both DomTree and PostDomTree need to call the update function separately on both trees.
- People need to construct an additional DeferredDominance class to use functions only receiving DDT.
—After the patch—
Patch by Chijun Sima <simachijun@gmail.com>.
Reviewers: kuhar, brzycki, dmgreen, grosser, davide
Reviewed By: kuhar, brzycki
Author: NutshellySima
Subscribers: vsk, mgorny, llvm-commits
Differential Revision: https://reviews.llvm.org/D48383
llvm-svn: 336163
Summary:
This patch is the first in a series of patches related to the [[ http://lists.llvm.org/pipermail/llvm-dev/2018-June/123883.html | RFC - A new dominator tree updater for LLVM ]].
This patch introduces the DomTreeUpdater class, which provides a cleaner API to perform updates on available dominator trees (none, only DomTree, only PostDomTree, both) using different update strategies (eagerly or lazily) to simplify the updating process.
—Prior to the patch—
- Directly calling update functions of DominatorTree updates the data structure eagerly while DeferredDominance does updates lazily.
- DeferredDominance class cannot be used when a PostDominatorTree also needs to be updated.
- Functions receiving DT/DDT need to branch a lot which is currently necessary.
- Functions using both DomTree and PostDomTree need to call the update function separately on both trees.
- People need to construct an additional DeferredDominance class to use functions only receiving DDT.
—After the patch—
Patch by Chijun Sima <simachijun@gmail.com>.
Reviewers: kuhar, brzycki, dmgreen, grosser, davide
Reviewed By: kuhar, brzycki
Subscribers: vsk, mgorny, llvm-commits
Author: NutshellySima
Differential Revision: https://reviews.llvm.org/D48383
llvm-svn: 336114
