[PATCH] D141487: [LoopUnroll] Directly update DT instead of DTU.

[Florian Hahn via Phabricator via llvm-commits]

fhahn marked an inline comment as done.
fhahn added a comment.

In D141487#4045554 <https://reviews.llvm.org/D141487#4045554>, @asbirlea wrote:

> I'm curious where all the time is spent in the 200s to 2s case. Is Eager strategy just as slow?

The DTU here was using the lazy strategy.

A profile is below (note that this is on a different (slower) machine, so it takes longer than 200s :)) . AFACIT most of the time is spent discovering reachability after deleting edges. I think the main reason manual updates are much quicker here is that we can use the loop structure to avoid determining reachability; after updating the DT for nodes connected to the exits, no other nodes in the DT should need updating.

  8.06 min   99.9%	0 s	 	             llvm::UnrollLoop(llvm::Loop*, llvm::UnrollLoopOptions, llvm::LoopInfo*, llvm::ScalarEvolution*, llvm::DominatorTree*, llvm::AssumptionCache*, llvm::TargetTransformInfo const*, llvm::OptimizationRemarkEmitter*, bool, llvm::Loop**)
  8.04 min   99.8%	0 s	 	              llvm::DomTreeUpdater::getDomTree()
  8.04 min   99.7%	0 s	 	               llvm::DomTreeUpdater::applyDomTreeUpdates()
  8.04 min   99.7%	0 s	 	                llvm::DominatorTreeBase<llvm::BasicBlock, false>::applyUpdates(llvm::ArrayRef<llvm::cfg::Update<llvm::BasicBlock*> >)
  8.04 min   99.7%	0 s	 	                 void llvm::DomTreeBuilder::ApplyUpdates<llvm::DominatorTreeBase<llvm::BasicBlock, false> >(llvm::DominatorTreeBase<llvm::BasicBlock, false>&, llvm::GraphDiff<llvm::DominatorTreeBase<llvm::BasicBlock, false>::NodePtr, llvm::DominatorTreeBase<llvm::BasicBlock, false>::IsPostDominator>&, llvm::GraphDiff<llvm::DominatorTreeBase<llvm::BasicBlock, false>::NodePtr, llvm::DominatorTreeBase<llvm::BasicBlock, false>::IsPostDominator>*)
  8.04 min   99.7%	2.00 ms	 	                  llvm::DomTreeBuilder::SemiNCAInfo<llvm::DominatorTreeBase<llvm::BasicBlock, false> >::ApplyUpdates(llvm::DominatorTreeBase<llvm::BasicBlock, false>&, llvm::GraphDiff<llvm::BasicBlock*, false>&, llvm::GraphDiff<llvm::BasicBlock*, false>*)
  8.04 min   99.7%	3.00 ms	 	                   llvm::DomTreeBuilder::SemiNCAInfo<llvm::DominatorTreeBase<llvm::BasicBlock, false> >::ApplyNextUpdate(llvm::DominatorTreeBase<llvm::BasicBlock, false>&, llvm::DomTreeBuilder::SemiNCAInfo<llvm::DominatorTreeBase<llvm::BasicBlock, false> >::BatchUpdateInfo&)
  7.10 min   88.0%	6.00 ms	 	                    llvm::DomTreeBuilder::SemiNCAInfo<llvm::DominatorTreeBase<llvm::BasicBlock, false> >::DeleteEdge(llvm::DominatorTreeBase<llvm::BasicBlock, false>&, llvm::DomTreeBuilder::SemiNCAInfo<llvm::DominatorTreeBase<llvm::BasicBlock, false> >::BatchUpdateInfo*, llvm::BasicBlock*, llvm::BasicBlock*)
  7.09 min   88.0%	5.00 ms	 	                     llvm::DomTreeBuilder::SemiNCAInfo<llvm::DominatorTreeBase<llvm::BasicBlock, false> >::DeleteReachable(llvm::DominatorTreeBase<llvm::BasicBlock, false>&, llvm::DomTreeBuilder::SemiNCAInfo<llvm::DominatorTreeBase<llvm::BasicBlock, false> >::BatchUpdateInfo*, llvm::DomTreeNodeBase<llvm::BasicBlock>*, llvm::DomTreeNodeBase<llvm::BasicBlock>*)
  4.61 min   57.2%	2.88 s	 	                      unsigned int llvm::DomTreeBuilder::SemiNCAInfo<llvm::DominatorTreeBase<llvm::BasicBlock, false> >::runDFS<false, llvm::DomTreeBuilder::SemiNCAInfo<llvm::DominatorTreeBase<llvm::BasicBlock, false> >::DeleteReachable(llvm::DominatorTreeBase<llvm::BasicBlock, false>&, llvm::DomTreeBuilder::SemiNCAInfo<llvm::DominatorTreeBase<llvm::BasicBlock, false> >::BatchUpdateInfo*, llvm::DomTreeNodeBase<llvm::BasicBlock>*, llvm::DomTreeNodeBase<llvm::BasicBlock>*)::'lambda'(llvm::BasicBlock*, llvm::BasicBlock*)>(llvm::BasicBlock*, unsigned int, llvm::DomTreeBuilder::SemiNCAInfo<llvm::DominatorTreeBase<llvm::BasicBlock, false> >::DeleteReachable(llvm::DominatorTreeBase<llvm::BasicBlock, false>&, llvm::DomTreeBuilder::SemiNCAInfo<llvm::DominatorTreeBase<llvm::BasicBlock, false> >::BatchUpdateInfo*, llvm::DomTreeNodeBase<llvm::BasicBlock>*, llvm::DomTreeNodeBase<llvm::BasicBlock>*)::'lambda'(llvm::BasicBlock*, llvm::BasicBlock*), unsigned int, llvm::DenseMap<llvm::BasicBlock*, unsigned int, llvm::DenseMapInfo<llvm::BasicBlock*, void>, llvm::detail::DenseMapPair<llvm::BasicBlock*, unsigned int> > const*)
  1.52 min   18.9%	5.86 s	 	                      llvm::DomTreeBuilder::SemiNCAInfo<llvm::DominatorTreeBase<llvm::BasicBlock, false> >::runSemiNCA(llvm::DominatorTreeBase<llvm::BasicBlock, false>&, unsigned int)
  41.53 s    8.5%	1.07 s	 	                      llvm::DomTreeBuilder::SemiNCAInfo<llvm::DominatorTreeBase<llvm::BasicBlock, false> >::reattachExistingSubtree(llvm::DominatorTreeBase<llvm::BasicBlock, false>&, llvm::DomTreeNodeBase<llvm::BasicBlock>*)
  15.22 s    3.1%	4.00 ms	 	                      llvm::DomTreeBuilder::SemiNCAInfo<llvm::DominatorTreeBase<llvm::BasicBlock, false> >::~SemiNCAInfo()
  452.00 ms    0.0%	0 s	 	                      0xfffffffffffffffe
  64.00 ms    0.0%	64.00 ms	 	                      DYLD-STUB$$llvm::DominatorTreeBase<llvm::BasicBlock, false>::getNode(llvm::BasicBlock const*) const
  31.00 ms    0.0%	0 s	 	                      llvm::DomTreeBuilder::SemiNCAInfo<llvm::DominatorTreeBase<llvm::BasicBlock, false> >::SemiNCAInfo(llvm::DomTreeBuilder::SemiNCAInfo<llvm::DominatorTreeBase<llvm::BasicBlock, false> >::BatchUpdateInfo*)
  29.00 ms    0.0%	29.00 ms	 	                      DYLD-STUB$$llvm::SmallVectorBase<unsigned int>::empty() const
  3.00 ms    0.0%	0 s	 	                      llvm::DominatorTreeBase<llvm::BasicBlock, false>::findNearestCommonDominator(llvm::BasicBlock*, llvm::BasicBlock*) const
  1.00 ms    0.0%	1.00 ms	 	                      DYLD-STUB$$llvm::DomTreeNodeBase<llvm::BasicBlock>::getLevel() const
  1.00 ms    0.0%	1.00 ms	 	                      DYLD-STUB$$llvm::DomTreeNodeBase<llvm::BasicBlock>::setIDom(llvm::DomTreeNodeBase<llvm::BasicBlock>*)
  1.00 ms    0.0%	0 s	 	                      llvm::DominatorTreeBase<llvm::BasicBlock, false>::getNode(llvm::BasicBlock const*) const
  90.00 ms    0.0%	1.00 ms	 	                     llvm::DomTreeBuilder::SemiNCAInfo<llvm::DominatorTreeBase<llvm::BasicBlock, false> >::DeleteEdge(llvm::DominatorTreeBase<llvm::BasicBlock, false>&, llvm::DomTreeBuilder::SemiNCAInfo<llvm::DominatorTreeBase<llvm::BasicBlock, false> >::BatchUpdateInfo*, llvm::BasicBlock*, llvm::BasicBlock*)::'lambda'(llvm::BasicBlock*, llvm::BasicBlock*)::operator()(llvm::BasicBlock*, llvm::BasicBlock*) const
  35.00 ms    0.0%	1.00 ms	 	                     llvm::DomTreeBuilder::SemiNCAInfo<llvm::DominatorTreeBase<llvm::BasicBlock, false> >::DeleteUnreachable(llvm::DominatorTreeBase<llvm::BasicBlock, false>&, llvm::DomTreeBuilder::SemiNCAInfo<llvm::DominatorTreeBase<llvm::BasicBlock, false> >::BatchUpdateInfo*, llvm::DomTreeNodeBase<llvm::BasicBlock>*)
  24.00 ms    0.0%	1.00 ms	 	                     llvm::DomTreeBuilder::SemiNCAInfo<llvm::DominatorTreeBase<llvm::BasicBlock, false> >::HasProperSupport(llvm::DominatorTreeBase<llvm::BasicBlock, false>&, llvm::DomTreeBuilder::SemiNCAInfo<llvm::DominatorTreeBase<llvm::BasicBlock, false> >::BatchUpdateInfo*, llvm::DomTreeNodeBase<llvm::BasicBlock>*)
  23.00 ms    0.0%	0 s	 	                     llvm::DominatorTreeBase<llvm::BasicBlock, false>::findNearestCommonDominator(llvm::BasicBlock*, llvm::BasicBlock*) const
  11.00 ms    0.0%	2.00 ms	 	                     llvm::DominatorTreeBase<llvm::BasicBlock, false>::getNode(llvm::BasicBlock const*) const
  1.00 ms    0.0%	1.00 ms	 	                     llvm::DomTreeNodeBase<llvm::BasicBlock>::getIDom() const
  56.59 s   11.7%	1.00 ms	 	                    llvm::DomTreeBuilder::SemiNCAInfo<llvm::DominatorTreeBase<llvm::BasicBlock, false> >::InsertEdge(llvm::DominatorTreeBase<llvm::BasicBlock, false>&, llvm::DomTreeBuilder::SemiNCAInfo<llvm::DominatorTreeBase<llvm::BasicBlock, false> >::BatchUpdateInfo*, llvm::BasicBlock*, llvm::BasicBlock*)
  54.00 ms    0.0%	7.00 ms	 	                    llvm::GraphDiff<llvm::BasicBlock*, false>::popUpdateForIncrementalUpdates()
  1.00 ms    0.0%	1.00 ms	 	                    llvm::cfg::Update<llvm::BasicBlock*>::getFrom() const


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