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Optimize a common case in the Lengauer-Tarjan dominators algorithm. This gives a 

9.7% speedup running domtree on test-suite.

Reviewed by Chris Lattner.

llvm-svn: 120003
This commit is contained in:
Cameron Zwarich 2010-11-23 06:32:37 +00:00
parent 2dd97d2d60
commit 767a389fa5
1 changed files with 9 additions and 2 deletions
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11
llvm/include/llvm/Analysis/DominatorInternals.h
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@ -278,9 +278,16 @@ void Calculate(DominatorTreeBase<typename GraphTraits<NodeT>::NodeType>& DT,
}
}
DT.Info[DT.Vertex[WInfo.Semi]].Bucket.push_back(W);
typename GraphT::NodeType* WParent = DT.Vertex[WInfo.Parent];
// If V is a non-root vertex and sdom(V) = parent(V), then idom(V) is
// necessarily parent(V). In this case, set idom(V) here and avoid placing
// V into a bucket.
if (WInfo.Semi == WInfo.Parent)
DT.IDoms[W] = WParent;
else
DT.Info[DT.Vertex[WInfo.Semi]].Bucket.push_back(W);
Link<GraphT>(DT, WInfo.Parent, W, WInfo);
// Step #3: Implicitly define the immediate dominator of vertices