reimplement dfs number computation to be significantly faster. This speeds up
natural loop canonicalization (which does many cfg xforms) by 4.3x, for
example. This also fixes a bug in postdom dfnumber computation.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@40920 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/PostDominators.cpp b/lib/Analysis/PostDominators.cpp
index 4622441..69e9cbe 100644
--- a/lib/Analysis/PostDominators.cpp
+++ b/lib/Analysis/PostDominators.cpp
@@ -193,15 +193,9 @@
Info.clear();
std::vector<BasicBlock*>().swap(Vertex);
- int dfsnum = 0;
- // Iterate over all nodes in depth first order...
- for (unsigned i = 0, e = Roots.size(); i != e; ++i)
- for (idf_iterator<BasicBlock*> I = idf_begin(Roots[i]),
- E = idf_end(Roots[i]); I != E; ++I) {
- if (!getNodeForBlock(*I)->getIDom())
- getNodeForBlock(*I)->assignDFSNumber(dfsnum);
- }
- DFSInfoValid = true;
+ // Start out with the DFS numbers being invalid. Let them be computed if
+ // demanded.
+ DFSInfoValid = false;
}