[PATCH] D38802: [Dominators] Remove the NCA check
Jakub Kuderski via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Wed Oct 11 07:52:57 PDT 2017
kuhar created this revision.
This patch removes the `verifyNCA` check.
The reason for this is that the other checks are sufficient to prove or disprove correctness of any DominatorTree, and that `verifyNCA` doesn't provide (in my option) better error messages then the other ones.
Additionally, this should give a (small) improvement to the total verification time, as the check is O(n), and checking the sibling property takes O(n^3).
https://reviews.llvm.org/D38802
Files:
include/llvm/Support/GenericDomTreeConstruction.h
Index: include/llvm/Support/GenericDomTreeConstruction.h
===================================================================
--- include/llvm/Support/GenericDomTreeConstruction.h
+++ include/llvm/Support/GenericDomTreeConstruction.h
@@ -1461,40 +1461,6 @@
return true;
}
- // Checks if for every edge From -> To in the graph
- // NCD(From, To) == IDom(To) or To.
- bool verifyNCD(const DomTreeT &DT) {
- clear();
- doFullDFSWalk(DT, AlwaysDescend);
-
- for (auto &BlockToInfo : NodeToInfo) {
- auto &Info = BlockToInfo.second;
-
- const NodePtr From = NumToNode[Info.Parent];
- if (!From) continue;
-
- const NodePtr To = BlockToInfo.first;
- const TreeNodePtr ToTN = DT.getNode(To);
- assert(ToTN);
-
- const NodePtr NCD = DT.findNearestCommonDominator(From, To);
- const TreeNodePtr NCDTN = DT.getNode(NCD);
- const TreeNodePtr ToIDom = ToTN->getIDom();
- if (NCDTN != ToTN && NCDTN != ToIDom) {
- errs() << "NearestCommonDominator verification failed:\n\tNCD(From:"
- << BlockNamePrinter(From) << ", To:" << BlockNamePrinter(To)
- << ") = " << BlockNamePrinter(NCD)
- << ",\t (should be To or IDom[To]: " << BlockNamePrinter(ToIDom)
- << ")\n";
- errs().flush();
-
- return false;
- }
- }
-
- return true;
- }
-
// The below routines verify the correctness of the dominator tree relative to
// the CFG it's coming from. A tree is a dominator tree iff it has two
// properties, called the parent property and the sibling property. Tarjan
@@ -1632,9 +1598,8 @@
bool Verify(const DomTreeT &DT) {
SemiNCAInfo<DomTreeT> SNCA(nullptr);
return SNCA.verifyRoots(DT) && SNCA.verifyReachability(DT) &&
- SNCA.VerifyLevels(DT) && SNCA.verifyNCD(DT) &&
- SNCA.verifyParentProperty(DT) && SNCA.verifySiblingProperty(DT) &&
- SNCA.VerifyDFSNumbers(DT);
+ SNCA.VerifyLevels(DT) && SNCA.verifyParentProperty(DT) &&
+ SNCA.verifySiblingProperty(DT) && SNCA.VerifyDFSNumbers(DT);
}
} // namespace DomTreeBuilder
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