[llvm] r354429 - [Dominators] Delete UpdateLevelsAfterInsertion in edge insertion of depth-based search for release builds

[Fangrui Song via llvm-commits]

Author: maskray
Date: Tue Feb 19 18:35:24 2019
New Revision: 354429

URL: http://llvm.org/viewvc/llvm-project?rev=354429&view=rev
Log:
[Dominators] Delete UpdateLevelsAfterInsertion in edge insertion of depth-based search for release builds

Summary:
After insertion of (From, To), v is affected iff
depth(NCD)+1 < depth(v) && path P from To to v exists where every w on P s.t. depth(v) <= depth(w)

All affected vertices change their idom to NCD.

If a vertex u has changed its depth, it must be a descendant of an
affected vertex v. Its depth must have been updated by UpdateLevel()
called by setIDom() of the first affected ancestor.

So UpdateLevelsAfterInsertion and its bookkeeping variable VisitedNotAffectedQueue are redundant.
Run them only in debug builds as a sanity check.

Reviewers: kuhar

Reviewed By: kuhar

Subscribers: kristina, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D58369

Modified:
    llvm/trunk/include/llvm/Support/GenericDomTreeConstruction.h

Modified: llvm/trunk/include/llvm/Support/GenericDomTreeConstruction.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Support/GenericDomTreeConstruction.h?rev=354429&r1=354428&r2=354429&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Support/GenericDomTreeConstruction.h (original)
+++ llvm/trunk/include/llvm/Support/GenericDomTreeConstruction.h Tue Feb 19 18:35:24 2019
@@ -632,7 +632,9 @@ struct SemiNCAInfo {
         Bucket;
     SmallDenseSet<TreeNodePtr, 8> Visited;
     SmallVector<TreeNodePtr, 8> Affected;
-    SmallVector<TreeNodePtr, 8> VisitedNotAffectedQueue;
+#ifndef NDEBUG
+    SmallVector<TreeNodePtr, 8> VisitedUnaffected;
+#endif
   };
 
   static void InsertEdge(DomTreeT &DT, const BatchUpdatePtr BUI,
@@ -800,8 +802,10 @@ struct SemiNCAInfo {
             // vertices. Store it in UnaffectedOnCurrentLevel.
             LLVM_DEBUG(dbgs() << "\t\tMarking visited not affected "
                               << BlockNamePrinter(Succ) << "\n");
-            II.VisitedNotAffectedQueue.push_back(SuccTN);
             UnaffectedOnCurrentLevel.push_back(SuccTN);
+#ifndef NDEBUG
+            II.VisitedUnaffected.push_back(SuccTN);
+#endif
           } else {
             // The condition is satisfied (Succ is affected). Add Succ to the
             // bucket queue.
@@ -833,20 +837,13 @@ struct SemiNCAInfo {
       TN->setIDom(NCD);
     }
 
-    UpdateLevelsAfterInsertion(II);
-    if (IsPostDom) UpdateRootsAfterUpdate(DT, BUI);
-  }
+#ifndef NDEBUG
+    for (const TreeNodePtr TN : II.VisitedUnaffected)
+      assert(TN->getLevel() == TN->getIDom()->getLevel() + 1 &&
+             "TN should have been updated by an affected ancestor");
+#endif
 
-  static void UpdateLevelsAfterInsertion(InsertionInfo &II) {
-    LLVM_DEBUG(
-        dbgs() << "Updating levels for visited but not affected nodes\n");
-
-    for (const TreeNodePtr TN : II.VisitedNotAffectedQueue) {
-      LLVM_DEBUG(dbgs() << "\tlevel(" << BlockNamePrinter(TN) << ") = ("
-                        << BlockNamePrinter(TN->getIDom()) << ") "
-                        << TN->getIDom()->getLevel() << " + 1\n");
-      TN->UpdateLevel();
-    }
+    if (IsPostDom) UpdateRootsAfterUpdate(DT, BUI);
   }
 
   // Handles insertion to previously unreachable nodes.