[llvm] r303443 - NewGVN: Get rid of most dominating leader check

[Daniel Berlin via llvm-commits]

Author: dannyb
Date: Fri May 19 14:01:24 2017
New Revision: 303443

URL: http://llvm.org/viewvc/llvm-project?rev=303443&view=rev
Log:
NewGVN: Get rid of most dominating leader check

Modified:
    llvm/trunk/lib/Transforms/Scalar/NewGVN.cpp

Modified: llvm/trunk/lib/Transforms/Scalar/NewGVN.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/NewGVN.cpp?rev=303443&r1=303442&r2=303443&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/NewGVN.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/NewGVN.cpp Fri May 19 14:01:24 2017
@@ -104,8 +104,6 @@ STATISTIC(NumGVNLeaderChanges, "Number o
 STATISTIC(NumGVNSortedLeaderChanges, "Number of sorted leader changes");
 STATISTIC(NumGVNAvoidedSortedLeaderChanges,
           "Number of avoided sorted leader changes");
-STATISTIC(NumGVNNotMostDominatingLeader,
-          "Number of times a member dominated it's new classes' leader");
 STATISTIC(NumGVNDeadStores, "Number of redundant/dead stores eliminated");
 DEBUG_COUNTER(VNCounter, "newgvn-vn",
               "Controls which instructions are value numbered")
@@ -1946,31 +1944,11 @@ void NewGVN::moveValueToNewCongruenceCla
   if (I == OldClass->getNextLeader().first)
     OldClass->resetNextLeader();
 
-  // It's possible, though unlikely, for us to discover equivalences such
-  // that the current leader does not dominate the old one.
-  // This statistic tracks how often this happens.
-  // We assert on phi nodes when this happens, currently, for debugging, because
-  // we want to make sure we name phi node cycles properly.
-  if (isa<Instruction>(NewClass->getLeader()) && NewClass->getLeader() &&
-      I != NewClass->getLeader()) {
-    auto *IBB = I->getParent();
-    auto *NCBB = cast<Instruction>(NewClass->getLeader())->getParent();
-    bool Dominated =
-        IBB == NCBB && InstrToDFSNum(I) < InstrToDFSNum(NewClass->getLeader());
-    Dominated = Dominated || DT->properlyDominates(IBB, NCBB);
-    if (Dominated) {
-      ++NumGVNNotMostDominatingLeader;
-      assert(
-          !isa<PHINode>(I) &&
-          "New class for instruction should not be dominated by instruction");
-    }
-  }
+  OldClass->erase(I);
+  NewClass->insert(I);
 
   if (NewClass->getLeader() != I)
     NewClass->addPossibleNextLeader({I, InstrToDFSNum(I)});
-
-  OldClass->erase(I);
-  NewClass->insert(I);
   // Handle our special casing of stores.
   if (auto *SI = dyn_cast<StoreInst>(I)) {
     OldClass->decStoreCount();