[Dominators] Remove verifyDomTree and add some verifying for Post Dom Trees

Removes verifyDomTree, using assert(verify()) everywhere instead, and
changes verify a little to always run IsSameAsFreshTree first in order
to print good output when we find errors. Also adds verifyAnalysis for
PostDomTrees, which will allow checking of PostDomTrees it the same way
we check DomTrees and MachineDomTrees.

Differential Revision: https://reviews.llvm.org/D41298



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@326315 91177308-0d34-0410-b5e6-96231b3b80d8

15 files changed, 73 insertions, 104 deletions

diff --git a/include/llvm/Analysis/PostDominators.h b/include/llvm/Analysis/PostDominators.h
index 90de6bef42a..9a8c4d7807d 100644
--- a/include/llvm/Analysis/PostDominators.h
+++ b/include/llvm/Analysis/PostDominators.h
@@ -76,6 +76,8 @@ struct PostDominatorTreeWrapperPass : public FunctionPass {
 
   bool runOnFunction(Function &F) override;
 
+  void verifyAnalysis() const override;
+
   void getAnalysisUsage(AnalysisUsage &AU) const override {
     AU.setPreservesAll();
   }
diff --git a/include/llvm/CodeGen/MachineDominators.h b/include/llvm/CodeGen/MachineDominators.h
index 98fdb51aae2..af642d9cfc9 100644
--- a/include/llvm/CodeGen/MachineDominators.h
+++ b/include/llvm/CodeGen/MachineDominators.h
@@ -249,12 +249,6 @@ public:
            "A basic block inserted via edge splitting cannot appear twice");
     CriticalEdgesToSplit.push_back({FromBB, ToBB, NewBB});
   }
-
-  /// \brief Verify the correctness of the domtree by re-computing it.
-  ///
-  /// This should only be used for debugging as it aborts the program if the
-  /// verification fails.
-  void verifyDomTree() const;
 };
 
 //===-------------------------------------
diff --git a/include/llvm/IR/Dominators.h b/include/llvm/IR/Dominators.h
index f41200283a4..f6811bc4470 100644
--- a/include/llvm/IR/Dominators.h
+++ b/include/llvm/IR/Dominators.h
@@ -174,12 +174,6 @@ class DominatorTree : public DominatorTreeBase<BasicBlock, false> {
   /// \brief Provide an overload for a Use.
   bool isReachableFromEntry(const Use &U) const;
 
-  /// \brief Verify the correctness of the domtree by re-computing it.
-  ///
-  /// This should only be used for debugging as it aborts the program if the
-  /// verification fails.
-  void verifyDomTree() const;
-
   // Pop up a GraphViz/gv window with the Dominator Tree rendered using `dot`.
   void viewGraph(const Twine &Name, const Twine &Title);
   void viewGraph();
diff --git a/include/llvm/Support/GenericDomTreeConstruction.h b/include/llvm/Support/GenericDomTreeConstruction.h
index 7524733b36b..7ec0638ad6e 100644
--- a/include/llvm/Support/GenericDomTreeConstruction.h
+++ b/include/llvm/Support/GenericDomTreeConstruction.h
@@ -1602,7 +1602,8 @@ struct SemiNCAInfo {
     const bool Different = DT.compare(FreshTree);
 
     if (Different) {
-      errs() << "DominatorTree is different than a freshly computed one!\n"
+      errs() << (DT.isPostDominator() ? "Post" : "")
+             << "DominatorTree is different than a freshly computed one!\n"
              << "\tCurrent:\n";
       DT.print(errs());
       errs() << "\n\tFreshly computed tree:\n";
@@ -1642,34 +1643,27 @@ void ApplyUpdates(DomTreeT &DT,
 template <class DomTreeT>
 bool Verify(const DomTreeT &DT, typename DomTreeT::VerificationLevel VL) {
   SemiNCAInfo<DomTreeT> SNCA(nullptr);
-  const bool InitialChecks = SNCA.verifyRoots(DT) &&
-                             SNCA.verifyReachability(DT) &&
-                             SNCA.VerifyLevels(DT) && SNCA.VerifyDFSNumbers(DT);
 
-  if (!InitialChecks)
+  // Simplist check is to compare against a new tree. This will also
+  // usefully print the old and new trees, if they are different.
+  if (!SNCA.IsSameAsFreshTree(DT))
     return false;
 
-  switch (VL) {
-  case DomTreeT::VerificationLevel::Fast:
-    return SNCA.IsSameAsFreshTree(DT);
-
-  case DomTreeT::VerificationLevel::Basic:
-    return SNCA.verifyParentProperty(DT) && SNCA.IsSameAsFreshTree(DT);
-
-  case DomTreeT::VerificationLevel::Full: {
-    bool FullRes
-        = SNCA.verifyParentProperty(DT) && SNCA.verifySiblingProperty(DT);
-
-    // Postdominators depend on root selection, make sure that a fresh tree
-    // looks the same.
-    if (DT.isPostDominator())
-      FullRes &= SNCA.IsSameAsFreshTree(DT);
+  // Common checks to verify the properties of the tree. O(N log N) at worst
+  if (!SNCA.verifyRoots(DT) || !SNCA.verifyReachability(DT) ||
+      !SNCA.VerifyLevels(DT) || !SNCA.VerifyDFSNumbers(DT))
+    return false;
 
-    return FullRes;
-  }
-  }
+  // Extra checks depending on VerificationLevel. Up to O(N^3)
+  if (VL == DomTreeT::VerificationLevel::Basic ||
+      VL == DomTreeT::VerificationLevel::Full)
+    if (!SNCA.verifyParentProperty(DT))
+      return false;
+  if (VL == DomTreeT::VerificationLevel::Full)
+    if (!SNCA.verifySiblingProperty(DT))
+      return false;
 
-  llvm_unreachable("Unhandled DomTree VerificationLevel");
+  return true;
 }
 
 }  // namespace DomTreeBuilder
diff --git a/lib/Analysis/PostDominators.cpp b/lib/Analysis/PostDominators.cpp
index 2282401085d..8ccba689ec5 100644
--- a/lib/Analysis/PostDominators.cpp
+++ b/lib/Analysis/PostDominators.cpp
@@ -21,6 +21,12 @@ using namespace llvm;
 
 #define DEBUG_TYPE "postdomtree"
 
+#ifdef EXPENSIVE_CHECKS
+static constexpr bool ExpensiveChecksEnabled = true;
+#else
+static constexpr bool ExpensiveChecksEnabled = false;
+#endif
+
 //===----------------------------------------------------------------------===//
 //  PostDominatorTree Implementation
 //===----------------------------------------------------------------------===//
@@ -44,6 +50,13 @@ bool PostDominatorTreeWrapperPass::runOnFunction(Function &F) {
   return false;
 }
 
+void PostDominatorTreeWrapperPass::verifyAnalysis() const {
+  if (VerifyDomInfo)
+    assert(DT.verify(PostDominatorTree::VerificationLevel::Full));
+  else if (ExpensiveChecksEnabled)
+    assert(DT.verify(PostDominatorTree::VerificationLevel::Basic));
+}
+
 void PostDominatorTreeWrapperPass::print(raw_ostream &OS, const Module *) const {
   DT.print(OS);
 }
diff --git a/lib/CodeGen/MachineDominators.cpp b/lib/CodeGen/MachineDominators.cpp
index 517ac29b645..6b280262645 100644
--- a/lib/CodeGen/MachineDominators.cpp
+++ b/lib/CodeGen/MachineDominators.cpp
@@ -65,8 +65,21 @@ void MachineDominatorTree::releaseMemory() {
 }
 
 void MachineDominatorTree::verifyAnalysis() const {
-  if (DT && VerifyMachineDomInfo)
-    verifyDomTree();
+  if (DT && VerifyMachineDomInfo) {
+    MachineFunction &F = *getRoot()->getParent();
+
+    DomTreeBase<MachineBasicBlock> OtherDT;
+    OtherDT.recalculate(F);
+    if (getRootNode()->getBlock() != OtherDT.getRootNode()->getBlock() ||
+        DT->compare(OtherDT)) {
+      errs() << "MachineDominatorTree for function " << F.getName()
+            << " is not up to date!\nComputed:\n";
+      DT->print(errs());
+      errs() << "\nActual:\n";
+      OtherDT.print(errs());
+      abort();
+    }
+  }
 }
 
 void MachineDominatorTree::print(raw_ostream &OS, const Module*) const {
@@ -138,21 +151,3 @@ void MachineDominatorTree::applySplitCriticalEdges() const {
   NewBBs.clear();
   CriticalEdgesToSplit.clear();
 }
-
-void MachineDominatorTree::verifyDomTree() const {
-  if (!DT)
-    return;
-  MachineFunction &F = *getRoot()->getParent();
-
-  DomTreeBase<MachineBasicBlock> OtherDT;
-  OtherDT.recalculate(F);
-  if (getRootNode()->getBlock() != OtherDT.getRootNode()->getBlock() ||
-      DT->compare(OtherDT)) {
-    errs() << "MachineDominatorTree for function " << F.getName()
-           << " is not up to date!\nComputed:\n";
-    DT->print(errs());
-    errs() << "\nActual:\n";
-    OtherDT.print(errs());
-    abort();
-  }
-}
diff --git a/lib/IR/Dominators.cpp b/lib/IR/Dominators.cpp
index 1429e1b9060..24b6c47d0fd 100644
--- a/lib/IR/Dominators.cpp
+++ b/lib/IR/Dominators.cpp
@@ -306,23 +306,6 @@ bool DominatorTree::isReachableFromEntry(const Use &U) const {
   return isReachableFromEntry(I->getParent());
 }
 
-void DominatorTree::verifyDomTree() const {
-  // Perform the expensive checks only when VerifyDomInfo is set.
-  VerificationLevel VL = VerificationLevel::Fast;
-  if (VerifyDomInfo)
-    VL = VerificationLevel::Full;
-  else if (ExpensiveChecksEnabled)
-    VL = VerificationLevel::Basic;
-
-  if (!verify(VL)) {
-    errs() << "\n~~~~~~~~~~~\n\t\tDomTree verification failed!\n~~~~~~~~~~~\n";
-    errs() << "\nCFG:\n";
-    getRoot()->getParent()->print(errs());
-    errs().flush();
-    abort();
-  }
-}
-
 //===----------------------------------------------------------------------===//
 //  DominatorTreeAnalysis and related pass implementations
 //===----------------------------------------------------------------------===//
@@ -353,8 +336,9 @@ PreservedAnalyses DominatorTreePrinterPass::run(Function &F,
 
 PreservedAnalyses DominatorTreeVerifierPass::run(Function &F,
                                                  FunctionAnalysisManager &AM) {
-  AM.getResult<DominatorTreeAnalysis>(F).verifyDomTree();
-
+  auto &DT = AM.getResult<DominatorTreeAnalysis>(F);
+  assert(DT.verify());
+  (void)DT;
   return PreservedAnalyses::all();
 }
 
@@ -377,8 +361,10 @@ bool DominatorTreeWrapperPass::runOnFunction(Function &F) {
 }
 
 void DominatorTreeWrapperPass::verifyAnalysis() const {
-  if (ExpensiveChecksEnabled || VerifyDomInfo)
-    DT.verifyDomTree();
+  if (VerifyDomInfo)
+    assert(DT.verify(DominatorTree::VerificationLevel::Full));
+  else if (ExpensiveChecksEnabled)
+    assert(DT.verify(DominatorTree::VerificationLevel::Basic));
 }
 
 void DominatorTreeWrapperPass::print(raw_ostream &OS, const Module *) const {
diff --git a/lib/Transforms/Scalar/LoopDistribute.cpp b/lib/Transforms/Scalar/LoopDistribute.cpp
index 0d7e3db901c..2f7b4923b33 100644
--- a/lib/Transforms/Scalar/LoopDistribute.cpp
+++ b/lib/Transforms/Scalar/LoopDistribute.cpp
@@ -780,7 +780,7 @@ public:
 
     if (LDistVerify) {
       LI->verify(*DT);
-      DT->verifyDomTree();
+      assert(DT->verify(DominatorTree::VerificationLevel::Fast));
     }
 
     ++NumLoopsDistributed;
diff --git a/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp b/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp
index aba732bc413..e3d2c1702df 100644
--- a/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp
+++ b/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp
@@ -637,7 +637,7 @@ static bool unswitchTrivialSwitch(Loop &L, SwitchInst &SI, DominatorTree &DT,
     BranchInst::Create(CommonSuccBB, BB);
   }
 
-  DT.verifyDomTree();
+  assert(DT.verify(DominatorTree::VerificationLevel::Fast));
   ++NumTrivial;
   ++NumSwitches;
   return true;
@@ -2079,11 +2079,9 @@ PreservedAnalyses SimpleLoopUnswitchPass::run(Loop &L, LoopAnalysisManager &AM,
                     NonTrivialUnswitchCB))
     return PreservedAnalyses::all();
 
-#ifndef NDEBUG
   // Historically this pass has had issues with the dominator tree so verify it
   // in asserts builds.
-  AR.DT.verifyDomTree();
-#endif
+  assert(AR.DT.verify(DominatorTree::VerificationLevel::Fast));
   return getLoopPassPreservedAnalyses();
 }
 
@@ -2147,11 +2145,10 @@ bool SimpleLoopUnswitchLegacyPass::runOnLoop(Loop *L, LPPassManager &LPM) {
   // loop.
   LPM.deleteSimpleAnalysisLoop(L);
 
-#ifndef NDEBUG
   // Historically this pass has had issues with the dominator tree so verify it
   // in asserts builds.
-  DT.verifyDomTree();
-#endif
+  assert(DT.verify(DominatorTree::VerificationLevel::Fast));
+
   return Changed;
 }
 
diff --git a/lib/Transforms/Utils/LibCallsShrinkWrap.cpp b/lib/Transforms/Utils/LibCallsShrinkWrap.cpp
index 42aca757c2a..80fb9cb1aae 100644
--- a/lib/Transforms/Utils/LibCallsShrinkWrap.cpp
+++ b/lib/Transforms/Utils/LibCallsShrinkWrap.cpp
@@ -529,10 +529,7 @@ static bool runImpl(Function &F, const TargetLibraryInfo &TLI,
   bool Changed = CCDCE.perform();
 
 // Verify the dominator after we've updated it locally.
-#ifndef NDEBUG
-  if (DT)
-    DT->verifyDomTree();
-#endif
+  assert(!DT || DT->verify(DominatorTree::VerificationLevel::Fast));
   return Changed;
 }
 
diff --git a/lib/Transforms/Utils/LoopUnroll.cpp b/lib/Transforms/Utils/LoopUnroll.cpp
index 92dfb1c7204..d7daf7aba9d 100644
--- a/lib/Transforms/Utils/LoopUnroll.cpp
+++ b/lib/Transforms/Utils/LoopUnroll.cpp
@@ -769,8 +769,8 @@ LoopUnrollResult llvm::UnrollLoop(
     }
   }
 
-  if (DT && UnrollVerifyDomtree)
-    DT->verifyDomTree();
+  assert(!DT || !UnrollVerifyDomtree ||
+      DT->verify(DominatorTree::VerificationLevel::Fast));
 
   // Merge adjacent basic blocks, if possible.
   SmallPtrSet<Loop *, 4> ForgottenLoops;
diff --git a/lib/Transforms/Utils/LoopUnrollPeel.cpp b/lib/Transforms/Utils/LoopUnrollPeel.cpp
index 4642a50ba6d..13749300984 100644
--- a/lib/Transforms/Utils/LoopUnrollPeel.cpp
+++ b/lib/Transforms/Utils/LoopUnrollPeel.cpp
@@ -500,10 +500,7 @@ bool llvm::peelLoop(Loop *L, unsigned PeelCount, LoopInfo *LI,
       // the original loop body.
       if (Iter == 0)
         DT->changeImmediateDominator(Exit, cast<BasicBlock>(LVMap[Latch]));
-#ifndef NDEBUG
-      if (VerifyDomInfo)
-        DT->verifyDomTree();
-#endif
+      assert(DT->verify(DominatorTree::VerificationLevel::Fast));
     }
 
     updateBranchWeights(InsertBot, cast<BranchInst>(VMap[LatchBR]), Iter,
diff --git a/lib/Transforms/Vectorize/LoopVectorize.cpp b/lib/Transforms/Vectorize/LoopVectorize.cpp
index 963dad5ff20..47a767ccbbe 100644
--- a/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -4779,7 +4779,7 @@ void InnerLoopVectorizer::updateAnalysis() {
   DT->addNewBlock(LoopScalarPreHeader, LoopBypassBlocks[0]);
   DT->changeImmediateDominator(LoopScalarBody, LoopScalarPreHeader);
   DT->changeImmediateDominator(LoopExitBlock, LoopBypassBlocks[0]);
-  DEBUG(DT->verifyDomTree());
+  assert(DT->verify(DominatorTree::VerificationLevel::Fast));
 }
 
 /// \brief Check whether it is safe to if-convert this phi node.
diff --git a/unittests/IR/DominatorTreeTest.cpp b/unittests/IR/DominatorTreeTest.cpp
index 6b427d9c30c..d7f77af27b1 100644
--- a/unittests/IR/DominatorTreeTest.cpp
+++ b/unittests/IR/DominatorTreeTest.cpp
@@ -264,14 +264,14 @@ TEST(DominatorTree, Unreachable) {
         EXPECT_EQ(DT->getNode(BB4)->getLevel(), 1U);
 
         // Change root node
-        DT->verifyDomTree();
+        EXPECT_TRUE(DT->verify());
         BasicBlock *NewEntry =
             BasicBlock::Create(F.getContext(), "new_entry", &F, BB0);
         BranchInst::Create(BB0, NewEntry);
         EXPECT_EQ(F.begin()->getName(), NewEntry->getName());
         EXPECT_TRUE(&F.getEntryBlock() == NewEntry);
         DT->setNewRoot(NewEntry);
-        DT->verifyDomTree();
+        EXPECT_TRUE(DT->verify());
       });
 }
 
diff --git a/unittests/Transforms/Scalar/LoopPassManagerTest.cpp b/unittests/Transforms/Scalar/LoopPassManagerTest.cpp
index 2b8130b9e00..57fb57ec66c 100644
--- a/unittests/Transforms/Scalar/LoopPassManagerTest.cpp
+++ b/unittests/Transforms/Scalar/LoopPassManagerTest.cpp
@@ -962,7 +962,7 @@ TEST_F(LoopPassManagerTest, LoopChildInsertion) {
         AR.DT.addNewBlock(NewLoop010PHBB, &Loop01BB);
         AR.DT.addNewBlock(NewLoop010BB, NewLoop010PHBB);
         AR.DT.addNewBlock(NewLoop01LatchBB, NewLoop010BB);
-        AR.DT.verifyDomTree();
+        EXPECT_TRUE(AR.DT.verify());
         L.addBasicBlockToLoop(NewLoop010PHBB, AR.LI);
         NewLoop->addBasicBlockToLoop(NewLoop010BB, AR.LI);
         L.addBasicBlockToLoop(NewLoop01LatchBB, AR.LI);
@@ -1004,7 +1004,7 @@ TEST_F(LoopPassManagerTest, LoopChildInsertion) {
         AR.DT.addNewBlock(NewLoop011PHBB, NewLoop010BB);
         auto *NewDTNode = AR.DT.addNewBlock(NewLoop011BB, NewLoop011PHBB);
         AR.DT.changeImmediateDominator(AR.DT[NewLoop01LatchBB], NewDTNode);
-        AR.DT.verifyDomTree();
+        EXPECT_TRUE(AR.DT.verify());
         L.addBasicBlockToLoop(NewLoop011PHBB, AR.LI);
         NewLoop->addBasicBlockToLoop(NewLoop011BB, AR.LI);
         NewLoop->verifyLoop();
@@ -1149,7 +1149,7 @@ TEST_F(LoopPassManagerTest, LoopPeerInsertion) {
         AR.DT.addNewBlock(NewLoop01PHBB, &Loop00BB);
         auto *NewDTNode = AR.DT.addNewBlock(NewLoop01BB, NewLoop01PHBB);
         AR.DT.changeImmediateDominator(AR.DT[&Loop02PHBB], NewDTNode);
-        AR.DT.verifyDomTree();
+        EXPECT_TRUE(AR.DT.verify());
         L.getParentLoop()->addBasicBlockToLoop(NewLoop01PHBB, AR.LI);
         NewLoop->addBasicBlockToLoop(NewLoop01BB, AR.LI);
         L.getParentLoop()->verifyLoop();
@@ -1216,7 +1216,7 @@ TEST_F(LoopPassManagerTest, LoopPeerInsertion) {
         AR.DT.addNewBlock(NewLoop040PHBB, NewLoop04BB);
         AR.DT.addNewBlock(NewLoop040BB, NewLoop040PHBB);
         AR.DT.addNewBlock(NewLoop04LatchBB, NewLoop040BB);
-        AR.DT.verifyDomTree();
+        EXPECT_TRUE(AR.DT.verify());
         L.getParentLoop()->addBasicBlockToLoop(NewLoop03PHBB, AR.LI);
         NewLoops[0]->addBasicBlockToLoop(NewLoop03BB, AR.LI);
         L.getParentLoop()->addBasicBlockToLoop(NewLoop04PHBB, AR.LI);
@@ -1271,7 +1271,7 @@ TEST_F(LoopPassManagerTest, LoopPeerInsertion) {
         AR.DT.addNewBlock(NewLoop1PHBB, &Loop0BB);
         auto *NewDTNode = AR.DT.addNewBlock(NewLoop1BB, NewLoop1PHBB);
         AR.DT.changeImmediateDominator(AR.DT[&Loop2PHBB], NewDTNode);
-        AR.DT.verifyDomTree();
+        EXPECT_TRUE(AR.DT.verify());
         NewLoop->addBasicBlockToLoop(NewLoop1BB, AR.LI);
         NewLoop->verifyLoop();
         Updater.addSiblingLoops({NewLoop});
@@ -1508,7 +1508,7 @@ TEST_F(LoopPassManagerTest, LoopDeletion) {
             AR.DT.addNewBlock(NewLoop03BB, NewLoop03PHBB);
             AR.DT.changeImmediateDominator(AR.DT[&Loop0LatchBB],
                                            AR.DT[NewLoop03BB]);
-            AR.DT.verifyDomTree();
+            EXPECT_TRUE(AR.DT.verify());
             ParentL->addBasicBlockToLoop(NewLoop03PHBB, AR.LI);
             NewSibling->addBasicBlockToLoop(NewLoop03BB, AR.LI);
             NewSibling->verifyLoop();