Do not verify MachimeDominatorTree if it is not calculated

If dominator tree is not calculated or is invalidated, set corresponding
pointer in the pass state to nullptr. Such pointer value will indicate
that operations with dominator tree are not allowed. In particular, it
allows to skip verification for such pass state. The dominator tree is
not calculated if the machine dominator pass was skipped, it occures in
the case of entities with linkage available_externally.

The change fixes some test fails observed when expensive checks
are enabled.

Differential Revision: https://reviews.llvm.org/D29280

llvm-svn: 296742

1 files changed, 14 insertions, 14 deletions

diff --git a/llvm/lib/CodeGen/MachineDominators.cpp b/llvm/lib/CodeGen/MachineDominators.cpp
index 303a6a9263b..e3a6c51c47a 100644
--- a/llvm/lib/CodeGen/MachineDominators.cpp
+++ b/llvm/lib/CodeGen/MachineDominators.cpp
@@ -49,32 +49,29 @@ void MachineDominatorTree::getAnalysisUsage(AnalysisUsage &AU) const {
 bool MachineDominatorTree::runOnMachineFunction(MachineFunction &F) {
   CriticalEdgesToSplit.clear();
   NewBBs.clear();
+  DT.reset(new DominatorTreeBase<MachineBasicBlock>(false));
   DT->recalculate(F);
-
   return false;
 }
 
 MachineDominatorTree::MachineDominatorTree()
     : MachineFunctionPass(ID) {
   initializeMachineDominatorTreePass(*PassRegistry::getPassRegistry());
-  DT = new DominatorTreeBase<MachineBasicBlock>(false);
-}
-
-MachineDominatorTree::~MachineDominatorTree() {
-  delete DT;
 }
 
 void MachineDominatorTree::releaseMemory() {
-  DT->releaseMemory();
+  CriticalEdgesToSplit.clear();
+  DT.reset(nullptr);
 }
 
 void MachineDominatorTree::verifyAnalysis() const {
-  if (VerifyMachineDomInfo)
+  if (DT && VerifyMachineDomInfo)
     verifyDomTree();
 }
 
 void MachineDominatorTree::print(raw_ostream &OS, const Module*) const {
-  DT->print(OS);
+  if (DT)
+    DT->print(OS);
 }
 
 void MachineDominatorTree::applySplitCriticalEdges() const {
@@ -143,15 +140,18 @@ void MachineDominatorTree::applySplitCriticalEdges() const {
 }
 
 void MachineDominatorTree::verifyDomTree() const {
+  if (!DT)
+    return;
   MachineFunction &F = *getRoot()->getParent();
 
-  MachineDominatorTree OtherDT;
-  OtherDT.DT->recalculate(F);
-  if (compare(OtherDT)) {
+  DominatorTreeBase<MachineBasicBlock> OtherDT(false);
+  OtherDT.recalculate(F);
+  if (getRootNode()->getBlock() != OtherDT.getRootNode()->getBlock() ||
+      DT->compare(OtherDT)) {
     errs() << "MachineDominatorTree is not up to date!\nComputed:\n";
-    print(errs(), nullptr);
+    DT->print(errs());
     errs() << "\nActual:\n";
-    OtherDT.print(errs(), nullptr);
+    OtherDT.print(errs());
     abort();
   }
 }