[DomTreeUpdater] Ignore updates when both DT and PDT are nullptrs

Summary:
Previously, when both DT and PDT are nullptrs and the UpdateStrategy is Lazy, DomTreeUpdater still pends updates inside.
After this patch, DomTreeUpdater will ignore all updates from(`applyUpdates()/insertEdge*()/deleteEdge*()`) in this case. (call `delBB()` still pends BasicBlock deletion until a flush event according to the doc).
The behavior of DomTreeUpdater previously documented won't change after the patch.

Reviewers: dmgreen, davide, kuhar, brzycki, grosser

Reviewed By: kuhar

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D48974

llvm-svn: 336968

1 files changed, 5 insertions, 5 deletions

diff --git a/llvm/unittests/IR/DomTreeUpdaterTest.cpp b/llvm/unittests/IR/DomTreeUpdaterTest.cpp
index 10d84442617..03b6b529fd8 100644
--- a/llvm/unittests/IR/DomTreeUpdaterTest.cpp
+++ b/llvm/unittests/IR/DomTreeUpdaterTest.cpp
@@ -72,8 +72,8 @@ TEST(DomTreeUpdater, EagerUpdateBasicOperations) {
   SwitchInst *SI = dyn_cast<SwitchInst>(BB0->getTerminator());
   ASSERT_NE(SI, nullptr) << "Couldn't get SwitchInst.";
 
-  ASSERT_FALSE(DTU.insertEdgeRelaxed(BB0, BB0));
-  ASSERT_TRUE(DTU.deleteEdgeRelaxed(BB0, BB0));
+  DTU.insertEdgeRelaxed(BB0, BB0);
+  DTU.deleteEdgeRelaxed(BB0, BB0);
 
   // Delete edge bb0 -> bb3 and push the update twice to verify duplicate
   // entries are discarded.
@@ -106,9 +106,9 @@ TEST(DomTreeUpdater, EagerUpdateBasicOperations) {
   ASSERT_FALSE(DTU.hasPendingUpdates());
 
   // Invalid Insert: no edge bb1 -> bb2 after change to bb0.
-  ASSERT_FALSE(DTU.insertEdgeRelaxed(BB1, BB2));
+  DTU.insertEdgeRelaxed(BB1, BB2);
   // Invalid Delete: edge exists bb0 -> bb1 after change to bb0.
-  ASSERT_FALSE(DTU.deleteEdgeRelaxed(BB0, BB1));
+  DTU.deleteEdgeRelaxed(BB0, BB1);
 
   // DTU working with Eager UpdateStrategy does not need to flush.
   ASSERT_TRUE(DT.verify());
@@ -183,7 +183,7 @@ TEST(DomTreeUpdater, EagerUpdateReplaceEntryBB) {
   EXPECT_EQ(F->begin()->getName(), NewEntry->getName());
   EXPECT_TRUE(&F->getEntryBlock() == NewEntry);
 
-  ASSERT_TRUE(DTU.insertEdgeRelaxed(NewEntry, BB0));
+  DTU.insertEdgeRelaxed(NewEntry, BB0);
 
   // Changing the Entry BB requires a full recalculation of DomTree.
   DTU.recalculate(*F);