Revert "Do not verify dominator tree if it has no roots"

This reverts commit r293033, per Danny's comment.  In short, we require
domtrees to have roots at all times.

llvm-svn: 293075

3 files changed, 1 insertions, 9 deletions

diff --git a/llvm/lib/CodeGen/MachineDominators.cpp b/llvm/lib/CodeGen/MachineDominators.cpp
index 4e348877697..303a6a9263b 100644
--- a/llvm/lib/CodeGen/MachineDominators.cpp
+++ b/llvm/lib/CodeGen/MachineDominators.cpp
@@ -143,10 +143,6 @@ void MachineDominatorTree::applySplitCriticalEdges() const {
 }
 
 void MachineDominatorTree::verifyDomTree() const {
-  if (getRoots().empty())
-    // If dominator tree is unavailable, skip verification.
-    return;
-
   MachineFunction &F = *getRoot()->getParent();
 
   MachineDominatorTree OtherDT;
diff --git a/llvm/lib/IR/Dominators.cpp b/llvm/lib/IR/Dominators.cpp
index 392670bbd29..44948cc5831 100644
--- a/llvm/lib/IR/Dominators.cpp
+++ b/llvm/lib/IR/Dominators.cpp
@@ -291,10 +291,6 @@ bool DominatorTree::isReachableFromEntry(const Use &U) const {
 }
 
 void DominatorTree::verifyDomTree() const {
-  if (getRoots().empty())
-    // If dominator tree is unavailable, skip verification.
-    return;
-
   Function &F = *getRoot()->getParent();
 
   DominatorTree OtherDT;
diff --git a/llvm/test/CodeGen/Generic/externally_available.ll b/llvm/test/CodeGen/Generic/externally_available.ll
index 2376bc73992..7976cc97188 100644
--- a/llvm/test/CodeGen/Generic/externally_available.ll
+++ b/llvm/test/CodeGen/Generic/externally_available.ll
@@ -1,4 +1,4 @@
-; RUN: llc -verify-machine-dom-info < %s | not grep test_
+; RUN: llc < %s | not grep test_
 
 ; test_function should not be emitted to the .s file.
 define available_externally i32 @test_function() {