Do not verify dominator tree if it has no roots

If dominator tree has no roots, the pass that calculates it is
likely to be skipped. It occures, for instance, in the case of
entities with linkage available_externally. Do not run tree
verification in such case.

Differential Revision: https://reviews.llvm.org/D28767

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@293033 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/MachineDominators.cpp b/lib/CodeGen/MachineDominators.cpp
index 303a6a9263be7a51c81cc7ccc1c23386f40e48b0..4e34887769777633ea71dced17e550b028dce086 100644 (file)
--- a/lib/CodeGen/MachineDominators.cpp
+++ b/lib/CodeGen/MachineDominators.cpp
@@ -143,6 +143,10 @@ 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/lib/IR/Dominators.cpp b/lib/IR/Dominators.cpp
index 44948cc5831d785c0daaca63f5341233b2e79c70..392670bbd29c4c2895031ad5d564ef74cf7867ba 100644 (file)
--- a/lib/IR/Dominators.cpp
+++ b/lib/IR/Dominators.cpp
@@ -291,6 +291,10 @@ 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/test/CodeGen/Generic/externally_available.ll b/test/CodeGen/Generic/externally_available.ll
index 7976cc971880f117b49f248885808291d77c93a8..2376bc7399277c40a7fc1973c831aab20d190c9f 100644 (file)
--- a/test/CodeGen/Generic/externally_available.ll
+++ b/test/CodeGen/Generic/externally_available.ll
@@ -1,4 +1,4 @@
-; RUN: llc < %s | not grep test_
+; RUN: llc -verify-machine-dom-info < %s | not grep test_
 
 ; test_function should not be emitted to the .s file.
 define available_externally i32 @test_function() {