Don't try to move a MBB into the fall-through position if it's a landing pad or

branches only to a landing pad. Without this check, the compiler would go into
an infinite loop because the branch to a landing pad is an "abnormal" edge which
wasn't being taken into account.

This is the meat of that fix:

  if (!PrevBB.canFallThrough() && !MBB->BranchesToLandingPad(MBB)) {

The other stuff is simplification of the "branches to a landing pad" code.

llvm-svn: 91161

1 files changed, 3 insertions, 10 deletions

diff --git a/llvm/lib/CodeGen/MachineBasicBlock.cpp b/llvm/lib/CodeGen/MachineBasicBlock.cpp
index 0097dd16105..80b4b0ffd8d 100644
--- a/llvm/lib/CodeGen/MachineBasicBlock.cpp
+++ b/llvm/lib/CodeGen/MachineBasicBlock.cpp
@@ -457,16 +457,9 @@ MachineBasicBlock::BranchesToLandingPad(const MachineBasicBlock *MBB) const {
   SmallSet<const MachineBasicBlock*, 32> Visited;
   const MachineBasicBlock *CurMBB = MBB;
 
-  while (!Visited.count(CurMBB) && !CurMBB->isLandingPad()) {
-    if (CurMBB->size() != 1 || CurMBB->succ_empty() || CurMBB->succ_size() != 1)
-      break;
-
-    const TargetInstrInfo *TII =
-      CurMBB->getParent()->getTarget().getInstrInfo();
-    if (!TII->isUnpredicatedTerminator(CurMBB->begin()))
-      break;
-
-    Visited.insert(CurMBB);
+  while (!CurMBB->isLandingPad()) {
+    if (CurMBB->succ_size() != 1) break;
+    if (!Visited.insert(CurMBB)) break;
     CurMBB = *CurMBB->succ_begin();
   }