Restrict the definition of loop preheader to avoid EH blocks

Differential Revision: https://reviews.llvm.org/D34487

llvm-svn: 306070

llvm/lib/CodeGen/MachineBasicBlock.cpp

@@ -228,6 +228,12 @@ LLVM_DUMP_METHOD void MachineBasicBlock::dump() const {
 }
 #endif
 
+bool MachineBasicBlock::isLegalToHoistInto() const {
+  if (isReturnBlock() || hasEHPadSuccessor())
+    return false;
+  return true;
+}
+
 StringRef MachineBasicBlock::getName() const {
   if (const BasicBlock *LBB = getBasicBlock())
     return LBB->getName();