1 files changed, 21 insertions, 0 deletions
diff --git a/lib/CodeGen/TargetInstrInfoImpl.cpp b/lib/CodeGen/TargetInstrInfoImpl.cpp
index 0b791e4a71..8aca0ccd42 100644
--- a/lib/CodeGen/TargetInstrInfoImpl.cpp
+++ b/lib/CodeGen/TargetInstrInfoImpl.cpp
@@ -139,6 +139,27 @@ void TargetInstrInfoImpl::reMaterialize(MachineBasicBlock &MBB,
   MBB.insert(I, MI);
 }
 
+bool TargetInstrInfoImpl::isDeadInstruction(const MachineInstr *MI) const {
+  const TargetInstrDesc &TID = MI->getDesc();
+  if (TID.mayLoad() || TID.mayStore() || TID.isCall() || TID.isTerminator() ||
+      TID.isCall() || TID.isBarrier() || TID.isReturn() ||
+      TID.hasUnmodeledSideEffects())
+    return false;
+  for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
+    const MachineOperand &MO = MI->getOperand(i);
+    if (!MO.isReg() || !MO.getReg())
+      continue;
+    if (MO.isDef() && !MO.isDead())
+      return false;
+    if (MO.isUse() && MO.isKill())
+      // FIXME: We can't remove kill markers or else the scavenger will assert.
+      // An alternative is to add a ADD pseudo instruction to replace kill
+      // markers.
+      return false;
+  }
+  return true;
+}
+
 unsigned
 TargetInstrInfoImpl::GetFunctionSizeInBytes(const MachineFunction &MF) const {
   unsigned FnSize = 0;