Add an assertion

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@11830 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/RegAllocLinearScan.cpp

@@ -378,6 +378,7 @@ void RA::assignRegOrStackSlotAtInterval(IntervalPtrs::value_type cur)
     }
     DEBUG(std::cerr << "\t\tregister with min weight: "
           << mri_->getName(minReg) << " (" << minWeight << ")\n");
+    assert(minReg != 0 && "Didn't find a register to spill?");
 
     // if the current has the minimum weight, we need to modify it,
     // push it back in unhandled and let the linear scan algorithm run