[NFC] Assert non-zero factor before division

This is to ensure that zero denominator leads to controlled
assertion failure rather than UB.

llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp

@@ -3919,6 +3919,7 @@ void LSRInstance::GenerateICmpZeroScales(LSRUse &LU, unsigned LUIdx,
     if (Base.BaseOffset == std::numeric_limits<int64_t>::min() && Factor == -1)
       continue;
     int64_t NewBaseOffset = (uint64_t)Base.BaseOffset * Factor;
+    assert(Factor != 0 && "Zero factor not expected!");
     if (NewBaseOffset / Factor != Base.BaseOffset)
       continue;
     // If the offset will be truncated at this use, check that it is in bounds.