  This paper argues and shows that speculative vectorization, where a loop with
rare or unknown memory dependencies are still vectorized, is fundamentally
vulnerable and cannot be mitigated by existing defenses. We implement a simple
proof of concept and show the leakage in Apple M2 SoC. We describe the source
of leakage using Microarchitectural Leakage Descriptors MLD and we additionally
describe principles to extend MLD for other optimization. Also as part of
implementation we reverse engineer the M2 cache size and use threaded timer to
differentiate between cache hit and miss.
