Shifting off the edge

Understanding bit shift boundaries and memory safety in C++

This hard computer architecture question tests whether you understand the memory and register-level guarantees that keep bit shift operations confined to their target variable. It probes the distinction between what the language promises and what the CPU actually enforces.

Candidates working through this need to reason about how compilers allocate variables in memory, how shift instructions operate at the processor level, and what assumptions are safe to make about adjacent data. The question rewards clarity about the layers involved—from the C++ abstract machine down to actual hardware semantics—and demands that you distinguish between language-level guarantees and implementation details.

• Variable alignment and memory layout
• CPU instruction semantics for shift operations
• Compiler optimizations and register allocation
• Undefined behavior vs. well-defined hardware behaviour