Redesigning the memory hierarchy for memory-safe programming languages

Abstract

We present Hotpads, a new memory hierarchy designed from the ground up for modern, memory-safe languages like Java, Go, and Rust. Memory-safe languages hide the memory layout from the programmer. This prevents memory corruption bugs, improves programmability, and enables automatic memory management. Hotpads extends the same insight to the memory hierarchy: it hides the memory layout from software and enables hardware to take control over it, dispensing with the conventional flat address space abstraction. This avoids the need for associative caches and virtual memory. Instead, Hotpads moves objects across a hierarchy of directly-addressed memories. It rewrites pointers to avoid most associative lookups, provides hardware support for memory allocation, and unifies hierarchical garbage collection and data placement. As a result, Hotpads improves memory performance and efficiency substantially, and unlocks many new optimizations. This thesis contributes important optimizations for Hotpads and a comprehensive evaluation of Hotpads against prior work.