Compiler-Directed Scratchpad Memory Management via Graph Coloring

Scratchpad memory (SPM), a fast on-chip SRAM managed by software, is widely used in embedded systems. This article introduces a general-purpose compiler approach, called memory coloring, to assign static data aggregates, such as arrays and structs, in a program to an SPM. The novelty of this approach lies in partitioning the SPM into a pseudo-register file (with interchangeable and aliased registers), splitting the live ranges of data aggregates to create potential data transfer statements between SPM and off-chip memory, and finally, adapting an existing graph coloring algorithm for register allocation to assign the data aggregates to the pseudo-register file. Our experimental results using a set of 10 C benchmarks from MediaBench and MiBench show that our methodology is capable of managing SPMs efficiently and effectively for large embedded applications. In addition, our SPM allocator can obtain close to optimal solutions when evaluated and compared against an existing heuristics-based SPM allocator and an ILP-based SPM allocator.