This document discusses the development of an OpenCL compiler called VC4C for the VideoCore IV GPU found in the Raspberry Pi. It provides an overview of the VC4 architecture including its quad processing units, texture and memory lookup unit, uniform cache, and vertex pipe memory. It then introduces VC4C as an open-source project that compiles OpenCL to optimized assembly for the VC4. Several challenges are discussed such as limited registers, cache incoherency, and complex iteration patterns from OpenCL IDs. Optimization techniques explored include constant handling, vectorization, kernel fusion, and software pipelining. In conclusion, VC4C remains a work in progress but provides an opportunity for compiler optimization on an unoptimized