VLIW Architectures: Compilers and Instruction Level Parallelism

This lecture discusses Very Long Instruction Word (VLIW) architectures and their compilers, focusing on how they exploit instruction level parallelism (ILP). The instructor begins by contrasting VLIW with traditional architectures, emphasizing the need for explicit parallelism in programming. The lecture covers the evolution from sequential to pipelined architectures, explaining the role of dynamic scheduling in superscalar processors and how VLIW simplifies this by shifting scheduling responsibilities to the compiler. The instructor highlights the advantages of VLIW, such as reduced hardware complexity and increased clock frequency, while also addressing challenges like code bloating and binary incompatibility. Various techniques for optimizing VLIW compilers are explored, including loop unrolling, software pipelining, and predicated execution. The lecture concludes with a discussion on the IA-64 architecture, illustrating how VLIW principles are applied in real-world processors, and the implications of these designs on performance and efficiency in computing.