14-05-2014, 03:23 PM
VLIW Architectures
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What is VLIW Architectures ?
• VLIW means Very Long Instruction Word
• machines exploiting parallelism at the instruction level
• Several operations are executed in parallel on different
functional units, such as machinery superescalares
• The difference is in control of the order and the termination of
operations
• Superescalares: the dependencies are resolved in time for
implementation by a dedicated hardware
• VLIW: dependencies are resolved at the time of compilation
by compiler
Principles of VLIW Operation
• Statically scheduled ILP architecture.
• Wide instructions specify many independent simple operations.
• Multiple functional units executes all operations in an instruction
concurrently, providing fine‐grain parallelism within instruction
• Instructions directly control hardware with minimal decoding.
• A powerful optimizing compiler is responsible for extracting ILP
and scheduling operations to exploit available parallel resources