Transcript What Is a Compiler When The Architecture Is Not Hard(ware) ?

Customization Using Variable
Instruction Sets
Krishna V Palem
CTO
Proceler Inc.
UCB November 8, 2001
Krishna V Palem
Proceler Inc.
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Designing Instruction Sets
 Choice of instructions is determined by several
trade-offs
– Implementation in a fixed silicon area
– Ability of the compiler to exploit its presence
– Trade-off between impact on cycle time vs. frequency
 Implementation cost is amortized across many
applications
– Infeasible to tailor support for a small number of low
volume applications
 Reconfigurable logic enables a new degree of
freedom
UCB – November 8, 2001
Krishna V Palem
Proceler Inc.
Dynamically Variable Instruction Set
Architecture (DVAITA)
• Software engineer
• C programming
• Algorithm Design
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Off-line Construction
Fundamentally alters the
hardware/software interface
Synthesis
Compiler
Map
Fixed ISA
DVAITA ISA
Place
Application
specific
Soft Processor
Microprocessor
core
UCB – November 8, 2001
Reconfigurable
Logic
Soft
Micro-architecture
Components
Krishna V Palem
Proceler Inc.
4
DVAITA
 DVAITA is a “soft” ISA
– Pre-synthesized, pre-placed instruction implementations
 DVAITA compiler
– Analysis, program transformation, and scheduling
algorithms
– Compilation to a domain specific ISA
– Create a customized micro-architecture at compile time
 DVAITA Hardware Support Package
– Analogy with Board Support Packages (BSP)
– Run-time for host-FPGA communication
– Abstraction for linking the supporting hardware/software
interfaces
UCB – November 8, 2001
Krishna V Palem
Proceler Inc.
5
DVAITA Enabled Customization
 Customization at the domain level
– Soft ISAs for DSP, Telecommunications, Industrial
automation and control, etc.
 Customization at the program level
– Tailored micro-architecture produced at compile time
 Customization at the operation level
– Tailored arithmetic and logic operations, for example,
power vs. speed
UCB – November 8, 2001
Krishna V Palem
Proceler Inc.
Compiling Code Segments to Hardware
L1: for (…){
L2: for (…) {
..
}
..
}
…
…
L3: for (…){
L4: for (…) {
L5: for (…) {
…
}
..
}
..
}
UCB – November 8, 2001
DVAITA ISA
• Datapath
• Control
• Memory
• I/O Interfaces
DVAITA ISA
• Datapath
• Control
• Memory
• I/O Interfaces
Krishna V Palem
Proceler Inc.
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Compile-time generation of
Application-specific soft processors
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ISAs can be
selected on a
domain specific
basis
UCB – November 8, 2001
Krishna V Palem
Proceler Inc.
8
Application-Specific Soft Processors
Software Engineer
•C Programming
•Algorithm Design
Application-specific
soft processors
Communication
Reconfigurable
Computing System
(RCS)
Microprocessor
core
Compiler
Soft Microarchitecture
Components
Networking
Security
Reconfigurable
Logic
UCB – November 8, 2001
Krishna V Palem
Proceler Inc.
9
Commercial Hardware Platforms
 High-end System-on-a-Chip solutions
– Xilinx Virtex 2 with embedded PPC 405
– Altera Excalibur with embedded ARM
 Low-end System-on-a-Chip solutions
– Triscend Configurable System on a Chip (CSoC) with
embedded ARM
– Atmel Field Programmable System Level Integrated
Circuits (FPSLIC) with embedded 8-bit custom RISC
processor
 Board-level products
– Mix embedded processors and commercial FPGA
solutions
UCB – November 8, 2001
Krishna V Palem
Proceler Inc.
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More Generally Architecture Assembly
Applications

An ISA view

Synthesis and other
hardware design off-line

Much closer to compiler “Compiler” selects assembles
and optimizes program
optimizations implies
Build off-line
(synthesis, place
and route)
Program
Prebuilt
Implementations
faster compile time
Data path
Storage
Interconnect
Dynamically variable ISA
Architecture implementation
UCB – November 8, 2001
Also applicable to yield fixed
implementations in silicon
Krishna V Palem
Proceler Inc.
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Placing in Perspective
UCB – November 8, 2001
Krishna V Palem
Proceler Inc.
The Space for these Technologies
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ASIC
Designed with
EDA Tools
PICO
CMP
NP
Software
programmable
CMP: Custom
Microprocessor
COTS
PROCESSOR
NP: Network
processor
Speed to market
UCB – November 8, 2001
Krishna V Palem
Proceler Inc.