Hybridthreads Compiler: C to VHDL Jim Stevens ([e-mail]) and Fabrice Baijot ([e-mail])

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Hybridthreads Compiler C to VHDLJim Stevens
(jstevens_at_ittc.ku.edu) and Fabrice Baijot
(bricefab_at_ittc.ku.edu)
Background
Approach

• Leverage existing GCC front end with custom VHDL
  back end
• HIFGEN extension to GCC translates GIMPLE into
  new Hardware Intermediate Form (HIF) language
• Back end is a compiler for HIF called HIF2VHDL

• Hthreads OS eliminates the HW/SW boundary for
  CPU/FPGA applications
• Threads in both software and hardware
• OS services available to hardware threads
• Creating hardware threads in VHDL still difficult
  for software engineers
• Need a compiler that can translate unaltered C
  threads into VHDL
• Allow for fast design space exploration
• Enable software engineers to create custom
  hardware

Design Flow
Implementation
Status

• HIFGEN
• Walks GIMPLE tree to generate equivalent HIF
• Runs after GCCs GIMPLE optimizers (many free
  optimizations)
• HIF2VHDL
• Parses and type checks the HIF code
• Elaborates HIF into a low level CFG language
• Clean up optimizations
• Generates VHDL code that implements the hardware
  thread with a finite state machine

• HTC 1.0 (completed summer 2006)
• 32-bit primitive types/operations (ints and
  pointers)
• Aggregate types/operations (arrays and structs)
• Demonstrates function call model in hardware
  threads
• HTC 2.0 (currently in development)
• Complete support for ANSI C language
• Framework for future research in high-level
  language to hardware compilation and FPGA
  programming models