The synthesis
of target agnostic JIT

Boris Shingarov

www.shingarov.com

"Portable" VMs

  • Impossible
  • Beyond the "Uniprocessor Era"

Processor Description Languages

  • G. Zimmerman. The MIMOLA Design System: A Computer Aided Digital Processor Design Method.
    (Kiel Radioastronomical Observatory, 1979)
  • High-Level Synthesis
    • PDL → Silicon
    • PDL → FPGA
    • PDL → FSS Simulator
    • PDL → Language Toolchain

PDL Example

  • ArchC
  • Open source
  • SystemC modeling / simulation
  • High-fidelity FSS (Syscall mode also possible)
    • Runs unmodified Linux on ARM, SPARC, MIPS, PowerPC

Instruction semantics in ArchC

  • Simulation-oriented PDL
  • Arbitrary procedural code
  • ACCGen Extension
    • RTL-level declarative semantics
  • Synthesize compiler backend from ArchC+ACCGen

Machine Description-based code generation

  • Tree Matching
  • Aho & Johnson, 1976
  • Cattell, 1980
  • Ganapathi & Fischer, 1985
  • Aho & al., 1989

Experimental Implementation

  • Pharo / Cog
  • PetitParser for the ArchC grammar
  • Structural description in Smalltalk objects
  • Instruction encodings in Smalltalk objects
  • RTL semantics in a logic database

Tree matching as backtracking

  • Design goal: simplicity
  • LaLonde & van Gulik, 1988
  • Prolog/V by Mike Teng
  • Squeak port by Bolot Kerimbaev
  • Partial Pharo port
  • Every instruction semantic statement is a logic rule
    • ...semantic is... → assert

Future work

  • Platform ABI
  • Simulator Integration
    • M5sim / GEM5
      • Smalltalk-aware modules
    • ArchC SystemC

Future Work (cont.)

  • Tree rewriting
    • mov r1, r2
      mov r2, r3
      mov r3, r4
      add r4, 1, r5
  • costs

Future Work (cont.)

  • Bootstrapping
    • VM-dependent
      • mixed-mode
      • ahead-of-time