A little compiler project#

Goals#

• AOT compiler that bundles IR so code can also be specialized at run-time (JIT)
• Little target language with enough features to be interesting
• Good test infrastructure

Non-goals#

• Massive existing language

Thoughts#

• Source language
  • Lox
• Desired language features
  • Structs
  • Static typing
  • Monomorphization of functions by type
  • Garbage collection
  • Userland annotations for specialization based on parameter values
• Use Chris Fallin's register allocator verifier
• Run the program until some userland freeze call and then AOT?
  • Kind of like JIT, but only once, more time to optimize
  • Kind of like wizer
• Add weval so that people can write interpreters and get method JITs "for free"

Plan#

• Create an AOT compiler that gives no thought to performance of generated code
  • Parser
  • IR
  • Register allocation
  • Code generation
  • Make all calls indirect, kind of like the PLT. This will allow us to swap out the code at run-time.
  • Optional interprocedural SCCP like in Loupe
• Add runtime support for profiling execution
  • Number of times a function is called
  • Branch prediction
  • Find monomorphic attribute lookups
  • Find monomorphic call sites
  • Find monomorphic parameter values
• Use existing AOT compiler for JIT
  • Enable inlining
  • Think about how to do deopt into AOT code
• Rewrite register allocator
  • AOT: Graph coloring?
  • JIT: Linear scan?
  • For both: Ian Rogers' https://arxiv.org/pdf/2011.05608