Commits on Jan 30, 2024

1. A new, statically typed, JIT IR. …

   This reworks the JIT IR, incorporating the wisdom we've absorbed through
   studying PyPy and LuaJIT's JIT IRs.
   
   The JIT IR is now a vector of word-sized instructions that can be
   matched and destructured using Rust's type system. This differs slightly
   from PyPy and LuaJIT, which use bytestreams, but we want static
   type-safety.
   
   Any information that can't fit inline in the instruction word (e.g.
   operands and their types) are referenced using indices into an auxiliary
   vector containing the overflow information. This idea was borrowed from
   LuaJIT.
   
   Some of the auxiliary vectors are stored in the AOT module, thus sharing
   constructs with the AOT IR, for example, functions and types. Indices
   for these vectors are 24-bit. Indices for the other auxiliary vectors
   are 16-bit and for these there is (currently) no sharing with the AOT
   module.
   
   Obviously the reduced-size indices mean that we can only represent a
   limited number of vector elements. This is fine, as we don't expect
   traces to be so large that the indices overflow and if they do we can
   just abort the trace and remain sound.
   
   A note on mutability: you may mutate the instruction stream so long as
   you don't cause any index skew. It's OK to replace/mutate an
   instruction, but you must NOT remove instructions.
   
   The AOT IR remains immutable.
   
   The IR is not finished and has a lot of dead code, hence we mark the
   whole module `#![allow(dead_code)]`. This will eventually be deleted.
   
   Co-authored-by: Edd Barrett <[email protected]>

   

   ptersilie and vext01 committed Jan 30, 2024
   Configuration menu

   • View commit details
   • Copy full SHA for 875cc02
   • Browse repository at this point

   Copy the full SHA

   875cc02 View commit details

   Browse the repository at this point in the history