• SSA is broken by simplify_loads() & branches rewriting/simplification
  • add support for bitwise enums (wip)


  • document the API
  • document the limitations of modifying ptrlists during list walking
  • document the data structures
  • document flow of data / architecture / code structure


  • if a variable has its address taken but in an unreachable BB then its MOD_ADDRESSABLE may be wrong and it won’t be SSA converted.
    • let kill_insn() check killing of SYMADDR,
    • add the sym into a list and
    • recalculate the addressability before memops’s SSA conversion
  • bool_ctype should be split into internal 1-bit / external 8-bit


  • there are 60 failing tests. They should be fixed (but most are non-trivial to fix).


  • GCC’s -Wenum-compare / clangs’s -Wenum-conversion -Wassign-enum
  • parse _attribute((fallthrough))
  • add support for format(printf()) (WIP by Ben Dooks)
  • make use of UNDEFs (issues warnings, simplification, … ?)
  • make memory accesses more explicit: add EXPR_ACCESS (wip)
  • it would be nice to do our own parsing of floating point (wip)
  • some header files needed for crypto/ need __vector or __fp16
  • some even need __complex


  • a lot of small simplifications are waiting to be upstreamed
  • the domtree need to be rebuilt (or updated)
  • critical edges need to be split
  • the current way of doing CSE uses a lot of time
  • add SSA based DCE
  • add SSA based PRE
  • Add SSA based SCCP
  • add a pass to inline small functions during simplification.
  • use better/more systematic use of internal verification framework
  • tracking of operands size should be improved (WIP)
  • OP_INLINE is sometimes in the way
  • would be nice to strictly separate phases that don’t changes the CFG and thus the dominance tree.


  • pseudos are untyped, it’s usually OK but often it complicates things:

    • PSEUDO_REGs are defined by instructions and their type is normally retrievable via this defining instruction but in some cases they’re not: for example, pseudos defined by ASM output.
    • PSEUDO_ARGs are considered as defined by OP_ENTRY and are used like this for liveness trackability but their type can’t simply be retrieved via this instruction like PSEUDO_REGs are (with ->def->type).
    • PSEUDO_VALs are completely typeless.

    Maybe a few bits should be used to store some kind of low-level type.

  • OP_SET should return a bool, always

  • add IR instructions for va_arg() & friends

  • add a possibility to import of file in “IR assembly”

  • dump the symtable

  • dump the CFG


  • fix …

Internal backends

  • it would be nice the upstream the code generator
  • add a pass to transform 3-addresses code to 2-addresses
  • add some basic register allocation
  • add a pass to order the BBs and changes 2-ways CBR into one-way branches
  • what can be done for x86?
  • add support to add constraints in the MD rules

Longer term/to investigate

  • attributes are represented as ctypes’s alignment, modifiers & contexts but plenty of attributes doesn’t fit, for example they need arguments.

    • format(printf, …),
    • section(”…”)
    • assume_aligned(alignment[, offsert])
    • error(”message”), warning(”message”)
  • should support “-Werror=…” ?

  • All warning messages should include the option how to disable it. For example:

    “warning: Variable length array is used.”

    should be something like:

    “warning: Variable length array is used. (-Wno-vla)”

  • ptrlists must not have elements removed while being iterated; this should somehow be enforced.

  • having ‘struct symbol’ used to represent symbols and types is quite handy but it also creates lots of problems and complications

  • Possible mixup of symbol for a function designator being not a pointer? This seems to make evaluation of function pointers much more complex than needed.

  • extend test-inspect to inspect more AST fields.

  • extend test-inspect to inspect instructions.