llvm-6502/docs/ChrisNotes.txt

* Need to implement constant propogation of cast instructions!
* Fix DCE to elminate br <c>, %L1, %L1 so that it can optimize the main of
  fib.ll better.  Currently I have to do this to get best results:
     as < fib.ll | opt -inline -sccp -dce -sccp -dce |dis
* Fix DCE to work better, so that SCCP can show it's true value.
* Implement ADCE
* Fix the const pool printer to print out constants in some sort of "sorted"
  order.  Then enable TestOptimizer.sh to diff -sccp output.  Currently it 
  doesn't work because the diff fails because of ordering of the constant 
  pool. :(
* Maybe ConstantPool objects should keep themselves sorted as things are 
  inserted.
* Enable DoConstantPoolMerging to do trivial DCE of constant values.
* Should provide "castTerminator, castPHI, etc" functions in Instruction, and
  similar functions in other classes, that effectively do dynamic casts.  This
  would allow code like this:
    if (I->isTerminator()) {
      TerminatorInst *TI = (TerminatorInst*)I;
      ...
    }
  to be written as:
    if (TerminatorInst *TI = I->castTerminatorInst()) {
       ...
    }
* Think about whether edge split SSA form would be useful to do.
* Inlining should attempt to give block names the same name in the inlined 
  method (using SymbolTable::getUniqueName)
* The dropAllReferences code can be a noop when NDEBUG!!!
* Finish xvcg output
* pred/succ iterators on basic blocks don't handle switch statements correctly
* Provide a pass that eliminates critical edges from the CFG
* Provide a print pass to print out xvcg format files for vis
* I need to provide an option to the bytecode loader to ignore memory 
  dependance edges.  Instead, the VM would just treat memory operations 
  (load, store, getfield, putfield, call) as pinned instructions.
* I need to have a way to prevent taking the address of a constant pool
  reference.  You should only be able to take the address of a variable.
  Maybe taking the address of a constant copies it?  What about virtual 
  function tables?  Maybe a const pointer would be better...
* Need a way to attach bytecode block info at various levels of asm code.
* Need to be able to inflate recursive types.  %x = { *%x }, %x = %x ()
* Recognize and save comments in assembly and bytecode format
* Encode line number table in bytecode (like #line), optional table

* Encode negative relative offsets in the bytecode file

* Implement switch to switch on a constant pool array of type: 
  [{ label, int }] or [label]   (lookup vs index switch)
* Apparently bison has a %pure_parser option.  Maybe useful for Assembly/Parser

* Implement a header file that can read either assembly or bytecode, implement 
  a writer that can output either based on what is read with this reader..
* Implement the following derived types:
  * pointer                          int *
  * "packed format", like this:    [4 x sbyte]: Packed SIMD datatype
* Maybe 'tailcall' also?
* Include a method level bytecode block that defines a mapping between values 
  and registers that defines a minimally register allocated code.  This can
  make me finally address how to encode extensions in assembly.
* Bytecode reader should use extensions that may or may not be linked into the
  application to read blocks.  Thus an easy way to ignore symbol table info
  would be to not link in that reader into the app.