llvm-6502/docs/ChrisNotes.txt
2001-09-07 16:13:58 +00:00

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* Need to implement getelementptr, load, and store for indirection through
arrays and multidim arrays
* Indirect calls should use the icall instruction
* Rewrite the llvm parser/lexer in http://www.antlr.org when time permits.
They actually do C++. Imagine that.
* 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 the constprop br <x> <dst1> <dst1> case. Must handle PHI nodes correctly
* 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. :(
* 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
* 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... Alternatively,
we could alloca a local variable, copy a constant into it, and use that...
* Need a way to attach bytecode block info at various levels of asm code.
* 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.