cbc/ToDo

= ToDo

== Current

- generate IR
- simplify IR node name: IntValue -> Int, StringValue -> Str.
- make operators signed, instead of having signed value types.
- refactoring: rename class: Assmebler -> AssermblyFile
- refactoring: remove CodeGenerator.stackGrowsLower
- refactoring: remove AssemblyFile stack.
- refactoring: remove CodeGenerator#compileLHS (resolve in IR generation)
- refactoring: CodeGeneratorOptions should not provide PeepholeOptimizer
- refactoring: classify Assembler
- refactoring: classify Linker
* use enum for register names

== Done

- generate resolved AST
        - constant table
        - types
        - scope, frame
- integer literal
	- 1, 2, 3, ...
	- octal (010)
	- hex (0x1f)
	- 1U, 1L, 1UL
- character literal
	- 'c'
	- standard escape sequence ('\n', ...)
	- octal escape sequence ('\077')
- string literal
	- "string"
	- standard escape sequence ('\n', ...)
	- octal escape sequence ("\077")
- import
        - single import
        - recursive import
        - import function
        - import type
- build x86 test environment
- compile "Hello, World"
- write unit tests
- funcall
        - 0 arg
        - 1 arg
        - 2 args
        - 3
        - 4 - 10 args
- variables
        - param
                - reference
                - assign
        - lvar
                - assign
                - reference
                - initializer
        - common symbol
                - assign
                - reference
        - global variable
                - define
                - reference
                - assign
        - private common symbol
                - assign
                - reference
        - private global variable
                - define
                - assign
                - reference
        - function-static variable
                - assign
                - reference
                - initializer
- op
        - +
        - -
        - *
        - /
        - %
- bitwise op
        - ~
        - &
        - |
        - ^
        - >>
        - <<
- unary op
        - +@
        - -@
        - !
- comparison op
        - ==
        - !=
        - >
        - >=
        - <
        - <=
- self assignment
        - +=, -=, *=, ...
        - ++
        - --
- control structure
        - if
        - while
                - flow
                - break
                - continue
        - for
                - flow
                - break
                - continue
        - do...while
                - flow
                - break
                - continue
        - switch
        - goto
- valued control structure
        - &&
        - ||
        - a ? b : c
- array
        - as LHS
        - as RHS
        - reject negative length array definition
- struct
        - as LHS
        - as RHS
        - recursive definition with pointer
- union
        - as LHS
        - as RHS
        - recursive definition with pointer
- pointer
        - *ptr
        - *ptr = val
        - ptr->memb
        - ptr->memb = val
        - &expr
- function pointer
        - refer
        - call ptr(arg)
- complex LHS
        - local variable
        - parameter
        - global variables / common symbols
        - static variables
        - *arr[0] = ...
        - *st.memb = ...
        - *ptr++ = ...
        - *(ptr + N) = ...
        - their combination
- bare block ({...})
- cast
- semantic check (control)
        - reject break from out of loop/switch
        - reject continue from out of loop
- semantic check (reference)
        - check all symbols are resolved
        - check duplicated parameters
        - check if the calling function exists
        - warn unused static variables
        - warn unused local variables
        - warn unused static functions
        - check if aref base expr is indexable (a must be indeable where a[0])
        - check if funcall base expr is callable (a must be callable where a())
- semantic check (type)
        - simple type check (binary ops, unary ops)
        - a[0]
        - *ptr
        - ct.memb
        - ptr->memb
        - funcall args
        - prohibit circular struct/union definition
        - implicit cast
        - validate struct/union member (ct.memb)
        - validate struct/union member (ct->memb)
        - check duplicated struct/union members
        - ptr + int; ptr - int
        - check return type
        - check if &expr is assignable
        - use user type instead of struct/union
        - do not use #equals for type check
        - check if void is not used with array, struct, union.
- op for various types
        - signed char
        - signed short
        - signed int
        - signed long
        - unsigned char
        - unsigned short
        - unsigned int
        - unsigned long
- Multibyte input
- parse command line option
- --dump-tokens
- --dump-ast
- print node location in error message
- parse command line option more precisely
- --dump-reference
- --dump-semantic
- add standard load path (use -I option)
- call GNU as and GNU ld instead of gcc.
- rename asm methods
- lvar overlapped allocation
- pointer comparison
        - ptr==ptr should work
        - ptr&&ptr should work
        - cond?ptr:ptr should work
        - !ptr should work
- implement NULL as reserved word
- duplicated import did not propagate symbols
- test if static function is really static
- test switch stmt
- remove FIXME from Entity.java
- implement cast
- dump UTF-8 string byte by byte.
- sizeof
- calculate address on AX register.
- prohibit multi-dimension array without size
- extern gvar access
- implement source repository
- handle multiple arguments (source files, assembly files, object files)
- -l
- -L
- -Wl, -Xlinker
- -Wa, -Xassembler
- write install.sh
- va_list
- objectify instruction
- fix &puts
- AsmEntity -> AsmOperand
- Symbol -> LabelRef
- Literal should not inherit AsmEntity
- toString -> toSource
- reject struct/union/array on stmt context
- ComplexType -> CompositeType
- impelement -O options
- -O (peephole optimization)
        - movl $0, %eax => xorl %eax, %eax
        - addl $1, %eax  => incl %eax
        - addl $-1, %eax => decl %eax
        - subl $1, %eax  => decl %eax
        - subl $-1, %eax => incl %eax
        - addl $0, %eax => NONE
        - subl $0, %eax => NONE
        - imull $0, %eax => xorl %eax, %eax
        - imull $1, %eax => NONE
- generate prologue/epilogue after function body.
- -O (fast immediate load)
- check "puts = str"
- -O (jump elimination)
- useless label elimination
- -fPIC (PIC generation)
- -shared
- Java 5
- label refactoring
        - Label -> Symbol
        - all Symbols should be got from objects
        - implement unnamed (code) Label
- bin/cbc: resolve symbolic link
- --readonly-plt
- -fPIE, -pie
        - implement difference against PIC
- check opassign semantic as operator
- use enum for compiler mode.
- type handling
        - "extern char*[] sys_errlist" is array, not pointer
        - &puts should be typed as int(*)(char*)*, not int(*)(char*)**