ATLAS / C SUBSET

C Subset

Current feature coverage. Target: practical C99 + MSVC extensions.

IMPL: implemented · PART: parsed, not fully lowered · TODO: not supported

entries: 38 IMPL: 28 PART: 4 TODO: 6

feature	status	notes
TYPES
`int`, `char`, `short`, `long`, `long long`	IMPL
`unsigned` variants	IMPL
`float`, `double`	PART	parsing, IR, and type checking only — codegen (SSE2) not implemented
Pointers and pointer arithmetic	IMPL
Arrays (fixed size)	IMPL
`struct` and `union`	IMPL
Anonymous struct/union fields	IMPL	flattened into parent namespace during IR lowering
`enum` with constant expressions	IMPL	constants folded at parse time
`typedef`	IMPL	cycle detection; multiple declarators per typedef
Bitfields	TODO
CONTROL FLOW
`if` / `else`	IMPL
`while`, `do-while`, `for`	IMPL
`switch` / `case` / `default`	PART	parsed and type-checked; IR lowering not yet implemented
`break`, `continue`	IMPL
`goto` and labeled statements	PART	parsed; IR lowering not yet implemented
`return`	IMPL
FUNCTIONS
Function definitions and calls	IMPL
Variadic functions (`...`, `va_list`)	IMPL	`__va_start` intrinsic; arg registers spilled to shadow space
Function pointers and indirect calls	IMPL	`CALL RAX`
More than 4 arguments	IMPL	args 5+ spilled to stack per x64 ABI
EXPRESSIONS
All binary operators	IMPL	arithmetic, bitwise, logical, comparison, comma
All assignment operators	IMPL	`= += -= *= /= %= &= \|= ^= <<= >>=`
Increment / decrement (`++`, `--`)	IMPL	pre and post forms
Ternary operator	IMPL
Casts	IMPL
`sizeof`, `alignof`	IMPL	correct struct alignment semantics with `#pragma pack`
Struct member access (`.` and `->`)	IMPL
Address-of, dereference	IMPL
Struct/array initializer lists (`{1, 2, 3}`)	TODO
PREPROCESSOR
`#define` macros (object and function-like)	IMPL
Variadic macros (`__VA_ARGS__`)	IMPL
Token pasting (`##`) and stringification (`#`)	IMPL
`#include` — local and system headers	IMPL
`#ifdef` / `#ifndef` / `#if` / `#elif`	IMPL
`#pragma pack`	IMPL	push/pop stack; both `#pragma pack` and `__pragma(pack(...))` forms
Windows SDK headers (`<windows.h>`, `<stdio.h>`, etc.)	IMPL	SDK paths discovered at runtime from environment
MSVC extension keywords	IMPL	`__declspec` `__cdecl` `__stdcall` `__int64` `__forceinline` ...
COMPILER FEATURES
Multi-file compilation (`-c` + link)	IMPL	custom `CCOBJ001` object format
Dead code elimination	IMPL	BFS reachability from `main` over merged reloc graph
Peephole optimizer	IMPL	stack value tracking, runs to fixed point
Precompiled headers	IMPL	binary AST + macro + typedef + enum serialization
Semantic type checker	IMPL	line:col errors before IR lowering
Register allocator	TODO	currently spills everything to `[RBP-N]`
Float/double codegen (SSE2)	TODO
VLAs	TODO
Inline assembly	TODO
Debug info (CodeView / PDB)	TODO
Linux ELF target	TODO	System V AMD64 ABI

// roadmap

switch statement lowering to conditional branches
goto and labeled break/continue
Struct and array initializer lists ({1, 2, 3})
Floating-point codegen (SSE2)
Bitfield support
Register allocator (linear scan)
Stronger constant propagation and dead-store elimination
Debug info (CodeView / PDB)
Linux ELF target (System V AMD64 ABI)
Test suite with expected-output .c files