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tests, but at what cost

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This commit is contained in:
iris
2026-06-12 05:09:38 -04:00
parent 7004cdbfe2
commit ceebcdc0e3
7 changed files with 288 additions and 57 deletions
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src/arch/x86_64/encode.rs
+48 -31
View File
@@ -15,7 +15,8 @@ pub struct Code {
#[derive(Clone, Copy)]
pub struct Mem {
pub reg: Reg,
pub disp: u32,
pub disp: i32,
pub width: Width,
}
#[derive(Clone, Copy)]
@@ -31,8 +32,8 @@ pub enum RegMem {
Mem(Mem),
}
pub fn mem(reg: Reg, disp: u32) -> Mem {
Mem { reg, disp }
pub fn mem(reg: Reg, disp: i32, width: Width) -> Mem {
Mem { reg, disp, width }
}
impl Code {
@@ -40,7 +41,7 @@ impl Code {
let dst = dst.into();
let src = src.into();
match dst {
RegMem::Reg(dst) => match src {
RegMem::Reg(mut dst) => match src {
RegImmMem::Reg(src) => {
if dst.width() != src.width() {
return Err("src and dst are not same width".into());
@@ -57,13 +58,17 @@ impl Code {
self.bytes.push(modrm_regs(src, dst));
}
RegImmMem::Imm(src) => {
let src_width = Width::fit(src);
if src_width > dst.width() {
return Err("immediate cannot fit in register".into());
}
self.prefix16(dst);
if src_width <= Width::B32 {
dst.lower64();
}
if dst.requires_rex() {
self.bytes.push(rex(dst.width(), 0, 0, dst));
}
if src > dst.width().max() {
return Err("immediate cannot fit in register".into());
}
let opcode = 0xb0 | ((dst.width().gt8() as u8) << 3);
self.bytes.push(opcode | dst.base());
self.bytes.extend(&src.to_le_bytes()[..dst.width().bytes()]);
@@ -73,14 +78,22 @@ impl Code {
RegMem::Mem(dst) => match src {
RegImmMem::Reg(src) => todo!(),
RegImmMem::Imm(src) => {
if src > u32::MAX as u64 {
let src_width = Width::fit(src);
if src_width == Width::B64 {
return Err("cannot move 64 bit immediate into memory".into());
}
let src = src as u32;
self.bytes.extend([rex(1, dst.reg, 0, 0), 0xc7]);
match dst.reg.width() {
Width::B8 | Width::B16 => return Err("invalid register width".into()),
Width::B32 => self.bytes.push(0x67),
Width::B64 => (),
}
self.prefix16(src_width);
if dst.reg.requires_mem_rex() {
self.bytes.push(rex(src_width, 0, 0, dst.reg));
}
self.bytes.push(0xc6 | (src_width != Width::B8) as u8);
self.modrm_regdisp(dst.reg, dst.disp);
self.bytes.extend(src.to_le_bytes());
self.bytes.extend(&src.to_le_bytes()[..src_width.bytes()]);
}
RegImmMem::Mem(_) => return Err("cannot move memory to memory".into()),
},
@@ -100,18 +113,16 @@ impl Code {
Width::B16 => {}
_ => return Err("register must be 64 or 16 bit".into()),
},
RegImmMem::Imm(imm) => match imm.try_into() {
Ok(imm) => {
const U8: u32 = 2 << 8;
if let 0..U8 = imm {
self.bytes.push(0x6a);
self.bytes.push(imm as u8);
} else {
self.bytes.push(0x68);
self.bytes.extend(imm.to_le_bytes());
}
RegImmMem::Imm(imm) => match Width::fit(imm) {
Width::B8 => {
self.bytes.push(0x6a);
self.bytes.push(imm as u8);
}
Err(_) => return Err("immediate must be 32 bit".into()),
Width::B16 | Width::B32 => {
self.bytes.push(0x68);
self.bytes.extend((imm as u32).to_le_bytes());
}
Width::B64 => return Err("immediate must be 32 bit or less".into()),
},
RegImmMem::Mem(mem) => todo!(),
}
@@ -170,18 +181,24 @@ impl Code {
}
}
fn modrm_regdisp(&mut self, reg: Reg, disp: u32) {
let disp8 = disp < u8::MAX as u32;
let mod_ = if disp8 { 0b01 } else { 0b10 };
fn modrm_regdisp(&mut self, reg: Reg, disp: i32) {
const I8_MIN: i32 = i8::MIN as i32;
const I8_MAX: i32 = i8::MAX as i32;
let mod_ = match disp {
0 => 0b00,
I8_MIN..=I8_MAX => 0b01,
_ => 0b10,
};
self.bytes.push(modrm(mod_, 0, reg.base()));
if reg.val() == rsp.val() {
// SIB
self.bytes.push(0x24);
}
if disp8 {
self.bytes.push(disp as u8);
} else {
self.bytes.extend(disp.to_le_bytes());
match mod_ {
0b00 => (),
0b01 => self.bytes.push(disp as u8),
0b10 => self.bytes.extend(disp.to_le_bytes()),
_ => unreachable!(),
}
}
@@ -245,6 +262,6 @@ impl From<i64> for RegImmMem {
impl From<i32> for RegImmMem {
fn from(value: i32) -> Self {
Self::Imm(value as u32 as u64)
Self::Imm(value as u64)
}
}
src/arch/x86_64/reg.rs
+102 -18
View File
@@ -5,33 +5,34 @@ pub struct Reg {
width: Width,
}
#[derive(Debug, Clone, Copy, PartialEq)]
#[derive(Debug, Clone, Copy, PartialEq, PartialOrd)]
#[repr(u8)]
pub enum Width {
B64,
B32,
B16,
B8,
B8 = 0,
B16 = 1,
B32 = 2,
B64 = 3,
}
def_regs! { Reg;
def_regs! {
0b0000 : rax eax ax al,
0b0001 : rcx ecx cx cl,
0b0001 : rcx ecx cx cl !_,
0b0010 : rdx edx dx dl,
0b0011 : rbx ebx bx bl,
0b0100 : rsp esp sp spl norex=ah,
0b0100 : rsp esp sp spl norex=ah !_,
0b0101 : rbp ebp bp bpl norex=ch,
0b0110 : rsi esi si sil norex=dh,
0b0110 : rsi esi si sil norex=dh !_,
0b0111 : rdi edi di dil norex=bh,
0b1000 : r8 r8d r8w r8b,
0b1001 : r9 r9d r9w r9b,
0b1001 : r9 r9d r9w r9b !_,
0b1010 : r10 r10d r10w r10b,
0b1011 : r11 r11d r11w r11b,
0b1100 : r12 r12d r12w r12b,
0b1101 : r13 r13d r13w r13b,
0b1110 : r14 r14d r14w r14b,
0b1111 : r15 r15d r15w r15b,
0b1111 : r15 r15d r15w r15b !_,
}
impl Reg {
@@ -49,16 +50,29 @@ impl Reg {
self.high
}
pub fn val(&self) -> u8 {
self.val
}
pub fn width(&self) -> Width {
self.width
}
/// if self has 64 bit width, changes width to 32 bit
pub fn lower64(&mut self) {
self.width.lower64()
}
pub fn requires_rex(&self) -> bool {
self.gt8()
|| self.width == Width::B64
|| (self.gt4() && self.width == Width::B8 && !self.high)
}
pub fn requires_mem_rex(&self) -> bool {
self.gt8() || (self.gt4() && self.width == Width::B8 && !self.high)
}
pub fn incompatible(&self, other: &Reg) -> bool {
(self.requires_rex() && other.high) || (self.high && other.requires_rex())
}
@@ -77,6 +91,13 @@ impl Width {
Self::B8 { .. } => u8::MAX as u64,
}
}
pub fn lower64(&mut self) {
if matches!(self, Width::B64) {
*self = Width::B32;
}
}
pub const fn bytes(&self) -> usize {
match self {
Self::B64 => 8,
@@ -85,29 +106,75 @@ impl Width {
Self::B8 { .. } => 1,
}
}
pub const fn fit(val: u64) -> Self {
const B8: u64 = 1 << 8;
const B16: u64 = 1 << 16;
const B32: u64 = 1 << 32;
match val {
..B8 => Self::B8,
B8..B16 => Self::B16,
B16..B32 => Self::B32,
B32.. => Self::B64,
}
}
pub const fn fiti(val: u64) -> Self {
match val {
..0x80 => Self::B8,
0x80..0x8000 => Self::B16,
0x8000..0x8000_0000 => Self::B32,
0x8000_0000.. => Self::B64,
}
}
/// greater than 8 bits
pub const fn gt8(&self) -> bool {
!matches!(self, Self::B8)
}
}
macro_rules! filter {
($($filtered:ident)*; ! $_:tt $($item:ident)*; $($rest:tt)*) => {
filter!($($filtered)* $($item)*; $($rest)*)
};
($($filtered:ident)*; $($item:ident)*; $($rest:tt)*) => {
filter!($($filtered)*; $($rest)*)
};
($($filtered:ident)*;) => {
[$($filtered, )*]
};
}
use filter;
macro_rules! def_regs {
($Struct: ident; $($val:literal : $B64:ident $B32:ident $B16:ident $B8:ident $(norex=$B8H:ident)?,)*) => {
($($val:literal : $B64:ident $B32:ident $B16:ident $B8:ident $(norex=$B8H:ident)? $(!$imp:tt)?,)*) => {
$(
#[allow(non_upper_case_globals)]
pub const $B64: $Struct = $Struct::new($val, Width::B64, false);
pub const $B64: Reg = Reg::new($val, Width::B64, false);
#[allow(non_upper_case_globals)]
pub const $B32: $Struct = $Struct::new($val, Width::B32, false);
pub const $B32: Reg = Reg::new($val, Width::B32, false);
#[allow(non_upper_case_globals)]
pub const $B16: $Struct = $Struct::new($val, Width::B16, false);
pub const $B16: Reg = Reg::new($val, Width::B16, false);
#[allow(non_upper_case_globals)]
pub const $B8 : $Struct = $Struct::new($val, Width::B8 , false);
pub const $B8 : Reg = Reg::new($val, Width::B8 , false);
$(
#[allow(non_upper_case_globals)]
pub const $B8H: $Struct = $Struct::new($val, Width::B8, true);
pub const $B8H: Reg = Reg::new($val, Width::B8, true);
)?
)*
impl $Struct {
impl Reg {
#[cfg(test)]
pub const ALL: &[Reg] = &[
$( $B64, $B32, $B16, $B8, $($B8H,)? )*
];
#[cfg(test)]
pub const IMPORTANT: &[Reg] = &
filter!(; $($(!$imp)? $B64 $B32 $B16 $B8 $($B8H)?; )* )
;
pub fn parse(s: &str) -> Option<Self> {
Some(match s.to_lowercase().as_str() {
$(
@@ -123,6 +190,23 @@ macro_rules! def_regs {
})
}
}
impl std::fmt::Display for Reg {
#[allow(non_upper_case_globals)]
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
write!(f, "{}", match *self {
$(
$B64 => stringify!($B64),
$B32 => stringify!($B32),
$B16 => stringify!($B16),
$B8 => stringify!($B8),
$(
$B8H => stringify!($B8H),
)?
)*
_ => "UNKNOWN",
})
}
}
};
}
src/arch/x86_64/test/bin.rs
+1 -1
View File
@@ -94,7 +94,7 @@ fn windows() -> Result<(), CompilerMsg> {
c.lea(rdx, text_sym);
c.mov(r8d, text.len() as u64)?;
c.lea(r9, written);
c.mov(mem(rsp, 0x20), 0)?;
c.mov(mem(rsp, 0x20, Width::B32), 0)?;
c.call_mem(write_file);
// exit
c.mov(ecx, 39)?;
src/arch/x86_64/test/mod.rs
+2
View File
@@ -1,5 +1,7 @@
pub mod bin;
#[cfg(test)]
mod nasm;
#[cfg(test)]
mod reg;
#[cfg(test)]
use super::*;
src/arch/x86_64/test/nasm.rs
+127
View File
@@ -0,0 +1,127 @@
use crate::arch::x86_64::*;
use std::{fs::OpenOptions, io::Write, process::Command};
const DISPS: &[i32] = &[
0x0,
0x1,
i8::MIN as i32,
i8::MAX as i32,
i16::MIN as i32,
i16::MAX as i32,
i32::MAX,
];
const IMMS: &[u64] = &[
0x0,
0x1,
u8::MAX as u64,
u8::MAX as u64 + 1,
u16::MAX as u64,
u16::MAX as u64 + 1,
u32::MAX as u64,
u32::MAX as u64 + 1,
// nasm likes to think u64::MAX is -1i32 for some reason
i64::MAX as u64,
];
#[test]
fn mov() {
for &reg in Reg::IMPORTANT {
for &disp in DISPS {
for &imm in IMMS {
let width = Width::fit(imm);
let size = match width {
Width::B8 => "BYTE",
Width::B16 => "WORD",
Width::B32 => "DWORD",
Width::B64 => "QWORD",
};
let ddisp = (disp as i64).abs();
let sign = if disp < 0 { '-' } else { '+' };
eq!(
format!("mov {size} [{reg}{sign}0x{ddisp:x}], 0x{imm:x}"),
mov(mem(reg, disp, width), imm)
);
}
}
}
for &r1 in Reg::IMPORTANT {
for &r2 in Reg::IMPORTANT {
eq!(format!("mov {r1}, {r2}"), mov(r1, r2));
}
}
for &r1 in Reg::IMPORTANT {
for &imm in IMMS {
eq!(format!("mov {r1}, 0x{imm:x}"), mov(r1, imm));
}
}
}
macro_rules! eq {
($asm:expr, $instr:ident $args:tt $(,)?) => {
let asm = $asm;
let expected = nasm(asm.as_ref());
let mut code = Code::default();
let res = code.$instr $args;
match (expected, res) {
(Ok(_), Err(e)) => {
panic!("{asm}: failed to compile: {}", e.msg);
}
(Err(e), Ok(_)) => {
let res = &code.bytes[..];
panic!("{asm}: should not have compiled:\n{e}\ngot: {res:x?}");
}
(Err(_), Err(_)) => (),
(Ok(expected), Ok(_)) => {
let res = &code.bytes[..];
if expected != res {
panic!("{asm}: expected {expected:x?}, got {res:x?}")
}
}
}
};
}
use eq;
fn nasm(input: &str) -> Result<Vec<u8>, String> {
let fin = "/tmp/69420nasm_in.asm";
let fout = "/tmp/69420nasm_out.o";
let input = "result:".to_string() + input;
write(fin, input.as_bytes());
run(["nasm", "-w+error", "-felf64", fin, &format!("-o{fout}")])?;
let output = run(["objdump", "--no-addresses", "-dw", "-Mintel", fout])?;
let mut iter = output.lines().skip_while(|l| !l.contains("result")).skip(1);
let res_line = iter.next().unwrap().trim();
let end = res_line.find("\t").unwrap();
let res_line = &res_line[..end];
let bytes = res_line
.trim()
.split(" ")
.map(|s| u8::from_str_radix(s, 16).unwrap())
.collect();
Ok(bytes)
}
fn run<const N: usize>(input: [&str; N]) -> Result<String, String> {
let path = input[0];
let mut cmd = Command::new(path);
cmd.args(&input[1..]);
let output = cmd.output().expect("failed to run");
if output.status.code().unwrap() != 0 {
return Err(output.stderr.try_into().unwrap());
}
Ok(output.stdout.try_into().unwrap())
}
fn write(path: &str, binary: &[u8]) {
let mut file = OpenOptions::new()
.create(true)
.write(true)
.truncate(true)
.open(path)
.expect("Failed to create file");
file.write_all(binary).expect("Failed to write to file");
file.sync_all().expect("Failed to sync file");
}
src/arch/x86_64/test/reg.rs
+2 -1
View File
@@ -13,9 +13,10 @@ macro_rules! eq {
};
}
// used objdump on some nasm compiled assembly
#[test]
fn mov_reg_reg() {
// used objdump on some nasm compiled assembly
eq!([0x48, 0x89, 0xd8], mov(rax, rbx));
eq!([0x89, 0xd8], mov(eax, ebx));
eq!([0x66, 0x89, 0xd8], mov(ax, bx));
src/arch/x86_64/util.rs
+6 -6
View File
@@ -22,7 +22,7 @@ pub fn rex(w: impl RexBit, r: impl RexBit, x: impl RexBit, b: impl RexBit) -> u8
#[inline(always)]
pub fn bit(val: impl RexBit, pos: u8) -> u8 {
(val.val() as u8) << pos
(val.rex() as u8) << pos
}
/// assumes the next instruction is directly after
@@ -33,29 +33,29 @@ pub fn addr_offset(pos: usize, addr: u64) -> [u8; 4] {
}
pub trait RexBit {
fn val(self) -> bool;
fn rex(self) -> bool;
}
impl RexBit for u8 {
fn val(self) -> bool {
fn rex(self) -> bool {
self != 0
}
}
impl RexBit for bool {
fn val(self) -> bool {
fn rex(self) -> bool {
self
}
}
impl<R: Into<Reg>> RexBit for R {
fn val(self) -> bool {
fn rex(self) -> bool {
self.into().gt8()
}
}
impl RexBit for Width {
fn val(self) -> bool {
fn rex(self) -> bool {
self == Width::B64
}
}