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-rw-r--r--examples/tiny_vm.rs697
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diff --git a/examples/tiny_vm.rs b/examples/tiny_vm.rs
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+//! TinyVm example.
+//!
+//! This example introduces as simple 16 bit virtual machine the [`TinyVm`]. The VM consits of
+//! three registers defined in [`TinyReg`], a separate _data_ and _insutrction_ memory and a small
+//! set of instructions [`TinyInsn`], sufficient to implement a guest program to compute the
+//! fiibonacci sequence.
+//!
+//! The `TinyVm` implements a simple _just-in-time (JIT)_ compiler to demonstrate the
+//! [`juicebox_asm`] crate. Additionally, it implements a reference _interpreter_.
+//!
+//! ```
+//! fn main() {
+//! let mut prog = Vec::new();
+//! prog.push(TinyInsn::LoadImm(TinyReg::A, 100));
+//! prog.push(TinyInsn::Add(TinyReg::B, TinyReg::A));
+//! prog.push(TinyInsn::Addi(TinyReg::C, 100));
+//! prog.push(TinyInsn::Halt);
+//!
+//! let mut vm = TinyVm::new(prog);
+//! vm.interp();
+//!
+//! assert_eq!(100, vm.read_reg(TinyReg::A));
+//! assert_eq!(100, vm.read_reg(TinyReg::B));
+//! assert_eq!(100, vm.read_reg(TinyReg::C));
+//! assert_eq!(4, vm.icnt);
+//! assert_eq!(4, vm.pc);
+//!
+//! vm.pc = 0;
+//! vm.jit();
+//!
+//! assert_eq!(100, vm.read_reg(TinyReg::A));
+//! assert_eq!(200, vm.read_reg(TinyReg::B));
+//! assert_eq!(200, vm.read_reg(TinyReg::C));
+//! assert_eq!(8, vm.icnt);
+//! assert_eq!(4, vm.pc);
+//! }
+//! ```
+
+#[cfg(not(any(target_arch = "x86_64", target_os = "linux")))]
+compile_error!("Only supported on x86_64 with SystemV abi");
+
+use juicebox_asm::prelude::*;
+use juicebox_asm::Runtime;
+
+/// A guest physical address.
+pub struct PhysAddr(pub u16);
+
+impl Into<usize> for PhysAddr {
+ fn into(self) -> usize {
+ self.0 as usize
+ }
+}
+
+/// The registers for the [`TinyVm`].
+#[derive(Debug, PartialEq, Clone, Copy)]
+pub enum TinyReg {
+ A,
+ B,
+ C,
+}
+
+impl TinyReg {
+ #[inline]
+ fn idx(&self) -> usize {
+ *self as usize
+ }
+}
+
+/// The instructions for the [`TinyVm`].
+#[derive(Debug, PartialEq, Clone, Copy)]
+pub enum TinyInsn {
+ /// Halt the VM.
+ Halt,
+ /// Load the immediate value into the register `reg = imm`.
+ LoadImm(TinyReg, u16),
+ /// Load a value from the memory (absolute addressing) into the register `reg = mem[imm]`.
+ Load(TinyReg, u16),
+ /// Store a value from the register into the memory (absolute addressing) `mem[imm] = reg`.
+ Store(TinyReg, u16),
+ /// Add the register to the register `reg1 += reg2`.
+ Add(TinyReg, TinyReg),
+ /// Add the immediate to the register `reg += imm`.
+ Addi(TinyReg, i16),
+ /// Jump unconditional (absolute addressing) `pc = disp`.
+ Branch(usize),
+ /// Jump if the register is zero (absolute addressing) `pc = (reg == 0) ? disp : pc++`.
+ BranchZero(TinyReg, usize),
+}
+
+/// Value returned from a [`JitFn`].
+#[repr(C)]
+struct JitRet(u64, u64);
+
+/// Function signature defining the simple JIT ABI used in this example.
+/// A `JitFn` represents the entry point to a jit compiled _basic block_ of the guest software.
+///
+/// ```text
+/// JIT entry:
+/// arg0: pointer to guest registers
+/// arg1: pointer to guest data memory
+///
+/// JIT exit:
+/// JitRet(0, N): Halt instruction, executed N instructions.
+/// JitRet(N, R): N!=0
+/// End of basic block, executed N instructions,
+/// must re-enter at `pc = R`.
+/// ```
+type JitFn = extern "C" fn(*mut u16, *mut u8) -> JitRet;
+
+/// The `TinyVm` virtual machine state.
+pub struct TinyVm {
+ /// Data memory, covering full 16 bit guest address space.
+ ///
+ /// For simplicity add additional trailing 1 byte to support an unaligned access to 0xffff
+ /// without any special handling.
+ dmem: [u8; 0x1_0000 + 1],
+ /// Instruction memory.
+ imem: Vec<TinyInsn>,
+ /// VM registers.
+ regs: [u16; 3],
+ /// VM program counter.
+ pc: usize,
+ /// VM executed instruction counter (perf counter).
+ icnt: usize,
+
+ // -- JIT state.
+ /// Mapping of guest PCs to jitted host code (`JitFn`). This mapping is filled when guest
+ /// _basic blocks_ are jitted.
+ jit_cache: Vec<Option<JitFn>>,
+ /// JIT runtime maintaining the host pages containing the jitted guest code.
+ rt: Runtime,
+}
+
+impl TinyVm {
+ /// Create a new [`TinyVm`] and initialize the instruction memory from `code`.
+ pub fn new(code: Vec<TinyInsn>) -> Self {
+ let mut jit_cache = Vec::with_capacity(code.len());
+ jit_cache.resize(code.len(), None);
+
+ TinyVm {
+ dmem: [0; 0x1_0000 + 1],
+ imem: code,
+ regs: [0; 3],
+ pc: 0,
+ icnt: 0,
+ // -- JIT state.
+ jit_cache,
+ rt: Runtime::new(),
+ }
+ }
+
+ /// Read guest register.
+ #[inline]
+ pub fn read_reg(&self, reg: TinyReg) -> u16 {
+ self.regs[reg.idx()]
+ }
+
+ /// Write guest register.
+ #[inline]
+ pub fn write_reg(&mut self, reg: TinyReg, val: u16) {
+ self.regs[reg.idx()] = val;
+ }
+
+ /// Read guest data memory.
+ #[inline]
+ pub fn read_mem(&self, paddr: PhysAddr) -> u16 {
+ // dmem covers whole 16 bit address space + 1 byte for unaligned access at 0xffff.
+ let bytes = self.dmem[paddr.into()..][..2].try_into().unwrap();
+ u16::from_le_bytes(bytes)
+ }
+
+ /// Write guest data memory.
+ #[inline]
+ pub fn write_mem(&mut self, paddr: PhysAddr, val: u16) {
+ let bytes = val.to_le_bytes();
+ self.dmem[paddr.into()..][..2].copy_from_slice(&bytes);
+ }
+
+ /// Dump the VM state to stdout.
+ pub fn dump(&self) {
+ println!("-- TinyVm state --");
+ println!(" ICNT: {}", self.icnt);
+ println!(" PC : {:02x}", self.pc - 1);
+ println!(
+ " A:{:04x} B:{:04x} C:{:04x}",
+ self.read_reg(TinyReg::A),
+ self.read_reg(TinyReg::B),
+ self.read_reg(TinyReg::C),
+ );
+ }
+
+ /// Run in interpreter mode until the next [`TinyInsn::Halt`] instruction is hit.
+ pub fn interp(&mut self) {
+ 'outer: loop {
+ let insn = self.imem[self.pc];
+ //println!("[0x{:02x}] {:?}", self.pc, insn);
+
+ self.pc = self.pc.wrapping_add(1);
+ self.icnt += 1;
+
+ match insn {
+ TinyInsn::Halt => {
+ break 'outer;
+ }
+ TinyInsn::LoadImm(a, imm) => {
+ self.write_reg(a, imm);
+ }
+ TinyInsn::Load(a, addr) => {
+ let val = self.read_mem(PhysAddr(addr));
+ self.write_reg(a, val);
+ }
+ TinyInsn::Store(a, addr) => {
+ let val = self.read_reg(a);
+ self.write_mem(PhysAddr(addr), val);
+ }
+ TinyInsn::Add(a, b) => {
+ let res = self.read_reg(a).wrapping_add(self.read_reg(b));
+ self.write_reg(a, res);
+ }
+ TinyInsn::Addi(a, imm) => {
+ let res = self.read_reg(a).wrapping_add(imm as u16);
+ self.write_reg(a, res);
+ }
+ TinyInsn::Branch(disp) => {
+ self.pc = disp;
+ }
+ TinyInsn::BranchZero(a, disp) => {
+ if self.read_reg(a) == 0 {
+ self.pc = disp;
+ }
+ }
+ }
+ }
+ }
+
+ /// Run in JIT mode until the next [`TinyInsn::Halt`] instruction is hit. Translate guest
+ /// _basic blocks_ on demand.
+ pub fn jit(&mut self) {
+ 'outer: loop {
+ if let Some(bb_fn) = self.jit_cache[self.pc] {
+ match bb_fn(self.regs.as_mut_ptr(), self.dmem.as_mut_ptr()) {
+ JitRet(0, insn) => {
+ self.pc += insn as usize;
+ self.icnt += insn as usize;
+ break 'outer;
+ }
+ JitRet(insn, reenter_pc) => {
+ self.pc = reenter_pc as usize;
+ self.icnt += insn as usize;
+ }
+ }
+ } else {
+ let bb_fn = self.translate_next_bb();
+ self.jit_cache[self.pc] = Some(bb_fn);
+ //println!("[0x{:02x}] translated bb at {:p}", self.pc, bb_fn);
+ }
+ }
+ }
+
+ /// Translate the bb at the current pc and return a JitFn pointer to it.
+ fn translate_next_bb(&mut self) -> JitFn {
+ let mut bb = Asm::new();
+ let mut pc = self.pc;
+
+ 'outer: loop {
+ let insn = self.imem[pc];
+
+ pc = pc.wrapping_add(1);
+
+ // JIT ABI.
+ // enter
+ // rdi => regs
+ // rsi => dmem
+ // exit
+ // rax => JitRet(0,
+ // rdx => 1)
+
+ // Generate memory operand into regs for guest register.
+ let reg_op = |r: TinyReg| {
+ MemOp::IndirectDisp(Reg64::rdi, (r.idx() * 2).try_into().expect("only 3 regs"))
+ };
+
+ // Generate memory operand into dmem for guest phys address.
+ let mem_op = |paddr: u16| MemOp::IndirectDisp(Reg64::rsi, paddr.into());
+
+ // Compute instructions in translated basic block.
+ let bb_icnt = || -> u64 { (pc - self.pc).try_into().unwrap() };
+
+ let reenter_pc = |pc: usize| -> u64 { pc.try_into().unwrap() };
+
+ match insn {
+ TinyInsn::Halt => {
+ bb.mov(Reg64::rax, Imm64::from(0));
+ bb.mov(Reg64::rdx, Imm64::from(bb_icnt()));
+ bb.ret();
+ break 'outer;
+ }
+ TinyInsn::LoadImm(a, imm) => {
+ bb.mov(reg_op(a), Imm16::from(imm));
+ }
+ TinyInsn::Load(a, addr) => {
+ bb.mov(Reg16::ax, mem_op(addr));
+ bb.mov(reg_op(a), Reg16::ax);
+ }
+ TinyInsn::Store(a, addr) => {
+ bb.mov(Reg16::ax, reg_op(a));
+ bb.mov(mem_op(addr), Reg16::ax);
+ }
+ TinyInsn::Add(a, b) => {
+ bb.mov(Reg16::ax, reg_op(b));
+ bb.add(reg_op(a), Reg16::ax);
+ }
+ TinyInsn::Addi(a, imm) => {
+ bb.add(reg_op(a), Imm16::from(imm));
+ }
+ TinyInsn::Branch(disp) => {
+ bb.mov(Reg64::rax, Imm64::from(bb_icnt()));
+ bb.mov(Reg64::rdx, Imm64::from(reenter_pc(disp)));
+ bb.ret();
+ break 'outer;
+ }
+ TinyInsn::BranchZero(a, disp) => {
+ bb.cmp(reg_op(a), Imm16::from(0u16));
+ bb.mov(Reg64::rax, Imm64::from(bb_icnt()));
+ bb.mov(Reg64::rdx, Imm64::from(reenter_pc(disp)));
+
+ let mut skip_next_pc = Label::new();
+ // If register is zero, skip setting next pc as reenter pc.
+ bb.jz(&mut skip_next_pc);
+ bb.mov(Reg64::rdx, Imm64::from(reenter_pc(pc)));
+ bb.bind(&mut skip_next_pc);
+ bb.ret();
+ break 'outer;
+ }
+ }
+ }
+
+ unsafe { self.rt.add_code::<JitFn>(bb.into_code()) }
+ }
+}
+
+/// A minial fixup utility to implement jump labels when constructing guest programs.
+pub struct Fixup {
+ pc: usize,
+}
+
+impl Fixup {
+ /// Create a new `Fixup` at the current pc.
+ pub fn new(pc: usize) -> Self {
+ Fixup { pc }
+ }
+
+ /// Bind the `Fixup` to the current location of `prog` and resolve the `Fixup`.
+ pub fn bind(self, prog: &mut Vec<TinyInsn>) {
+ let plen = prog.len();
+ let insn = prog.get_mut(self.pc).expect(&format!(
+ "Trying to apply Fixup, but Fixup is out of range pc={} prog.len={}",
+ self.pc, plen
+ ));
+
+ match insn {
+ TinyInsn::Branch(disp) | TinyInsn::BranchZero(_, disp) => {
+ *disp = plen;
+ }
+ _ => {
+ unimplemented!("Trying to fixup non-branch instruction '{:?}'", *insn);
+ }
+ }
+ }
+}
+
+/// Generate a guest program to compute the fiibonacci sequence for `n`.
+pub fn make_tinyvm_fib(start_n: u16) -> Vec<TinyInsn> {
+ // Reference implementation:
+ //
+ // int fib(int n)
+ // int tmp = 0;
+ // int prv = 1;
+ // int sum = 0;
+ // loop:
+ // if (n == 0) goto end;
+ // tmp = sum;
+ // sum += prv;
+ // prv = tmp;
+ // --n;
+ // goto loop;
+ // end:
+ // return sum;
+
+ // Variables live in memory, bin to fixed addresses.
+ let tmp = 0u16;
+ let prv = 2u16;
+ let sum = 4u16;
+ // Loop counter mapped to register.
+ let n = TinyReg::C;
+
+ let mut prog = Vec::with_capacity(32);
+
+ // n = start_n
+ prog.push(TinyInsn::LoadImm(n, start_n));
+
+ // tmp = sum = 0
+ prog.push(TinyInsn::LoadImm(TinyReg::A, 0));
+ prog.push(TinyInsn::Store(TinyReg::A, tmp));
+ prog.push(TinyInsn::Store(TinyReg::A, sum));
+
+ // prv = 1
+ prog.push(TinyInsn::LoadImm(TinyReg::A, 1));
+ prog.push(TinyInsn::Store(TinyReg::A, prv));
+
+ // Create loop_start label.
+ let loop_start = prog.len();
+
+ // Create fixup to capture PC that need to be patched later.
+ let end_fixup = Fixup::new(prog.len());
+
+ // if (n == 0) goto end
+ prog.push(TinyInsn::BranchZero(n, 0xdead));
+
+ // tmp = sum
+ prog.push(TinyInsn::Load(TinyReg::A, sum));
+ prog.push(TinyInsn::Store(TinyReg::A, tmp));
+
+ // sum += prv
+ prog.push(TinyInsn::Load(TinyReg::B, prv));
+ prog.push(TinyInsn::Add(TinyReg::A, TinyReg::B));
+ prog.push(TinyInsn::Store(TinyReg::A, sum));
+
+ // prv = tmp
+ prog.push(TinyInsn::Load(TinyReg::A, tmp));
+ prog.push(TinyInsn::Store(TinyReg::A, prv));
+
+ // --n
+ prog.push(TinyInsn::Addi(n, -1));
+
+ // goto loop_start
+ prog.push(TinyInsn::Branch(loop_start));
+
+ // Bind end fixup to current PC, to patch branch to jump to here.
+ end_fixup.bind(&mut prog);
+
+ // TinyReg::A = sum
+ prog.push(TinyInsn::Load(TinyReg::A, sum));
+
+ // Halt the VM.
+ prog.push(TinyInsn::Halt);
+
+ prog
+}
+
+/// Generate a test program for the jit.
+pub fn make_tinyvm_jit_test() -> Vec<TinyInsn> {
+ let mut prog = Vec::with_capacity(32);
+
+ prog.push(TinyInsn::Branch(1));
+ prog.push(TinyInsn::LoadImm(TinyReg::A, 0x0010));
+ prog.push(TinyInsn::LoadImm(TinyReg::B, 0x0));
+
+ let start = prog.len();
+ let end = Fixup::new(prog.len());
+ prog.push(TinyInsn::BranchZero(TinyReg::A, 0xdead));
+ prog.push(TinyInsn::LoadImm(TinyReg::C, 0x1));
+ prog.push(TinyInsn::Add(TinyReg::B, TinyReg::C));
+ prog.push(TinyInsn::Addi(TinyReg::A, -1));
+ prog.push(TinyInsn::Branch(start));
+ end.bind(&mut prog);
+ prog.push(TinyInsn::LoadImm(TinyReg::A, 0xabcd));
+ prog.push(TinyInsn::Store(TinyReg::A, 0xffff));
+ prog.push(TinyInsn::Load(TinyReg::C, 0xffff));
+ prog.push(TinyInsn::Halt);
+ prog.push(TinyInsn::Halt);
+ prog.push(TinyInsn::Halt);
+ prog.push(TinyInsn::Halt);
+
+ prog
+}
+
+/// Generate a simple count down loop to crunch some instructions.
+pub fn make_tinyvm_jit_perf() -> Vec<TinyInsn> {
+ let mut prog = Vec::with_capacity(32);
+
+ prog.push(TinyInsn::Halt);
+ prog.push(TinyInsn::LoadImm(TinyReg::A, 0xffff));
+ prog.push(TinyInsn::LoadImm(TinyReg::B, 1));
+ prog.push(TinyInsn::LoadImm(TinyReg::C, 2));
+ prog.push(TinyInsn::Addi(TinyReg::A, -1));
+ prog.push(TinyInsn::BranchZero(TinyReg::A, 0));
+ prog.push(TinyInsn::Branch(2));
+ prog
+}
+
+fn main() {
+ let use_jit = match std::env::args().nth(1) {
+ Some(a) if a == "-h" || a == "--help" => {
+ println!("Usage: tiny_vm [mode]");
+ println!("");
+ println!("Options:");
+ println!(" mode if mode is 'jit' then run in jit mode, else in interpreter mode");
+ std::process::exit(0);
+ }
+ Some(a) if a == "jit" => true,
+ _ => false,
+ };
+
+ let mut vm = TinyVm::new(make_tinyvm_fib(42));
+
+ if use_jit {
+ println!("Run in jit mode..");
+ vm.jit();
+ } else {
+ println!("Run in interpreter mode..");
+ vm.interp();
+ }
+ vm.dump();
+}
+
+#[cfg(test)]
+mod test {
+ use super::*;
+
+ fn fib_rs(n: u64) -> u64 {
+ if n < 2 {
+ n
+ } else {
+ let mut fib_n_m1 = 0;
+ let mut fib_n = 1;
+ for _ in 1..n {
+ let tmp = fib_n + fib_n_m1;
+ fib_n_m1 = fib_n;
+ fib_n = tmp;
+ }
+ fib_n
+ }
+ }
+
+ #[test]
+ fn test_fib_interp() {
+ for n in 0..92 {
+ let mut vm = TinyVm::new(make_tinyvm_fib(n));
+ vm.interp();
+
+ assert_eq!((fib_rs(n as u64) & 0xffff) as u16, vm.read_reg(TinyReg::A));
+ }
+ }
+
+ #[test]
+ fn test_fib_jit() {
+ for n in 0..92 {
+ let mut vm = TinyVm::new(make_tinyvm_fib(n));
+ vm.jit();
+
+ assert_eq!((fib_rs(n as u64) & 0xffff) as u16, vm.read_reg(TinyReg::A));
+ }
+ }
+
+ #[test]
+ fn test_fib_icnt() {
+ let mut vm1 = TinyVm::new(make_tinyvm_fib(91));
+ vm1.interp();
+ let mut vm2 = TinyVm::new(make_tinyvm_fib(91));
+ vm2.jit();
+
+ assert_eq!(vm1.icnt, vm2.icnt);
+ assert_eq!(vm1.pc, vm2.pc);
+ }
+
+ #[test]
+ fn test_jit_load_imm() {
+ let mut prog = Vec::new();
+ prog.push(TinyInsn::LoadImm(TinyReg::A, 0x1111));
+ prog.push(TinyInsn::LoadImm(TinyReg::B, 0x2222));
+ prog.push(TinyInsn::LoadImm(TinyReg::C, 0x3333));
+ prog.push(TinyInsn::Halt);
+
+ let mut vm = TinyVm::new(prog);
+ vm.jit();
+
+ assert_eq!(0x1111, vm.read_reg(TinyReg::A));
+ assert_eq!(0x2222, vm.read_reg(TinyReg::B));
+ assert_eq!(0x3333, vm.read_reg(TinyReg::C));
+
+ assert_eq!(4, vm.icnt);
+ assert_eq!(4, vm.pc);
+ }
+
+ #[test]
+ fn test_jit_add() {
+ let mut prog = Vec::new();
+ prog.push(TinyInsn::LoadImm(TinyReg::A, 0));
+ prog.push(TinyInsn::Addi(TinyReg::A, 123));
+
+ prog.push(TinyInsn::LoadImm(TinyReg::B, 100));
+ prog.push(TinyInsn::LoadImm(TinyReg::C, 200));
+ prog.push(TinyInsn::Add(TinyReg::B, TinyReg::C));
+ prog.push(TinyInsn::Halt);
+
+ let mut vm = TinyVm::new(prog);
+ vm.jit();
+
+ assert_eq!(123, vm.read_reg(TinyReg::A));
+ assert_eq!(300, vm.read_reg(TinyReg::B));
+ assert_eq!(200, vm.read_reg(TinyReg::C));
+
+ assert_eq!(6, vm.icnt);
+ assert_eq!(6, vm.pc);
+ }
+
+ #[test]
+ fn test_jit_load_store() {
+ let mut prog = Vec::new();
+ prog.push(TinyInsn::Load(TinyReg::A, 0xffff));
+
+ prog.push(TinyInsn::LoadImm(TinyReg::B, 0xf00d));
+ prog.push(TinyInsn::Store(TinyReg::B, 0x8000));
+ prog.push(TinyInsn::Halt);
+
+ let mut vm = TinyVm::new(prog);
+ vm.write_mem(PhysAddr(0xffff), 0xaabb);
+ vm.jit();
+
+ assert_eq!(0xaabb, vm.read_reg(TinyReg::A));
+ assert_eq!(0xf00d, vm.read_mem(PhysAddr(0x8000)));
+
+ assert_eq!(4, vm.icnt);
+ assert_eq!(4, vm.pc);
+ }
+
+ #[test]
+ fn test_jit_branch() {
+ let mut prog = Vec::new();
+ prog.push(TinyInsn::Branch(2));
+ prog.push(TinyInsn::Halt);
+ prog.push(TinyInsn::Branch(6));
+ prog.push(TinyInsn::LoadImm(TinyReg::A, 1));
+ prog.push(TinyInsn::LoadImm(TinyReg::B, 2));
+ prog.push(TinyInsn::LoadImm(TinyReg::C, 3));
+ prog.push(TinyInsn::Branch(1));
+
+ let mut vm = TinyVm::new(prog);
+ vm.jit();
+
+ assert_eq!(0, vm.read_reg(TinyReg::A));
+ assert_eq!(0, vm.read_reg(TinyReg::B));
+ assert_eq!(0, vm.read_reg(TinyReg::C));
+
+ assert_eq!(4, vm.icnt);
+ assert_eq!(2, vm.pc);
+ }
+
+ #[test]
+ fn test_jit_branch_zero() {
+ let mut prog = Vec::new();
+ prog.push(TinyInsn::LoadImm(TinyReg::A, 1));
+ prog.push(TinyInsn::BranchZero(TinyReg::A, 5));
+ prog.push(TinyInsn::LoadImm(TinyReg::A, 0));
+ prog.push(TinyInsn::BranchZero(TinyReg::A, 5));
+ prog.push(TinyInsn::LoadImm(TinyReg::B, 22));
+ prog.push(TinyInsn::Halt);
+
+ let mut vm = TinyVm::new(prog);
+ vm.jit();
+
+ assert_eq!(0, vm.read_reg(TinyReg::A));
+ assert_eq!(0, vm.read_reg(TinyReg::B));
+ assert_eq!(0, vm.read_reg(TinyReg::C));
+
+ assert_eq!(5, vm.icnt);
+ assert_eq!(6, vm.pc);
+ }
+
+ #[test]
+ fn test_mixed() {
+ let mut prog = Vec::new();
+ prog.push(TinyInsn::LoadImm(TinyReg::A, 100));
+ prog.push(TinyInsn::Add(TinyReg::B, TinyReg::A));
+ prog.push(TinyInsn::Addi(TinyReg::C, 100));
+ prog.push(TinyInsn::Halt);
+
+ let mut vm = TinyVm::new(prog);
+ vm.interp();
+
+ assert_eq!(100, vm.read_reg(TinyReg::A));
+ assert_eq!(100, vm.read_reg(TinyReg::B));
+ assert_eq!(100, vm.read_reg(TinyReg::C));
+ assert_eq!(4, vm.icnt);
+ assert_eq!(4, vm.pc);
+
+ vm.pc = 0;
+ vm.jit();
+
+ assert_eq!(100, vm.read_reg(TinyReg::A));
+ assert_eq!(200, vm.read_reg(TinyReg::B));
+ assert_eq!(200, vm.read_reg(TinyReg::C));
+ assert_eq!(8, vm.icnt);
+ assert_eq!(4, vm.pc);
+ }
+}
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-21 21:09:09 +0000