Files
nix-js/fix-vm/src/dispatch_tailcall.rs
T

296 lines
9.0 KiB
Rust

#![cfg(feature = "tailcall")]
use gc_arena::Mutation;
use crate::{BytecodeReader, StepResult, Vm, VmContext};
pub(crate) enum TailResult {
YieldFuel(u32),
Done,
}
pub(crate) type OpFn<'gc, C> = extern "rust-preserve-none" fn(
&mut Vm<'gc>,
&Mutation<'gc>,
&mut C,
&[u8],
&DispatchTable<'gc, C>,
u32,
u32,
) -> TailResult;
pub(crate) struct DispatchTable<'gc, C: VmContext>(pub(crate) [OpFn<'gc, C>; 256]);
extern "rust-preserve-none" fn op_illegal<'gc, C: VmContext>(
_vm: &mut Vm<'gc>,
_mc: &Mutation<'gc>,
_ctx: &mut C,
_bc: &[u8],
_table: &DispatchTable<'gc, C>,
pc: u32,
_fuel: u32,
) -> TailResult {
panic!("illegal opcode at pc = {pc}");
}
macro_rules! tail_dispatch_after {
($result:expr, $new_pc:expr, $vm:ident, $mc:ident, $ctx:ident, $bc:ident, $table:ident, $fuel:ident) => {{
match $result {
StepResult::Continue => {}
StepResult::Done => return TailResult::Done,
}
let new_pc: u32 = $new_pc;
if $fuel == 0 {
return TailResult::YieldFuel(new_pc);
}
let next_op = $bc[new_pc as usize] as usize;
become $table.0[next_op]($vm, $mc, $ctx, $bc, $table, new_pc, $fuel - 1)
}};
}
macro_rules! tail_fn {
($name:ident, ()) => {
extern "rust-preserve-none" fn $name<'gc, C: VmContext>(
vm: &mut Vm<'gc>,
mc: &Mutation<'gc>,
ctx: &mut C,
bc: &[u8],
table: &DispatchTable<'gc, C>,
pc: u32,
fuel: u32,
) -> TailResult {
let result = vm.$name();
tail_dispatch_after!(result, pc + 1, vm, mc, ctx, bc, table, fuel)
}
};
($name:ident, (reader)) => {
extern "rust-preserve-none" fn $name<'gc, C: VmContext>(
vm: &mut Vm<'gc>,
mc: &Mutation<'gc>,
ctx: &mut C,
bc: &[u8],
table: &DispatchTable<'gc, C>,
pc: u32,
fuel: u32,
) -> TailResult {
let mut reader = BytecodeReader::from_after_op(bc, pc as usize);
let result = vm.$name(&mut reader);
tail_dispatch_after!(result, reader.pc() as u32, vm, mc, ctx, bc, table, fuel)
}
};
($name:ident, (reader, mc)) => {
extern "rust-preserve-none" fn $name<'gc, C: VmContext>(
vm: &mut Vm<'gc>,
mc: &Mutation<'gc>,
ctx: &mut C,
bc: &[u8],
table: &DispatchTable<'gc, C>,
pc: u32,
fuel: u32,
) -> TailResult {
let mut reader = BytecodeReader::from_after_op(bc, pc as usize);
let result = vm.$name(&mut reader, mc);
tail_dispatch_after!(result, reader.pc() as u32, vm, mc, ctx, bc, table, fuel)
}
};
($name:ident, (ctx, reader, mc)) => {
extern "rust-preserve-none" fn $name<'gc, C: VmContext>(
vm: &mut Vm<'gc>,
mc: &Mutation<'gc>,
ctx: &mut C,
bc: &[u8],
table: &DispatchTable<'gc, C>,
pc: u32,
fuel: u32,
) -> TailResult {
let mut reader = BytecodeReader::from_after_op(bc, pc as usize);
let result = vm.$name(ctx, &mut reader, mc);
tail_dispatch_after!(result, reader.pc() as u32, vm, mc, ctx, bc, table, fuel)
}
};
($name:ident, (ctx)) => {
extern "rust-preserve-none" fn $name<'gc, C: VmContext>(
vm: &mut Vm<'gc>,
mc: &Mutation<'gc>,
ctx: &mut C,
bc: &[u8],
table: &DispatchTable<'gc, C>,
pc: u32,
fuel: u32,
) -> TailResult {
let result = vm.$name(ctx);
tail_dispatch_after!(result, pc + 1, vm, mc, ctx, bc, table, fuel)
}
};
}
tail_fn!(op_push_smi, (reader));
tail_fn!(op_push_bigint, (reader, mc));
tail_fn!(op_push_float, (reader));
tail_fn!(op_push_string, (reader));
tail_fn!(op_push_null, ());
tail_fn!(op_push_true, ());
tail_fn!(op_push_false, ());
tail_fn!(op_load_local, (reader));
tail_fn!(op_load_outer, (reader));
tail_fn!(op_store_local, (reader, mc));
tail_fn!(op_alloc_locals, (reader, mc));
tail_fn!(op_make_thunk, (reader, mc));
tail_fn!(op_make_closure, (reader, mc));
tail_fn!(op_make_pattern_closure, (reader, mc));
tail_fn!(op_call, (ctx, reader, mc));
tail_fn!(op_return, (ctx, reader, mc));
tail_fn!(op_make_attrs, (ctx, reader, mc));
tail_fn!(op_make_empty_attrs, ());
tail_fn!(op_select_static, (ctx, reader, mc));
tail_fn!(op_select_dynamic, (ctx, reader, mc));
tail_fn!(op_jump_if_select_succeeded, (reader));
tail_fn!(op_has_attr, (reader));
tail_fn!(op_make_list, (ctx, reader, mc));
tail_fn!(op_make_empty_list, ());
tail_fn!(op_add, (ctx, reader, mc));
tail_fn!(op_sub, (reader, mc));
tail_fn!(op_mul, (reader, mc));
tail_fn!(op_div, (reader, mc));
tail_fn!(op_eq, (ctx, reader, mc));
tail_fn!(op_neq, (ctx, reader, mc));
tail_fn!(op_lt, (ctx, reader, mc));
tail_fn!(op_gt, (ctx, reader, mc));
tail_fn!(op_leq, (ctx, reader, mc));
tail_fn!(op_geq, (ctx, reader, mc));
tail_fn!(op_concat, (reader, mc));
tail_fn!(op_update, (reader, mc));
tail_fn!(op_neg, ());
tail_fn!(op_not, ());
tail_fn!(op_jump_if_false, (reader, mc));
tail_fn!(op_jump_if_true, (reader, mc));
tail_fn!(op_jump, (reader));
tail_fn!(op_concat_strings, (ctx, reader, mc));
tail_fn!(op_resolve_path, (ctx));
tail_fn!(op_assert, (reader));
tail_fn!(op_push_with, (ctx, reader, mc));
tail_fn!(op_pop_with, ());
tail_fn!(op_lookup_with, (ctx, reader, mc));
tail_fn!(op_prepare_with, ());
tail_fn!(op_load_builtins, ());
tail_fn!(op_load_builtin, (reader));
tail_fn!(op_mk_pos, (reader));
tail_fn!(op_load_repl_binding, (reader));
tail_fn!(op_load_scoped_binding, (reader));
macro_rules! table {
($($variant:ident => $fn:ident),* $(,)?) => {
impl<'gc, C: VmContext> DispatchTable<'gc, C> {
pub(crate) const NEW: Self = {
let mut arr: [OpFn<'gc, C>; 256] = [op_illegal; 256];
$( arr[fix_codegen::Op::$variant as usize] = $fn; )*
DispatchTable(arr)
};
}
// Exhaustiveness check: fails to compile if `fix_codegen::Op` gains,
// loses, or renames a variant that isn't wired up above.
#[allow(dead_code)]
const _: fn(fix_codegen::Op) = |op| match op {
$( fix_codegen::Op::$variant => (), )*
};
};
}
table! {
PushSmi => op_push_smi,
PushBigInt => op_push_bigint,
PushFloat => op_push_float,
PushString => op_push_string,
PushNull => op_push_null,
PushTrue => op_push_true,
PushFalse => op_push_false,
LoadLocal => op_load_local,
LoadOuter => op_load_outer,
StoreLocal => op_store_local,
AllocLocals => op_alloc_locals,
MakeThunk => op_make_thunk,
MakeClosure => op_make_closure,
MakePatternClosure => op_make_pattern_closure,
Call => op_call,
Return => op_return,
MakeAttrs => op_make_attrs,
MakeEmptyAttrs => op_make_empty_attrs,
SelectStatic => op_select_static,
SelectDynamic => op_select_dynamic,
JumpIfSelectSucceeded => op_jump_if_select_succeeded,
HasAttr => op_has_attr,
MakeList => op_make_list,
MakeEmptyList => op_make_empty_list,
OpAdd => op_add,
OpSub => op_sub,
OpMul => op_mul,
OpDiv => op_div,
OpEq => op_eq,
OpNeq => op_neq,
OpLt => op_lt,
OpGt => op_gt,
OpLeq => op_leq,
OpGeq => op_geq,
OpConcat => op_concat,
OpUpdate => op_update,
OpNeg => op_neg,
OpNot => op_not,
JumpIfFalse => op_jump_if_false,
JumpIfTrue => op_jump_if_true,
Jump => op_jump,
ConcatStrings => op_concat_strings,
ResolvePath => op_resolve_path,
Assert => op_assert,
PushWith => op_push_with,
PopWith => op_pop_with,
LookupWith => op_lookup_with,
PrepareWith => op_prepare_with,
LoadBuiltins => op_load_builtins,
LoadBuiltin => op_load_builtin,
MkPos => op_mk_pos,
LoadReplBinding => op_load_repl_binding,
LoadScopedBinding => op_load_scoped_binding,
Illegal => op_illegal,
}
pub(crate) fn run_tailcall<'gc, C: VmContext>(
vm: &mut Vm<'gc>,
mc: &Mutation<'gc>,
ctx: &mut C,
bc: &[u8],
pc: u32,
) -> TailResult {
const FUEL: u32 = 1024;
let table = &DispatchTable::<'gc, C>::NEW;
let op = bc[pc as usize] as usize;
table.0[op](vm, mc, ctx, bc, table, pc, FUEL)
}