use anyhow::{anyhow, bail, Error};
use std::cmp;
use std::collections::{BTreeMap, HashMap, HashSet};
use walrus::ir::*;
use walrus::{ExportId, ImportId, InstrLocId, TypeId};
use walrus::{FunctionId, GlobalId, InitExpr, Module, TableId, ValType};
const DEFAULT_MIN: u32 = 32;
#[derive(Default)]
pub struct Context {
imports: HashMap<ImportId, Function>,
exports: HashMap<ExportId, Function>,
elements: BTreeMap<u32, (u32, Function)>,
next_element: u32,
table: Option<TableId>,
}
pub struct Meta {
pub table: TableId,
pub alloc: Option<FunctionId>,
pub drop_slice: Option<FunctionId>,
pub live_count: Option<FunctionId>,
}
struct Transform<'a> {
cx: &'a mut Context,
intrinsic_map: HashMap<FunctionId, Intrinsic>,
import_map: HashMap<FunctionId, FunctionId>,
shims: HashSet<FunctionId>,
table: TableId,
clone_ref: Option<FunctionId>,
heap_alloc: Option<FunctionId>,
heap_dealloc: Option<FunctionId>,
stack_pointer: GlobalId,
}
struct Function {
args: HashMap<usize, bool>,
ret_anyref: bool,
}
enum Intrinsic {
TableGrow,
TableSetNull,
DropRef,
CloneRef,
}
impl Context {
pub fn prepare(&mut self, module: &mut Module) -> Result<(), Error> {
let mut tables = module.tables.iter().filter_map(|t| match &t.kind {
walrus::TableKind::Function(f) => Some(f),
_ => None,
});
if let Some(t) = tables.next() {
if tables.next().is_some() {
bail!("more than one function table present")
}
self.next_element = t.elements.len() as u32;
}
drop(tables);
let kind = walrus::TableKind::Anyref(Default::default());
self.table = Some(module.tables.add_local(DEFAULT_MIN, None, kind));
Ok(())
}
pub fn import_xform(
&mut self,
id: ImportId,
anyref: &[(usize, bool)],
ret_anyref: bool,
) -> &mut Self {
if let Some(f) = self.function(anyref, ret_anyref) {
self.imports.insert(id, f);
}
self
}
pub fn export_xform(
&mut self,
id: ExportId,
anyref: &[(usize, bool)],
ret_anyref: bool,
) -> &mut Self {
if let Some(f) = self.function(anyref, ret_anyref) {
self.exports.insert(id, f);
}
self
}
pub fn table_element_xform(
&mut self,
idx: u32,
anyref: &[(usize, bool)],
ret_anyref: bool,
) -> Option<u32> {
self.function(anyref, ret_anyref).map(|f| {
let ret = self.next_element;
self.next_element += 1;
self.elements.insert(ret, (idx, f));
ret
})
}
fn function(&self, anyref: &[(usize, bool)], ret_anyref: bool) -> Option<Function> {
if !ret_anyref && anyref.len() == 0 {
return None;
}
Some(Function {
args: anyref.iter().cloned().collect(),
ret_anyref,
})
}
pub fn run(&mut self, module: &mut Module) -> Result<Meta, Error> {
let table = self.table.unwrap();
let init = InitExpr::Value(Value::I32(DEFAULT_MIN as i32));
let stack_pointer = module.globals.add_local(ValType::I32, true, init);
let mut heap_alloc = None;
let mut heap_dealloc = None;
let mut drop_slice = None;
let mut live_count = None;
let mut to_delete = Vec::new();
for export in module.exports.iter() {
let f = match export.item {
walrus::ExportItem::Function(f) => f,
_ => continue,
};
match export.name.as_str() {
"__anyref_table_alloc" => heap_alloc = Some(f),
"__anyref_table_dealloc" => heap_dealloc = Some(f),
"__anyref_drop_slice" => drop_slice = Some(f),
"__anyref_heap_live_count" => live_count = Some(f),
_ => continue,
}
to_delete.push(export.id());
}
for id in to_delete {
module.exports.delete(id);
}
let mut clone_ref = None;
if let Some(heap_alloc) = heap_alloc {
let mut builder =
walrus::FunctionBuilder::new(&mut module.types, &[ValType::I32], &[ValType::I32]);
let arg = module.locals.add(ValType::I32);
let local = module.locals.add(ValType::I32);
let mut body = builder.func_body();
body.call(heap_alloc)
.local_tee(local)
.local_get(arg)
.table_get(table)
.table_set(table)
.local_get(local);
let func = builder.finish(vec![arg], &mut module.funcs);
let name = "__wbindgen_object_clone_ref".to_string();
module.funcs.get_mut(func).name = Some(name);
clone_ref = Some(func);
}
Transform {
cx: self,
intrinsic_map: HashMap::new(),
import_map: HashMap::new(),
shims: HashSet::new(),
table,
clone_ref,
heap_alloc,
heap_dealloc,
stack_pointer,
}
.run(module)?;
Ok(Meta {
table,
alloc: heap_alloc,
drop_slice,
live_count,
})
}
}
impl Transform<'_> {
fn run(&mut self, module: &mut Module) -> Result<(), Error> {
self.find_intrinsics(module)?;
self.process_imports(module)?;
assert!(self.cx.imports.is_empty());
self.process_exports(module)?;
assert!(self.cx.exports.is_empty());
self.process_elements(module)?;
assert!(self.cx.elements.is_empty());
if self.shims.is_empty() {
return Ok(());
}
self.rewrite_calls(module)?;
Ok(())
}
fn find_intrinsics(&mut self, module: &mut Module) -> Result<(), Error> {
for import in module.imports.iter_mut() {
let f = match import.kind {
walrus::ImportKind::Function(f) => f,
_ => continue,
};
if import.module == "__wbindgen_anyref_xform__" {
match import.name.as_str() {
"__wbindgen_anyref_table_grow" => {
self.intrinsic_map.insert(f, Intrinsic::TableGrow);
}
"__wbindgen_anyref_table_set_null" => {
self.intrinsic_map.insert(f, Intrinsic::TableSetNull);
}
n => bail!("unknown intrinsic: {}", n),
}
} else if import.module == "__wbindgen_placeholder__" {
match import.name.as_str() {
"__wbindgen_object_drop_ref" => {
self.intrinsic_map.insert(f, Intrinsic::DropRef);
}
"__wbindgen_object_clone_ref" => {
self.intrinsic_map.insert(f, Intrinsic::CloneRef);
}
_ => continue,
}
} else {
continue;
}
import.name = format!("{}_unused", import.name);
}
Ok(())
}
fn heap_alloc(&self) -> Result<FunctionId, Error> {
self.heap_alloc
.ok_or_else(|| anyhow!("failed to find the `__wbindgen_anyref_table_alloc` function"))
}
fn clone_ref(&self) -> Result<FunctionId, Error> {
self.clone_ref
.ok_or_else(|| anyhow!("failed to find intrinsics to enable `clone_ref` function"))
}
fn heap_dealloc(&self) -> Result<FunctionId, Error> {
self.heap_dealloc
.ok_or_else(|| anyhow!("failed to find the `__wbindgen_anyref_table_dealloc` function"))
}
fn process_imports(&mut self, module: &mut Module) -> Result<(), Error> {
for import in module.imports.iter_mut() {
let f = match import.kind {
walrus::ImportKind::Function(f) => f,
_ => continue,
};
let func = match self.cx.imports.remove(&import.id()) {
Some(s) => s,
None => continue,
};
let (shim, anyref_ty) = self.append_shim(
f,
&import.name,
func,
&mut module.types,
&mut module.funcs,
&mut module.locals,
)?;
self.import_map.insert(f, shim);
match &mut module.funcs.get_mut(f).kind {
walrus::FunctionKind::Import(f) => f.ty = anyref_ty,
_ => unreachable!(),
}
}
Ok(())
}
fn process_exports(&mut self, module: &mut Module) -> Result<(), Error> {
for export in module.exports.iter_mut() {
let f = match export.item {
walrus::ExportItem::Function(f) => f,
_ => continue,
};
let function = match self.cx.exports.remove(&export.id()) {
Some(s) => s,
None => continue,
};
let (shim, _anyref_ty) = self.append_shim(
f,
&export.name,
function,
&mut module.types,
&mut module.funcs,
&mut module.locals,
)?;
export.item = shim.into();
}
Ok(())
}
fn process_elements(&mut self, module: &mut Module) -> Result<(), Error> {
let table = match module.tables.main_function_table()? {
Some(t) => t,
None => return Ok(()),
};
let table = module.tables.get_mut(table);
let kind = match &mut table.kind {
walrus::TableKind::Function(f) => f,
_ => unreachable!(),
};
if kind.relative_elements.len() > 0 {
bail!("not compatible with relative element initializers yet");
}
while let Some((idx, function)) = self.cx.elements.remove(&(kind.elements.len() as u32)) {
let target = kind.elements[idx as usize].unwrap();
let (shim, _anyref_ty) = self.append_shim(
target,
&format!("closure{}", idx),
function,
&mut module.types,
&mut module.funcs,
&mut module.locals,
)?;
kind.elements.push(Some(shim));
}
table.initial = cmp::max(table.initial, kind.elements.len() as u32);
if let Some(max) = table.maximum {
table.maximum = Some(cmp::max(max, kind.elements.len() as u32));
}
Ok(())
}
fn append_shim(
&mut self,
shim_target: FunctionId,
name: &str,
mut func: Function,
types: &mut walrus::ModuleTypes,
funcs: &mut walrus::ModuleFunctions,
locals: &mut walrus::ModuleLocals,
) -> Result<(FunctionId, TypeId), Error> {
let target = funcs.get_mut(shim_target);
let (is_export, ty) = match &target.kind {
walrus::FunctionKind::Import(f) => (false, f.ty),
walrus::FunctionKind::Local(f) => (true, f.ty()),
_ => unreachable!(),
};
let target_ty = types.get(ty);
let target_ty_params = target_ty.params().to_vec();
let target_ty_results = target_ty.results().to_vec();
enum Convert {
None,
Store { owned: bool },
Load { owned: bool },
}
let mut param_tys = Vec::new();
let mut param_convert = Vec::new();
let mut anyref_stack = 0;
for (i, old_ty) in target_ty.params().iter().enumerate() {
let is_owned = func.args.remove(&i);
let new_ty = is_owned
.map(|_which| ValType::Anyref)
.unwrap_or(old_ty.clone());
param_tys.push(new_ty.clone());
if new_ty == *old_ty {
param_convert.push(Convert::None);
} else if is_export {
param_convert.push(Convert::Store {
owned: is_owned.unwrap(),
});
if is_owned == Some(false) {
anyref_stack += 1;
}
} else {
param_convert.push(Convert::Load {
owned: is_owned.unwrap(),
});
}
}
let new_ret = if func.ret_anyref {
assert_eq!(target_ty.results(), &[ValType::I32]);
vec![ValType::Anyref]
} else {
target_ty.results().to_vec()
};
let anyref_ty = types.add(¶m_tys, &new_ret);
let shim_ty = if is_export { anyref_ty } else { ty };
let mut builder = walrus::FunctionBuilder::new(
types,
if is_export {
¶m_tys
} else {
&target_ty_params
},
if is_export {
&new_ret
} else {
&target_ty_results
},
);
let mut body = builder.func_body();
let params = types
.get(shim_ty)
.params()
.iter()
.cloned()
.map(|ty| locals.add(ty))
.collect::<Vec<_>>();
let fp = locals.add(ValType::I32);
let scratch_i32 = locals.add(ValType::I32);
let scratch_anyref = locals.add(ValType::Anyref);
if anyref_stack > 0 {
body.global_get(self.stack_pointer)
.const_(Value::I32(anyref_stack))
.binop(BinaryOp::I32Sub)
.local_tee(fp)
.global_set(self.stack_pointer);
}
let mut next_stack_offset = 0;
for (i, convert) in param_convert.iter().enumerate() {
match *convert {
Convert::None => {
body.local_get(params[i]);
}
Convert::Load { owned: true } => {
body.local_get(params[i])
.table_get(self.table)
.local_get(params[i])
.call(self.heap_dealloc()?);
}
Convert::Load { owned: false } => {
body.local_get(params[i]).table_get(self.table);
}
Convert::Store { owned: true } => {
body.call(self.heap_alloc()?)
.local_tee(scratch_i32)
.local_get(params[i])
.table_set(self.table)
.local_get(scratch_i32);
}
Convert::Store { owned: false } => {
body.local_get(fp);
let idx_local = if next_stack_offset == 0 {
fp
} else {
body.i32_const(next_stack_offset)
.binop(BinaryOp::I32Add)
.local_tee(scratch_i32);
scratch_i32
};
next_stack_offset += 1;
body.local_get(params[i])
.table_set(self.table)
.local_get(idx_local);
}
}
}
body.call(shim_target);
if func.ret_anyref {
if is_export {
body.local_tee(scratch_i32)
.table_get(self.table)
.local_get(scratch_i32)
.call(self.heap_dealloc()?);
} else {
body.local_set(scratch_anyref)
.call(self.heap_alloc()?)
.local_tee(scratch_i32)
.local_get(scratch_anyref)
.table_set(self.table)
.local_get(scratch_i32);
}
}
if anyref_stack > 0 {
for i in 0..anyref_stack {
body.local_get(fp);
if i > 0 {
body.i32_const(i).binop(BinaryOp::I32Add);
}
body.ref_null();
body.table_set(self.table);
}
body.local_get(fp)
.i32_const(anyref_stack)
.binop(BinaryOp::I32Add)
.global_set(self.stack_pointer);
}
let id = builder.finish(params, funcs);
let name = format!("{} anyref shim", name);
funcs.get_mut(id).name = Some(name);
self.shims.insert(id);
Ok((id, anyref_ty))
}
fn rewrite_calls(&mut self, module: &mut Module) -> Result<(), Error> {
for (id, func) in module.funcs.iter_local_mut() {
if self.shims.contains(&id) {
continue;
}
let entry = func.entry_block();
dfs_pre_order_mut(
&mut Rewrite {
clone_ref: self.clone_ref()?,
heap_dealloc: self.heap_dealloc()?,
xform: self,
},
func,
entry,
);
}
return Ok(());
struct Rewrite<'a, 'b> {
xform: &'a Transform<'b>,
clone_ref: FunctionId,
heap_dealloc: FunctionId,
}
impl VisitorMut for Rewrite<'_, '_> {
fn start_instr_seq_mut(&mut self, seq: &mut InstrSeq) {
for i in (0..seq.instrs.len()).rev() {
let call = match &mut seq.instrs[i].0 {
Instr::Call(call) => call,
_ => continue,
};
let intrinsic = match self.xform.intrinsic_map.get(&call.func) {
Some(f) => f,
None => {
if let Some(f) = self.xform.import_map.get(&call.func) {
call.func = *f;
}
continue;
}
};
match intrinsic {
Intrinsic::TableGrow => {
seq.instrs[i].0 = TableGrow {
table: self.xform.table,
}
.into();
seq.instrs
.insert(i - 1, (RefNull {}.into(), InstrLocId::default()));
}
Intrinsic::TableSetNull => {
seq.instrs[i].0 = TableSet {
table: self.xform.table,
}
.into();
seq.instrs
.insert(i, (RefNull {}.into(), InstrLocId::default()));
}
Intrinsic::DropRef => call.func = self.heap_dealloc,
Intrinsic::CloneRef => call.func = self.clone_ref,
}
}
}
}
}
}