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Fix the anyref xform working on empty modules (#1861)
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If there's no need for a transformation then there's no need to inject
anything, so make sure that wasm-bindgen with anyref passes enabled
works on non-wasm-bindgen blobs as well.

Closes bytecodealliance/cargo-wasi#16
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@alexcrichton
alexcrichton committed Nov 18, 2019
1 parent a8882dc commit aca49e1
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Showing 2 changed files with 114 additions and 48 deletions.
126 changes: 78 additions & 48 deletions crates/anyref-xform/src/lib.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -58,9 +58,9 @@ struct Transform<'a> {
// Indices of items that we have injected or found. This state is maintained
// during the pass execution.
table: TableId,
clone_ref: FunctionId,
heap_alloc: FunctionId,
heap_dealloc: FunctionId,
clone_ref: Option<FunctionId>,
heap_alloc: Option<FunctionId>,
heap_dealloc: Option<FunctionId>,
stack_pointer: GlobalId,
}

Expand Down Expand Up @@ -185,33 +185,34 @@ impl Context {
_ => {}
}
}
let heap_alloc = heap_alloc.ok_or_else(|| anyhow!("failed to find heap alloc"))?;
let heap_dealloc = heap_dealloc.ok_or_else(|| anyhow!("failed to find heap dealloc"))?;

// Create a shim function that looks like:
//
// (func __wbindgen_object_clone_ref (param i32) (result i32)
// (local i32)
// (table.set
// (tee_local 1 (call $heap_alloc))
// (table.get (local.get 0)))
// (local.get 1))
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 clone_ref = builder.finish(vec![arg], &mut module.funcs);
let name = "__wbindgen_object_clone_ref".to_string();
module.funcs.get_mut(clone_ref).name = Some(name);
let mut clone_ref = None;
if let Some(heap_alloc) = heap_alloc {
// Create a shim function that looks like:
//
// (func __wbindgen_object_clone_ref (param i32) (result i32)
// (local i32)
// (table.set
// (tee_local 1 (call $heap_alloc))
// (table.get (local.get 0)))
// (local.get 1))
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);
}

// And run the transformation!
Transform {
Expand All @@ -236,9 +237,9 @@ impl Transform<'_> {
self.find_intrinsics(module)?;

// Perform transformations of imports, exports, and function pointers.
self.process_imports(module);
self.process_imports(module)?;
assert!(self.cx.imports.is_empty());
self.process_exports(module);
self.process_exports(module)?;
assert!(self.cx.exports.is_empty());
self.process_elements(module)?;
assert!(self.cx.elements.is_empty());
Expand All @@ -251,7 +252,7 @@ impl Transform<'_> {

// Perform all instruction transformations to rewrite calls between
// functions and make sure everything is still hooked up right.
self.rewrite_calls(module);
self.rewrite_calls(module)?;

Ok(())
}
Expand Down Expand Up @@ -297,7 +298,22 @@ impl Transform<'_> {
Ok(())
}

fn process_imports(&mut self, module: &mut Module) {
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,
Expand All @@ -315,16 +331,17 @@ impl Transform<'_> {
&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) {
fn process_exports(&mut self, module: &mut Module) -> Result<(), Error> {
// let mut new_exports = Vec::new();
for export in module.exports.iter_mut() {
let f = match export.item {
Expand All @@ -342,9 +359,10 @@ impl Transform<'_> {
&mut module.types,
&mut module.funcs,
&mut module.locals,
);
)?;
export.item = shim.into();
}
Ok(())
}

fn process_elements(&mut self, module: &mut Module) -> Result<(), Error> {
Expand Down Expand Up @@ -372,7 +390,7 @@ impl Transform<'_> {
&mut module.types,
&mut module.funcs,
&mut module.locals,
);
)?;
kind.elements.push(Some(shim));
}

Expand All @@ -393,7 +411,7 @@ impl Transform<'_> {
types: &mut walrus::ModuleTypes,
funcs: &mut walrus::ModuleFunctions,
locals: &mut walrus::ModuleLocals,
) -> (FunctionId, TypeId) {
) -> 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),
Expand Down Expand Up @@ -508,15 +526,15 @@ impl Transform<'_> {
body.local_get(params[i])
.table_get(self.table)
.local_get(params[i])
.call(self.heap_dealloc);
.call(self.heap_dealloc()?);
}
Convert::Load { owned: false } => {
body.local_get(params[i]).table_get(self.table);
}
Convert::Store { owned: true } => {
// Allocate space for the anyref, store it, and then leave
// the index of the allocated anyref on the stack.
body.call(self.heap_alloc)
body.call(self.heap_alloc()?)
.local_tee(scratch_i32)
.local_get(params[i])
.table_set(self.table)
Expand Down Expand Up @@ -559,13 +577,13 @@ impl Transform<'_> {
body.local_tee(scratch_i32)
.table_get(self.table)
.local_get(scratch_i32)
.call(self.heap_dealloc);
.call(self.heap_dealloc()?);
} else {
// Imports are the opposite, we have any anyref on the stack
// and convert it to an i32 by allocating space for it and
// storing it there.
body.local_set(scratch_anyref)
.call(self.heap_alloc)
.call(self.heap_alloc()?)
.local_tee(scratch_i32)
.local_get(scratch_anyref)
.table_set(self.table)
Expand Down Expand Up @@ -604,20 +622,32 @@ impl Transform<'_> {
let name = format!("{}_anyref_shim", name);
funcs.get_mut(id).name = Some(name);
self.shims.insert(id);
(id, anyref_ty)
Ok((id, anyref_ty))
}

fn rewrite_calls(&mut self, module: &mut Module) {
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 { xform: self }, func, entry);
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<'_, '_> {
Expand Down Expand Up @@ -664,8 +694,8 @@ impl Transform<'_> {
seq.instrs
.insert(i, (RefNull {}.into(), InstrLocId::default()));
}
Intrinsic::DropRef => call.func = self.xform.heap_dealloc,
Intrinsic::CloneRef => call.func = self.xform.clone_ref,
Intrinsic::DropRef => call.func = self.heap_dealloc,
Intrinsic::CloneRef => call.func = self.clone_ref,
}
}
}
Expand Down
36 changes: 36 additions & 0 deletions crates/cli/tests/wasm-bindgen/main.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -197,3 +197,39 @@ fn bin_crate_works() {
.success()
.stdout("hello, world\n");
}

#[test]
fn empty_interface_types() {
let (mut cmd, _out_dir) = Project::new("empty_interface_types")
.file(
"src/lib.rs",
r#"
#[no_mangle]
pub extern fn foo() {}
"#
)
.file(
"Cargo.toml",
&format!(
"
[package]
name = \"empty_interface_types\"
authors = []
version = \"1.0.0\"
edition = '2018'
[dependencies]
wasm-bindgen = {{ path = '{}' }}
[lib]
crate-type = ['cdylib']
[workspace]
",
repo_root().display(),
),
)
.wasm_bindgen("");
cmd.env("WASM_INTERFACE_TYPES", "1");
cmd.assert().success();
}

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