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Add generic/typed take_struct imports + ops #11713

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faa4512
add generic/typed take_struct imports + ops
khagankhan Sep 18, 2025
b83186f
Address clippy error
khagankhan Sep 18, 2025
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105 changes: 90 additions & 15 deletions crates/fuzzing/src/generators/table_ops.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,9 @@ const TABLE_SIZE_RANGE: RangeInclusive<u32> = 0..=100;
const MAX_REC_GROUPS_RANGE: RangeInclusive<u32> = 0..=10;
const MAX_OPS: usize = 100;

const STRUCT_BASE: u32 = 5;
const TYPED_FN_BASE: u32 = 4;
Comment on lines +22 to +23
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Not necessary in this PR, but it would probably be easier/cleaner down the line to switch from constants to using the wasm_encoder::{Type,Func}Section::len methods to keep track of these things, so that we don't need to update these constants every time we unconditionally add a new type/function.

https://docs.rs/wasm-encoder/latest/wasm_encoder/struct.TypeSection.html#method.len


/// RecGroup ID struct definition.
#[derive(
Debug, Copy, Clone, Eq, PartialOrd, PartialEq, Ord, Hash, Default, Serialize, Deserialize,
Expand Down Expand Up @@ -191,6 +194,14 @@ impl TableOps {
vec![ValType::EXTERNREF, ValType::EXTERNREF, ValType::EXTERNREF],
);

types.ty().function(
vec![ValType::Ref(RefType {
nullable: false,
heap_type: wasm_encoder::HeapType::ANY,
})],
vec![],
);

let mut rec_groups: BTreeMap<RecGroupId, Vec<TypeId>> = self
.types
.rec_groups
Expand Down Expand Up @@ -219,16 +230,45 @@ impl TableOps {
}
};

let mut struct_count: u32 = 0;
for type_ids in rec_groups.values() {
let members: Vec<wasm_encoder::SubType> = type_ids.iter().map(encode_ty_id).collect();
types.ty().rec(members);
struct_count += type_ids.len() as u32;
}

let typed_ft_base: u32 = STRUCT_BASE + struct_count;
for i in 0..struct_count {
let concrete = STRUCT_BASE + i;
types.ty().function(
vec![ValType::Ref(RefType {
nullable: false,
heap_type: wasm_encoder::HeapType::Concrete(concrete),
})],
vec![],
);
}

// Import the GC function.
let mut imports = ImportSection::new();
imports.import("", "gc", EntityType::Function(0));
imports.import("", "take_refs", EntityType::Function(2));
imports.import("", "make_refs", EntityType::Function(3));
imports.import("", "take_struct", EntityType::Function(4));

let mut typed_names: Vec<String> = Vec::new();

for i in 0..struct_count {
Comment on lines +259 to +261
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Would be nice to have a single-sentence comment for readers here describing what this code is doing, so that they don't have to scrutinize it to figure out what is going on. Something like

For each of our concrete struct types, define a function import that takes an argument of that concrete type.

let concrete = STRUCT_BASE + i;
let ty_idx = typed_ft_base + i; //
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Empty comment at the end of line?

let name = format!("take_struct_{concrete}");
typed_names.push(name);
imports.import(
"",
typed_names.last().unwrap().as_str(),
EntityType::Function(ty_idx),
);
Comment on lines +264 to +270
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You can avoid the wonky .last() stuff by pushing the name after defining the import:

Suggested change
let name = format!("take_struct_{concrete}");
typed_names.push(name);
imports.import(
"",
typed_names.last().unwrap().as_str(),
EntityType::Function(ty_idx),
);
let name = format!("take_struct_{concrete}");
imports.import(
"",
&name,
EntityType::Function(ty_idx),
);
typed_names.push(name);

}

// Define our table.
let mut tables = TableSection::new();
Expand Down Expand Up @@ -258,7 +298,8 @@ impl TableOps {
functions.function(1);

let mut exports = ExportSection::new();
exports.export("run", ExportKind::Func, 3);
let imported_fn_count: u32 = 4 + struct_count;
exports.export("run", ExportKind::Func, imported_fn_count);

// Give ourselves one scratch local that we can use in various `TableOp`
// implementations.
Expand Down Expand Up @@ -600,6 +641,8 @@ define_table_ops! {
LocalSet(local_index: |ops| ops.num_params => u32) : 1 => 0,

StructNew(type_index: |ops| ops.max_types => u32) : 0 => 0,
TakeStructCall(type_index: |ops| ops.max_types => u32) : 0 => 0,
TakeTypedStructCall(type_index: |ops| ops.max_types => u32) : 0 => 0,

Drop : 1 => 0,

Expand All @@ -611,6 +654,7 @@ impl TableOp {
let gc_func_idx = 0;
let take_refs_func_idx = 1;
let make_refs_func_idx = 2;
let take_structref_idx = 3;

match self {
Self::Gc() => {
Expand Down Expand Up @@ -651,8 +695,18 @@ impl TableOp {
func.instruction(&Instruction::RefNull(wasm_encoder::HeapType::EXTERN));
}
Self::StructNew(x) => {
func.instruction(&Instruction::StructNew(x + 4));
func.instruction(&Instruction::Drop);
func.instruction(&Instruction::StructNew(x + 5));
func.instruction(&Instruction::Call(take_structref_idx));
}
Self::TakeStructCall(x) => {
func.instruction(&Instruction::StructNew(x + 5));
func.instruction(&Instruction::Call(take_structref_idx));
}
Self::TakeTypedStructCall(x) => {
let s = STRUCT_BASE + x;
let f = TYPED_FN_BASE + x;
func.instruction(&Instruction::StructNew(s));
func.instruction(&Instruction::Call(f));
Comment on lines +698 to +709
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Nothing to change in this PR, but I want to point out that these emitted instruction sequences are not our ideal end state. We want to separate struct.new from various calls and drops and have the existing TableOp::Drop be used to drop struct refs and we want the take_* calls to take a struct ref from the stack, not create a new one to pass to the import. This will require updating the abstract stack representation to track types, however, so it should be left to a follow up PR.

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Yes, I agree!

}
}
}
Expand Down Expand Up @@ -726,7 +780,7 @@ mod tests {

let mut session = mutatis::Session::new();

for _ in 0..5 {
for _ in 0..2048 {
session.mutate(&mut res)?;
let wasm = res.to_wasm_binary();

Expand All @@ -738,7 +792,6 @@ mod tests {
let wat = wasmprinter::print_bytes(&wasm).expect("[-] Failed .print_bytes(&wasm).");
let result = validator.validate_all(&wasm);
log::debug!("{wat}");
println!("{wat}");
assert!(
result.is_ok(),
"\n[-] Invalid wat: {}\n\t\t==== Failed Wat ====\n{}",
Expand Down Expand Up @@ -788,37 +841,59 @@ mod tests {
(type (;1;) (func (param externref externref)))
(type (;2;) (func (param externref externref externref)))
(type (;3;) (func (result externref externref externref)))
(type (;4;) (func (param (ref any))))
(rec
(type (;4;) (struct))
(type (;5;) (struct))
)
(rec)
(rec
(type (;5;) (struct))
(type (;6;) (struct))
)
(rec
(type (;6;) (struct))
(type (;7;) (struct))
(type (;8;) (struct))
(type (;9;) (struct))
)
(rec
(type (;9;) (struct))
(type (;10;) (struct))
(type (;11;) (struct))
)
(rec
(type (;11;) (struct))
(type (;12;) (struct))
(type (;13;) (struct))
)
(rec
(type (;13;) (struct))
(type (;14;) (struct))
)
(type (;15;) (func (param (ref 5))))
(type (;16;) (func (param (ref 6))))
(type (;17;) (func (param (ref 7))))
(type (;18;) (func (param (ref 8))))
(type (;19;) (func (param (ref 9))))
(type (;20;) (func (param (ref 10))))
(type (;21;) (func (param (ref 11))))
(type (;22;) (func (param (ref 12))))
(type (;23;) (func (param (ref 13))))
(type (;24;) (func (param (ref 14))))
(import "" "gc" (func (;0;) (type 0)))
(import "" "take_refs" (func (;1;) (type 2)))
(import "" "make_refs" (func (;2;) (type 3)))
(import "" "take_struct" (func (;3;) (type 4)))
(import "" "take_struct_5" (func (;4;) (type 15)))
(import "" "take_struct_6" (func (;5;) (type 16)))
(import "" "take_struct_7" (func (;6;) (type 17)))
(import "" "take_struct_8" (func (;7;) (type 18)))
(import "" "take_struct_9" (func (;8;) (type 19)))
(import "" "take_struct_10" (func (;9;) (type 20)))
(import "" "take_struct_11" (func (;10;) (type 21)))
(import "" "take_struct_12" (func (;11;) (type 22)))
(import "" "take_struct_13" (func (;12;) (type 23)))
(import "" "take_struct_14" (func (;13;) (type 24)))
(table (;0;) 5 externref)
(global (;0;) (mut externref) ref.null extern)
(global (;1;) (mut externref) ref.null extern)
(export "run" (func 3))
(func (;3;) (type 1) (param externref externref)
(export "run" (func 14))
(func (;14;) (type 1) (param externref externref)
(local externref)
loop ;; label = @1
ref.null extern
Expand All @@ -828,8 +903,8 @@ mod tests {
local.get 0
global.set 0
global.get 0
struct.new 4
drop
struct.new 5
call 3
drop
drop
drop
Expand Down
32 changes: 32 additions & 0 deletions crates/fuzzing/src/oracles.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -919,6 +919,38 @@ pub fn table_ops(
});
linker.define(&store, "", "make_refs", func).unwrap();

let func_ty = FuncType::new(
store.engine(),
vec![ValType::Ref(RefType::new(false, HeapType::Any))],
vec![],
);

let func = Func::new(&mut store, func_ty, {
move |_caller: Caller<'_, StoreLimits>, _params, _results| {
log::info!("table_ops: take_struct(<ref any>)");
Ok(())
}
});

linker.define(&store, "", "take_struct", func).unwrap();

for imp in module.imports() {
if imp.module() == "" {
let name = imp.name();
if name.starts_with("take_struct_") {
if let wasmtime::ExternType::Func(ft) = imp.ty() {
let imp_name = name.to_string();
let func =
Func::new(&mut store, ft.clone(), move |_caller, _params, _results| {
log::info!("table_ops: {imp_name}(<typed structref>)");
Ok(())
});
linker.define(&store, "", name, func).unwrap();
}
}
}
}

let instance = linker.instantiate(&mut store, &module).unwrap();
let run = instance.get_func(&mut store, "run").unwrap();

Expand Down