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wasm: Ensure List literals have an initialized capacity field

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Brian Carroll 2022-07-29 15:18:15 +02:00
parent 82e514678e
commit 5c6eed570d
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1 changed files with 13 additions and 4 deletions
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17
crates/compiler/gen_wasm/src/backend.rs
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@ -1479,7 +1479,14 @@ impl<'a> WasmBackend<'a> {
// length of the list
self.code_builder.get_local(stack_local_id);
self.code_builder.i32_const(elems.len() as i32);
self.code_builder.i32_store(Align::Bytes4, stack_offset + 4);
self.code_builder
.i32_store(Align::Bytes4, stack_offset + 4 * Builtin::WRAPPER_LEN);
// capacity of the list
self.code_builder.get_local(stack_local_id);
self.code_builder.i32_const(elems.len() as i32);
self.code_builder
.i32_store(Align::Bytes4, stack_offset + 4 * Builtin::WRAPPER_CAPACITY);
let mut elem_offset = 0;
@ -1521,12 +1528,14 @@ impl<'a> WasmBackend<'a> {
if let StoredValue::StackMemory { location, .. } = storage {
let (local_id, offset) = location.local_and_offset(self.storage.stack_frame_pointer);
// This is a minor cheat.
// What we want to write to stack memory is { elements: null, length: 0 }
// But instead of two 32-bit stores, we can do a single 64-bit store.
// Store 12 bytes of zeros { elements: null, length: 0, capacity: 0 }
debug_assert_eq!(Builtin::LIST_WORDS, 3);
self.code_builder.get_local(local_id);
self.code_builder.i64_const(0);
self.code_builder.i64_store(Align::Bytes4, offset);
self.code_builder.get_local(local_id);
self.code_builder.i32_const(0);
self.code_builder.i32_store(Align::Bytes4, offset + 8);
} else {
internal_error!("Unexpected storage for {:?}", sym)
}