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Fix equality on empty structures

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This commit is contained in:
Brian Carroll 2021-12-24 17:47:18 +00:00
parent a0afb64cb0
commit da4cf721cc
2 changed files with 17 additions and 12 deletions
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27
compiler/gen_wasm/src/backend.rs
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@ -1133,20 +1133,27 @@ impl<'a> WasmBackend<'a> {
}
}
// Empty record is always equal to empty record.
// There are no runtime arguments to check, so just emit true or false.
Layout::Struct(fields) if fields.is_empty() => {
self.code_builder
.i32_const(if lowlevel == LowLevel::Eq { 1 } else { 0 });
}
// Void is always equal to void. This is the type for the contents of the empty list in `[] == []`
// This code will never execute, but we need a true or false value to type-check
Layout::Union(UnionLayout::NonRecursive(tags)) if tags.is_empty() => {
self.code_builder
.i32_const(if lowlevel == LowLevel::Eq { 1 } else { 0 });
}
Layout::Builtin(Builtin::Dict(_, _) | Builtin::Set(_) | Builtin::List(_))
| Layout::Struct(_)
| Layout::Union(_)
| Layout::LambdaSet(_) => {
if arg_layout.stack_size(PTR_SIZE) == 0 {
// A zero-size type has only one possible value, like `{}` or `Unit`
// The arguments don't exist at runtime. Just emit True (Eq) or False (NotEq).
let result = matches!(lowlevel, LowLevel::Eq);
self.code_builder.i32_const(result as i32);
} else {
self.build_eq_specialized(&arg_layout, arguments, return_sym, storage);
if matches!(lowlevel, LowLevel::NotEq) {
self.code_builder.i32_eqz();
}
self.build_eq_specialized(&arg_layout, arguments, return_sym, storage);
if matches!(lowlevel, LowLevel::NotEq) {
self.code_builder.i32_eqz();
}
}