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Split out an Enum type from the Variant type (#211)
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* Split out an `Enum` type from the `Variant` type

This was not 100% straightforward as the lowering of an enum wants to be
`the_value as i32` in the Rust-to-wasm generator, but that's not working
because sometimes `the_value` has type `&T` instead of `T` which can't
be cast to `i32`. This means that lowerings in Rust are now always
producing a `match` statement which should optimize to the same thing
but won't be as easy on the eyes.

Additionally a small change was made to the C code generator that
`expected<_, _>` is now represented as a struct-of-union instead of
special-cased to be an `enum`. The only reason it was special cased
prior was that it was accidentally interpreted as an `enum` due to the
`Variant::is_enum` check (which is now removed).

* Move a test
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@alexcrichton
alexcrichton authored May 3, 2022
1 parent 744d5dd commit d218845
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Showing 30 changed files with 817 additions and 1,020 deletions.
163 changes: 86 additions & 77 deletions crates/gen-c/src/lib.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -165,7 +165,8 @@ impl C {
match ty {
Type::Id(id) => match &iface.types[*id].kind {
TypeDefKind::Type(t) => self.is_arg_by_pointer(iface, t),
TypeDefKind::Variant(v) => !v.is_enum(),
TypeDefKind::Variant(_) => true,
TypeDefKind::Enum(_) => false,
TypeDefKind::Flags(_) => false,
TypeDefKind::Tuple(_) | TypeDefKind::Record(_) | TypeDefKind::List(_) => true,
},
Expand Down Expand Up @@ -244,6 +245,7 @@ impl C {
TypeDefKind::Type(t) => self.print_ty(iface, t),
TypeDefKind::Flags(_)
| TypeDefKind::Tuple(_)
| TypeDefKind::Enum(_)
| TypeDefKind::Record(_)
| TypeDefKind::List(_)
| TypeDefKind::Variant(_) => {
Expand Down Expand Up @@ -282,7 +284,9 @@ impl C {
}
match &ty.kind {
TypeDefKind::Type(t) => self.print_ty_name(iface, t),
TypeDefKind::Record(_) | TypeDefKind::Flags(_) => unimplemented!(),
TypeDefKind::Record(_) | TypeDefKind::Flags(_) | TypeDefKind::Enum(_) => {
unimplemented!()
}
TypeDefKind::Tuple(t) => {
self.src.h("tuple");
self.src.h(&t.types.len().to_string());
Expand Down Expand Up @@ -324,7 +328,10 @@ impl C {
self.src.h("typedef ");
let kind = &iface.types[ty].kind;
match kind {
TypeDefKind::Type(_) | TypeDefKind::Flags(_) | TypeDefKind::Record(_) => {
TypeDefKind::Type(_)
| TypeDefKind::Flags(_)
| TypeDefKind::Record(_)
| TypeDefKind::Enum(_) => {
unreachable!()
}
TypeDefKind::Tuple(t) => {
Expand All @@ -347,25 +354,21 @@ impl C {
self.src.h(" val;\n");
self.src.h("}");
} else if let Some((ok, err)) = v.as_expected() {
if ok.is_none() && err.is_none() {
self.src.h("uint8_t");
} else {
self.src.h("struct {
// 0 if `val` is `ok`, 1 otherwise
uint8_t tag;
union {
");
if let Some(ok) = ok {
self.print_ty(iface, ok);
self.src.h(" ok;\n");
}
if let Some(err) = err {
self.print_ty(iface, err);
self.src.h(" err;\n");
}
self.src.h("} val;\n");
self.src.h("}");
self.src.h("struct {
// 0 if `val` is `ok`, 1 otherwise
uint8_t tag;
union {
");
if let Some(ok) = ok {
self.print_ty(iface, ok);
self.src.h(" ok;\n");
}
if let Some(err) = err {
self.print_ty(iface, err);
self.src.h(" err;\n");
}
self.src.h("} val;\n");
self.src.h("}");
} else {
unimplemented!();
}
Expand Down Expand Up @@ -453,6 +456,7 @@ impl C {
TypeDefKind::Type(t) => self.free(iface, t, "ptr"),

TypeDefKind::Flags(_) => {}
TypeDefKind::Enum(_) => {}

TypeDefKind::Record(r) => {
for field in r.fields.iter() {
Expand Down Expand Up @@ -527,6 +531,7 @@ impl C {
TypeDefKind::Record(r) => r.fields.iter().any(|t| self.owns_anything(iface, &t.ty)),
TypeDefKind::Tuple(t) => t.types.iter().any(|t| self.owns_anything(iface, t)),
TypeDefKind::Flags(_) => false,
TypeDefKind::Enum(_) => false,
TypeDefKind::List(_) => true,
TypeDefKind::Variant(v) => v
.cases
Expand Down Expand Up @@ -597,8 +602,8 @@ impl Return {
// other records/lists/buffers always go to return pointers
TypeDefKind::List(_) => self.retptrs.push(*orig_ty),

// Enums are scalars (this includes bools)
TypeDefKind::Variant(v) if v.is_enum() => {
// Enums are scalars
TypeDefKind::Enum(_) => {
self.scalar = Some(Scalar::Type(*orig_ty));
}

Expand All @@ -617,17 +622,15 @@ impl Return {
// returned through the normal returns.
if let Some((ok, err)) = r.as_expected() {
if let Some(Type::Id(err)) = err {
if let TypeDefKind::Variant(e) = &iface.types[*err].kind {
if e.is_enum() {
self.scalar = Some(Scalar::ExpectedEnum {
err: *err,
max_err: e.cases.len(),
});
if let Some(ok) = ok {
self.splat_tuples(iface, ok, ok);
}
return;
if let TypeDefKind::Enum(e) = &iface.types[*err].kind {
self.scalar = Some(Scalar::ExpectedEnum {
err: *err,
max_err: e.cases.len(),
});
if let Some(ok) = ok {
self.splat_tuples(iface, ok, ok);
}
return;
}
}
}
Expand Down Expand Up @@ -760,40 +763,31 @@ impl Generator for C {
let prev = mem::take(&mut self.src.header);
self.docs(docs);
self.names.insert(&name.to_snake_case()).unwrap();
if variant.is_enum() {
self.src.h("typedef ");
self.src.h(int_repr(variant.tag));
self.src.h(" ");
self.print_namespace(iface);
self.src.h(&name.to_snake_case());
self.src.h("_t;\n");
} else {
self.src.h("typedef struct {\n");
self.src.h(int_repr(variant.tag));
self.src.h(" tag;\n");
match variant.as_option() {
Some(ty) => {
self.print_ty(iface, ty);
self.src.h(" val;\n");
}
None => {
self.src.h("union {\n");
for case in variant.cases.iter() {
if let Some(ty) = &case.ty {
self.print_ty(iface, ty);
self.src.h(" ");
self.src.h(&case_field_name(case));
self.src.h(";\n");
}
self.src.h("typedef struct {\n");
self.src.h(int_repr(variant.tag));
self.src.h(" tag;\n");
match variant.as_option() {
Some(ty) => {
self.print_ty(iface, ty);
self.src.h(" val;\n");
}
None => {
self.src.h("union {\n");
for case in variant.cases.iter() {
if let Some(ty) = &case.ty {
self.print_ty(iface, ty);
self.src.h(" ");
self.src.h(&case_field_name(case));
self.src.h(";\n");
}
self.src.h("} val;\n");
}
self.src.h("} val;\n");
}
self.src.h("} ");
self.print_namespace(iface);
self.src.h(&name.to_snake_case());
self.src.h("_t;\n");
}
self.src.h("} ");
self.print_namespace(iface);
self.src.h(&name.to_snake_case());
self.src.h("_t;\n");
for (i, case) in variant.cases.iter().enumerate() {
self.src.h(&format!(
"#define {}_{}_{} {}\n",
Expand All @@ -808,6 +802,30 @@ impl Generator for C {
.insert(id, mem::replace(&mut self.src.header, prev));
}

fn type_enum(&mut self, iface: &Interface, id: TypeId, name: &str, enum_: &Enum, docs: &Docs) {
let prev = mem::take(&mut self.src.header);
self.docs(docs);
self.names.insert(&name.to_snake_case()).unwrap();
self.src.h("typedef ");
self.src.h(int_repr(enum_.tag()));
self.src.h(" ");
self.print_namespace(iface);
self.src.h(&name.to_snake_case());
self.src.h("_t;\n");
for (i, case) in enum_.cases.iter().enumerate() {
self.src.h(&format!(
"#define {}_{}_{} {}\n",
iface.name.to_shouty_snake_case(),
name.to_shouty_snake_case(),
case.name.to_shouty_snake_case(),
i,
));
}

self.types
.insert(id, mem::replace(&mut self.src.header, prev));
}

fn type_resource(&mut self, iface: &Interface, ty: ResourceId) {
drop((iface, ty));
}
Expand Down Expand Up @@ -1477,6 +1495,7 @@ impl Bindgen for FunctionBindgen<'_> {
results.push(format!("*{}", name));
self.payloads.push(name);
}

Instruction::VariantLower {
variant,
results: result_types,
Expand All @@ -1491,11 +1510,6 @@ impl Bindgen for FunctionBindgen<'_> {
.drain(self.payloads.len() - variant.cases.len()..)
.collect::<Vec<_>>();

if results.len() == 1 && variant.is_enum() {
results.push(format!("(int32_t) {}", operands[0]));
return;
}

let mut variant_results = Vec::new();
for ty in result_types.iter() {
let name = self.locals.tmp("variant");
Expand All @@ -1507,11 +1521,7 @@ impl Bindgen for FunctionBindgen<'_> {
variant_results.push(name);
}

let expr_to_match = if variant.is_enum() {
operands[0].to_string()
} else {
format!("({}).tag", operands[0])
};
let expr_to_match = format!("({}).tag", operands[0]);

self.src
.push_str(&format!("switch ((int32_t) {}) {{\n", expr_to_match));
Expand Down Expand Up @@ -1549,10 +1559,6 @@ impl Bindgen for FunctionBindgen<'_> {
.drain(self.blocks.len() - variant.cases.len()..)
.collect::<Vec<_>>();

if variant.is_enum() {
return results.push(operands.pop().unwrap());
}

let ty = self.gen.type_string(iface, &Type::Id(*ty));
let result = self.locals.tmp("variant");
self.src.push_str(&format!("{} {};\n", ty, result));
Expand Down Expand Up @@ -1583,6 +1589,9 @@ impl Bindgen for FunctionBindgen<'_> {
results.push(result);
}

Instruction::EnumLower { .. } => results.push(format!("(int32_t) {}", operands[0])),
Instruction::EnumLift { .. } => results.push(operands.pop().unwrap()),

Instruction::ListCanonLower { .. } | Instruction::StringLower { .. } => {
results.push(format!("(int32_t) ({}).ptr", operands[0]));
results.push(format!("(int32_t) ({}).len", operands[0]));
Expand Down
4 changes: 4 additions & 0 deletions crates/gen-core/src/lib.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -65,6 +65,7 @@ pub trait Generator {
variant: &Variant,
docs: &Docs,
);
fn type_enum(&mut self, iface: &Interface, id: TypeId, name: &str, enum_: &Enum, docs: &Docs);
fn type_resource(&mut self, iface: &Interface, ty: ResourceId);
fn type_alias(&mut self, iface: &Interface, id: TypeId, name: &str, ty: &Type, docs: &Docs);
fn type_list(&mut self, iface: &Interface, id: TypeId, name: &str, ty: &Type, docs: &Docs);
Expand Down Expand Up @@ -92,6 +93,7 @@ pub trait Generator {
TypeDefKind::Record(record) => self.type_record(iface, id, name, record, &ty.docs),
TypeDefKind::Flags(flags) => self.type_flags(iface, id, name, flags, &ty.docs),
TypeDefKind::Tuple(tuple) => self.type_tuple(iface, id, name, tuple, &ty.docs),
TypeDefKind::Enum(enum_) => self.type_enum(iface, id, name, enum_, &ty.docs),
TypeDefKind::Variant(variant) => {
self.type_variant(iface, id, name, variant, &ty.docs)
}
Expand Down Expand Up @@ -198,6 +200,7 @@ impl Types {
}
}
TypeDefKind::Flags(_) => {}
TypeDefKind::Enum(_) => {}
TypeDefKind::Variant(v) => {
for case in v.cases.iter() {
if let Some(ty) = &case.ty {
Expand Down Expand Up @@ -241,6 +244,7 @@ impl Types {
}
}
TypeDefKind::Flags(_) => {}
TypeDefKind::Enum(_) => {}
TypeDefKind::Variant(v) => {
for case in v.cases.iter() {
if let Some(ty) = &case.ty {
Expand Down
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