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merged 2 commits into from
Feb 2, 2020
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ir: codegen: Handle too large bitfield units. #1719

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780f2ba
ir: Deindent some code trivially.
emilio Feb 2, 2020
ca95f41
ir: codegen: Handle too large bitfield units.
emilio Feb 2, 2020
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24 changes: 16 additions & 8 deletions src/codegen/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1310,23 +1310,26 @@ impl<'a> FieldCodegen<'a> for BitfieldUnit {
F: Extend<proc_macro2::TokenStream>,
M: Extend<proc_macro2::TokenStream>,
{
use ir::ty::RUST_DERIVE_IN_ARRAY_LIMIT;

result.saw_bitfield_unit();

let layout = self.layout();
let unit_field_ty = helpers::bitfield_unit(ctx, layout);
let field_ty = {
let ty = helpers::bitfield_unit(ctx, self.layout());
if parent.is_union() && !parent.can_be_rust_union(ctx) {
result.saw_bindgen_union();
if ctx.options().enable_cxx_namespaces {
quote! {
root::__BindgenUnionField<#ty>
root::__BindgenUnionField<#unit_field_ty>
}
} else {
quote! {
__BindgenUnionField<#ty>
__BindgenUnionField<#unit_field_ty>
}
}
} else {
ty
unit_field_ty.clone()
}
};

Expand All @@ -1338,19 +1341,24 @@ impl<'a> FieldCodegen<'a> for BitfieldUnit {
};
fields.extend(Some(field));

let unit_field_ty = helpers::bitfield_unit(ctx, self.layout());

let ctor_name = self.ctor_name();
let mut ctor_params = vec![];
let mut ctor_impl = quote! {};
let mut generate_ctor = true;

// We cannot generate any constructor if the underlying storage can't
// implement AsRef<[u8]> / AsMut<[u8]> / etc.
let mut generate_ctor = layout.size <= RUST_DERIVE_IN_ARRAY_LIMIT;

for bf in self.bitfields() {
// Codegen not allowed for anonymous bitfields
if bf.name().is_none() {
continue;
}

if layout.size > RUST_DERIVE_IN_ARRAY_LIMIT {
continue;
}

let mut bitfield_representable_as_int = true;

bf.codegen(
Expand Down Expand Up @@ -1395,7 +1403,7 @@ impl<'a> FieldCodegen<'a> for BitfieldUnit {
}));
}

struct_layout.saw_bitfield_unit(self.layout());
struct_layout.saw_bitfield_unit(layout);
}
}

Expand Down
49 changes: 31 additions & 18 deletions src/ir/analysis/derive.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -240,25 +240,24 @@ impl<'ctx> CannotDerive<'ctx> {
self.derive_trait
);
return CanDerive::No;
} else {
if self.derive_trait.can_derive_large_array() {
trace!(" array can derive {}", self.derive_trait);
return CanDerive::Yes;
} else {
if len <= RUST_DERIVE_IN_ARRAY_LIMIT {
trace!(
" array is small enough to derive {}",
self.derive_trait
);
return CanDerive::Yes;
} else {
trace!(
" array is too large to derive {}, but it may be implemented", self.derive_trait
);
return CanDerive::Manually;
}
}
}

if self.derive_trait.can_derive_large_array() {
trace!(" array can derive {}", self.derive_trait);
return CanDerive::Yes;
}

if len > RUST_DERIVE_IN_ARRAY_LIMIT {
trace!(
" array is too large to derive {}, but it may be implemented", self.derive_trait
);
return CanDerive::Manually;
}
trace!(
" array is small enough to derive {}",
self.derive_trait
);
return CanDerive::Yes;
}
TypeKind::Vector(t, len) => {
let inner_type =
Expand Down Expand Up @@ -362,6 +361,20 @@ impl<'ctx> CannotDerive<'ctx> {
return CanDerive::No;
}

// Bitfield units are always represented as arrays of u8, but
// they're not traced as arrays, so we need to check here
// instead.
if !self.derive_trait.can_derive_large_array() &&
info.has_too_large_bitfield_unit() &&
!item.is_opaque(self.ctx, &())
{
trace!(
" cannot derive {} for comp with too large bitfield unit",
self.derive_trait
);
return CanDerive::No;
}

let pred = self.derive_trait.consider_edge_comp();
return self.constrain_join(item, pred);
}
Expand Down
64 changes: 50 additions & 14 deletions src/ir/comp.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -6,9 +6,9 @@ use super::context::{BindgenContext, FunctionId, ItemId, TypeId, VarId};
use super::dot::DotAttributes;
use super::item::{IsOpaque, Item};
use super::layout::Layout;
// use super::ty::RUST_DERIVE_IN_ARRAY_LIMIT;
use super::template::TemplateParameters;
use super::traversal::{EdgeKind, Trace, Tracer};
use super::ty::RUST_DERIVE_IN_ARRAY_LIMIT;
use clang;
use codegen::struct_layout::{align_to, bytes_from_bits_pow2};
use ir::derive::CanDeriveCopy;
Expand Down Expand Up @@ -497,7 +497,7 @@ fn raw_fields_to_fields_and_bitfield_units<I>(
ctx: &BindgenContext,
raw_fields: I,
packed: bool,
) -> Result<Vec<Field>, ()>
) -> Result<(Vec<Field>, bool), ()>
where
I: IntoIterator<Item = RawField>,
{
Expand Down Expand Up @@ -543,7 +543,7 @@ where
"The above loop should consume all items in `raw_fields`"
);

Ok(fields)
Ok((fields, bitfield_unit_count != 0))
}

/// Given a set of contiguous raw bitfields, group and allocate them into
Expand Down Expand Up @@ -707,7 +707,10 @@ where
#[derive(Debug)]
enum CompFields {
BeforeComputingBitfieldUnits(Vec<RawField>),
AfterComputingBitfieldUnits(Vec<Field>),
AfterComputingBitfieldUnits {
fields: Vec<Field>,
has_bitfield_units: bool,
},
ErrorComputingBitfieldUnits,
}

Expand Down Expand Up @@ -744,10 +747,13 @@ impl CompFields {
let result = raw_fields_to_fields_and_bitfield_units(ctx, raws, packed);

match result {
Ok(fields_and_units) => {
Ok((fields, has_bitfield_units)) => {
mem::replace(
self,
CompFields::AfterComputingBitfieldUnits(fields_and_units),
CompFields::AfterComputingBitfieldUnits {
fields,
has_bitfield_units,
},
);
}
Err(()) => {
Expand All @@ -758,11 +764,11 @@ impl CompFields {

fn deanonymize_fields(&mut self, ctx: &BindgenContext, methods: &[Method]) {
let fields = match *self {
CompFields::AfterComputingBitfieldUnits(ref mut fields) => fields,
CompFields::ErrorComputingBitfieldUnits => {
// Nothing to do here.
return;
}
CompFields::AfterComputingBitfieldUnits {
ref mut fields, ..
} => fields,
// Nothing to do here.
CompFields::ErrorComputingBitfieldUnits => return,
CompFields::BeforeComputingBitfieldUnits(_) => {
panic!("Not yet computed bitfield units.");
}
Expand Down Expand Up @@ -859,7 +865,7 @@ impl Trace for CompFields {
tracer.visit_kind(f.ty().into(), EdgeKind::Field);
}
}
CompFields::AfterComputingBitfieldUnits(ref fields) => {
CompFields::AfterComputingBitfieldUnits { ref fields, .. } => {
for f in fields {
f.trace(context, tracer, &());
}
Expand Down Expand Up @@ -1061,7 +1067,7 @@ impl CompInfo {
/// Construct a new compound type.
pub fn new(kind: CompKind) -> Self {
CompInfo {
kind: kind,
kind,
fields: CompFields::default(),
template_params: vec![],
methods: vec![],
Expand Down Expand Up @@ -1124,13 +1130,43 @@ impl CompInfo {
pub fn fields(&self) -> &[Field] {
match self.fields {
CompFields::ErrorComputingBitfieldUnits => &[],
CompFields::AfterComputingBitfieldUnits(ref fields) => fields,
CompFields::AfterComputingBitfieldUnits { ref fields, .. } => {
fields
}
CompFields::BeforeComputingBitfieldUnits(_) => {
panic!("Should always have computed bitfield units first");
}
}
}

fn has_bitfields(&self) -> bool {
match self.fields {
CompFields::ErrorComputingBitfieldUnits => false,
CompFields::AfterComputingBitfieldUnits {
has_bitfield_units,
..
} => has_bitfield_units,
CompFields::BeforeComputingBitfieldUnits(_) => {
panic!("Should always have computed bitfield units first");
}
}
}

/// Returns whether we have a too large bitfield unit, in which case we may
/// not be able to derive some of the things we should be able to normally
/// derive.
pub fn has_too_large_bitfield_unit(&self) -> bool {
if !self.has_bitfields() {
return false;
}
self.fields().iter().any(|field| match *field {
Field::DataMember(..) => false,
Field::Bitfields(ref unit) => {
unit.layout.size > RUST_DERIVE_IN_ARRAY_LIMIT
}
})
}

/// Does this type have any template parameters that aren't types
/// (e.g. int)?
pub fn has_non_type_template_params(&self) -> bool {
Expand Down
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