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use crate::{FlagsRepr, Int, Resolve, Type, TypeDef, TypeDefKind};
#[derive(Default)]
pub struct SizeAlign {
map: Vec<(usize, usize)>,
}
impl SizeAlign {
pub fn fill(&mut self, resolve: &Resolve) {
self.map = Vec::new();
for (_, ty) in resolve.types.iter() {
let pair = self.calculate(ty);
self.map.push(pair);
}
}
fn calculate(&self, ty: &TypeDef) -> (usize, usize) {
match &ty.kind {
TypeDefKind::Type(t) => (self.size(t), self.align(t)),
TypeDefKind::List(_) => (8, 4),
TypeDefKind::Record(r) => self.record(r.fields.iter().map(|f| &f.ty)),
TypeDefKind::Tuple(t) => self.record(t.types.iter()),
TypeDefKind::Flags(f) => match f.repr() {
FlagsRepr::U8 => (1, 1),
FlagsRepr::U16 => (2, 2),
FlagsRepr::U32(n) => (n * 4, 4),
},
TypeDefKind::Variant(v) => self.variant(v.tag(), v.cases.iter().map(|c| c.ty.as_ref())),
TypeDefKind::Enum(e) => self.variant(e.tag(), []),
TypeDefKind::Option(t) => self.variant(Int::U8, [Some(t)]),
TypeDefKind::Result(r) => self.variant(Int::U8, [r.ok.as_ref(), r.err.as_ref()]),
TypeDefKind::Union(u) => self.variant(u.tag(), u.cases.iter().map(|c| Some(&c.ty))),
TypeDefKind::Future(_) => (4, 4),
TypeDefKind::Stream(_) => (4, 4),
TypeDefKind::Unknown => unreachable!(),
}
}
pub fn size(&self, ty: &Type) -> usize {
match ty {
Type::Bool | Type::U8 | Type::S8 => 1,
Type::U16 | Type::S16 => 2,
Type::U32 | Type::S32 | Type::Float32 | Type::Char => 4,
Type::U64 | Type::S64 | Type::Float64 | Type::String => 8,
Type::Id(id) => self.map[id.index()].0,
}
}
pub fn align(&self, ty: &Type) -> usize {
match ty {
Type::Bool | Type::U8 | Type::S8 => 1,
Type::U16 | Type::S16 => 2,
Type::U32 | Type::S32 | Type::Float32 | Type::Char | Type::String => 4,
Type::U64 | Type::S64 | Type::Float64 => 8,
Type::Id(id) => self.map[id.index()].1,
}
}
pub fn field_offsets<'a>(
&self,
types: impl IntoIterator<Item = &'a Type>,
) -> Vec<(usize, &'a Type)> {
let mut cur = 0;
types
.into_iter()
.map(|ty| {
let ret = align_to(cur, self.align(ty));
cur = ret + self.size(ty);
(ret, ty)
})
.collect()
}
pub fn payload_offset<'a>(
&self,
tag: Int,
cases: impl IntoIterator<Item = Option<&'a Type>>,
) -> usize {
let mut max_align = 1;
for ty in cases {
if let Some(ty) = ty {
max_align = max_align.max(self.align(ty));
}
}
let tag_size = int_size_align(tag).0;
align_to(tag_size, max_align)
}
pub fn record<'a>(&self, types: impl Iterator<Item = &'a Type>) -> (usize, usize) {
let mut size = 0;
let mut align = 1;
for ty in types {
let field_size = self.size(ty);
let field_align = self.align(ty);
size = align_to(size, field_align) + field_size;
align = align.max(field_align);
}
(align_to(size, align), align)
}
pub fn params<'a>(&self, types: impl IntoIterator<Item = &'a Type>) -> (usize, usize) {
self.record(types.into_iter())
}
fn variant<'a>(
&self,
tag: Int,
types: impl IntoIterator<Item = Option<&'a Type>>,
) -> (usize, usize) {
let (discrim_size, discrim_align) = int_size_align(tag);
let mut case_size = 0;
let mut case_align = 1;
for ty in types {
if let Some(ty) = ty {
case_size = case_size.max(self.size(ty));
case_align = case_align.max(self.align(ty));
}
}
let align = discrim_align.max(case_align);
(
align_to(align_to(discrim_size, case_align) + case_size, align),
align,
)
}
}
fn int_size_align(i: Int) -> (usize, usize) {
match i {
Int::U8 => (1, 1),
Int::U16 => (2, 2),
Int::U32 => (4, 4),
Int::U64 => (8, 8),
}
}
pub(crate) fn align_to(val: usize, align: usize) -> usize {
(val + align - 1) & !(align - 1)
}