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use std::fmt::{self, Debug};
use std::num::NonZero;
use std::ops::RangeInclusive;
use serde::Serialize;
use crate::compiler_interface::with;
use crate::mir::FieldIdx;
use crate::target::{MachineInfo, MachineSize as Size};
use crate::ty::{Align, IndexedVal, Ty, VariantIdx};
use crate::{error, Error, Opaque};
/// A function ABI definition.
#[derive(Clone, Debug, PartialEq, Eq, Hash, Serialize)]
pub struct FnAbi {
/// The types of each argument.
pub args: Vec<ArgAbi>,
/// The expected return type.
pub ret: ArgAbi,
/// The count of non-variadic arguments.
///
/// Should only be different from `args.len()` when a function is a C variadic function.
pub fixed_count: u32,
/// The ABI convention.
pub conv: CallConvention,
/// Whether this is a variadic C function,
pub c_variadic: bool,
}
/// Information about the ABI of a function's argument, or return value.
#[derive(Clone, Debug, PartialEq, Eq, Hash, Serialize)]
pub struct ArgAbi {
pub ty: Ty,
pub layout: Layout,
pub mode: PassMode,
}
/// How a function argument should be passed in to the target function.
#[derive(Clone, Debug, PartialEq, Eq, Hash, Serialize)]
pub enum PassMode {
/// Ignore the argument.
///
/// The argument is either uninhabited or a ZST.
Ignore,
/// Pass the argument directly.
///
/// The argument has a layout abi of `Scalar` or `Vector`.
Direct(Opaque),
/// Pass a pair's elements directly in two arguments.
///
/// The argument has a layout abi of `ScalarPair`.
Pair(Opaque, Opaque),
/// Pass the argument after casting it.
Cast { pad_i32: bool, cast: Opaque },
/// Pass the argument indirectly via a hidden pointer.
Indirect { attrs: Opaque, meta_attrs: Opaque, on_stack: bool },
}
/// The layout of a type, alongside the type itself.
#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, Serialize)]
pub struct TyAndLayout {
pub ty: Ty,
pub layout: Layout,
}
/// The layout of a type in memory.
#[derive(Clone, Debug, PartialEq, Eq, Hash, Serialize)]
pub struct LayoutShape {
/// The fields location withing the layout
pub fields: FieldsShape,
/// Encodes information about multi-variant layouts.
/// Even with `Multiple` variants, a layout still has its own fields! Those are then
/// shared between all variants.
///
/// To access all fields of this layout, both `fields` and the fields of the active variant
/// must be taken into account.
pub variants: VariantsShape,
/// The `abi` defines how this data is passed between functions.
pub abi: ValueAbi,
/// The ABI mandated alignment in bytes.
pub abi_align: Align,
/// The size of this layout in bytes.
pub size: Size,
}
impl LayoutShape {
/// Returns `true` if the layout corresponds to an unsized type.
#[inline]
pub fn is_unsized(&self) -> bool {
self.abi.is_unsized()
}
#[inline]
pub fn is_sized(&self) -> bool {
!self.abi.is_unsized()
}
/// Returns `true` if the type is sized and a 1-ZST (meaning it has size 0 and alignment 1).
pub fn is_1zst(&self) -> bool {
self.is_sized() && self.size.bits() == 0 && self.abi_align == 1
}
}
#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, Serialize)]
pub struct Layout(usize);
impl Layout {
pub fn shape(self) -> LayoutShape {
with(|cx| cx.layout_shape(self))
}
}
impl IndexedVal for Layout {
fn to_val(index: usize) -> Self {
Layout(index)
}
fn to_index(&self) -> usize {
self.0
}
}
/// Describes how the fields of a type are shaped in memory.
#[derive(Clone, Debug, PartialEq, Eq, Hash, Serialize)]
pub enum FieldsShape {
/// Scalar primitives and `!`, which never have fields.
Primitive,
/// All fields start at no offset. The `usize` is the field count.
Union(NonZero<usize>),
/// Array/vector-like placement, with all fields of identical types.
Array { stride: Size, count: u64 },
/// Struct-like placement, with precomputed offsets.
///
/// Fields are guaranteed to not overlap, but note that gaps
/// before, between and after all the fields are NOT always
/// padding, and as such their contents may not be discarded.
/// For example, enum variants leave a gap at the start,
/// where the discriminant field in the enum layout goes.
Arbitrary {
/// Offsets for the first byte of each field,
/// ordered to match the source definition order.
/// I.e.: It follows the same order as [crate::ty::VariantDef::fields()].
/// This vector does not go in increasing order.
offsets: Vec<Size>,
},
}
impl FieldsShape {
pub fn fields_by_offset_order(&self) -> Vec<FieldIdx> {
match self {
FieldsShape::Primitive => vec![],
FieldsShape::Union(_) | FieldsShape::Array { .. } => (0..self.count()).collect(),
FieldsShape::Arbitrary { offsets, .. } => {
let mut indices = (0..offsets.len()).collect::<Vec<_>>();
indices.sort_by_key(|idx| offsets[*idx]);
indices
}
}
}
pub fn count(&self) -> usize {
match self {
FieldsShape::Primitive => 0,
FieldsShape::Union(count) => count.get(),
FieldsShape::Array { count, .. } => *count as usize,
FieldsShape::Arbitrary { offsets, .. } => offsets.len(),
}
}
}
#[derive(Clone, Debug, PartialEq, Eq, Hash, Serialize)]
pub enum VariantsShape {
/// Single enum variants, structs/tuples, unions, and all non-ADTs.
Single { index: VariantIdx },
/// Enum-likes with more than one inhabited variant: each variant comes with
/// a *discriminant* (usually the same as the variant index but the user can
/// assign explicit discriminant values). That discriminant is encoded
/// as a *tag* on the machine. The layout of each variant is
/// a struct, and they all have space reserved for the tag.
/// For enums, the tag is the sole field of the layout.
Multiple {
tag: Scalar,
tag_encoding: TagEncoding,
tag_field: usize,
variants: Vec<LayoutShape>,
},
}
#[derive(Clone, Debug, PartialEq, Eq, Hash, Serialize)]
pub enum TagEncoding {
/// The tag directly stores the discriminant, but possibly with a smaller layout
/// (so converting the tag to the discriminant can require sign extension).
Direct,
/// Niche (values invalid for a type) encoding the discriminant:
/// Discriminant and variant index coincide.
/// The variant `untagged_variant` contains a niche at an arbitrary
/// offset (field `tag_field` of the enum), which for a variant with
/// discriminant `d` is set to
/// `(d - niche_variants.start).wrapping_add(niche_start)`.
///
/// For example, `Option<(usize, &T)>` is represented such that
/// `None` has a null pointer for the second tuple field, and
/// `Some` is the identity function (with a non-null reference).
Niche {
untagged_variant: VariantIdx,
niche_variants: RangeInclusive<VariantIdx>,
niche_start: u128,
},
}
/// Describes how values of the type are passed by target ABIs,
/// in terms of categories of C types there are ABI rules for.
#[derive(Clone, Debug, PartialEq, Eq, Hash, Serialize)]
pub enum ValueAbi {
Uninhabited,
Scalar(Scalar),
ScalarPair(Scalar, Scalar),
Vector {
element: Scalar,
count: u64,
},
Aggregate {
/// If true, the size is exact, otherwise it's only a lower bound.
sized: bool,
},
}
impl ValueAbi {
/// Returns `true` if the layout corresponds to an unsized type.
pub fn is_unsized(&self) -> bool {
match *self {
ValueAbi::Uninhabited
| ValueAbi::Scalar(_)
| ValueAbi::ScalarPair(..)
| ValueAbi::Vector { .. } => false,
ValueAbi::Aggregate { sized } => !sized,
}
}
}
/// Information about one scalar component of a Rust type.
#[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, Serialize)]
pub enum Scalar {
Initialized {
/// The primitive type used to represent this value.
value: Primitive,
/// The range that represents valid values.
/// The range must be valid for the `primitive` size.
valid_range: WrappingRange,
},
Union {
/// Unions never have niches, so there is no `valid_range`.
/// Even for unions, we need to use the correct registers for the kind of
/// values inside the union, so we keep the `Primitive` type around.
/// It is also used to compute the size of the scalar.
value: Primitive,
},
}
impl Scalar {
pub fn has_niche(&self, target: &MachineInfo) -> bool {
match self {
Scalar::Initialized { value, valid_range } => {
!valid_range.is_full(value.size(target)).unwrap()
}
Scalar::Union { .. } => false,
}
}
}
/// Fundamental unit of memory access and layout.
#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, Serialize)]
pub enum Primitive {
/// The `bool` is the signedness of the `Integer` type.
///
/// One would think we would not care about such details this low down,
/// but some ABIs are described in terms of C types and ISAs where the
/// integer arithmetic is done on {sign,zero}-extended registers, e.g.
/// a negative integer passed by zero-extension will appear positive in
/// the callee, and most operations on it will produce the wrong values.
Int {
length: IntegerLength,
signed: bool,
},
Float {
length: FloatLength,
},
Pointer(AddressSpace),
}
impl Primitive {
pub fn size(self, target: &MachineInfo) -> Size {
match self {
Primitive::Int { length, .. } => Size::from_bits(length.bits()),
Primitive::Float { length } => Size::from_bits(length.bits()),
Primitive::Pointer(_) => target.pointer_width,
}
}
}
/// Enum representing the existing integer lengths.
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, Serialize)]
pub enum IntegerLength {
I8,
I16,
I32,
I64,
I128,
}
/// Enum representing the existing float lengths.
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, Serialize)]
pub enum FloatLength {
F16,
F32,
F64,
F128,
}
impl IntegerLength {
pub fn bits(self) -> usize {
match self {
IntegerLength::I8 => 8,
IntegerLength::I16 => 16,
IntegerLength::I32 => 32,
IntegerLength::I64 => 64,
IntegerLength::I128 => 128,
}
}
}
impl FloatLength {
pub fn bits(self) -> usize {
match self {
FloatLength::F16 => 16,
FloatLength::F32 => 32,
FloatLength::F64 => 64,
FloatLength::F128 => 128,
}
}
}
/// An identifier that specifies the address space that some operation
/// should operate on. Special address spaces have an effect on code generation,
/// depending on the target and the address spaces it implements.
#[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash, Serialize)]
pub struct AddressSpace(pub u32);
impl AddressSpace {
/// The default address space, corresponding to data space.
pub const DATA: Self = AddressSpace(0);
}
/// Inclusive wrap-around range of valid values (bitwise representation), that is, if
/// start > end, it represents `start..=MAX`, followed by `0..=end`.
///
/// That is, for an i8 primitive, a range of `254..=2` means following
/// sequence:
///
/// 254 (-2), 255 (-1), 0, 1, 2
#[derive(Clone, Copy, PartialEq, Eq, Hash, Serialize)]
pub struct WrappingRange {
pub start: u128,
pub end: u128,
}
impl WrappingRange {
/// Returns `true` if `size` completely fills the range.
#[inline]
pub fn is_full(&self, size: Size) -> Result<bool, Error> {
let Some(max_value) = size.unsigned_int_max() else {
return Err(error!("Expected size <= 128 bits, but found {} instead", size.bits()));
};
if self.start <= max_value && self.end <= max_value {
Ok(self.start == (self.end.wrapping_add(1) & max_value))
} else {
Err(error!("Range `{self:?}` out of bounds for size `{}` bits.", size.bits()))
}
}
/// Returns `true` if `v` is contained in the range.
#[inline(always)]
pub fn contains(&self, v: u128) -> bool {
if self.wraps_around() {
self.start <= v || v <= self.end
} else {
self.start <= v && v <= self.end
}
}
/// Returns `true` if the range wraps around.
/// I.e., the range represents the union of `self.start..=MAX` and `0..=self.end`.
/// Returns `false` if this is a non-wrapping range, i.e.: `self.start..=self.end`.
#[inline]
pub fn wraps_around(&self) -> bool {
self.start > self.end
}
}
impl Debug for WrappingRange {
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
if self.start > self.end {
write!(fmt, "(..={}) | ({}..)", self.end, self.start)?;
} else {
write!(fmt, "{}..={}", self.start, self.end)?;
}
Ok(())
}
}
/// General language calling conventions.
#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, Serialize)]
pub enum CallConvention {
C,
Rust,
Cold,
PreserveMost,
PreserveAll,
// Target-specific calling conventions.
ArmAapcs,
CCmseNonSecureCall,
Msp430Intr,
PtxKernel,
X86Fastcall,
X86Intr,
X86Stdcall,
X86ThisCall,
X86VectorCall,
X86_64SysV,
X86_64Win64,
AvrInterrupt,
AvrNonBlockingInterrupt,
RiscvInterrupt,
}