1276 lines
42 KiB
Rust
1276 lines
42 KiB
Rust
pub use Integer::*;
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pub use Primitive::*;
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use crate::spec::Target;
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use std::convert::{TryFrom, TryInto};
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use std::fmt;
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use std::num::NonZeroUsize;
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use std::ops::{Add, AddAssign, Deref, Mul, Range, RangeInclusive, Sub};
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use std::str::FromStr;
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use rustc_index::vec::{Idx, IndexVec};
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use rustc_macros::HashStable_Generic;
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use rustc_serialize::json::{Json, ToJson};
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use rustc_span::Span;
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pub mod call;
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/// Parsed [Data layout](https://llvm.org/docs/LangRef.html#data-layout)
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/// for a target, which contains everything needed to compute layouts.
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pub struct TargetDataLayout {
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pub endian: Endian,
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pub i1_align: AbiAndPrefAlign,
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pub i8_align: AbiAndPrefAlign,
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pub i16_align: AbiAndPrefAlign,
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pub i32_align: AbiAndPrefAlign,
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pub i64_align: AbiAndPrefAlign,
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pub i128_align: AbiAndPrefAlign,
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pub f32_align: AbiAndPrefAlign,
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pub f64_align: AbiAndPrefAlign,
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pub pointer_size: Size,
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pub pointer_align: AbiAndPrefAlign,
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pub aggregate_align: AbiAndPrefAlign,
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/// Alignments for vector types.
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pub vector_align: Vec<(Size, AbiAndPrefAlign)>,
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pub instruction_address_space: AddressSpace,
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/// Minimum size of #[repr(C)] enums (default I32 bits)
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pub c_enum_min_size: Integer,
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}
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impl Default for TargetDataLayout {
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/// Creates an instance of `TargetDataLayout`.
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fn default() -> TargetDataLayout {
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let align = |bits| Align::from_bits(bits).unwrap();
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TargetDataLayout {
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endian: Endian::Big,
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i1_align: AbiAndPrefAlign::new(align(8)),
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i8_align: AbiAndPrefAlign::new(align(8)),
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i16_align: AbiAndPrefAlign::new(align(16)),
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i32_align: AbiAndPrefAlign::new(align(32)),
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i64_align: AbiAndPrefAlign { abi: align(32), pref: align(64) },
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i128_align: AbiAndPrefAlign { abi: align(32), pref: align(64) },
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f32_align: AbiAndPrefAlign::new(align(32)),
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f64_align: AbiAndPrefAlign::new(align(64)),
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pointer_size: Size::from_bits(64),
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pointer_align: AbiAndPrefAlign::new(align(64)),
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aggregate_align: AbiAndPrefAlign { abi: align(0), pref: align(64) },
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vector_align: vec![
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(Size::from_bits(64), AbiAndPrefAlign::new(align(64))),
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(Size::from_bits(128), AbiAndPrefAlign::new(align(128))),
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],
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instruction_address_space: AddressSpace::DATA,
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c_enum_min_size: Integer::I32,
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}
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}
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}
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impl TargetDataLayout {
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pub fn parse(target: &Target) -> Result<TargetDataLayout, String> {
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// Parse an address space index from a string.
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let parse_address_space = |s: &str, cause: &str| {
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s.parse::<u32>().map(AddressSpace).map_err(|err| {
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format!("invalid address space `{}` for `{}` in \"data-layout\": {}", s, cause, err)
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})
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};
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// Parse a bit count from a string.
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let parse_bits = |s: &str, kind: &str, cause: &str| {
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s.parse::<u64>().map_err(|err| {
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format!("invalid {} `{}` for `{}` in \"data-layout\": {}", kind, s, cause, err)
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})
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};
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// Parse a size string.
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let size = |s: &str, cause: &str| parse_bits(s, "size", cause).map(Size::from_bits);
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// Parse an alignment string.
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let align = |s: &[&str], cause: &str| {
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if s.is_empty() {
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return Err(format!("missing alignment for `{}` in \"data-layout\"", cause));
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}
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let align_from_bits = |bits| {
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Align::from_bits(bits).map_err(|err| {
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format!("invalid alignment for `{}` in \"data-layout\": {}", cause, err)
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})
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};
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let abi = parse_bits(s[0], "alignment", cause)?;
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let pref = s.get(1).map_or(Ok(abi), |pref| parse_bits(pref, "alignment", cause))?;
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Ok(AbiAndPrefAlign { abi: align_from_bits(abi)?, pref: align_from_bits(pref)? })
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};
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let mut dl = TargetDataLayout::default();
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let mut i128_align_src = 64;
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for spec in target.data_layout.split('-') {
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let spec_parts = spec.split(':').collect::<Vec<_>>();
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match &*spec_parts {
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["e"] => dl.endian = Endian::Little,
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["E"] => dl.endian = Endian::Big,
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[p] if p.starts_with('P') => {
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dl.instruction_address_space = parse_address_space(&p[1..], "P")?
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}
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["a", ref a @ ..] => dl.aggregate_align = align(a, "a")?,
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["f32", ref a @ ..] => dl.f32_align = align(a, "f32")?,
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["f64", ref a @ ..] => dl.f64_align = align(a, "f64")?,
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[p @ "p", s, ref a @ ..] | [p @ "p0", s, ref a @ ..] => {
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dl.pointer_size = size(s, p)?;
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dl.pointer_align = align(a, p)?;
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}
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[s, ref a @ ..] if s.starts_with('i') => {
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let bits = match s[1..].parse::<u64>() {
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Ok(bits) => bits,
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Err(_) => {
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size(&s[1..], "i")?; // For the user error.
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continue;
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}
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};
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let a = align(a, s)?;
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match bits {
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1 => dl.i1_align = a,
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8 => dl.i8_align = a,
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16 => dl.i16_align = a,
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32 => dl.i32_align = a,
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64 => dl.i64_align = a,
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_ => {}
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}
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if bits >= i128_align_src && bits <= 128 {
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// Default alignment for i128 is decided by taking the alignment of
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// largest-sized i{64..=128}.
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i128_align_src = bits;
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dl.i128_align = a;
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}
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}
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[s, ref a @ ..] if s.starts_with('v') => {
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let v_size = size(&s[1..], "v")?;
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let a = align(a, s)?;
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if let Some(v) = dl.vector_align.iter_mut().find(|v| v.0 == v_size) {
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v.1 = a;
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continue;
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}
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// No existing entry, add a new one.
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dl.vector_align.push((v_size, a));
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}
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_ => {} // Ignore everything else.
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}
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}
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// Perform consistency checks against the Target information.
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if dl.endian != target.endian {
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return Err(format!(
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"inconsistent target specification: \"data-layout\" claims \
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architecture is {}-endian, while \"target-endian\" is `{}`",
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dl.endian.as_str(),
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target.endian.as_str(),
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));
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}
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if dl.pointer_size.bits() != target.pointer_width.into() {
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return Err(format!(
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"inconsistent target specification: \"data-layout\" claims \
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pointers are {}-bit, while \"target-pointer-width\" is `{}`",
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dl.pointer_size.bits(),
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target.pointer_width
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));
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}
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dl.c_enum_min_size = Integer::from_size(Size::from_bits(target.c_enum_min_bits))?;
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Ok(dl)
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}
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/// Returns exclusive upper bound on object size.
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///
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/// The theoretical maximum object size is defined as the maximum positive `isize` value.
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/// This ensures that the `offset` semantics remain well-defined by allowing it to correctly
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/// index every address within an object along with one byte past the end, along with allowing
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/// `isize` to store the difference between any two pointers into an object.
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///
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/// The upper bound on 64-bit currently needs to be lower because LLVM uses a 64-bit integer
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/// to represent object size in bits. It would need to be 1 << 61 to account for this, but is
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/// currently conservatively bounded to 1 << 47 as that is enough to cover the current usable
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/// address space on 64-bit ARMv8 and x86_64.
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pub fn obj_size_bound(&self) -> u64 {
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match self.pointer_size.bits() {
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16 => 1 << 15,
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32 => 1 << 31,
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64 => 1 << 47,
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bits => panic!("obj_size_bound: unknown pointer bit size {}", bits),
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}
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}
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pub fn ptr_sized_integer(&self) -> Integer {
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match self.pointer_size.bits() {
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16 => I16,
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32 => I32,
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64 => I64,
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bits => panic!("ptr_sized_integer: unknown pointer bit size {}", bits),
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}
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}
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pub fn vector_align(&self, vec_size: Size) -> AbiAndPrefAlign {
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for &(size, align) in &self.vector_align {
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if size == vec_size {
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return align;
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}
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}
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// Default to natural alignment, which is what LLVM does.
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// That is, use the size, rounded up to a power of 2.
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AbiAndPrefAlign::new(Align::from_bytes(vec_size.bytes().next_power_of_two()).unwrap())
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}
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}
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pub trait HasDataLayout {
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fn data_layout(&self) -> &TargetDataLayout;
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}
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impl HasDataLayout for TargetDataLayout {
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#[inline]
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fn data_layout(&self) -> &TargetDataLayout {
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self
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}
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}
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/// Endianness of the target, which must match cfg(target-endian).
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#[derive(Copy, Clone, PartialEq)]
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pub enum Endian {
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Little,
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Big,
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}
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impl Endian {
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pub fn as_str(&self) -> &'static str {
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match self {
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Self::Little => "little",
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Self::Big => "big",
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}
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}
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}
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impl fmt::Debug for Endian {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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f.write_str(self.as_str())
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}
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}
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impl FromStr for Endian {
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type Err = String;
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fn from_str(s: &str) -> Result<Self, Self::Err> {
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match s {
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"little" => Ok(Self::Little),
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"big" => Ok(Self::Big),
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_ => Err(format!(r#"unknown endian: "{}""#, s)),
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}
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}
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}
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impl ToJson for Endian {
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fn to_json(&self) -> Json {
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self.as_str().to_json()
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}
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}
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/// Size of a type in bytes.
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#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, Encodable, Decodable)]
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#[derive(HashStable_Generic)]
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pub struct Size {
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// The top 3 bits are ALWAYS zero.
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raw: u64,
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}
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impl Size {
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pub const ZERO: Size = Size { raw: 0 };
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/// Rounds `bits` up to the next-higher byte boundary, if `bits` is
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/// is not aligned.
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pub fn from_bits(bits: impl TryInto<u64>) -> Size {
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let bits = bits.try_into().ok().unwrap();
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#[cold]
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fn overflow(bits: u64) -> ! {
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panic!("Size::from_bits({}) has overflowed", bits);
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}
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// This is the largest value of `bits` that does not cause overflow
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// during rounding, and guarantees that the resulting number of bytes
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// cannot cause overflow when multiplied by 8.
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if bits > 0xffff_ffff_ffff_fff8 {
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overflow(bits);
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}
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// Avoid potential overflow from `bits + 7`.
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Size { raw: bits / 8 + ((bits % 8) + 7) / 8 }
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}
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#[inline]
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pub fn from_bytes(bytes: impl TryInto<u64>) -> Size {
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let bytes: u64 = bytes.try_into().ok().unwrap();
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Size { raw: bytes }
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}
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#[inline]
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pub fn bytes(self) -> u64 {
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self.raw
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}
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#[inline]
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pub fn bytes_usize(self) -> usize {
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self.bytes().try_into().unwrap()
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}
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#[inline]
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pub fn bits(self) -> u64 {
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self.raw << 3
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}
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#[inline]
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pub fn bits_usize(self) -> usize {
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self.bits().try_into().unwrap()
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}
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#[inline]
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pub fn align_to(self, align: Align) -> Size {
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let mask = align.bytes() - 1;
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Size::from_bytes((self.bytes() + mask) & !mask)
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}
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#[inline]
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pub fn is_aligned(self, align: Align) -> bool {
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let mask = align.bytes() - 1;
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self.bytes() & mask == 0
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}
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#[inline]
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pub fn checked_add<C: HasDataLayout>(self, offset: Size, cx: &C) -> Option<Size> {
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let dl = cx.data_layout();
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let bytes = self.bytes().checked_add(offset.bytes())?;
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if bytes < dl.obj_size_bound() { Some(Size::from_bytes(bytes)) } else { None }
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}
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#[inline]
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pub fn checked_mul<C: HasDataLayout>(self, count: u64, cx: &C) -> Option<Size> {
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let dl = cx.data_layout();
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let bytes = self.bytes().checked_mul(count)?;
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if bytes < dl.obj_size_bound() { Some(Size::from_bytes(bytes)) } else { None }
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}
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/// Truncates `value` to `self` bits and then sign-extends it to 128 bits
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/// (i.e., if it is negative, fill with 1's on the left).
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#[inline]
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pub fn sign_extend(self, value: u128) -> u128 {
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let size = self.bits();
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if size == 0 {
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// Truncated until nothing is left.
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return 0;
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}
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// Sign-extend it.
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let shift = 128 - size;
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// Shift the unsigned value to the left, then shift back to the right as signed
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// (essentially fills with sign bit on the left).
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(((value << shift) as i128) >> shift) as u128
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}
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/// Truncates `value` to `self` bits.
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#[inline]
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pub fn truncate(self, value: u128) -> u128 {
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let size = self.bits();
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if size == 0 {
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// Truncated until nothing is left.
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return 0;
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}
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let shift = 128 - size;
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// Truncate (shift left to drop out leftover values, shift right to fill with zeroes).
|
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(value << shift) >> shift
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}
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}
|
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|
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// Panicking addition, subtraction and multiplication for convenience.
|
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// Avoid during layout computation, return `LayoutError` instead.
|
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|
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impl Add for Size {
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type Output = Size;
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#[inline]
|
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fn add(self, other: Size) -> Size {
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Size::from_bytes(self.bytes().checked_add(other.bytes()).unwrap_or_else(|| {
|
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panic!("Size::add: {} + {} doesn't fit in u64", self.bytes(), other.bytes())
|
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}))
|
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}
|
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}
|
||
|
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impl Sub for Size {
|
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type Output = Size;
|
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#[inline]
|
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fn sub(self, other: Size) -> Size {
|
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Size::from_bytes(self.bytes().checked_sub(other.bytes()).unwrap_or_else(|| {
|
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panic!("Size::sub: {} - {} would result in negative size", self.bytes(), other.bytes())
|
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}))
|
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}
|
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}
|
||
|
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impl Mul<Size> for u64 {
|
||
type Output = Size;
|
||
#[inline]
|
||
fn mul(self, size: Size) -> Size {
|
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size * self
|
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}
|
||
}
|
||
|
||
impl Mul<u64> for Size {
|
||
type Output = Size;
|
||
#[inline]
|
||
fn mul(self, count: u64) -> Size {
|
||
match self.bytes().checked_mul(count) {
|
||
Some(bytes) => Size::from_bytes(bytes),
|
||
None => panic!("Size::mul: {} * {} doesn't fit in u64", self.bytes(), count),
|
||
}
|
||
}
|
||
}
|
||
|
||
impl AddAssign for Size {
|
||
#[inline]
|
||
fn add_assign(&mut self, other: Size) {
|
||
*self = *self + other;
|
||
}
|
||
}
|
||
|
||
/// Alignment of a type in bytes (always a power of two).
|
||
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, Encodable, Decodable)]
|
||
#[derive(HashStable_Generic)]
|
||
pub struct Align {
|
||
pow2: u8,
|
||
}
|
||
|
||
impl Align {
|
||
pub const ONE: Align = Align { pow2: 0 };
|
||
|
||
#[inline]
|
||
pub fn from_bits(bits: u64) -> Result<Align, String> {
|
||
Align::from_bytes(Size::from_bits(bits).bytes())
|
||
}
|
||
|
||
#[inline]
|
||
pub fn from_bytes(align: u64) -> Result<Align, String> {
|
||
// Treat an alignment of 0 bytes like 1-byte alignment.
|
||
if align == 0 {
|
||
return Ok(Align::ONE);
|
||
}
|
||
|
||
#[cold]
|
||
fn not_power_of_2(align: u64) -> String {
|
||
format!("`{}` is not a power of 2", align)
|
||
}
|
||
|
||
#[cold]
|
||
fn too_large(align: u64) -> String {
|
||
format!("`{}` is too large", align)
|
||
}
|
||
|
||
let mut bytes = align;
|
||
let mut pow2: u8 = 0;
|
||
while (bytes & 1) == 0 {
|
||
pow2 += 1;
|
||
bytes >>= 1;
|
||
}
|
||
if bytes != 1 {
|
||
return Err(not_power_of_2(align));
|
||
}
|
||
if pow2 > 29 {
|
||
return Err(too_large(align));
|
||
}
|
||
|
||
Ok(Align { pow2 })
|
||
}
|
||
|
||
#[inline]
|
||
pub fn bytes(self) -> u64 {
|
||
1 << self.pow2
|
||
}
|
||
|
||
#[inline]
|
||
pub fn bits(self) -> u64 {
|
||
self.bytes() * 8
|
||
}
|
||
|
||
/// Computes the best alignment possible for the given offset
|
||
/// (the largest power of two that the offset is a multiple of).
|
||
///
|
||
/// N.B., for an offset of `0`, this happens to return `2^64`.
|
||
#[inline]
|
||
pub fn max_for_offset(offset: Size) -> Align {
|
||
Align { pow2: offset.bytes().trailing_zeros() as u8 }
|
||
}
|
||
|
||
/// Lower the alignment, if necessary, such that the given offset
|
||
/// is aligned to it (the offset is a multiple of the alignment).
|
||
#[inline]
|
||
pub fn restrict_for_offset(self, offset: Size) -> Align {
|
||
self.min(Align::max_for_offset(offset))
|
||
}
|
||
}
|
||
|
||
/// A pair of alignments, ABI-mandated and preferred.
|
||
#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, Encodable, Decodable)]
|
||
#[derive(HashStable_Generic)]
|
||
pub struct AbiAndPrefAlign {
|
||
pub abi: Align,
|
||
pub pref: Align,
|
||
}
|
||
|
||
impl AbiAndPrefAlign {
|
||
pub fn new(align: Align) -> AbiAndPrefAlign {
|
||
AbiAndPrefAlign { abi: align, pref: align }
|
||
}
|
||
|
||
pub fn min(self, other: AbiAndPrefAlign) -> AbiAndPrefAlign {
|
||
AbiAndPrefAlign { abi: self.abi.min(other.abi), pref: self.pref.min(other.pref) }
|
||
}
|
||
|
||
pub fn max(self, other: AbiAndPrefAlign) -> AbiAndPrefAlign {
|
||
AbiAndPrefAlign { abi: self.abi.max(other.abi), pref: self.pref.max(other.pref) }
|
||
}
|
||
}
|
||
|
||
/// Integers, also used for enum discriminants.
|
||
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, HashStable_Generic)]
|
||
pub enum Integer {
|
||
I8,
|
||
I16,
|
||
I32,
|
||
I64,
|
||
I128,
|
||
}
|
||
|
||
impl Integer {
|
||
pub fn size(self) -> Size {
|
||
match self {
|
||
I8 => Size::from_bytes(1),
|
||
I16 => Size::from_bytes(2),
|
||
I32 => Size::from_bytes(4),
|
||
I64 => Size::from_bytes(8),
|
||
I128 => Size::from_bytes(16),
|
||
}
|
||
}
|
||
|
||
pub fn align<C: HasDataLayout>(self, cx: &C) -> AbiAndPrefAlign {
|
||
let dl = cx.data_layout();
|
||
|
||
match self {
|
||
I8 => dl.i8_align,
|
||
I16 => dl.i16_align,
|
||
I32 => dl.i32_align,
|
||
I64 => dl.i64_align,
|
||
I128 => dl.i128_align,
|
||
}
|
||
}
|
||
|
||
/// Finds the smallest Integer type which can represent the signed value.
|
||
pub fn fit_signed(x: i128) -> Integer {
|
||
match x {
|
||
-0x0000_0000_0000_0080..=0x0000_0000_0000_007f => I8,
|
||
-0x0000_0000_0000_8000..=0x0000_0000_0000_7fff => I16,
|
||
-0x0000_0000_8000_0000..=0x0000_0000_7fff_ffff => I32,
|
||
-0x8000_0000_0000_0000..=0x7fff_ffff_ffff_ffff => I64,
|
||
_ => I128,
|
||
}
|
||
}
|
||
|
||
/// Finds the smallest Integer type which can represent the unsigned value.
|
||
pub fn fit_unsigned(x: u128) -> Integer {
|
||
match x {
|
||
0..=0x0000_0000_0000_00ff => I8,
|
||
0..=0x0000_0000_0000_ffff => I16,
|
||
0..=0x0000_0000_ffff_ffff => I32,
|
||
0..=0xffff_ffff_ffff_ffff => I64,
|
||
_ => I128,
|
||
}
|
||
}
|
||
|
||
/// Finds the smallest integer with the given alignment.
|
||
pub fn for_align<C: HasDataLayout>(cx: &C, wanted: Align) -> Option<Integer> {
|
||
let dl = cx.data_layout();
|
||
|
||
for candidate in [I8, I16, I32, I64, I128] {
|
||
if wanted == candidate.align(dl).abi && wanted.bytes() == candidate.size().bytes() {
|
||
return Some(candidate);
|
||
}
|
||
}
|
||
None
|
||
}
|
||
|
||
/// Find the largest integer with the given alignment or less.
|
||
pub fn approximate_align<C: HasDataLayout>(cx: &C, wanted: Align) -> Integer {
|
||
let dl = cx.data_layout();
|
||
|
||
// FIXME(eddyb) maybe include I128 in the future, when it works everywhere.
|
||
for candidate in [I64, I32, I16] {
|
||
if wanted >= candidate.align(dl).abi && wanted.bytes() >= candidate.size().bytes() {
|
||
return candidate;
|
||
}
|
||
}
|
||
I8
|
||
}
|
||
|
||
fn from_size(size: Size) -> Result<Self, String> {
|
||
match size.bits() {
|
||
8 => Ok(Integer::I8),
|
||
16 => Ok(Integer::I16),
|
||
32 => Ok(Integer::I32),
|
||
64 => Ok(Integer::I64),
|
||
128 => Ok(Integer::I128),
|
||
_ => Err(format!("rust does not support integers with {} bits", size.bits())),
|
||
}
|
||
}
|
||
}
|
||
|
||
/// Fundamental unit of memory access and layout.
|
||
#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, HashStable_Generic)]
|
||
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(Integer, bool),
|
||
F32,
|
||
F64,
|
||
Pointer,
|
||
}
|
||
|
||
impl Primitive {
|
||
pub fn size<C: HasDataLayout>(self, cx: &C) -> Size {
|
||
let dl = cx.data_layout();
|
||
|
||
match self {
|
||
Int(i, _) => i.size(),
|
||
F32 => Size::from_bits(32),
|
||
F64 => Size::from_bits(64),
|
||
Pointer => dl.pointer_size,
|
||
}
|
||
}
|
||
|
||
pub fn align<C: HasDataLayout>(self, cx: &C) -> AbiAndPrefAlign {
|
||
let dl = cx.data_layout();
|
||
|
||
match self {
|
||
Int(i, _) => i.align(dl),
|
||
F32 => dl.f32_align,
|
||
F64 => dl.f64_align,
|
||
Pointer => dl.pointer_align,
|
||
}
|
||
}
|
||
|
||
pub fn is_float(self) -> bool {
|
||
matches!(self, F32 | F64)
|
||
}
|
||
|
||
pub fn is_int(self) -> bool {
|
||
matches!(self, Int(..))
|
||
}
|
||
}
|
||
|
||
/// Inclusive wrap-around range of valid values, 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
|
||
///
|
||
/// This is intended specifically to mirror LLVM’s `!range` metadata,
|
||
/// semantics.
|
||
#[derive(Clone, PartialEq, Eq, Hash, Debug)]
|
||
#[derive(HashStable_Generic)]
|
||
pub struct AllocationRange {
|
||
pub start: u128,
|
||
pub end: u128,
|
||
}
|
||
|
||
impl AllocationRange {
|
||
/// Returns `true` if `v` is contained in the range.
|
||
#[inline]
|
||
pub fn contains(&self, v: u128) -> bool {
|
||
if self.start <= self.end {
|
||
self.start <= v && v <= self.end
|
||
} else {
|
||
self.start <= v || v <= self.end
|
||
}
|
||
}
|
||
|
||
/// Returns `true` if zero is contained in the range.
|
||
/// Equal to `range.contains(0)` but should be faster.
|
||
#[inline]
|
||
pub fn contains_zero(&self) -> bool {
|
||
!(self.start <= self.end && self.start != 0)
|
||
}
|
||
}
|
||
|
||
/// Information about one scalar component of a Rust type.
|
||
#[derive(Clone, PartialEq, Eq, Hash, Debug)]
|
||
#[derive(HashStable_Generic)]
|
||
pub struct Scalar {
|
||
pub value: Primitive,
|
||
|
||
// FIXME(eddyb) always use the shortest range, e.g., by finding
|
||
// the largest space between two consecutive valid values and
|
||
// taking everything else as the (shortest) valid range.
|
||
pub valid_range: AllocationRange,
|
||
}
|
||
|
||
impl Scalar {
|
||
pub fn is_bool(&self) -> bool {
|
||
matches!(self.value, Int(I8, false))
|
||
&& matches!(self.valid_range, AllocationRange { start: 0, end: 1 })
|
||
}
|
||
|
||
/// Returns the valid range as a `x..y` range.
|
||
///
|
||
/// If `x` and `y` are equal, the range is full, not empty.
|
||
pub fn valid_range_exclusive<C: HasDataLayout>(&self, cx: &C) -> Range<u128> {
|
||
// For a (max) value of -1, max will be `-1 as usize`, which overflows.
|
||
// However, that is fine here (it would still represent the full range),
|
||
// i.e., if the range is everything.
|
||
let bits = self.value.size(cx).bits();
|
||
assert!(bits <= 128);
|
||
let mask = !0u128 >> (128 - bits);
|
||
let start = self.valid_range.start;
|
||
let end = self.valid_range.end;
|
||
assert_eq!(start, start & mask);
|
||
assert_eq!(end, end & mask);
|
||
start..(end.wrapping_add(1) & mask)
|
||
}
|
||
}
|
||
|
||
/// Describes how the fields of a type are located in memory.
|
||
#[derive(PartialEq, Eq, Hash, Debug, HashStable_Generic)]
|
||
pub enum FieldsShape {
|
||
/// Scalar primitives and `!`, which never have fields.
|
||
Primitive,
|
||
|
||
/// All fields start at no offset. The `usize` is the field count.
|
||
Union(NonZeroUsize),
|
||
|
||
/// 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.
|
||
/// This vector does not go in increasing order.
|
||
// FIXME(eddyb) use small vector optimization for the common case.
|
||
offsets: Vec<Size>,
|
||
|
||
/// Maps source order field indices to memory order indices,
|
||
/// depending on how the fields were reordered (if at all).
|
||
/// This is a permutation, with both the source order and the
|
||
/// memory order using the same (0..n) index ranges.
|
||
///
|
||
/// Note that during computation of `memory_index`, sometimes
|
||
/// it is easier to operate on the inverse mapping (that is,
|
||
/// from memory order to source order), and that is usually
|
||
/// named `inverse_memory_index`.
|
||
///
|
||
// FIXME(eddyb) build a better abstraction for permutations, if possible.
|
||
// FIXME(camlorn) also consider small vector optimization here.
|
||
memory_index: Vec<u32>,
|
||
},
|
||
}
|
||
|
||
impl FieldsShape {
|
||
pub fn count(&self) -> usize {
|
||
match *self {
|
||
FieldsShape::Primitive => 0,
|
||
FieldsShape::Union(count) => count.get(),
|
||
FieldsShape::Array { count, .. } => count.try_into().unwrap(),
|
||
FieldsShape::Arbitrary { ref offsets, .. } => offsets.len(),
|
||
}
|
||
}
|
||
|
||
pub fn offset(&self, i: usize) -> Size {
|
||
match *self {
|
||
FieldsShape::Primitive => {
|
||
unreachable!("FieldsShape::offset: `Primitive`s have no fields")
|
||
}
|
||
FieldsShape::Union(count) => {
|
||
assert!(
|
||
i < count.get(),
|
||
"tried to access field {} of union with {} fields",
|
||
i,
|
||
count
|
||
);
|
||
Size::ZERO
|
||
}
|
||
FieldsShape::Array { stride, count } => {
|
||
let i = u64::try_from(i).unwrap();
|
||
assert!(i < count);
|
||
stride * i
|
||
}
|
||
FieldsShape::Arbitrary { ref offsets, .. } => offsets[i],
|
||
}
|
||
}
|
||
|
||
pub fn memory_index(&self, i: usize) -> usize {
|
||
match *self {
|
||
FieldsShape::Primitive => {
|
||
unreachable!("FieldsShape::memory_index: `Primitive`s have no fields")
|
||
}
|
||
FieldsShape::Union(_) | FieldsShape::Array { .. } => i,
|
||
FieldsShape::Arbitrary { ref memory_index, .. } => memory_index[i].try_into().unwrap(),
|
||
}
|
||
}
|
||
|
||
/// Gets source indices of the fields by increasing offsets.
|
||
#[inline]
|
||
pub fn index_by_increasing_offset<'a>(&'a self) -> impl Iterator<Item = usize> + 'a {
|
||
let mut inverse_small = [0u8; 64];
|
||
let mut inverse_big = vec![];
|
||
let use_small = self.count() <= inverse_small.len();
|
||
|
||
// We have to write this logic twice in order to keep the array small.
|
||
if let FieldsShape::Arbitrary { ref memory_index, .. } = *self {
|
||
if use_small {
|
||
for i in 0..self.count() {
|
||
inverse_small[memory_index[i] as usize] = i as u8;
|
||
}
|
||
} else {
|
||
inverse_big = vec![0; self.count()];
|
||
for i in 0..self.count() {
|
||
inverse_big[memory_index[i] as usize] = i as u32;
|
||
}
|
||
}
|
||
}
|
||
|
||
(0..self.count()).map(move |i| match *self {
|
||
FieldsShape::Primitive | FieldsShape::Union(_) | FieldsShape::Array { .. } => i,
|
||
FieldsShape::Arbitrary { .. } => {
|
||
if use_small {
|
||
inverse_small[i] as usize
|
||
} else {
|
||
inverse_big[i] as usize
|
||
}
|
||
}
|
||
})
|
||
}
|
||
}
|
||
|
||
/// 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)]
|
||
pub struct AddressSpace(pub u32);
|
||
|
||
impl AddressSpace {
|
||
/// The default address space, corresponding to data space.
|
||
pub const DATA: Self = AddressSpace(0);
|
||
}
|
||
|
||
/// 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, PartialEq, Eq, Hash, Debug, HashStable_Generic)]
|
||
pub enum Abi {
|
||
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 Abi {
|
||
/// Returns `true` if the layout corresponds to an unsized type.
|
||
#[inline]
|
||
pub fn is_unsized(&self) -> bool {
|
||
match *self {
|
||
Abi::Uninhabited | Abi::Scalar(_) | Abi::ScalarPair(..) | Abi::Vector { .. } => false,
|
||
Abi::Aggregate { sized } => !sized,
|
||
}
|
||
}
|
||
|
||
/// Returns `true` if this is a single signed integer scalar
|
||
pub fn is_signed(&self) -> bool {
|
||
match *self {
|
||
Abi::Scalar(ref scal) => match scal.value {
|
||
Primitive::Int(_, signed) => signed,
|
||
_ => false,
|
||
},
|
||
_ => panic!("`is_signed` on non-scalar ABI {:?}", self),
|
||
}
|
||
}
|
||
|
||
/// Returns `true` if this is an uninhabited type
|
||
#[inline]
|
||
pub fn is_uninhabited(&self) -> bool {
|
||
matches!(*self, Abi::Uninhabited)
|
||
}
|
||
|
||
/// Returns `true` is this is a scalar type
|
||
#[inline]
|
||
pub fn is_scalar(&self) -> bool {
|
||
matches!(*self, Abi::Scalar(_))
|
||
}
|
||
}
|
||
|
||
rustc_index::newtype_index! {
|
||
pub struct VariantIdx {
|
||
derive [HashStable_Generic]
|
||
}
|
||
}
|
||
|
||
#[derive(PartialEq, Eq, Hash, Debug, HashStable_Generic)]
|
||
pub enum Variants {
|
||
/// 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: IndexVec<VariantIdx, Layout>,
|
||
},
|
||
}
|
||
|
||
#[derive(PartialEq, Eq, Hash, Debug, HashStable_Generic)]
|
||
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 `dataful_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 {
|
||
dataful_variant: VariantIdx,
|
||
niche_variants: RangeInclusive<VariantIdx>,
|
||
niche_start: u128,
|
||
},
|
||
}
|
||
|
||
#[derive(Clone, PartialEq, Eq, Hash, Debug, HashStable_Generic)]
|
||
pub struct Niche {
|
||
pub offset: Size,
|
||
pub scalar: Scalar,
|
||
}
|
||
|
||
impl Niche {
|
||
pub fn from_scalar<C: HasDataLayout>(cx: &C, offset: Size, scalar: Scalar) -> Option<Self> {
|
||
let niche = Niche { offset, scalar };
|
||
if niche.available(cx) > 0 { Some(niche) } else { None }
|
||
}
|
||
|
||
pub fn available<C: HasDataLayout>(&self, cx: &C) -> u128 {
|
||
let Scalar { value, valid_range: ref v } = self.scalar;
|
||
let bits = value.size(cx).bits();
|
||
assert!(bits <= 128);
|
||
let max_value = !0u128 >> (128 - bits);
|
||
|
||
// Find out how many values are outside the valid range.
|
||
let niche = v.end.wrapping_add(1)..v.start;
|
||
niche.end.wrapping_sub(niche.start) & max_value
|
||
}
|
||
|
||
pub fn reserve<C: HasDataLayout>(&self, cx: &C, count: u128) -> Option<(u128, Scalar)> {
|
||
assert!(count > 0);
|
||
|
||
let Scalar { value, valid_range: ref v } = self.scalar;
|
||
let bits = value.size(cx).bits();
|
||
assert!(bits <= 128);
|
||
let max_value = !0u128 >> (128 - bits);
|
||
|
||
if count > max_value {
|
||
return None;
|
||
}
|
||
|
||
// Compute the range of invalid values being reserved.
|
||
let start = v.end.wrapping_add(1) & max_value;
|
||
let end = v.end.wrapping_add(count) & max_value;
|
||
|
||
if v.contains(end) {
|
||
return None;
|
||
}
|
||
|
||
Some((start, Scalar { value, valid_range: AllocationRange { start: v.start, end } }))
|
||
}
|
||
}
|
||
|
||
#[derive(PartialEq, Eq, Hash, Debug, HashStable_Generic)]
|
||
pub struct Layout {
|
||
/// Says where the fields are located within 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. One of them will be the discriminant,
|
||
/// but e.g. generators can have more.
|
||
///
|
||
/// To access all fields of this layout, both `fields` and the fields of the active variant
|
||
/// must be taken into account.
|
||
pub variants: Variants,
|
||
|
||
/// The `abi` defines how this data is passed between functions, and it defines
|
||
/// value restrictions via `valid_range`.
|
||
///
|
||
/// Note that this is entirely orthogonal to the recursive structure defined by
|
||
/// `variants` and `fields`; for example, `ManuallyDrop<Result<isize, isize>>` has
|
||
/// `Abi::ScalarPair`! So, even with non-`Aggregate` `abi`, `fields` and `variants`
|
||
/// have to be taken into account to find all fields of this layout.
|
||
pub abi: Abi,
|
||
|
||
/// The leaf scalar with the largest number of invalid values
|
||
/// (i.e. outside of its `valid_range`), if it exists.
|
||
pub largest_niche: Option<Niche>,
|
||
|
||
pub align: AbiAndPrefAlign,
|
||
pub size: Size,
|
||
}
|
||
|
||
impl Layout {
|
||
pub fn scalar<C: HasDataLayout>(cx: &C, scalar: Scalar) -> Self {
|
||
let largest_niche = Niche::from_scalar(cx, Size::ZERO, scalar.clone());
|
||
let size = scalar.value.size(cx);
|
||
let align = scalar.value.align(cx);
|
||
Layout {
|
||
variants: Variants::Single { index: VariantIdx::new(0) },
|
||
fields: FieldsShape::Primitive,
|
||
abi: Abi::Scalar(scalar),
|
||
largest_niche,
|
||
size,
|
||
align,
|
||
}
|
||
}
|
||
}
|
||
|
||
/// The layout of a type, alongside the type itself.
|
||
/// Provides various type traversal APIs (e.g., recursing into fields).
|
||
///
|
||
/// Note that the layout is NOT guaranteed to always be identical
|
||
/// to that obtained from `layout_of(ty)`, as we need to produce
|
||
/// layouts for which Rust types do not exist, such as enum variants
|
||
/// or synthetic fields of enums (i.e., discriminants) and fat pointers.
|
||
#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
|
||
pub struct TyAndLayout<'a, Ty> {
|
||
pub ty: Ty,
|
||
pub layout: &'a Layout,
|
||
}
|
||
|
||
impl<'a, Ty> Deref for TyAndLayout<'a, Ty> {
|
||
type Target = &'a Layout;
|
||
fn deref(&self) -> &&'a Layout {
|
||
&self.layout
|
||
}
|
||
}
|
||
|
||
/// Trait for context types that can compute layouts of things.
|
||
pub trait LayoutOf {
|
||
type Ty;
|
||
type TyAndLayout;
|
||
|
||
fn layout_of(&self, ty: Self::Ty) -> Self::TyAndLayout;
|
||
fn spanned_layout_of(&self, ty: Self::Ty, _span: Span) -> Self::TyAndLayout {
|
||
self.layout_of(ty)
|
||
}
|
||
}
|
||
|
||
/// The `TyAndLayout` above will always be a `MaybeResult<TyAndLayout<'_, Self>>`.
|
||
/// We can't add the bound due to the lifetime, but this trait is still useful when
|
||
/// writing code that's generic over the `LayoutOf` impl.
|
||
pub trait MaybeResult<T> {
|
||
type Error;
|
||
|
||
fn from(x: Result<T, Self::Error>) -> Self;
|
||
fn to_result(self) -> Result<T, Self::Error>;
|
||
}
|
||
|
||
impl<T> MaybeResult<T> for T {
|
||
type Error = !;
|
||
|
||
fn from(Ok(x): Result<T, Self::Error>) -> Self {
|
||
x
|
||
}
|
||
fn to_result(self) -> Result<T, Self::Error> {
|
||
Ok(self)
|
||
}
|
||
}
|
||
|
||
impl<T, E> MaybeResult<T> for Result<T, E> {
|
||
type Error = E;
|
||
|
||
fn from(x: Result<T, Self::Error>) -> Self {
|
||
x
|
||
}
|
||
fn to_result(self) -> Result<T, Self::Error> {
|
||
self
|
||
}
|
||
}
|
||
|
||
#[derive(Copy, Clone, PartialEq, Eq, Debug)]
|
||
pub enum PointerKind {
|
||
/// Most general case, we know no restrictions to tell LLVM.
|
||
Shared,
|
||
|
||
/// `&T` where `T` contains no `UnsafeCell`, is `noalias` and `readonly`.
|
||
Frozen,
|
||
|
||
/// `&mut T` which is `noalias` but not `readonly`.
|
||
UniqueBorrowed,
|
||
|
||
/// `Box<T>`, unlike `UniqueBorrowed`, it also has `noalias` on returns.
|
||
UniqueOwned,
|
||
}
|
||
|
||
#[derive(Copy, Clone, Debug)]
|
||
pub struct PointeeInfo {
|
||
pub size: Size,
|
||
pub align: Align,
|
||
pub safe: Option<PointerKind>,
|
||
pub address_space: AddressSpace,
|
||
}
|
||
|
||
pub trait TyAndLayoutMethods<'a, C: LayoutOf<Ty = Self>>: Sized {
|
||
fn for_variant(
|
||
this: TyAndLayout<'a, Self>,
|
||
cx: &C,
|
||
variant_index: VariantIdx,
|
||
) -> TyAndLayout<'a, Self>;
|
||
fn field(this: TyAndLayout<'a, Self>, cx: &C, i: usize) -> C::TyAndLayout;
|
||
fn pointee_info_at(this: TyAndLayout<'a, Self>, cx: &C, offset: Size) -> Option<PointeeInfo>;
|
||
}
|
||
|
||
impl<'a, Ty> TyAndLayout<'a, Ty> {
|
||
pub fn for_variant<C>(self, cx: &C, variant_index: VariantIdx) -> Self
|
||
where
|
||
Ty: TyAndLayoutMethods<'a, C>,
|
||
C: LayoutOf<Ty = Ty>,
|
||
{
|
||
Ty::for_variant(self, cx, variant_index)
|
||
}
|
||
|
||
/// Callers might want to use `C: LayoutOf<Ty=Ty, TyAndLayout: MaybeResult<Self>>`
|
||
/// to allow recursion (see `might_permit_zero_init` below for an example).
|
||
pub fn field<C>(self, cx: &C, i: usize) -> C::TyAndLayout
|
||
where
|
||
Ty: TyAndLayoutMethods<'a, C>,
|
||
C: LayoutOf<Ty = Ty>,
|
||
{
|
||
Ty::field(self, cx, i)
|
||
}
|
||
|
||
pub fn pointee_info_at<C>(self, cx: &C, offset: Size) -> Option<PointeeInfo>
|
||
where
|
||
Ty: TyAndLayoutMethods<'a, C>,
|
||
C: LayoutOf<Ty = Ty>,
|
||
{
|
||
Ty::pointee_info_at(self, cx, offset)
|
||
}
|
||
}
|
||
|
||
impl<'a, Ty> TyAndLayout<'a, Ty> {
|
||
/// Returns `true` if the layout corresponds to an unsized type.
|
||
pub fn is_unsized(&self) -> bool {
|
||
self.abi.is_unsized()
|
||
}
|
||
|
||
/// Returns `true` if the type is a ZST and not unsized.
|
||
pub fn is_zst(&self) -> bool {
|
||
match self.abi {
|
||
Abi::Scalar(_) | Abi::ScalarPair(..) | Abi::Vector { .. } => false,
|
||
Abi::Uninhabited => self.size.bytes() == 0,
|
||
Abi::Aggregate { sized } => sized && self.size.bytes() == 0,
|
||
}
|
||
}
|
||
|
||
/// Determines if this type permits "raw" initialization by just transmuting some
|
||
/// memory into an instance of `T`.
|
||
/// `zero` indicates if the memory is zero-initialized, or alternatively
|
||
/// left entirely uninitialized.
|
||
/// This is conservative: in doubt, it will answer `true`.
|
||
///
|
||
/// FIXME: Once we removed all the conservatism, we could alternatively
|
||
/// create an all-0/all-undef constant and run the const value validator to see if
|
||
/// this is a valid value for the given type.
|
||
pub fn might_permit_raw_init<C, E>(self, cx: &C, zero: bool) -> Result<bool, E>
|
||
where
|
||
Self: Copy,
|
||
Ty: TyAndLayoutMethods<'a, C>,
|
||
C: LayoutOf<Ty = Ty, TyAndLayout: MaybeResult<Self, Error = E>> + HasDataLayout,
|
||
{
|
||
let scalar_allows_raw_init = move |s: &Scalar| -> bool {
|
||
if zero {
|
||
// The range must contain 0.
|
||
s.valid_range.contains_zero()
|
||
} else {
|
||
// The range must include all values. `valid_range_exclusive` handles
|
||
// the wrap-around using target arithmetic; with wrap-around then the full
|
||
// range is one where `start == end`.
|
||
let range = s.valid_range_exclusive(cx);
|
||
range.start == range.end
|
||
}
|
||
};
|
||
|
||
// Check the ABI.
|
||
let valid = match &self.abi {
|
||
Abi::Uninhabited => false, // definitely UB
|
||
Abi::Scalar(s) => scalar_allows_raw_init(s),
|
||
Abi::ScalarPair(s1, s2) => scalar_allows_raw_init(s1) && scalar_allows_raw_init(s2),
|
||
Abi::Vector { element: s, count } => *count == 0 || scalar_allows_raw_init(s),
|
||
Abi::Aggregate { .. } => true, // Fields are checked below.
|
||
};
|
||
if !valid {
|
||
// This is definitely not okay.
|
||
return Ok(false);
|
||
}
|
||
|
||
// If we have not found an error yet, we need to recursively descend into fields.
|
||
match &self.fields {
|
||
FieldsShape::Primitive | FieldsShape::Union { .. } => {}
|
||
FieldsShape::Array { .. } => {
|
||
// FIXME(#66151): For now, we are conservative and do not check arrays.
|
||
}
|
||
FieldsShape::Arbitrary { offsets, .. } => {
|
||
for idx in 0..offsets.len() {
|
||
let field = self.field(cx, idx).to_result()?;
|
||
if !field.might_permit_raw_init(cx, zero)? {
|
||
// We found a field that is unhappy with this kind of initialization.
|
||
return Ok(false);
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
// FIXME(#66151): For now, we are conservative and do not check `self.variants`.
|
||
Ok(true)
|
||
}
|
||
}
|