957 lines
30 KiB
Rust
957 lines
30 KiB
Rust
// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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pub use self::Integer::*;
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pub use self::Primitive::*;
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use spec::Target;
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use std::{cmp, fmt};
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use std::ops::{Add, Deref, Sub, Mul, AddAssign, Range, RangeInclusive};
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use rustc_data_structures::indexed_vec::{Idx, IndexVec};
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pub mod call;
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/// Parsed [Data layout](http://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: Align,
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pub i8_align: Align,
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pub i16_align: Align,
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pub i32_align: Align,
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pub i64_align: Align,
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pub i128_align: Align,
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pub f32_align: Align,
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pub f64_align: Align,
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pub pointer_size: Size,
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pub pointer_align: Align,
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pub aggregate_align: Align,
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/// Alignments for vector types.
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pub vector_align: Vec<(Size, Align)>,
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pub instruction_address_space: u32,
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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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TargetDataLayout {
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endian: Endian::Big,
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i1_align: Align::from_bits(8, 8).unwrap(),
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i8_align: Align::from_bits(8, 8).unwrap(),
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i16_align: Align::from_bits(16, 16).unwrap(),
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i32_align: Align::from_bits(32, 32).unwrap(),
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i64_align: Align::from_bits(32, 64).unwrap(),
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i128_align: Align::from_bits(32, 64).unwrap(),
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f32_align: Align::from_bits(32, 32).unwrap(),
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f64_align: Align::from_bits(64, 64).unwrap(),
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pointer_size: Size::from_bits(64),
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pointer_align: Align::from_bits(64, 64).unwrap(),
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aggregate_align: Align::from_bits(0, 64).unwrap(),
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vector_align: vec![
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(Size::from_bits(64), Align::from_bits(64, 64).unwrap()),
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(Size::from_bits(128), Align::from_bits(128, 128).unwrap())
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],
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instruction_address_space: 0,
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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_err(|err| {
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format!("invalid address space `{}` for `{}` in \"data-layout\": {}",
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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\": {}",
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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| {
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parse_bits(s, "size", cause).map(Size::from_bits)
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};
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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 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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Align::from_bits(abi, pref).map_err(|err| {
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format!("invalid alignment for `{}` in \"data-layout\": {}",
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cause, err)
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})
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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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match spec.split(':').collect::<Vec<_>>()[..] {
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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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let endian_str = match dl.endian {
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Endian::Little => "little",
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Endian::Big => "big"
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};
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if endian_str != target.target_endian {
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return Err(format!("inconsistent target specification: \"data-layout\" claims \
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architecture is {}-endian, while \"target-endian\" is `{}`",
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endian_str, target.target_endian));
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}
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if dl.pointer_size.bits().to_string() != target.target_pointer_width {
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return Err(format!("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(), target.target_pointer_width));
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}
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Ok(dl)
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}
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/// Return 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) -> Align {
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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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let align = vec_size.bytes().next_power_of_two();
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Align::from_bytes(align, align).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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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)]
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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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/// Size of a type in bytes.
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#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
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pub struct Size {
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raw: u64
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}
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impl Size {
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pub const ZERO: Size = Self::from_bytes(0);
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#[inline]
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pub fn from_bits(bits: u64) -> Size {
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// Avoid potential overflow from `bits + 7`.
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Size::from_bytes(bits / 8 + ((bits % 8) + 7) / 8)
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}
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#[inline]
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pub const fn from_bytes(bytes: u64) -> Size {
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Size {
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raw: bytes
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}
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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 bits(self) -> u64 {
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self.bytes().checked_mul(8).unwrap_or_else(|| {
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panic!("Size::bits: {} bytes in bits doesn't fit in u64", self.bytes())
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})
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}
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#[inline]
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pub fn abi_align(self, align: Align) -> Size {
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let mask = align.abi() - 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_abi_aligned(self, align: Align) -> bool {
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let mask = align.abi() - 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() {
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Some(Size::from_bytes(bytes))
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} else {
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None
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}
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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() {
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Some(Size::from_bytes(bytes))
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} else {
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None
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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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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 {
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type Output = Size;
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#[inline]
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fn mul(self, size: Size) -> Size {
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size * self
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}
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}
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impl Mul<u64> for Size {
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type Output = Size;
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#[inline]
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fn mul(self, count: u64) -> Size {
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match self.bytes().checked_mul(count) {
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Some(bytes) => Size::from_bytes(bytes),
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None => {
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panic!("Size::mul: {} * {} doesn't fit in u64", self.bytes(), count)
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}
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}
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}
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}
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impl AddAssign for Size {
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#[inline]
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fn add_assign(&mut self, other: Size) {
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*self = *self + other;
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}
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}
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/// Alignment of a type in bytes, both ABI-mandated and preferred.
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/// Each field is a power of two, giving the alignment a maximum value
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/// of 2<sup>(2<sup>8</sup> - 1)</sup>, which is limited by LLVM to a
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/// maximum capacity of 2<sup>29</sup> or 536870912.
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#[derive(Copy, Clone, PartialEq, Eq, Ord, PartialOrd, Hash, Debug, RustcEncodable, RustcDecodable)]
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pub struct Align {
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abi_pow2: u8,
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pref_pow2: u8,
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}
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impl Align {
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pub fn from_bits(abi: u64, pref: u64) -> Result<Align, String> {
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Align::from_bytes(Size::from_bits(abi).bytes(),
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Size::from_bits(pref).bytes())
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}
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pub fn from_bytes(abi: u64, pref: u64) -> Result<Align, String> {
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let log2 = |align: u64| {
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// Treat an alignment of 0 bytes like 1-byte alignment.
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if align == 0 {
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return Ok(0);
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}
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let mut bytes = align;
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let mut pow: u8 = 0;
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while (bytes & 1) == 0 {
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pow += 1;
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bytes >>= 1;
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}
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if bytes != 1 {
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Err(format!("`{}` is not a power of 2", align))
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} else if pow > 29 {
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Err(format!("`{}` is too large", align))
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} else {
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Ok(pow)
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}
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};
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Ok(Align {
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abi_pow2: log2(abi)?,
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pref_pow2: log2(pref)?,
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})
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}
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pub fn abi(self) -> u64 {
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1 << self.abi_pow2
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}
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pub fn pref(self) -> u64 {
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1 << self.pref_pow2
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}
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pub fn abi_bits(self) -> u64 {
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self.abi() * 8
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}
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pub fn pref_bits(self) -> u64 {
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self.pref() * 8
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}
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pub fn min(self, other: Align) -> Align {
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Align {
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abi_pow2: cmp::min(self.abi_pow2, other.abi_pow2),
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pref_pow2: cmp::min(self.pref_pow2, other.pref_pow2),
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}
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}
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pub fn max(self, other: Align) -> Align {
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Align {
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abi_pow2: cmp::max(self.abi_pow2, other.abi_pow2),
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pref_pow2: cmp::max(self.pref_pow2, other.pref_pow2),
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}
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}
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/// Compute the best alignment possible for the given offset
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/// (the largest power of two that the offset is a multiple of).
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///
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/// NB: for an offset of `0`, this happens to return `2^64`.
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pub fn max_for_offset(offset: Size) -> Align {
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let pow2 = offset.bytes().trailing_zeros() as u8;
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Align {
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abi_pow2: pow2,
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pref_pow2: pow2,
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}
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}
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/// Lower the alignment, if necessary, such that the given offset
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/// is aligned to it (the offset is a multiple of the alignment).
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pub fn restrict_for_offset(self, offset: Size) -> Align {
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self.min(Align::max_for_offset(offset))
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}
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}
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/// Integers, also used for enum discriminants.
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#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
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pub enum Integer {
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I8,
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I16,
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I32,
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I64,
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I128,
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}
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impl Integer {
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pub fn size(self) -> Size {
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match self {
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I8 => Size::from_bytes(1),
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I16 => Size::from_bytes(2),
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I32 => Size::from_bytes(4),
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I64 => Size::from_bytes(8),
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I128 => Size::from_bytes(16),
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}
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}
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pub fn align<C: HasDataLayout>(self, cx: &C) -> Align {
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let dl = cx.data_layout();
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match self {
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I8 => dl.i8_align,
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I16 => dl.i16_align,
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I32 => dl.i32_align,
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I64 => dl.i64_align,
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I128 => dl.i128_align,
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}
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}
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/// Find the smallest Integer type which can represent the signed value.
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pub fn fit_signed(x: i128) -> Integer {
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match x {
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-0x0000_0000_0000_0080..=0x0000_0000_0000_007f => I8,
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-0x0000_0000_0000_8000..=0x0000_0000_0000_7fff => I16,
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-0x0000_0000_8000_0000..=0x0000_0000_7fff_ffff => I32,
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-0x8000_0000_0000_0000..=0x7fff_ffff_ffff_ffff => I64,
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_ => I128
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}
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}
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/// Find the smallest Integer type which can represent the unsigned value.
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pub fn fit_unsigned(x: u128) -> Integer {
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match x {
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0..=0x0000_0000_0000_00ff => I8,
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0..=0x0000_0000_0000_ffff => I16,
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0..=0x0000_0000_ffff_ffff => I32,
|
||
0..=0xffff_ffff_ffff_ffff => I64,
|
||
_ => I128,
|
||
}
|
||
}
|
||
|
||
/// Find the smallest integer with the given alignment.
|
||
pub fn for_abi_align<C: HasDataLayout>(cx: &C, align: Align) -> Option<Integer> {
|
||
let dl = cx.data_layout();
|
||
|
||
let wanted = align.abi();
|
||
for &candidate in &[I8, I16, I32, I64, I128] {
|
||
if wanted == candidate.align(dl).abi() && wanted == candidate.size().bytes() {
|
||
return Some(candidate);
|
||
}
|
||
}
|
||
None
|
||
}
|
||
|
||
/// Find the largest integer with the given alignment or less.
|
||
pub fn approximate_abi_align<C: HasDataLayout>(cx: &C, align: Align) -> Integer {
|
||
let dl = cx.data_layout();
|
||
|
||
let wanted = align.abi();
|
||
// 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 >= candidate.size().bytes() {
|
||
return candidate;
|
||
}
|
||
}
|
||
I8
|
||
}
|
||
}
|
||
|
||
|
||
#[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Copy,
|
||
PartialOrd, Ord)]
|
||
pub enum FloatTy {
|
||
F32,
|
||
F64,
|
||
}
|
||
|
||
impl fmt::Debug for FloatTy {
|
||
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
|
||
fmt::Display::fmt(self, f)
|
||
}
|
||
}
|
||
|
||
impl fmt::Display for FloatTy {
|
||
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
|
||
write!(f, "{}", self.ty_to_string())
|
||
}
|
||
}
|
||
|
||
impl FloatTy {
|
||
pub fn ty_to_string(self) -> &'static str {
|
||
match self {
|
||
FloatTy::F32 => "f32",
|
||
FloatTy::F64 => "f64",
|
||
}
|
||
}
|
||
|
||
pub fn bit_width(self) -> usize {
|
||
match self {
|
||
FloatTy::F32 => 32,
|
||
FloatTy::F64 => 64,
|
||
}
|
||
}
|
||
}
|
||
|
||
/// Fundamental unit of memory access and layout.
|
||
#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
|
||
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),
|
||
Float(FloatTy),
|
||
Pointer
|
||
}
|
||
|
||
impl<'a, 'tcx> Primitive {
|
||
pub fn size<C: HasDataLayout>(self, cx: &C) -> Size {
|
||
let dl = cx.data_layout();
|
||
|
||
match self {
|
||
Int(i, _) => i.size(),
|
||
Float(FloatTy::F32) => Size::from_bits(32),
|
||
Float(FloatTy::F64) => Size::from_bits(64),
|
||
Pointer => dl.pointer_size
|
||
}
|
||
}
|
||
|
||
pub fn align<C: HasDataLayout>(self, cx: &C) -> Align {
|
||
let dl = cx.data_layout();
|
||
|
||
match self {
|
||
Int(i, _) => i.align(dl),
|
||
Float(FloatTy::F32) => dl.f32_align,
|
||
Float(FloatTy::F64) => dl.f64_align,
|
||
Pointer => dl.pointer_align
|
||
}
|
||
}
|
||
|
||
pub fn is_float(self) -> bool {
|
||
match self {
|
||
Float(_) => true,
|
||
_ => false
|
||
}
|
||
}
|
||
|
||
pub fn is_int(self) -> bool {
|
||
match self {
|
||
Int(..) => true,
|
||
_ => false,
|
||
}
|
||
}
|
||
}
|
||
|
||
/// Information about one scalar component of a Rust type.
|
||
#[derive(Clone, PartialEq, Eq, Hash, Debug)]
|
||
pub struct Scalar {
|
||
pub value: Primitive,
|
||
|
||
/// Inclusive wrap-around range of valid values, that is, if
|
||
/// start > end, it represents `start..=max_value()`,
|
||
/// 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.
|
||
// 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: RangeInclusive<u128>,
|
||
}
|
||
|
||
impl Scalar {
|
||
pub fn is_bool(&self) -> bool {
|
||
if let Int(I8, _) = self.value {
|
||
self.valid_range == (0..=1)
|
||
} else {
|
||
false
|
||
}
|
||
}
|
||
|
||
/// 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)]
|
||
pub enum FieldPlacement {
|
||
/// All fields start at no offset. The `usize` is the field count.
|
||
///
|
||
/// In the case of primitives the number of fields is `0`.
|
||
Union(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.
|
||
/// 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 how fields were permuted.
|
||
// FIXME(camlorn) also consider small vector optimization here.
|
||
memory_index: Vec<u32>
|
||
}
|
||
}
|
||
|
||
impl FieldPlacement {
|
||
pub fn count(&self) -> usize {
|
||
match *self {
|
||
FieldPlacement::Union(count) => count,
|
||
FieldPlacement::Array { count, .. } => {
|
||
let usize_count = count as usize;
|
||
assert_eq!(usize_count as u64, count);
|
||
usize_count
|
||
}
|
||
FieldPlacement::Arbitrary { ref offsets, .. } => offsets.len()
|
||
}
|
||
}
|
||
|
||
pub fn offset(&self, i: usize) -> Size {
|
||
match *self {
|
||
FieldPlacement::Union(_) => Size::ZERO,
|
||
FieldPlacement::Array { stride, count } => {
|
||
let i = i as u64;
|
||
assert!(i < count);
|
||
stride * i
|
||
}
|
||
FieldPlacement::Arbitrary { ref offsets, .. } => offsets[i]
|
||
}
|
||
}
|
||
|
||
pub fn memory_index(&self, i: usize) -> usize {
|
||
match *self {
|
||
FieldPlacement::Union(_) |
|
||
FieldPlacement::Array { .. } => i,
|
||
FieldPlacement::Arbitrary { ref memory_index, .. } => {
|
||
let r = memory_index[i];
|
||
assert_eq!(r as usize as u32, r);
|
||
r as usize
|
||
}
|
||
}
|
||
}
|
||
|
||
/// Get 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 FieldPlacement::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 {
|
||
FieldPlacement::Union(_) |
|
||
FieldPlacement::Array { .. } => i,
|
||
FieldPlacement::Arbitrary { .. } => {
|
||
if use_small { inverse_small[i] as usize }
|
||
else { inverse_big[i] as usize }
|
||
}
|
||
}
|
||
})
|
||
}
|
||
}
|
||
|
||
/// 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)]
|
||
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.
|
||
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,
|
||
},
|
||
_ => false,
|
||
}
|
||
}
|
||
|
||
/// Returns true if this is an uninhabited type
|
||
pub fn is_uninhabited(&self) -> bool {
|
||
match *self {
|
||
Abi::Uninhabited => true,
|
||
_ => false,
|
||
}
|
||
}
|
||
}
|
||
|
||
newtype_index! {
|
||
pub struct VariantIdx { .. }
|
||
}
|
||
|
||
#[derive(PartialEq, Eq, Hash, Debug)]
|
||
pub enum Variants {
|
||
/// Single enum variants, structs/tuples, unions, and all non-ADTs.
|
||
Single {
|
||
index: VariantIdx,
|
||
},
|
||
|
||
/// General-case enums: for each case there is a struct, and they all have
|
||
/// all space reserved for the tag, and their first field starts
|
||
/// at a non-0 offset, after where the tag would go.
|
||
Tagged {
|
||
tag: Scalar,
|
||
variants: IndexVec<VariantIdx, LayoutDetails>,
|
||
},
|
||
|
||
/// Multiple cases distinguished by a niche (values invalid for a type):
|
||
/// the variant `dataful_variant` contains a niche at an arbitrary
|
||
/// offset (field 0 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).
|
||
NicheFilling {
|
||
dataful_variant: VariantIdx,
|
||
niche_variants: RangeInclusive<VariantIdx>,
|
||
niche: Scalar,
|
||
niche_start: u128,
|
||
variants: IndexVec<VariantIdx, LayoutDetails>,
|
||
}
|
||
}
|
||
|
||
#[derive(PartialEq, Eq, Hash, Debug)]
|
||
pub struct LayoutDetails {
|
||
pub variants: Variants,
|
||
pub fields: FieldPlacement,
|
||
pub abi: Abi,
|
||
pub align: Align,
|
||
pub size: Size
|
||
}
|
||
|
||
impl LayoutDetails {
|
||
pub fn scalar<C: HasDataLayout>(cx: &C, scalar: Scalar) -> Self {
|
||
let size = scalar.value.size(cx);
|
||
let align = scalar.value.align(cx);
|
||
LayoutDetails {
|
||
variants: Variants::Single { index: VariantIdx::new(0) },
|
||
fields: FieldPlacement::Union(0),
|
||
abi: Abi::Scalar(scalar),
|
||
size,
|
||
align,
|
||
}
|
||
}
|
||
}
|
||
|
||
/// The details of the layout of a type, alongside the type itself.
|
||
/// Provides various type traversal APIs (e.g. recursing into fields).
|
||
///
|
||
/// Note that the details are NOT guaranteed to always be identical
|
||
/// to those 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 TyLayout<'a, Ty> {
|
||
pub ty: Ty,
|
||
pub details: &'a LayoutDetails
|
||
}
|
||
|
||
impl<'a, Ty> Deref for TyLayout<'a, Ty> {
|
||
type Target = &'a LayoutDetails;
|
||
fn deref(&self) -> &&'a LayoutDetails {
|
||
&self.details
|
||
}
|
||
}
|
||
|
||
pub trait LayoutOf {
|
||
type Ty;
|
||
type TyLayout;
|
||
|
||
fn layout_of(&self, ty: Self::Ty) -> Self::TyLayout;
|
||
}
|
||
|
||
pub trait TyLayoutMethods<'a, C: LayoutOf<Ty = Self>>: Sized {
|
||
fn for_variant(
|
||
this: TyLayout<'a, Self>,
|
||
cx: &C,
|
||
variant_index: VariantIdx,
|
||
) -> TyLayout<'a, Self>;
|
||
fn field(this: TyLayout<'a, Self>, cx: &C, i: usize) -> C::TyLayout;
|
||
}
|
||
|
||
impl<'a, Ty> TyLayout<'a, Ty> {
|
||
pub fn for_variant<C>(self, cx: &C, variant_index: VariantIdx) -> Self
|
||
where Ty: TyLayoutMethods<'a, C>, C: LayoutOf<Ty = Ty> {
|
||
Ty::for_variant(self, cx, variant_index)
|
||
}
|
||
pub fn field<C>(self, cx: &C, i: usize) -> C::TyLayout
|
||
where Ty: TyLayoutMethods<'a, C>, C: LayoutOf<Ty = Ty> {
|
||
Ty::field(self, cx, i)
|
||
}
|
||
}
|
||
|
||
impl<'a, Ty> TyLayout<'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
|
||
}
|
||
}
|
||
|
||
pub fn size_and_align(&self) -> (Size, Align) {
|
||
(self.size, self.align)
|
||
}
|
||
}
|