4946e1a463
types are always known and hence the ParameterEnvironment is not necessary. For other `Sized` queries, use the trait infrastructure just like `Copy`.
1225 lines
49 KiB
Rust
1225 lines
49 KiB
Rust
// Copyright 2013 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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//! # Representation of Algebraic Data Types
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//!
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//! This module determines how to represent enums, structs, and tuples
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//! based on their monomorphized types; it is responsible both for
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//! choosing a representation and translating basic operations on
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//! values of those types. (Note: exporting the representations for
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//! debuggers is handled in debuginfo.rs, not here.)
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//!
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//! Note that the interface treats everything as a general case of an
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//! enum, so structs/tuples/etc. have one pseudo-variant with
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//! discriminant 0; i.e., as if they were a univariant enum.
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//!
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//! Having everything in one place will enable improvements to data
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//! structure representation; possibilities include:
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//!
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//! - User-specified alignment (e.g., cacheline-aligning parts of
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//! concurrently accessed data structures); LLVM can't represent this
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//! directly, so we'd have to insert padding fields in any structure
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//! that might contain one and adjust GEP indices accordingly. See
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//! issue #4578.
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//!
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//! - Store nested enums' discriminants in the same word. Rather, if
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//! some variants start with enums, and those enums representations
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//! have unused alignment padding between discriminant and body, the
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//! outer enum's discriminant can be stored there and those variants
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//! can start at offset 0. Kind of fancy, and might need work to
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//! make copies of the inner enum type cooperate, but it could help
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//! with `Option` or `Result` wrapped around another enum.
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//!
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//! - Tagged pointers would be neat, but given that any type can be
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//! used unboxed and any field can have pointers (including mutable)
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//! taken to it, implementing them for Rust seems difficult.
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#![allow(unsigned_negation)]
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pub use self::Repr::*;
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use std::num::Int;
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use std::rc::Rc;
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use llvm::{ValueRef, True, IntEQ, IntNE};
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use back::abi::FAT_PTR_ADDR;
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use middle::subst;
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use middle::subst::Subst;
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use trans::_match;
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use trans::build::*;
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use trans::cleanup;
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use trans::cleanup::CleanupMethods;
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use trans::common::*;
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use trans::datum;
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use trans::machine;
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use trans::type_::Type;
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use trans::type_of;
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use middle::ty::{mod, Ty};
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use middle::ty::Disr;
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use syntax::ast;
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use syntax::attr;
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use syntax::attr::IntType;
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use util::ppaux::ty_to_string;
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type Hint = attr::ReprAttr;
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/// Representations.
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#[deriving(Eq, PartialEq, Show)]
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pub enum Repr<'tcx> {
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/// C-like enums; basically an int.
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CEnum(IntType, Disr, Disr), // discriminant range (signedness based on the IntType)
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/// Single-case variants, and structs/tuples/records.
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///
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/// Structs with destructors need a dynamic destroyedness flag to
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/// avoid running the destructor too many times; this is included
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/// in the `Struct` if present.
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Univariant(Struct<'tcx>, bool),
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/// General-case enums: for each case there is a struct, and they
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/// all start with a field for the discriminant.
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///
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/// Types with destructors need a dynamic destroyedness flag to
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/// avoid running the destructor too many times; the last argument
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/// indicates whether such a flag is present.
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General(IntType, Vec<Struct<'tcx>>, bool),
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/// Two cases distinguished by a nullable pointer: the case with discriminant
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/// `nndiscr` must have single field which is known to be nonnull due to its type.
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/// The other case is known to be zero sized. Hence we represent the enum
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/// as simply a nullable pointer: if not null it indicates the `nndiscr` variant,
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/// otherwise it indicates the other case.
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RawNullablePointer {
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nndiscr: Disr,
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nnty: Ty<'tcx>,
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nullfields: Vec<Ty<'tcx>>
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},
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/// Two cases distinguished by a nullable pointer: the case with discriminant
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/// `nndiscr` is represented by the struct `nonnull`, where the `discrfield`th
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/// field is known to be nonnull due to its type; if that field is null, then
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/// it represents the other case, which is inhabited by at most one value
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/// (and all other fields are undefined/unused).
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///
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/// For example, `std::option::Option` instantiated at a safe pointer type
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/// is represented such that `None` is a null pointer and `Some` is the
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/// identity function.
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StructWrappedNullablePointer {
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nonnull: Struct<'tcx>,
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nndiscr: Disr,
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discrfield: DiscrField,
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nullfields: Vec<Ty<'tcx>>,
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}
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}
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/// For structs, and struct-like parts of anything fancier.
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#[deriving(Eq, PartialEq, Show)]
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pub struct Struct<'tcx> {
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// If the struct is DST, then the size and alignment do not take into
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// account the unsized fields of the struct.
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pub size: u64,
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pub align: u32,
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pub sized: bool,
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pub packed: bool,
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pub fields: Vec<Ty<'tcx>>
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}
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/// Convenience for `represent_type`. There should probably be more or
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/// these, for places in trans where the `Ty` isn't directly
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/// available.
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pub fn represent_node<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
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node: ast::NodeId) -> Rc<Repr<'tcx>> {
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represent_type(bcx.ccx(), node_id_type(bcx, node))
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}
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/// Decides how to represent a given type.
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pub fn represent_type<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
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t: Ty<'tcx>) -> Rc<Repr<'tcx>> {
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debug!("Representing: {}", ty_to_string(cx.tcx(), t));
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match cx.adt_reprs().borrow().get(&t) {
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Some(repr) => return repr.clone(),
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None => {}
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}
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let repr = Rc::new(represent_type_uncached(cx, t));
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debug!("Represented as: {}", repr);
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cx.adt_reprs().borrow_mut().insert(t, repr.clone());
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repr
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}
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fn represent_type_uncached<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
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t: Ty<'tcx>) -> Repr<'tcx> {
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match t.sty {
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ty::ty_tup(ref elems) => {
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Univariant(mk_struct(cx, elems[], false, t), false)
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}
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ty::ty_struct(def_id, substs) => {
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let fields = ty::lookup_struct_fields(cx.tcx(), def_id);
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let mut ftys = fields.iter().map(|field| {
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ty::lookup_field_type(cx.tcx(), def_id, field.id, substs)
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}).collect::<Vec<_>>();
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let packed = ty::lookup_packed(cx.tcx(), def_id);
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let dtor = ty::ty_dtor(cx.tcx(), def_id).has_drop_flag();
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if dtor { ftys.push(ty::mk_bool()); }
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Univariant(mk_struct(cx, ftys[], packed, t), dtor)
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}
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ty::ty_unboxed_closure(def_id, _, substs) => {
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let upvars = ty::unboxed_closure_upvars(cx.tcx(), def_id, substs);
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let upvar_types = upvars.iter().map(|u| u.ty).collect::<Vec<_>>();
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Univariant(mk_struct(cx, upvar_types[], false, t), false)
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}
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ty::ty_enum(def_id, substs) => {
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let cases = get_cases(cx.tcx(), def_id, substs);
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let hint = *ty::lookup_repr_hints(cx.tcx(), def_id)[].get(0)
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.unwrap_or(&attr::ReprAny);
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let dtor = ty::ty_dtor(cx.tcx(), def_id).has_drop_flag();
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if cases.len() == 0 {
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// Uninhabitable; represent as unit
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// (Typechecking will reject discriminant-sizing attrs.)
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assert_eq!(hint, attr::ReprAny);
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let ftys = if dtor { vec!(ty::mk_bool()) } else { vec!() };
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return Univariant(mk_struct(cx, ftys[], false, t),
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dtor);
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}
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if !dtor && cases.iter().all(|c| c.tys.len() == 0) {
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// All bodies empty -> intlike
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let discrs: Vec<u64> = cases.iter().map(|c| c.discr).collect();
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let bounds = IntBounds {
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ulo: *discrs.iter().min().unwrap(),
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uhi: *discrs.iter().max().unwrap(),
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slo: discrs.iter().map(|n| *n as i64).min().unwrap(),
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shi: discrs.iter().map(|n| *n as i64).max().unwrap()
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};
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return mk_cenum(cx, hint, &bounds);
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}
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// Since there's at least one
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// non-empty body, explicit discriminants should have
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// been rejected by a checker before this point.
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if !cases.iter().enumerate().all(|(i,c)| c.discr == (i as Disr)) {
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cx.sess().bug(format!("non-C-like enum {} with specified \
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discriminants",
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ty::item_path_str(cx.tcx(),
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def_id))[]);
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}
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if cases.len() == 1 {
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// Equivalent to a struct/tuple/newtype.
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// (Typechecking will reject discriminant-sizing attrs.)
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assert_eq!(hint, attr::ReprAny);
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let mut ftys = cases[0].tys.clone();
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if dtor { ftys.push(ty::mk_bool()); }
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return Univariant(mk_struct(cx, ftys[], false, t),
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dtor);
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}
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if !dtor && cases.len() == 2 && hint == attr::ReprAny {
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// Nullable pointer optimization
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let mut discr = 0;
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while discr < 2 {
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if cases[1 - discr].is_zerolen(cx, t) {
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let st = mk_struct(cx, cases[discr].tys[],
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false, t);
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match cases[discr].find_ptr(cx) {
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Some(ref df) if df.len() == 1 && st.fields.len() == 1 => {
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return RawNullablePointer {
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nndiscr: discr as Disr,
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nnty: st.fields[0],
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nullfields: cases[1 - discr].tys.clone()
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};
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}
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Some(mut discrfield) => {
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discrfield.push(0);
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discrfield.reverse();
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return StructWrappedNullablePointer {
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nndiscr: discr as Disr,
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nonnull: st,
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discrfield: discrfield,
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nullfields: cases[1 - discr].tys.clone()
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};
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}
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None => {}
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}
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}
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discr += 1;
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}
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}
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// The general case.
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assert!((cases.len() - 1) as i64 >= 0);
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let bounds = IntBounds { ulo: 0, uhi: (cases.len() - 1) as u64,
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slo: 0, shi: (cases.len() - 1) as i64 };
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let min_ity = range_to_inttype(cx, hint, &bounds);
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// Create the set of structs that represent each variant
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// Use the minimum integer type we figured out above
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let fields : Vec<_> = cases.iter().map(|c| {
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let mut ftys = vec!(ty_of_inttype(min_ity));
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ftys.push_all(c.tys.as_slice());
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if dtor { ftys.push(ty::mk_bool()); }
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mk_struct(cx, ftys.as_slice(), false, t)
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}).collect();
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// Check to see if we should use a different type for the
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// discriminant. If the overall alignment of the type is
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// the same as the first field in each variant, we can safely use
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// an alignment-sized type.
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// We increase the size of the discriminant to avoid LLVM copying
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// padding when it doesn't need to. This normally causes unaligned
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// load/stores and excessive memcpy/memset operations. By using a
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// bigger integer size, LLVM can be sure about it's contents and
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// won't be so conservative.
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// This check is needed to avoid increasing the size of types when
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// the alignment of the first field is smaller than the overall
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// alignment of the type.
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let (_, align) = union_size_and_align(fields.as_slice());
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let mut use_align = true;
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for st in fields.iter() {
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// Get the first non-zero-sized field
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let field = st.fields.iter().skip(1).filter(|ty| {
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let t = type_of::sizing_type_of(cx, **ty);
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machine::llsize_of_real(cx, t) != 0 ||
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// This case is only relevant for zero-sized types with large alignment
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machine::llalign_of_min(cx, t) != 1
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}).next();
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if let Some(field) = field {
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let field_align = type_of::align_of(cx, *field);
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if field_align != align {
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use_align = false;
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break;
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}
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}
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}
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let ity = if use_align {
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// Use the overall alignment
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match align {
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1 => attr::UnsignedInt(ast::TyU8),
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2 => attr::UnsignedInt(ast::TyU16),
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4 => attr::UnsignedInt(ast::TyU32),
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8 if machine::llalign_of_min(cx, Type::i64(cx)) == 8 =>
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attr::UnsignedInt(ast::TyU64),
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_ => min_ity // use min_ity as a fallback
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}
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} else {
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min_ity
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};
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let fields : Vec<_> = cases.iter().map(|c| {
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let mut ftys = vec!(ty_of_inttype(ity));
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ftys.push_all(c.tys[]);
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if dtor { ftys.push(ty::mk_bool()); }
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mk_struct(cx, ftys[], false, t)
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}).collect();
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ensure_enum_fits_in_address_space(cx, ity, fields[], t);
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General(ity, fields, dtor)
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}
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_ => cx.sess().bug(format!("adt::represent_type called on non-ADT type: {}",
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ty_to_string(cx.tcx(), t))[])
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}
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}
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// this should probably all be in ty
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struct Case<'tcx> {
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discr: Disr,
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tys: Vec<Ty<'tcx>>
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}
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/// This represents the (GEP) indices to follow to get to the discriminant field
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pub type DiscrField = Vec<uint>;
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fn find_discr_field_candidate<'tcx>(tcx: &ty::ctxt<'tcx>,
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ty: Ty<'tcx>,
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mut path: DiscrField) -> Option<DiscrField> {
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match ty.sty {
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// Fat &T/&mut T/Box<T> i.e. T is [T], str, or Trait
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ty::ty_rptr(_, ty::mt { ty, .. }) | ty::ty_uniq(ty) if !type_is_sized(tcx, ty) => {
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path.push(FAT_PTR_ADDR);
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Some(path)
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},
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// Regular thin pointer: &T/&mut T/Box<T>
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ty::ty_rptr(..) | ty::ty_uniq(..) => Some(path),
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// Functions are just pointers
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ty::ty_bare_fn(..) => Some(path),
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// Closures are a pair of pointers: the code and environment
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ty::ty_closure(..) => {
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path.push(FAT_PTR_ADDR);
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Some(path)
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},
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// Is this the NonZero lang item wrapping a pointer or integer type?
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ty::ty_struct(did, substs) if Some(did) == tcx.lang_items.non_zero() => {
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let nonzero_fields = ty::lookup_struct_fields(tcx, did);
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assert_eq!(nonzero_fields.len(), 1);
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let nonzero_field = ty::lookup_field_type(tcx, did, nonzero_fields[0].id, substs);
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match nonzero_field.sty {
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ty::ty_ptr(..) | ty::ty_int(..) | ty::ty_uint(..) => {
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path.push(0);
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Some(path)
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},
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_ => None
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}
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},
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// Perhaps one of the fields of this struct is non-zero
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// let's recurse and find out
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ty::ty_struct(def_id, substs) => {
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let fields = ty::lookup_struct_fields(tcx, def_id);
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for (j, field) in fields.iter().enumerate() {
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let field_ty = ty::lookup_field_type(tcx, def_id, field.id, substs);
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if let Some(mut fpath) = find_discr_field_candidate(tcx, field_ty, path.clone()) {
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fpath.push(j);
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return Some(fpath);
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}
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}
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None
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},
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// Can we use one of the fields in this tuple?
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ty::ty_tup(ref tys) => {
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for (j, &ty) in tys.iter().enumerate() {
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if let Some(mut fpath) = find_discr_field_candidate(tcx, ty, path.clone()) {
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fpath.push(j);
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return Some(fpath);
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}
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}
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None
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},
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// Is this a fixed-size array of something non-zero
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// with at least one element?
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ty::ty_vec(ety, Some(d)) if d > 0 => {
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if let Some(mut vpath) = find_discr_field_candidate(tcx, ety, path) {
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vpath.push(0);
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Some(vpath)
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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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// Anything else is not a pointer
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_ => None
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}
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}
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|
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impl<'tcx> Case<'tcx> {
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fn is_zerolen<'a>(&self, cx: &CrateContext<'a, 'tcx>, scapegoat: Ty<'tcx>) -> bool {
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mk_struct(cx, self.tys[], false, scapegoat).size == 0
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}
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fn find_ptr<'a>(&self, cx: &CrateContext<'a, 'tcx>) -> Option<DiscrField> {
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for (i, &ty) in self.tys.iter().enumerate() {
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if let Some(mut path) = find_discr_field_candidate(cx.tcx(), ty, vec![]) {
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path.push(i);
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return Some(path);
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}
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}
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None
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}
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}
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fn get_cases<'tcx>(tcx: &ty::ctxt<'tcx>,
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def_id: ast::DefId,
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substs: &subst::Substs<'tcx>)
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-> Vec<Case<'tcx>> {
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ty::enum_variants(tcx, def_id).iter().map(|vi| {
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let arg_tys = vi.args.iter().map(|&raw_ty| {
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raw_ty.subst(tcx, substs)
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}).collect();
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Case { discr: vi.disr_val, tys: arg_tys }
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}).collect()
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}
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|
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fn mk_struct<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
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tys: &[Ty<'tcx>], packed: bool,
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scapegoat: Ty<'tcx>)
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-> Struct<'tcx> {
|
|
let sized = tys.iter().all(|&ty| type_is_sized(cx.tcx(), ty));
|
|
let lltys : Vec<Type> = if sized {
|
|
tys.iter()
|
|
.map(|&ty| type_of::sizing_type_of(cx, ty)).collect()
|
|
} else {
|
|
tys.iter().filter(|&ty| type_is_sized(cx.tcx(), *ty))
|
|
.map(|&ty| type_of::sizing_type_of(cx, ty)).collect()
|
|
};
|
|
|
|
ensure_struct_fits_in_address_space(cx, lltys[], packed, scapegoat);
|
|
|
|
let llty_rec = Type::struct_(cx, lltys[], packed);
|
|
Struct {
|
|
size: machine::llsize_of_alloc(cx, llty_rec),
|
|
align: machine::llalign_of_min(cx, llty_rec),
|
|
sized: sized,
|
|
packed: packed,
|
|
fields: tys.to_vec(),
|
|
}
|
|
}
|
|
|
|
#[deriving(Show)]
|
|
struct IntBounds {
|
|
slo: i64,
|
|
shi: i64,
|
|
ulo: u64,
|
|
uhi: u64
|
|
}
|
|
|
|
fn mk_cenum<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
|
|
hint: Hint, bounds: &IntBounds)
|
|
-> Repr<'tcx> {
|
|
let it = range_to_inttype(cx, hint, bounds);
|
|
match it {
|
|
attr::SignedInt(_) => CEnum(it, bounds.slo as Disr, bounds.shi as Disr),
|
|
attr::UnsignedInt(_) => CEnum(it, bounds.ulo, bounds.uhi)
|
|
}
|
|
}
|
|
|
|
fn range_to_inttype(cx: &CrateContext, hint: Hint, bounds: &IntBounds) -> IntType {
|
|
debug!("range_to_inttype: {} {}", hint, bounds);
|
|
// Lists of sizes to try. u64 is always allowed as a fallback.
|
|
#[allow(non_upper_case_globals)]
|
|
static choose_shortest: &'static[IntType] = &[
|
|
attr::UnsignedInt(ast::TyU8), attr::SignedInt(ast::TyI8),
|
|
attr::UnsignedInt(ast::TyU16), attr::SignedInt(ast::TyI16),
|
|
attr::UnsignedInt(ast::TyU32), attr::SignedInt(ast::TyI32)];
|
|
#[allow(non_upper_case_globals)]
|
|
static at_least_32: &'static[IntType] = &[
|
|
attr::UnsignedInt(ast::TyU32), attr::SignedInt(ast::TyI32)];
|
|
|
|
let attempts;
|
|
match hint {
|
|
attr::ReprInt(span, ity) => {
|
|
if !bounds_usable(cx, ity, bounds) {
|
|
cx.sess().span_bug(span, "representation hint insufficient for discriminant range")
|
|
}
|
|
return ity;
|
|
}
|
|
attr::ReprExtern => {
|
|
attempts = match cx.sess().target.target.arch[] {
|
|
// WARNING: the ARM EABI has two variants; the one corresponding to `at_least_32`
|
|
// appears to be used on Linux and NetBSD, but some systems may use the variant
|
|
// corresponding to `choose_shortest`. However, we don't run on those yet...?
|
|
"arm" => at_least_32,
|
|
_ => at_least_32,
|
|
}
|
|
}
|
|
attr::ReprAny => {
|
|
attempts = choose_shortest;
|
|
},
|
|
attr::ReprPacked => {
|
|
cx.tcx().sess.bug("range_to_inttype: found ReprPacked on an enum");
|
|
}
|
|
}
|
|
for &ity in attempts.iter() {
|
|
if bounds_usable(cx, ity, bounds) {
|
|
return ity;
|
|
}
|
|
}
|
|
return attr::UnsignedInt(ast::TyU64);
|
|
}
|
|
|
|
pub fn ll_inttype(cx: &CrateContext, ity: IntType) -> Type {
|
|
match ity {
|
|
attr::SignedInt(t) => Type::int_from_ty(cx, t),
|
|
attr::UnsignedInt(t) => Type::uint_from_ty(cx, t)
|
|
}
|
|
}
|
|
|
|
fn bounds_usable(cx: &CrateContext, ity: IntType, bounds: &IntBounds) -> bool {
|
|
debug!("bounds_usable: {} {}", ity, bounds);
|
|
match ity {
|
|
attr::SignedInt(_) => {
|
|
let lllo = C_integral(ll_inttype(cx, ity), bounds.slo as u64, true);
|
|
let llhi = C_integral(ll_inttype(cx, ity), bounds.shi as u64, true);
|
|
bounds.slo == const_to_int(lllo) as i64 && bounds.shi == const_to_int(llhi) as i64
|
|
}
|
|
attr::UnsignedInt(_) => {
|
|
let lllo = C_integral(ll_inttype(cx, ity), bounds.ulo, false);
|
|
let llhi = C_integral(ll_inttype(cx, ity), bounds.uhi, false);
|
|
bounds.ulo == const_to_uint(lllo) as u64 && bounds.uhi == const_to_uint(llhi) as u64
|
|
}
|
|
}
|
|
}
|
|
|
|
// FIXME(#17596) Ty<'tcx> is incorrectly invariant w.r.t 'tcx.
|
|
pub fn ty_of_inttype<'tcx>(ity: IntType) -> Ty<'tcx> {
|
|
match ity {
|
|
attr::SignedInt(t) => ty::mk_mach_int(t),
|
|
attr::UnsignedInt(t) => ty::mk_mach_uint(t)
|
|
}
|
|
}
|
|
|
|
// LLVM doesn't like types that don't fit in the address space
|
|
fn ensure_struct_fits_in_address_space<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
|
|
fields: &[Type],
|
|
packed: bool,
|
|
scapegoat: Ty<'tcx>) {
|
|
let mut offset = 0;
|
|
for &llty in fields.iter() {
|
|
// Invariant: offset < ccx.obj_size_bound() <= 1<<61
|
|
if !packed {
|
|
let type_align = machine::llalign_of_min(ccx, llty);
|
|
offset = roundup(offset, type_align);
|
|
}
|
|
// type_align is a power-of-2, so still offset < ccx.obj_size_bound()
|
|
// llsize_of_alloc(ccx, llty) is also less than ccx.obj_size_bound()
|
|
// so the sum is less than 1<<62 (and therefore can't overflow).
|
|
offset += machine::llsize_of_alloc(ccx, llty);
|
|
|
|
if offset >= ccx.obj_size_bound() {
|
|
ccx.report_overbig_object(scapegoat);
|
|
}
|
|
}
|
|
}
|
|
|
|
fn union_size_and_align(sts: &[Struct]) -> (machine::llsize, machine::llalign) {
|
|
let size = sts.iter().map(|st| st.size).max().unwrap();
|
|
let most_aligned = sts.iter().max_by(|st| st.align).unwrap();
|
|
(size, most_aligned.align)
|
|
}
|
|
|
|
fn ensure_enum_fits_in_address_space<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
|
|
discr: IntType,
|
|
fields: &[Struct],
|
|
scapegoat: Ty<'tcx>) {
|
|
let discr_size = machine::llsize_of_alloc(ccx, ll_inttype(ccx, discr));
|
|
let (field_size, field_align) = union_size_and_align(fields);
|
|
|
|
// field_align < 1<<32, discr_size <= 8, field_size < OBJ_SIZE_BOUND <= 1<<61
|
|
// so the sum is less than 1<<62 (and can't overflow).
|
|
let total_size = roundup(discr_size, field_align) + field_size;
|
|
|
|
if total_size >= ccx.obj_size_bound() {
|
|
ccx.report_overbig_object(scapegoat);
|
|
}
|
|
}
|
|
|
|
|
|
/// LLVM-level types are a little complicated.
|
|
///
|
|
/// C-like enums need to be actual ints, not wrapped in a struct,
|
|
/// because that changes the ABI on some platforms (see issue #10308).
|
|
///
|
|
/// For nominal types, in some cases, we need to use LLVM named structs
|
|
/// and fill in the actual contents in a second pass to prevent
|
|
/// unbounded recursion; see also the comments in `trans::type_of`.
|
|
pub fn type_of<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>, r: &Repr<'tcx>) -> Type {
|
|
generic_type_of(cx, r, None, false, false)
|
|
}
|
|
// Pass dst=true if the type you are passing is a DST. Yes, we could figure
|
|
// this out, but if you call this on an unsized type without realising it, you
|
|
// are going to get the wrong type (it will not include the unsized parts of it).
|
|
pub fn sizing_type_of<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
|
|
r: &Repr<'tcx>, dst: bool) -> Type {
|
|
generic_type_of(cx, r, None, true, dst)
|
|
}
|
|
pub fn incomplete_type_of<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
|
|
r: &Repr<'tcx>, name: &str) -> Type {
|
|
generic_type_of(cx, r, Some(name), false, false)
|
|
}
|
|
pub fn finish_type_of<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
|
|
r: &Repr<'tcx>, llty: &mut Type) {
|
|
match *r {
|
|
CEnum(..) | General(..) | RawNullablePointer { .. } => { }
|
|
Univariant(ref st, _) | StructWrappedNullablePointer { nonnull: ref st, .. } =>
|
|
llty.set_struct_body(struct_llfields(cx, st, false, false)[],
|
|
st.packed)
|
|
}
|
|
}
|
|
|
|
fn generic_type_of<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
|
|
r: &Repr<'tcx>,
|
|
name: Option<&str>,
|
|
sizing: bool,
|
|
dst: bool) -> Type {
|
|
match *r {
|
|
CEnum(ity, _, _) => ll_inttype(cx, ity),
|
|
RawNullablePointer { nnty, .. } => type_of::sizing_type_of(cx, nnty),
|
|
Univariant(ref st, _) | StructWrappedNullablePointer { nonnull: ref st, .. } => {
|
|
match name {
|
|
None => {
|
|
Type::struct_(cx, struct_llfields(cx, st, sizing, dst)[],
|
|
st.packed)
|
|
}
|
|
Some(name) => { assert_eq!(sizing, false); Type::named_struct(cx, name) }
|
|
}
|
|
}
|
|
General(ity, ref sts, _) => {
|
|
// We need a representation that has:
|
|
// * The alignment of the most-aligned field
|
|
// * The size of the largest variant (rounded up to that alignment)
|
|
// * No alignment padding anywhere any variant has actual data
|
|
// (currently matters only for enums small enough to be immediate)
|
|
// * The discriminant in an obvious place.
|
|
//
|
|
// So we start with the discriminant, pad it up to the alignment with
|
|
// more of its own type, then use alignment-sized ints to get the rest
|
|
// of the size.
|
|
//
|
|
// FIXME #10604: this breaks when vector types are present.
|
|
let (size, align) = union_size_and_align(sts[]);
|
|
let align_s = align as u64;
|
|
let discr_ty = ll_inttype(cx, ity);
|
|
let discr_size = machine::llsize_of_alloc(cx, discr_ty);
|
|
let align_units = (size + align_s - 1) / align_s - 1;
|
|
let fill_ty = match align_s {
|
|
1 => Type::array(&Type::i8(cx), align_units),
|
|
2 => Type::array(&Type::i16(cx), align_units),
|
|
4 => Type::array(&Type::i32(cx), align_units),
|
|
8 if machine::llalign_of_min(cx, Type::i64(cx)) == 8 =>
|
|
Type::array(&Type::i64(cx), align_units),
|
|
a if a.count_ones() == 1 => Type::array(&Type::vector(&Type::i32(cx), a / 4),
|
|
align_units),
|
|
_ => panic!("unsupported enum alignment: {}", align)
|
|
};
|
|
assert_eq!(machine::llalign_of_min(cx, fill_ty), align);
|
|
assert_eq!(align_s % discr_size, 0);
|
|
let fields = [discr_ty,
|
|
Type::array(&discr_ty, align_s / discr_size - 1),
|
|
fill_ty];
|
|
match name {
|
|
None => Type::struct_(cx, fields[], false),
|
|
Some(name) => {
|
|
let mut llty = Type::named_struct(cx, name);
|
|
llty.set_struct_body(fields[], false);
|
|
llty
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
fn struct_llfields<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>, st: &Struct<'tcx>,
|
|
sizing: bool, dst: bool) -> Vec<Type> {
|
|
if sizing {
|
|
st.fields.iter().filter(|&ty| !dst || type_is_sized(cx.tcx(), *ty))
|
|
.map(|&ty| type_of::sizing_type_of(cx, ty)).collect()
|
|
} else {
|
|
st.fields.iter().map(|&ty| type_of::type_of(cx, ty)).collect()
|
|
}
|
|
}
|
|
|
|
/// Obtain a representation of the discriminant sufficient to translate
|
|
/// destructuring; this may or may not involve the actual discriminant.
|
|
///
|
|
/// This should ideally be less tightly tied to `_match`.
|
|
pub fn trans_switch<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
|
|
r: &Repr<'tcx>, scrutinee: ValueRef)
|
|
-> (_match::BranchKind, Option<ValueRef>) {
|
|
match *r {
|
|
CEnum(..) | General(..) |
|
|
RawNullablePointer { .. } | StructWrappedNullablePointer { .. } => {
|
|
(_match::Switch, Some(trans_get_discr(bcx, r, scrutinee, None)))
|
|
}
|
|
Univariant(..) => {
|
|
(_match::Single, None)
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
|
|
/// Obtain the actual discriminant of a value.
|
|
pub fn trans_get_discr<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, r: &Repr<'tcx>,
|
|
scrutinee: ValueRef, cast_to: Option<Type>)
|
|
-> ValueRef {
|
|
let signed;
|
|
let val;
|
|
debug!("trans_get_discr r: {}", r);
|
|
match *r {
|
|
CEnum(ity, min, max) => {
|
|
val = load_discr(bcx, ity, scrutinee, min, max);
|
|
signed = ity.is_signed();
|
|
}
|
|
General(ity, ref cases, _) => {
|
|
let ptr = GEPi(bcx, scrutinee, &[0, 0]);
|
|
val = load_discr(bcx, ity, ptr, 0, (cases.len() - 1) as Disr);
|
|
signed = ity.is_signed();
|
|
}
|
|
Univariant(..) => {
|
|
val = C_u8(bcx.ccx(), 0);
|
|
signed = false;
|
|
}
|
|
RawNullablePointer { nndiscr, nnty, .. } => {
|
|
let cmp = if nndiscr == 0 { IntEQ } else { IntNE };
|
|
let llptrty = type_of::sizing_type_of(bcx.ccx(), nnty);
|
|
val = ICmp(bcx, cmp, Load(bcx, scrutinee), C_null(llptrty));
|
|
signed = false;
|
|
}
|
|
StructWrappedNullablePointer { nndiscr, ref discrfield, .. } => {
|
|
val = struct_wrapped_nullable_bitdiscr(bcx, nndiscr, discrfield, scrutinee);
|
|
signed = false;
|
|
}
|
|
}
|
|
match cast_to {
|
|
None => val,
|
|
Some(llty) => if signed { SExt(bcx, val, llty) } else { ZExt(bcx, val, llty) }
|
|
}
|
|
}
|
|
|
|
fn struct_wrapped_nullable_bitdiscr(bcx: Block, nndiscr: Disr, discrfield: &DiscrField,
|
|
scrutinee: ValueRef) -> ValueRef {
|
|
let llptrptr = GEPi(bcx, scrutinee, discrfield[]);
|
|
let llptr = Load(bcx, llptrptr);
|
|
let cmp = if nndiscr == 0 { IntEQ } else { IntNE };
|
|
ICmp(bcx, cmp, llptr, C_null(val_ty(llptr)))
|
|
}
|
|
|
|
/// Helper for cases where the discriminant is simply loaded.
|
|
fn load_discr(bcx: Block, ity: IntType, ptr: ValueRef, min: Disr, max: Disr)
|
|
-> ValueRef {
|
|
let llty = ll_inttype(bcx.ccx(), ity);
|
|
assert_eq!(val_ty(ptr), llty.ptr_to());
|
|
let bits = machine::llbitsize_of_real(bcx.ccx(), llty);
|
|
assert!(bits <= 64);
|
|
let bits = bits as uint;
|
|
let mask = (-1u64 >> (64 - bits)) as Disr;
|
|
if (max + 1) & mask == min & mask {
|
|
// i.e., if the range is everything. The lo==hi case would be
|
|
// rejected by the LLVM verifier (it would mean either an
|
|
// empty set, which is impossible, or the entire range of the
|
|
// type, which is pointless).
|
|
Load(bcx, ptr)
|
|
} else {
|
|
// llvm::ConstantRange can deal with ranges that wrap around,
|
|
// so an overflow on (max + 1) is fine.
|
|
LoadRangeAssert(bcx, ptr, min, (max+1), /* signed: */ True)
|
|
}
|
|
}
|
|
|
|
/// Yield information about how to dispatch a case of the
|
|
/// discriminant-like value returned by `trans_switch`.
|
|
///
|
|
/// This should ideally be less tightly tied to `_match`.
|
|
pub fn trans_case<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, r: &Repr, discr: Disr)
|
|
-> _match::OptResult<'blk, 'tcx> {
|
|
match *r {
|
|
CEnum(ity, _, _) => {
|
|
_match::SingleResult(Result::new(bcx, C_integral(ll_inttype(bcx.ccx(), ity),
|
|
discr as u64, true)))
|
|
}
|
|
General(ity, _, _) => {
|
|
_match::SingleResult(Result::new(bcx, C_integral(ll_inttype(bcx.ccx(), ity),
|
|
discr as u64, true)))
|
|
}
|
|
Univariant(..) => {
|
|
bcx.ccx().sess().bug("no cases for univariants or structs")
|
|
}
|
|
RawNullablePointer { .. } |
|
|
StructWrappedNullablePointer { .. } => {
|
|
assert!(discr == 0 || discr == 1);
|
|
_match::SingleResult(Result::new(bcx, C_bool(bcx.ccx(), discr != 0)))
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Set the discriminant for a new value of the given case of the given
|
|
/// representation.
|
|
pub fn trans_set_discr<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, r: &Repr<'tcx>,
|
|
val: ValueRef, discr: Disr) {
|
|
match *r {
|
|
CEnum(ity, min, max) => {
|
|
assert_discr_in_range(ity, min, max, discr);
|
|
Store(bcx, C_integral(ll_inttype(bcx.ccx(), ity), discr as u64, true),
|
|
val)
|
|
}
|
|
General(ity, ref cases, dtor) => {
|
|
if dtor {
|
|
let ptr = trans_field_ptr(bcx, r, val, discr,
|
|
cases[discr as uint].fields.len() - 2);
|
|
Store(bcx, C_u8(bcx.ccx(), 1), ptr);
|
|
}
|
|
Store(bcx, C_integral(ll_inttype(bcx.ccx(), ity), discr as u64, true),
|
|
GEPi(bcx, val, &[0, 0]))
|
|
}
|
|
Univariant(ref st, dtor) => {
|
|
assert_eq!(discr, 0);
|
|
if dtor {
|
|
Store(bcx, C_u8(bcx.ccx(), 1),
|
|
GEPi(bcx, val, &[0, st.fields.len() - 1]));
|
|
}
|
|
}
|
|
RawNullablePointer { nndiscr, nnty, ..} => {
|
|
if discr != nndiscr {
|
|
let llptrty = type_of::sizing_type_of(bcx.ccx(), nnty);
|
|
Store(bcx, C_null(llptrty), val)
|
|
}
|
|
}
|
|
StructWrappedNullablePointer { nndiscr, ref discrfield, .. } => {
|
|
if discr != nndiscr {
|
|
let llptrptr = GEPi(bcx, val, discrfield[]);
|
|
let llptrty = val_ty(llptrptr).element_type();
|
|
Store(bcx, C_null(llptrty), llptrptr)
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
fn assert_discr_in_range(ity: IntType, min: Disr, max: Disr, discr: Disr) {
|
|
match ity {
|
|
attr::UnsignedInt(_) => assert!(min <= discr && discr <= max),
|
|
attr::SignedInt(_) => assert!(min as i64 <= discr as i64 && discr as i64 <= max as i64)
|
|
}
|
|
}
|
|
|
|
/// The number of fields in a given case; for use when obtaining this
|
|
/// information from the type or definition is less convenient.
|
|
pub fn num_args(r: &Repr, discr: Disr) -> uint {
|
|
match *r {
|
|
CEnum(..) => 0,
|
|
Univariant(ref st, dtor) => {
|
|
assert_eq!(discr, 0);
|
|
st.fields.len() - (if dtor { 1 } else { 0 })
|
|
}
|
|
General(_, ref cases, dtor) => {
|
|
cases[discr as uint].fields.len() - 1 - (if dtor { 1 } else { 0 })
|
|
}
|
|
RawNullablePointer { nndiscr, ref nullfields, .. } => {
|
|
if discr == nndiscr { 1 } else { nullfields.len() }
|
|
}
|
|
StructWrappedNullablePointer { ref nonnull, nndiscr,
|
|
ref nullfields, .. } => {
|
|
if discr == nndiscr { nonnull.fields.len() } else { nullfields.len() }
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Access a field, at a point when the value's case is known.
|
|
pub fn trans_field_ptr<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, r: &Repr<'tcx>,
|
|
val: ValueRef, discr: Disr, ix: uint) -> ValueRef {
|
|
// Note: if this ever needs to generate conditionals (e.g., if we
|
|
// decide to do some kind of cdr-coding-like non-unique repr
|
|
// someday), it will need to return a possibly-new bcx as well.
|
|
match *r {
|
|
CEnum(..) => {
|
|
bcx.ccx().sess().bug("element access in C-like enum")
|
|
}
|
|
Univariant(ref st, _dtor) => {
|
|
assert_eq!(discr, 0);
|
|
struct_field_ptr(bcx, st, val, ix, false)
|
|
}
|
|
General(_, ref cases, _) => {
|
|
struct_field_ptr(bcx, &cases[discr as uint], val, ix + 1, true)
|
|
}
|
|
RawNullablePointer { nndiscr, ref nullfields, .. } |
|
|
StructWrappedNullablePointer { nndiscr, ref nullfields, .. } if discr != nndiscr => {
|
|
// The unit-like case might have a nonzero number of unit-like fields.
|
|
// (e.d., Result of Either with (), as one side.)
|
|
let ty = type_of::type_of(bcx.ccx(), nullfields[ix]);
|
|
assert_eq!(machine::llsize_of_alloc(bcx.ccx(), ty), 0);
|
|
// The contents of memory at this pointer can't matter, but use
|
|
// the value that's "reasonable" in case of pointer comparison.
|
|
PointerCast(bcx, val, ty.ptr_to())
|
|
}
|
|
RawNullablePointer { nndiscr, nnty, .. } => {
|
|
assert_eq!(ix, 0);
|
|
assert_eq!(discr, nndiscr);
|
|
let ty = type_of::type_of(bcx.ccx(), nnty);
|
|
PointerCast(bcx, val, ty.ptr_to())
|
|
}
|
|
StructWrappedNullablePointer { ref nonnull, nndiscr, .. } => {
|
|
assert_eq!(discr, nndiscr);
|
|
struct_field_ptr(bcx, nonnull, val, ix, false)
|
|
}
|
|
}
|
|
}
|
|
|
|
pub fn struct_field_ptr<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, st: &Struct<'tcx>, val: ValueRef,
|
|
ix: uint, needs_cast: bool) -> ValueRef {
|
|
let val = if needs_cast {
|
|
let ccx = bcx.ccx();
|
|
let fields = st.fields.iter().map(|&ty| type_of::type_of(ccx, ty)).collect::<Vec<_>>();
|
|
let real_ty = Type::struct_(ccx, fields[], st.packed);
|
|
PointerCast(bcx, val, real_ty.ptr_to())
|
|
} else {
|
|
val
|
|
};
|
|
|
|
GEPi(bcx, val, &[0, ix])
|
|
}
|
|
|
|
pub fn fold_variants<'blk, 'tcx, F>(bcx: Block<'blk, 'tcx>,
|
|
r: &Repr<'tcx>,
|
|
value: ValueRef,
|
|
mut f: F)
|
|
-> Block<'blk, 'tcx> where
|
|
F: FnMut(Block<'blk, 'tcx>, &Struct<'tcx>, ValueRef) -> Block<'blk, 'tcx>,
|
|
{
|
|
let fcx = bcx.fcx;
|
|
match *r {
|
|
Univariant(ref st, _) => {
|
|
f(bcx, st, value)
|
|
}
|
|
General(ity, ref cases, _) => {
|
|
let ccx = bcx.ccx();
|
|
let unr_cx = fcx.new_temp_block("enum-variant-iter-unr");
|
|
Unreachable(unr_cx);
|
|
|
|
let discr_val = trans_get_discr(bcx, r, value, None);
|
|
let llswitch = Switch(bcx, discr_val, unr_cx.llbb, cases.len());
|
|
let bcx_next = fcx.new_temp_block("enum-variant-iter-next");
|
|
|
|
for (discr, case) in cases.iter().enumerate() {
|
|
let mut variant_cx = fcx.new_temp_block(
|
|
format!("enum-variant-iter-{}", discr.to_string())[]
|
|
);
|
|
let rhs_val = C_integral(ll_inttype(ccx, ity), discr as u64, true);
|
|
AddCase(llswitch, rhs_val, variant_cx.llbb);
|
|
|
|
let fields = case.fields.iter().map(|&ty|
|
|
type_of::type_of(bcx.ccx(), ty)).collect::<Vec<_>>();
|
|
let real_ty = Type::struct_(ccx, fields[], case.packed);
|
|
let variant_value = PointerCast(variant_cx, value, real_ty.ptr_to());
|
|
|
|
variant_cx = f(variant_cx, case, variant_value);
|
|
Br(variant_cx, bcx_next.llbb);
|
|
}
|
|
|
|
bcx_next
|
|
}
|
|
_ => unreachable!()
|
|
}
|
|
}
|
|
|
|
/// Access the struct drop flag, if present.
|
|
pub fn trans_drop_flag_ptr<'blk, 'tcx>(mut bcx: Block<'blk, 'tcx>, r: &Repr<'tcx>, val: ValueRef)
|
|
-> datum::DatumBlock<'blk, 'tcx, datum::Expr> {
|
|
let ptr_ty = ty::mk_imm_ptr(bcx.tcx(), ty::mk_bool());
|
|
match *r {
|
|
Univariant(ref st, true) => {
|
|
let flag_ptr = GEPi(bcx, val, &[0, st.fields.len() - 1]);
|
|
datum::immediate_rvalue_bcx(bcx, flag_ptr, ptr_ty).to_expr_datumblock()
|
|
}
|
|
General(_, _, true) => {
|
|
let fcx = bcx.fcx;
|
|
let custom_cleanup_scope = fcx.push_custom_cleanup_scope();
|
|
let scratch = unpack_datum!(bcx, datum::lvalue_scratch_datum(
|
|
bcx, ty::mk_bool(), "drop_flag", false,
|
|
cleanup::CustomScope(custom_cleanup_scope), (), |_, bcx, _| bcx
|
|
));
|
|
bcx = fold_variants(bcx, r, val, |variant_cx, st, value| {
|
|
let ptr = struct_field_ptr(variant_cx, st, value, (st.fields.len() - 1), false);
|
|
datum::Datum::new(ptr, ptr_ty, datum::Rvalue::new(datum::ByRef))
|
|
.store_to(variant_cx, scratch.val)
|
|
});
|
|
let expr_datum = scratch.to_expr_datum();
|
|
fcx.pop_custom_cleanup_scope(custom_cleanup_scope);
|
|
datum::DatumBlock::new(bcx, expr_datum)
|
|
}
|
|
_ => bcx.ccx().sess().bug("tried to get drop flag of non-droppable type")
|
|
}
|
|
}
|
|
|
|
/// Construct a constant value, suitable for initializing a
|
|
/// GlobalVariable, given a case and constant values for its fields.
|
|
/// Note that this may have a different LLVM type (and different
|
|
/// alignment!) from the representation's `type_of`, so it needs a
|
|
/// pointer cast before use.
|
|
///
|
|
/// The LLVM type system does not directly support unions, and only
|
|
/// pointers can be bitcast, so a constant (and, by extension, the
|
|
/// GlobalVariable initialized by it) will have a type that can vary
|
|
/// depending on which case of an enum it is.
|
|
///
|
|
/// To understand the alignment situation, consider `enum E { V64(u64),
|
|
/// V32(u32, u32) }` on Windows. The type has 8-byte alignment to
|
|
/// accommodate the u64, but `V32(x, y)` would have LLVM type `{i32,
|
|
/// i32, i32}`, which is 4-byte aligned.
|
|
///
|
|
/// Currently the returned value has the same size as the type, but
|
|
/// this could be changed in the future to avoid allocating unnecessary
|
|
/// space after values of shorter-than-maximum cases.
|
|
pub fn trans_const<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, r: &Repr<'tcx>, discr: Disr,
|
|
vals: &[ValueRef]) -> ValueRef {
|
|
match *r {
|
|
CEnum(ity, min, max) => {
|
|
assert_eq!(vals.len(), 0);
|
|
assert_discr_in_range(ity, min, max, discr);
|
|
C_integral(ll_inttype(ccx, ity), discr as u64, true)
|
|
}
|
|
General(ity, ref cases, _) => {
|
|
let case = &cases[discr as uint];
|
|
let max_sz = cases.iter().map(|x| x.size).max().unwrap();
|
|
let lldiscr = C_integral(ll_inttype(ccx, ity), discr as u64, true);
|
|
let mut f = vec![lldiscr];
|
|
f.push_all(vals);
|
|
let mut contents = build_const_struct(ccx, case, f[]);
|
|
contents.push_all(&[padding(ccx, max_sz - case.size)]);
|
|
C_struct(ccx, contents[], false)
|
|
}
|
|
Univariant(ref st, _dro) => {
|
|
assert!(discr == 0);
|
|
let contents = build_const_struct(ccx, st, vals);
|
|
C_struct(ccx, contents[], st.packed)
|
|
}
|
|
RawNullablePointer { nndiscr, nnty, .. } => {
|
|
if discr == nndiscr {
|
|
assert_eq!(vals.len(), 1);
|
|
vals[0]
|
|
} else {
|
|
C_null(type_of::sizing_type_of(ccx, nnty))
|
|
}
|
|
}
|
|
StructWrappedNullablePointer { ref nonnull, nndiscr, .. } => {
|
|
if discr == nndiscr {
|
|
C_struct(ccx, build_const_struct(ccx,
|
|
nonnull,
|
|
vals)[],
|
|
false)
|
|
} else {
|
|
let vals = nonnull.fields.iter().map(|&ty| {
|
|
// Always use null even if it's not the `discrfield`th
|
|
// field; see #8506.
|
|
C_null(type_of::sizing_type_of(ccx, ty))
|
|
}).collect::<Vec<ValueRef>>();
|
|
C_struct(ccx, build_const_struct(ccx,
|
|
nonnull,
|
|
vals[])[],
|
|
false)
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Compute struct field offsets relative to struct begin.
|
|
fn compute_struct_field_offsets<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
|
|
st: &Struct<'tcx>) -> Vec<u64> {
|
|
let mut offsets = vec!();
|
|
|
|
let mut offset = 0;
|
|
for &ty in st.fields.iter() {
|
|
let llty = type_of::sizing_type_of(ccx, ty);
|
|
if !st.packed {
|
|
let type_align = type_of::align_of(ccx, ty);
|
|
offset = roundup(offset, type_align);
|
|
}
|
|
offsets.push(offset);
|
|
offset += machine::llsize_of_alloc(ccx, llty);
|
|
}
|
|
assert_eq!(st.fields.len(), offsets.len());
|
|
offsets
|
|
}
|
|
|
|
/// Building structs is a little complicated, because we might need to
|
|
/// insert padding if a field's value is less aligned than its type.
|
|
///
|
|
/// Continuing the example from `trans_const`, a value of type `(u32,
|
|
/// E)` should have the `E` at offset 8, but if that field's
|
|
/// initializer is 4-byte aligned then simply translating the tuple as
|
|
/// a two-element struct will locate it at offset 4, and accesses to it
|
|
/// will read the wrong memory.
|
|
fn build_const_struct<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
|
|
st: &Struct<'tcx>, vals: &[ValueRef])
|
|
-> Vec<ValueRef> {
|
|
assert_eq!(vals.len(), st.fields.len());
|
|
|
|
let target_offsets = compute_struct_field_offsets(ccx, st);
|
|
|
|
// offset of current value
|
|
let mut offset = 0;
|
|
let mut cfields = Vec::new();
|
|
for (&val, &target_offset) in vals.iter().zip(target_offsets.iter()) {
|
|
if !st.packed {
|
|
let val_align = machine::llalign_of_min(ccx, val_ty(val));
|
|
offset = roundup(offset, val_align);
|
|
}
|
|
if offset != target_offset {
|
|
cfields.push(padding(ccx, target_offset - offset));
|
|
offset = target_offset;
|
|
}
|
|
assert!(!is_undef(val));
|
|
cfields.push(val);
|
|
offset += machine::llsize_of_alloc(ccx, val_ty(val));
|
|
}
|
|
|
|
assert!(st.sized && offset <= st.size);
|
|
if offset != st.size {
|
|
cfields.push(padding(ccx, st.size - offset));
|
|
}
|
|
|
|
cfields
|
|
}
|
|
|
|
fn padding(ccx: &CrateContext, size: u64) -> ValueRef {
|
|
C_undef(Type::array(&Type::i8(ccx), size))
|
|
}
|
|
|
|
// FIXME this utility routine should be somewhere more general
|
|
#[inline]
|
|
fn roundup(x: u64, a: u32) -> u64 { let a = a as u64; ((x + (a - 1)) / a) * a }
|
|
|
|
/// Get the discriminant of a constant value.
|
|
pub fn const_get_discrim(ccx: &CrateContext, r: &Repr, val: ValueRef) -> Disr {
|
|
match *r {
|
|
CEnum(ity, _, _) => {
|
|
match ity {
|
|
attr::SignedInt(..) => const_to_int(val) as Disr,
|
|
attr::UnsignedInt(..) => const_to_uint(val) as Disr
|
|
}
|
|
}
|
|
General(ity, _, _) => {
|
|
match ity {
|
|
attr::SignedInt(..) => const_to_int(const_get_elt(ccx, val, &[0])) as Disr,
|
|
attr::UnsignedInt(..) => const_to_uint(const_get_elt(ccx, val, &[0])) as Disr
|
|
}
|
|
}
|
|
Univariant(..) => 0,
|
|
RawNullablePointer { .. } | StructWrappedNullablePointer { .. } => {
|
|
ccx.sess().bug("const discrim access of non c-like enum")
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Extract a field of a constant value, as appropriate for its
|
|
/// representation.
|
|
///
|
|
/// (Not to be confused with `common::const_get_elt`, which operates on
|
|
/// raw LLVM-level structs and arrays.)
|
|
pub fn const_get_field(ccx: &CrateContext, r: &Repr, val: ValueRef,
|
|
_discr: Disr, ix: uint) -> ValueRef {
|
|
match *r {
|
|
CEnum(..) => ccx.sess().bug("element access in C-like enum const"),
|
|
Univariant(..) => const_struct_field(ccx, val, ix),
|
|
General(..) => const_struct_field(ccx, val, ix + 1),
|
|
RawNullablePointer { .. } => {
|
|
assert_eq!(ix, 0);
|
|
val
|
|
},
|
|
StructWrappedNullablePointer{ .. } => const_struct_field(ccx, val, ix)
|
|
}
|
|
}
|
|
|
|
/// Extract field of struct-like const, skipping our alignment padding.
|
|
fn const_struct_field(ccx: &CrateContext, val: ValueRef, ix: uint) -> ValueRef {
|
|
// Get the ix-th non-undef element of the struct.
|
|
let mut real_ix = 0; // actual position in the struct
|
|
let mut ix = ix; // logical index relative to real_ix
|
|
let mut field;
|
|
loop {
|
|
loop {
|
|
field = const_get_elt(ccx, val, &[real_ix]);
|
|
if !is_undef(field) {
|
|
break;
|
|
}
|
|
real_ix = real_ix + 1;
|
|
}
|
|
if ix == 0 {
|
|
return field;
|
|
}
|
|
ix = ix - 1;
|
|
real_ix = real_ix + 1;
|
|
}
|
|
}
|