1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 //! This module contains the code to convert from the wacky tcx data
12 //! structures into the hair. The `builder` is generally ignorant of
13 //! the tcx etc, and instead goes through the `Cx` for most of its
18 use rustc::mir::transform::MirSource;
20 use rustc::middle::const_val::{ConstEvalErr, ConstVal};
21 use rustc_const_eval::ConstContext;
22 use rustc_data_structures::indexed_vec::Idx;
23 use rustc::hir::def_id::DefId;
24 use rustc::hir::map::blocks::FnLikeNode;
25 use rustc::middle::region::RegionMaps;
26 use rustc::infer::InferCtxt;
27 use rustc::ty::subst::Subst;
28 use rustc::ty::{self, Ty, TyCtxt};
29 use syntax::symbol::Symbol;
31 use rustc_const_math::{ConstInt, ConstUsize};
35 pub struct Cx<'a, 'gcx: 'a + 'tcx, 'tcx: 'a> {
36 tcx: TyCtxt<'a, 'gcx, 'tcx>,
37 infcx: &'a InferCtxt<'a, 'gcx, 'tcx>,
38 pub param_env: ty::ParamEnv<'tcx>,
39 pub region_maps: Rc<RegionMaps>,
40 pub tables: &'a ty::TypeckTables<'gcx>,
42 /// This is `Constness::Const` if we are compiling a `static`,
43 /// `const`, or the body of a `const fn`.
44 constness: hir::Constness,
46 /// What are we compiling?
49 /// True if this constant/function needs overflow checks.
53 impl<'a, 'gcx, 'tcx> Cx<'a, 'gcx, 'tcx> {
54 pub fn new(infcx: &'a InferCtxt<'a, 'gcx, 'tcx>, src: MirSource) -> Cx<'a, 'gcx, 'tcx> {
55 let constness = match src {
57 MirSource::Static(..) => hir::Constness::Const,
58 MirSource::Fn(id) => {
59 let fn_like = FnLikeNode::from_node(infcx.tcx.hir.get(id));
60 fn_like.map_or(hir::Constness::NotConst, |f| f.constness())
62 MirSource::Promoted(..) => bug!(),
66 let src_id = src.item_id();
67 let src_def_id = tcx.hir.local_def_id(src_id);
69 let param_env = tcx.param_env(src_def_id);
70 let region_maps = tcx.region_maps(src_def_id);
71 let tables = tcx.typeck_tables_of(src_def_id);
73 let attrs = tcx.hir.attrs(src_id);
75 // Some functions always have overflow checks enabled,
76 // however, they may not get codegen'd, depending on
77 // the settings for the crate they are translated in.
78 let mut check_overflow = attrs.iter()
79 .any(|item| item.check_name("rustc_inherit_overflow_checks"));
81 // Respect -C overflow-checks.
82 check_overflow |= tcx.sess.overflow_checks();
84 // Constants and const fn's always need overflow checks.
85 check_overflow |= constness == hir::Constness::Const;
87 Cx { tcx, infcx, param_env, region_maps, tables, constness, src, check_overflow }
91 impl<'a, 'gcx, 'tcx> Cx<'a, 'gcx, 'tcx> {
92 /// Normalizes `ast` into the appropriate `mirror` type.
93 pub fn mirror<M: Mirror<'tcx>>(&mut self, ast: M) -> M::Output {
97 pub fn usize_ty(&mut self) -> Ty<'tcx> {
101 pub fn usize_literal(&mut self, value: u64) -> Literal<'tcx> {
102 match ConstUsize::new(value, self.tcx.sess.target.uint_type) {
103 Ok(val) => Literal::Value { value: ConstVal::Integral(ConstInt::Usize(val)) },
104 Err(_) => bug!("usize literal out of range for target"),
108 pub fn bool_ty(&mut self) -> Ty<'tcx> {
112 pub fn unit_ty(&mut self) -> Ty<'tcx> {
116 pub fn true_literal(&mut self) -> Literal<'tcx> {
117 Literal::Value { value: ConstVal::Bool(true) }
120 pub fn false_literal(&mut self) -> Literal<'tcx> {
121 Literal::Value { value: ConstVal::Bool(false) }
124 pub fn const_eval_literal(&mut self, e: &hir::Expr) -> Literal<'tcx> {
125 let tcx = self.tcx.global_tcx();
126 match ConstContext::with_tables(tcx, self.tables()).eval(e) {
127 Ok(value) => Literal::Value { value: value },
128 Err(s) => self.fatal_const_eval_err(&s, e.span, "expression")
132 pub fn fatal_const_eval_err(&self,
133 err: &ConstEvalErr<'tcx>,
138 err.report(self.tcx, primary_span, primary_kind);
139 self.tcx.sess.abort_if_errors();
143 pub fn trait_method(&mut self,
148 -> (Ty<'tcx>, Literal<'tcx>) {
149 let method_name = Symbol::intern(method_name);
150 let substs = self.tcx.mk_substs_trait(self_ty, params);
151 for item in self.tcx.associated_items(trait_def_id) {
152 if item.kind == ty::AssociatedKind::Method && item.name == method_name {
153 let method_ty = self.tcx.type_of(item.def_id);
154 let method_ty = method_ty.subst(self.tcx, substs);
157 value: ConstVal::Function(item.def_id, substs),
162 bug!("found no method `{}` in `{:?}`", method_name, trait_def_id);
165 pub fn num_variants(&mut self, adt_def: &ty::AdtDef) -> usize {
166 adt_def.variants.len()
169 pub fn all_fields(&mut self, adt_def: &ty::AdtDef, variant_index: usize) -> Vec<Field> {
170 (0..adt_def.variants[variant_index].fields.len())
175 pub fn needs_drop(&mut self, ty: Ty<'tcx>) -> bool {
176 let (ty, param_env) = self.tcx.lift_to_global(&(ty, self.param_env)).unwrap_or_else(|| {
177 bug!("MIR: Cx::needs_drop({:?}, {:?}) got \
178 type with inference types/regions",
181 ty.needs_drop(self.tcx.global_tcx(), param_env)
184 pub fn tcx(&self) -> TyCtxt<'a, 'gcx, 'tcx> {
188 pub fn tables(&self) -> &'a ty::TypeckTables<'gcx> {
192 pub fn check_overflow(&self) -> bool {