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::infer::InferCtxt;
26 use rustc::ty::subst::Subst;
27 use rustc::ty::{self, Ty, TyCtxt};
28 use syntax::symbol::{Symbol, InternedString};
30 use rustc_const_math::{ConstInt, ConstUsize};
32 #[derive(Copy, Clone)]
33 pub struct Cx<'a, 'gcx: 'a + 'tcx, 'tcx: 'a> {
34 tcx: TyCtxt<'a, 'gcx, 'tcx>,
35 infcx: &'a InferCtxt<'a, 'gcx, 'tcx>,
36 constness: hir::Constness,
38 /// True if this constant/function needs overflow checks.
42 impl<'a, 'gcx, 'tcx> Cx<'a, 'gcx, 'tcx> {
43 pub fn new(infcx: &'a InferCtxt<'a, 'gcx, 'tcx>, src: MirSource) -> Cx<'a, 'gcx, 'tcx> {
44 let constness = match src {
46 MirSource::Static(..) => hir::Constness::Const,
47 MirSource::Fn(id) => {
48 let fn_like = FnLikeNode::from_node(infcx.tcx.hir.get(id));
49 fn_like.map_or(hir::Constness::NotConst, |f| f.constness())
51 MirSource::Promoted(..) => bug!(),
54 let attrs = infcx.tcx.hir.attrs(src.item_id());
56 // Some functions always have overflow checks enabled,
57 // however, they may not get codegen'd, depending on
58 // the settings for the crate they are translated in.
59 let mut check_overflow = attrs.iter()
60 .any(|item| item.check_name("rustc_inherit_overflow_checks"));
62 // Respect -C overflow-checks.
63 check_overflow |= infcx.tcx.sess.overflow_checks();
65 // Constants and const fn's always need overflow checks.
66 check_overflow |= constness == hir::Constness::Const;
72 check_overflow: check_overflow,
77 impl<'a, 'gcx, 'tcx> Cx<'a, 'gcx, 'tcx> {
78 /// Normalizes `ast` into the appropriate `mirror` type.
79 pub fn mirror<M: Mirror<'tcx>>(&mut self, ast: M) -> M::Output {
83 pub fn usize_ty(&mut self) -> Ty<'tcx> {
87 pub fn usize_literal(&mut self, value: u64) -> Literal<'tcx> {
88 match ConstUsize::new(value, self.tcx.sess.target.uint_type) {
89 Ok(val) => Literal::Value { value: ConstVal::Integral(ConstInt::Usize(val)) },
90 Err(_) => bug!("usize literal out of range for target"),
94 pub fn bool_ty(&mut self) -> Ty<'tcx> {
98 pub fn unit_ty(&mut self) -> Ty<'tcx> {
102 pub fn str_literal(&mut self, value: InternedString) -> Literal<'tcx> {
103 Literal::Value { value: ConstVal::Str(value) }
106 pub fn true_literal(&mut self) -> Literal<'tcx> {
107 Literal::Value { value: ConstVal::Bool(true) }
110 pub fn false_literal(&mut self) -> Literal<'tcx> {
111 Literal::Value { value: ConstVal::Bool(false) }
114 pub fn const_eval_literal(&mut self, e: &hir::Expr) -> Literal<'tcx> {
115 let tcx = self.tcx.global_tcx();
116 match ConstContext::with_tables(tcx, self.tables()).eval(e) {
117 Ok(value) => Literal::Value { value: value },
118 Err(s) => self.fatal_const_eval_err(&s, e.span, "expression")
122 pub fn fatal_const_eval_err(&self,
123 err: &ConstEvalErr<'tcx>,
128 err.report(self.tcx, primary_span, primary_kind);
129 self.tcx.sess.abort_if_errors();
133 pub fn trait_method(&mut self,
138 -> (Ty<'tcx>, Literal<'tcx>) {
139 let method_name = Symbol::intern(method_name);
140 let substs = self.tcx.mk_substs_trait(self_ty, params);
141 for item in self.tcx.associated_items(trait_def_id) {
142 if item.kind == ty::AssociatedKind::Method && item.name == method_name {
143 let method_ty = self.tcx.item_type(item.def_id);
144 let method_ty = method_ty.subst(self.tcx, substs);
147 value: ConstVal::Function(item.def_id, substs),
152 bug!("found no method `{}` in `{:?}`", method_name, trait_def_id);
155 pub fn num_variants(&mut self, adt_def: &ty::AdtDef) -> usize {
156 adt_def.variants.len()
159 pub fn all_fields(&mut self, adt_def: &ty::AdtDef, variant_index: usize) -> Vec<Field> {
160 (0..adt_def.variants[variant_index].fields.len())
165 pub fn needs_drop(&mut self, ty: Ty<'tcx>) -> bool {
166 let ty = self.tcx.lift_to_global(&ty).unwrap_or_else(|| {
167 bug!("MIR: Cx::needs_drop({}) got \
168 type with inference types/regions",
171 self.tcx.type_needs_drop_given_env(ty, &self.infcx.parameter_environment)
174 pub fn tcx(&self) -> TyCtxt<'a, 'gcx, 'tcx> {
178 pub fn tables(&self) -> &'a ty::TypeckTables<'gcx> {
179 self.infcx.tables.expect_interned()
182 pub fn check_overflow(&self) -> bool {