0dc215741b
The `type_overflow` lint, doesn't catch the overflow for `i64` because the overflow happens earlier in the parse phase when the `u64` as biggest possible int gets casted to `i64` , without checking the for overflows. We can't lint in the parse phase, so a refactoring of the `LitInt` type was necessary. The types `LitInt`, `LitUint` and `LitIntUnsuffixed` where merged to one type `LitInt` which stores it's value as `u64`. An additional parameter was added which indicate the signedness of the type and the sign of the value.
596 lines
21 KiB
Rust
596 lines
21 KiB
Rust
// Copyright 2012-2014 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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#![allow(non_camel_case_types)]
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#![allow(unsigned_negate)]
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use metadata::csearch;
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use middle::astencode;
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use middle::def;
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use middle::pat_util::def_to_path;
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use middle::ty;
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use middle::typeck::astconv;
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use util::nodemap::{DefIdMap};
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use syntax::ast::*;
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use syntax::parse::token::InternedString;
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use syntax::visit::Visitor;
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use syntax::visit;
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use syntax::{ast, ast_map, ast_util};
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use std::rc::Rc;
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use std::gc::{Gc, GC};
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//
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// This pass classifies expressions by their constant-ness.
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//
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// Constant-ness comes in 3 flavours:
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//
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// - Integer-constants: can be evaluated by the frontend all the way down
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// to their actual value. They are used in a few places (enum
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// discriminants, switch arms) and are a subset of
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// general-constants. They cover all the integer and integer-ish
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// literals (nil, bool, int, uint, char, iNN, uNN) and all integer
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// operators and copies applied to them.
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//
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// - General-constants: can be evaluated by LLVM but not necessarily by
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// the frontend; usually due to reliance on target-specific stuff such
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// as "where in memory the value goes" or "what floating point mode the
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// target uses". This _includes_ integer-constants, plus the following
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// constructors:
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//
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// fixed-size vectors and strings: [] and ""/_
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// vector and string slices: &[] and &""
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// tuples: (,)
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// enums: foo(...)
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// floating point literals and operators
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// & and * pointers
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// copies of general constants
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//
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// (in theory, probably not at first: if/match on integer-const
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// conditions / descriminants)
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//
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// - Non-constants: everything else.
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//
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pub enum constness {
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integral_const,
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general_const,
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non_const
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}
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type constness_cache = DefIdMap<constness>;
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pub fn join(a: constness, b: constness) -> constness {
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match (a, b) {
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(integral_const, integral_const) => integral_const,
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(integral_const, general_const)
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| (general_const, integral_const)
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| (general_const, general_const) => general_const,
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_ => non_const
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}
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}
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pub fn join_all<It: Iterator<constness>>(mut cs: It) -> constness {
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cs.fold(integral_const, |a, b| join(a, b))
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}
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pub fn lookup_const(tcx: &ty::ctxt, e: &Expr) -> Option<Gc<Expr>> {
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let opt_def = tcx.def_map.borrow().find_copy(&e.id);
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match opt_def {
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Some(def::DefStatic(def_id, false)) => {
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lookup_const_by_id(tcx, def_id)
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}
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Some(def::DefVariant(enum_def, variant_def, _)) => {
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lookup_variant_by_id(tcx, enum_def, variant_def)
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}
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_ => None
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}
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}
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pub fn lookup_variant_by_id(tcx: &ty::ctxt,
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enum_def: ast::DefId,
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variant_def: ast::DefId)
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-> Option<Gc<Expr>> {
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fn variant_expr(variants: &[ast::P<ast::Variant>],
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id: ast::NodeId) -> Option<Gc<Expr>> {
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for variant in variants.iter() {
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if variant.node.id == id {
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return variant.node.disr_expr;
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}
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}
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None
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}
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if ast_util::is_local(enum_def) {
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{
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match tcx.map.find(enum_def.node) {
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None => None,
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Some(ast_map::NodeItem(it)) => match it.node {
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ItemEnum(ast::EnumDef { variants: ref variants }, _) => {
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variant_expr(variants.as_slice(), variant_def.node)
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}
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_ => None
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},
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Some(_) => None
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}
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}
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} else {
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match tcx.extern_const_variants.borrow().find(&variant_def) {
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Some(&e) => return e,
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None => {}
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}
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let e = match csearch::maybe_get_item_ast(tcx, enum_def,
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|a, b, c, d| astencode::decode_inlined_item(a, b, c, d)) {
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csearch::found(ast::IIItem(item)) => match item.node {
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ItemEnum(ast::EnumDef { variants: ref variants }, _) => {
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variant_expr(variants.as_slice(), variant_def.node)
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}
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_ => None
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},
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_ => None
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};
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tcx.extern_const_variants.borrow_mut().insert(variant_def, e);
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return e;
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}
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}
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pub fn lookup_const_by_id(tcx: &ty::ctxt, def_id: ast::DefId)
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-> Option<Gc<Expr>> {
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if ast_util::is_local(def_id) {
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{
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match tcx.map.find(def_id.node) {
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None => None,
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Some(ast_map::NodeItem(it)) => match it.node {
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ItemStatic(_, ast::MutImmutable, const_expr) => {
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Some(const_expr)
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}
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_ => None
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},
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Some(_) => None
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}
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}
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} else {
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match tcx.extern_const_statics.borrow().find(&def_id) {
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Some(&e) => return e,
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None => {}
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}
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let e = match csearch::maybe_get_item_ast(tcx, def_id,
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|a, b, c, d| astencode::decode_inlined_item(a, b, c, d)) {
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csearch::found(ast::IIItem(item)) => match item.node {
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ItemStatic(_, ast::MutImmutable, const_expr) => Some(const_expr),
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_ => None
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},
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_ => None
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};
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tcx.extern_const_statics.borrow_mut().insert(def_id, e);
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return e;
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}
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}
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struct ConstEvalVisitor<'a> {
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tcx: &'a ty::ctxt,
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ccache: constness_cache,
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}
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impl<'a> ConstEvalVisitor<'a> {
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fn classify(&mut self, e: &Expr) -> constness {
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let did = ast_util::local_def(e.id);
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match self.ccache.find(&did) {
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Some(&x) => return x,
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None => {}
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}
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let cn = match e.node {
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ast::ExprLit(ref lit) => {
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match lit.node {
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ast::LitStr(..) | ast::LitFloat(..) => general_const,
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_ => integral_const
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}
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}
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ast::ExprUnary(_, ref inner) | ast::ExprParen(ref inner) =>
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self.classify(&**inner),
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ast::ExprBinary(_, ref a, ref b) =>
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join(self.classify(&**a), self.classify(&**b)),
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ast::ExprTup(ref es) |
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ast::ExprVec(ref es) =>
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join_all(es.iter().map(|e| self.classify(&**e))),
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ast::ExprVstore(ref e, vstore) => {
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match vstore {
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ast::ExprVstoreSlice => self.classify(&**e),
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ast::ExprVstoreUniq |
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ast::ExprVstoreMutSlice => non_const
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}
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}
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ast::ExprStruct(_, ref fs, None) => {
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let cs = fs.iter().map(|f| self.classify(&*f.expr));
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join_all(cs)
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}
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ast::ExprCast(ref base, _) => {
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let ty = ty::expr_ty(self.tcx, e);
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let base = self.classify(&**base);
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if ty::type_is_integral(ty) {
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join(integral_const, base)
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} else if ty::type_is_fp(ty) {
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join(general_const, base)
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} else {
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non_const
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}
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}
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ast::ExprField(ref base, _, _) => self.classify(&**base),
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ast::ExprIndex(ref base, ref idx) =>
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join(self.classify(&**base), self.classify(&**idx)),
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ast::ExprAddrOf(ast::MutImmutable, ref base) =>
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self.classify(&**base),
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// FIXME: (#3728) we can probably do something CCI-ish
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// surrounding nonlocal constants. But we don't yet.
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ast::ExprPath(_) => self.lookup_constness(e),
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ast::ExprRepeat(..) => general_const,
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ast::ExprBlock(ref block) => {
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match block.expr {
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Some(ref e) => self.classify(&**e),
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None => integral_const
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}
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}
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_ => non_const
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};
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self.ccache.insert(did, cn);
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cn
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}
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fn lookup_constness(&self, e: &Expr) -> constness {
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match lookup_const(self.tcx, e) {
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Some(rhs) => {
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let ty = ty::expr_ty(self.tcx, &*rhs);
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if ty::type_is_integral(ty) {
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integral_const
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} else {
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general_const
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}
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}
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None => non_const
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}
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}
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}
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impl<'a> Visitor<()> for ConstEvalVisitor<'a> {
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fn visit_expr_post(&mut self, e: &Expr, _: ()) {
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self.classify(e);
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}
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}
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pub fn process_crate(krate: &ast::Crate,
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tcx: &ty::ctxt) {
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let mut v = ConstEvalVisitor {
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tcx: tcx,
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ccache: DefIdMap::new(),
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};
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visit::walk_crate(&mut v, krate, ());
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tcx.sess.abort_if_errors();
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}
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// FIXME (#33): this doesn't handle big integer/float literals correctly
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// (nor does the rest of our literal handling).
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#[deriving(Clone, PartialEq)]
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pub enum const_val {
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const_float(f64),
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const_int(i64),
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const_uint(u64),
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const_str(InternedString),
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const_binary(Rc<Vec<u8> >),
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const_bool(bool),
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const_nil
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}
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pub fn const_expr_to_pat(tcx: &ty::ctxt, expr: Gc<Expr>) -> Gc<Pat> {
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let pat = match expr.node {
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ExprTup(ref exprs) =>
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PatTup(exprs.iter().map(|&expr| const_expr_to_pat(tcx, expr)).collect()),
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ExprCall(callee, ref args) => {
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let def = tcx.def_map.borrow().get_copy(&callee.id);
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tcx.def_map.borrow_mut().find_or_insert(expr.id, def);
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let path = match def {
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def::DefStruct(def_id) => def_to_path(tcx, def_id),
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def::DefVariant(_, variant_did, _) => def_to_path(tcx, variant_did),
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_ => unreachable!()
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};
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let pats = args.iter().map(|&expr| const_expr_to_pat(tcx, expr)).collect();
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PatEnum(path, Some(pats))
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}
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ExprStruct(ref path, ref fields, None) => {
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let field_pats = fields.iter().map(|field| FieldPat {
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ident: field.ident.node,
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pat: const_expr_to_pat(tcx, field.expr)
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}).collect();
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PatStruct(path.clone(), field_pats, false)
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}
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ExprVec(ref exprs) => {
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let pats = exprs.iter().map(|&expr| const_expr_to_pat(tcx, expr)).collect();
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PatVec(pats, None, vec![])
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}
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ExprPath(ref path) => {
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let opt_def = tcx.def_map.borrow().find_copy(&expr.id);
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match opt_def {
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Some(def::DefStruct(..)) =>
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PatStruct(path.clone(), vec![], false),
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Some(def::DefVariant(..)) =>
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PatEnum(path.clone(), None),
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_ => {
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match lookup_const(tcx, &*expr) {
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Some(actual) => return const_expr_to_pat(tcx, actual),
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_ => unreachable!()
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}
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}
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}
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}
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_ => PatLit(expr)
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};
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box (GC) Pat { id: expr.id, node: pat, span: expr.span }
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}
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pub fn eval_const_expr(tcx: &ty::ctxt, e: &Expr) -> const_val {
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match eval_const_expr_partial(tcx, e) {
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Ok(r) => r,
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Err(s) => tcx.sess.span_fatal(e.span, s.as_slice())
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}
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}
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pub fn eval_const_expr_partial<T: ty::ExprTyProvider>(tcx: &T, e: &Expr)
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-> Result<const_val, String> {
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fn fromb(b: bool) -> Result<const_val, String> { Ok(const_int(b as i64)) }
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match e.node {
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ExprUnary(UnNeg, ref inner) => {
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match eval_const_expr_partial(tcx, &**inner) {
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Ok(const_float(f)) => Ok(const_float(-f)),
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Ok(const_int(i)) => Ok(const_int(-i)),
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Ok(const_uint(i)) => Ok(const_uint(-i)),
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Ok(const_str(_)) => Err("negate on string".to_string()),
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Ok(const_bool(_)) => Err("negate on boolean".to_string()),
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ref err => ((*err).clone())
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}
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}
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ExprUnary(UnNot, ref inner) => {
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match eval_const_expr_partial(tcx, &**inner) {
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Ok(const_int(i)) => Ok(const_int(!i)),
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Ok(const_uint(i)) => Ok(const_uint(!i)),
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Ok(const_bool(b)) => Ok(const_bool(!b)),
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_ => Err("not on float or string".to_string())
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}
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}
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ExprBinary(op, ref a, ref b) => {
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match (eval_const_expr_partial(tcx, &**a),
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eval_const_expr_partial(tcx, &**b)) {
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(Ok(const_float(a)), Ok(const_float(b))) => {
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match op {
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BiAdd => Ok(const_float(a + b)),
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BiSub => Ok(const_float(a - b)),
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BiMul => Ok(const_float(a * b)),
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BiDiv => Ok(const_float(a / b)),
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BiRem => Ok(const_float(a % b)),
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BiEq => fromb(a == b),
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BiLt => fromb(a < b),
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BiLe => fromb(a <= b),
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BiNe => fromb(a != b),
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BiGe => fromb(a >= b),
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BiGt => fromb(a > b),
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_ => Err("can't do this op on floats".to_string())
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}
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}
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(Ok(const_int(a)), Ok(const_int(b))) => {
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match op {
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BiAdd => Ok(const_int(a + b)),
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BiSub => Ok(const_int(a - b)),
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BiMul => Ok(const_int(a * b)),
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BiDiv if b == 0 => {
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Err("attempted to divide by zero".to_string())
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}
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BiDiv => Ok(const_int(a / b)),
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BiRem if b == 0 => {
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Err("attempted remainder with a divisor of \
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zero".to_string())
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}
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BiRem => Ok(const_int(a % b)),
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BiAnd | BiBitAnd => Ok(const_int(a & b)),
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BiOr | BiBitOr => Ok(const_int(a | b)),
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BiBitXor => Ok(const_int(a ^ b)),
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BiShl => Ok(const_int(a << b as uint)),
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BiShr => Ok(const_int(a >> b as uint)),
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BiEq => fromb(a == b),
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BiLt => fromb(a < b),
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BiLe => fromb(a <= b),
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BiNe => fromb(a != b),
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BiGe => fromb(a >= b),
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BiGt => fromb(a > b)
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}
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}
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(Ok(const_uint(a)), Ok(const_uint(b))) => {
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match op {
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BiAdd => Ok(const_uint(a + b)),
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BiSub => Ok(const_uint(a - b)),
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BiMul => Ok(const_uint(a * b)),
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BiDiv if b == 0 => {
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Err("attempted to divide by zero".to_string())
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}
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BiDiv => Ok(const_uint(a / b)),
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BiRem if b == 0 => {
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Err("attempted remainder with a divisor of \
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zero".to_string())
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}
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BiRem => Ok(const_uint(a % b)),
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BiAnd | BiBitAnd => Ok(const_uint(a & b)),
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BiOr | BiBitOr => Ok(const_uint(a | b)),
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BiBitXor => Ok(const_uint(a ^ b)),
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BiShl => Ok(const_uint(a << b as uint)),
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BiShr => Ok(const_uint(a >> b as uint)),
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BiEq => fromb(a == b),
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BiLt => fromb(a < b),
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BiLe => fromb(a <= b),
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BiNe => fromb(a != b),
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BiGe => fromb(a >= b),
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BiGt => fromb(a > b),
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}
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}
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// shifts can have any integral type as their rhs
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(Ok(const_int(a)), Ok(const_uint(b))) => {
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match op {
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BiShl => Ok(const_int(a << b as uint)),
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BiShr => Ok(const_int(a >> b as uint)),
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_ => Err("can't do this op on an int and uint".to_string())
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}
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}
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(Ok(const_uint(a)), Ok(const_int(b))) => {
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match op {
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BiShl => Ok(const_uint(a << b as uint)),
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BiShr => Ok(const_uint(a >> b as uint)),
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_ => Err("can't do this op on a uint and int".to_string())
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}
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}
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(Ok(const_bool(a)), Ok(const_bool(b))) => {
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Ok(const_bool(match op {
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BiAnd => a && b,
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BiOr => a || b,
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|
BiBitXor => a ^ b,
|
|
BiBitAnd => a & b,
|
|
BiBitOr => a | b,
|
|
BiEq => a == b,
|
|
BiNe => a != b,
|
|
_ => return Err("can't do this op on bools".to_string())
|
|
}))
|
|
}
|
|
_ => Err("bad operands for binary".to_string())
|
|
}
|
|
}
|
|
ExprCast(ref base, ref target_ty) => {
|
|
// This tends to get called w/o the type actually having been
|
|
// populated in the ctxt, which was causing things to blow up
|
|
// (#5900). Fall back to doing a limited lookup to get past it.
|
|
let ety = ty::expr_ty_opt(tcx.ty_ctxt(), e)
|
|
.or_else(|| astconv::ast_ty_to_prim_ty(tcx.ty_ctxt(), &**target_ty))
|
|
.unwrap_or_else(|| {
|
|
tcx.ty_ctxt().sess.span_fatal(target_ty.span,
|
|
"target type not found for \
|
|
const cast")
|
|
});
|
|
|
|
let base = eval_const_expr_partial(tcx, &**base);
|
|
match base {
|
|
Err(_) => base,
|
|
Ok(val) => {
|
|
match ty::get(ety).sty {
|
|
ty::ty_float(_) => {
|
|
match val {
|
|
const_uint(u) => Ok(const_float(u as f64)),
|
|
const_int(i) => Ok(const_float(i as f64)),
|
|
const_float(f) => Ok(const_float(f)),
|
|
_ => Err("can't cast float to str".to_string()),
|
|
}
|
|
}
|
|
ty::ty_uint(_) => {
|
|
match val {
|
|
const_uint(u) => Ok(const_uint(u)),
|
|
const_int(i) => Ok(const_uint(i as u64)),
|
|
const_float(f) => Ok(const_uint(f as u64)),
|
|
_ => Err("can't cast str to uint".to_string()),
|
|
}
|
|
}
|
|
ty::ty_int(_) | ty::ty_bool => {
|
|
match val {
|
|
const_uint(u) => Ok(const_int(u as i64)),
|
|
const_int(i) => Ok(const_int(i)),
|
|
const_float(f) => Ok(const_int(f as i64)),
|
|
_ => Err("can't cast str to int".to_string()),
|
|
}
|
|
}
|
|
_ => Err("can't cast this type".to_string())
|
|
}
|
|
}
|
|
}
|
|
}
|
|
ExprPath(_) => {
|
|
match lookup_const(tcx.ty_ctxt(), e) {
|
|
Some(actual_e) => eval_const_expr_partial(tcx.ty_ctxt(), &*actual_e),
|
|
None => Err("non-constant path in constant expr".to_string())
|
|
}
|
|
}
|
|
ExprLit(ref lit) => Ok(lit_to_const(&**lit)),
|
|
// If we have a vstore, just keep going; it has to be a string
|
|
ExprVstore(ref e, _) => eval_const_expr_partial(tcx, &**e),
|
|
ExprParen(ref e) => eval_const_expr_partial(tcx, &**e),
|
|
ExprBlock(ref block) => {
|
|
match block.expr {
|
|
Some(ref expr) => eval_const_expr_partial(tcx, &**expr),
|
|
None => Ok(const_int(0i64))
|
|
}
|
|
}
|
|
_ => Err("unsupported constant expr".to_string())
|
|
}
|
|
}
|
|
|
|
pub fn lit_to_const(lit: &Lit) -> const_val {
|
|
match lit.node {
|
|
LitStr(ref s, _) => const_str((*s).clone()),
|
|
LitBinary(ref data) => {
|
|
const_binary(Rc::new(data.iter().map(|x| *x).collect()))
|
|
}
|
|
LitByte(n) => const_uint(n as u64),
|
|
LitChar(n) => const_uint(n as u64),
|
|
LitInt(n, ast::SignedIntLit(_, ast::Plus)) |
|
|
LitInt(n, ast::UnsuffixedIntLit(ast::Plus)) => const_int(n as i64),
|
|
LitInt(n, ast::SignedIntLit(_, ast::Minus)) |
|
|
LitInt(n, ast::UnsuffixedIntLit(ast::Minus)) => const_int(-(n as i64)),
|
|
LitInt(n, ast::UnsignedIntLit(_)) => const_uint(n),
|
|
LitFloat(ref n, _) |
|
|
LitFloatUnsuffixed(ref n) => {
|
|
const_float(from_str::<f64>(n.get()).unwrap() as f64)
|
|
}
|
|
LitNil => const_nil,
|
|
LitBool(b) => const_bool(b)
|
|
}
|
|
}
|
|
|
|
fn compare_vals<T: PartialOrd>(a: T, b: T) -> Option<int> {
|
|
Some(if a == b { 0 } else if a < b { -1 } else { 1 })
|
|
}
|
|
pub fn compare_const_vals(a: &const_val, b: &const_val) -> Option<int> {
|
|
match (a, b) {
|
|
(&const_int(a), &const_int(b)) => compare_vals(a, b),
|
|
(&const_uint(a), &const_uint(b)) => compare_vals(a, b),
|
|
(&const_float(a), &const_float(b)) => compare_vals(a, b),
|
|
(&const_str(ref a), &const_str(ref b)) => compare_vals(a, b),
|
|
(&const_bool(a), &const_bool(b)) => compare_vals(a, b),
|
|
(&const_binary(ref a), &const_binary(ref b)) => compare_vals(a, b),
|
|
(&const_nil, &const_nil) => compare_vals((), ()),
|
|
_ => None
|
|
}
|
|
}
|
|
|
|
pub fn compare_lit_exprs(tcx: &ty::ctxt, a: &Expr, b: &Expr) -> Option<int> {
|
|
compare_const_vals(&eval_const_expr(tcx, a), &eval_const_expr(tcx, b))
|
|
}
|