-// Copyright 2014-2018 The Rust Project Developers. See the COPYRIGHT
-// file at the top-level directory of this distribution.
-//
-// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
-// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
-// option. This file may not be copied, modified, or distributed
-// except according to those terms.
-
-
#![allow(clippy::float_cmp)]
-use crate::utils::{clip, sext, unsext};
-use rustc::hir::def::Def;
+use crate::utils::{clip, higher, sext, unsext};
+use if_chain::if_chain;
+use rustc::hir::def::{DefKind, Res};
use rustc::hir::*;
use rustc::lint::LateContext;
-use rustc::ty::subst::{Subst, Substs};
+use rustc::ty::subst::{Subst, SubstsRef};
use rustc::ty::{self, Instance, Ty, TyCtxt};
use rustc::{bug, span_bug};
+use rustc_data_structures::sync::Lrc;
use std::cmp::Ordering::{self, Equal};
use std::cmp::PartialOrd;
+use std::convert::TryFrom;
use std::convert::TryInto;
use std::hash::{Hash, Hasher};
-use std::rc::Rc;
use syntax::ast::{FloatTy, LitKind};
-use syntax::ptr::P;
+use syntax_pos::symbol::{LocalInternedString, Symbol};
/// A `LitKind`-like enum to fold constant `Expr`s into.
#[derive(Debug, Clone)]
pub enum Constant {
- /// a String "abc"
+ /// A `String` (e.g., "abc").
Str(String),
- /// a Binary String b"abc"
- Binary(Rc<Vec<u8>>),
- /// a single char 'a'
+ /// A binary string (e.g., `b"abc"`).
+ Binary(Lrc<Vec<u8>>),
+ /// A single `char` (e.g., `'a'`).
Char(char),
- /// an integer's bit representation
+ /// An integer's bit representation.
Int(u128),
- /// an f32
+ /// An `f32`.
F32(f32),
- /// an f64
+ /// An `f64`.
F64(f64),
- /// true or false
+ /// `true` or `false`.
Bool(bool),
- /// an array of constants
+ /// An array of constants.
Vec(Vec<Constant>),
- /// also an array, but with only one constant, repeated N times
+ /// Also an array, but with only one constant, repeated N times.
Repeat(Box<Constant>, u64),
- /// a tuple of constants
+ /// A tuple of constants.
Tuple(Vec<Constant>),
+ /// A raw pointer.
+ RawPtr(u128),
+ /// A literal with syntax error.
+ Err(Symbol),
}
impl PartialEq for Constant {
(&Constant::Char(l), &Constant::Char(r)) => l == r,
(&Constant::Int(l), &Constant::Int(r)) => l == r,
(&Constant::F64(l), &Constant::F64(r)) => {
- // we want `Fw32 == FwAny` and `FwAny == Fw64`, by transitivity we must have
- // `Fw32 == Fw64` so don’t compare them
- // to_bits is required to catch non-matching 0.0, -0.0, and NaNs
+ // We want `Fw32 == FwAny` and `FwAny == Fw64`, and by transitivity we must have
+ // `Fw32 == Fw64`, so don’t compare them.
+ // `to_bits` is required to catch non-matching 0.0, -0.0, and NaNs.
l.to_bits() == r.to_bits()
},
(&Constant::F32(l), &Constant::F32(r)) => {
- // we want `Fw32 == FwAny` and `FwAny == Fw64`, by transitivity we must have
- // `Fw32 == Fw64` so don’t compare them
- // to_bits is required to catch non-matching 0.0, -0.0, and NaNs
+ // We want `Fw32 == FwAny` and `FwAny == Fw64`, and by transitivity we must have
+ // `Fw32 == Fw64`, so don’t compare them.
+ // `to_bits` is required to catch non-matching 0.0, -0.0, and NaNs.
f64::from(l).to_bits() == f64::from(r).to_bits()
},
(&Constant::Bool(l), &Constant::Bool(r)) => l == r,
l == r
},
(&Constant::Repeat(ref lv, ref ls), &Constant::Repeat(ref rv, ref rs)) => ls == rs && lv == rv,
- _ => false, // TODO: Are there inter-type equalities?
+ // TODO: are there inter-type equalities?
+ _ => false,
}
}
}
where
H: Hasher,
{
+ std::mem::discriminant(self).hash(state);
match *self {
Constant::Str(ref s) => {
s.hash(state);
c.hash(state);
l.hash(state);
},
+ Constant::RawPtr(u) => {
+ u.hash(state);
+ },
+ Constant::Err(ref s) => {
+ s.hash(state);
+ },
}
}
}
impl Constant {
- pub fn partial_cmp(tcx: TyCtxt<'_, '_, '_>, cmp_type: ty::Ty<'_>, left: &Self, right: &Self) -> Option<Ordering> {
+ pub fn partial_cmp(tcx: TyCtxt<'_, '_, '_>, cmp_type: Ty<'_>, left: &Self, right: &Self) -> Option<Ordering> {
match (left, right) {
(&Constant::Str(ref ls), &Constant::Str(ref rs)) => Some(ls.cmp(rs)),
(&Constant::Char(ref l), &Constant::Char(ref r)) => Some(l.cmp(r)),
x => x,
}
},
- _ => None, // TODO: Are there any useful inter-type orderings?
+ // TODO: are there any useful inter-type orderings?
+ _ => None,
}
}
}
-/// parse a `LitKind` to a `Constant`
+/// Parses a `LitKind` to a `Constant`.
pub fn lit_to_constant<'tcx>(lit: &LitKind, ty: Ty<'tcx>) -> Constant {
use syntax::ast::*;
match *lit {
LitKind::Str(ref is, _) => Constant::Str(is.to_string()),
LitKind::Byte(b) => Constant::Int(u128::from(b)),
- LitKind::ByteStr(ref s) => Constant::Binary(Rc::clone(s)),
+ LitKind::ByteStr(ref s) => Constant::Binary(Lrc::clone(s)),
LitKind::Char(c) => Constant::Char(c),
LitKind::Int(n, _) => Constant::Int(n),
LitKind::Float(ref is, _) | LitKind::FloatUnsuffixed(ref is) => match ty.sty {
_ => bug!(),
},
LitKind::Bool(b) => Constant::Bool(b),
+ LitKind::Err(s) => Constant::Err(s),
}
}
e: &Expr,
) -> Option<(Constant, bool)> {
let mut cx = ConstEvalLateContext {
- tcx: lcx.tcx,
+ lcx,
tables,
param_env: lcx.param_env,
needed_resolution: false,
constant(lcx, tables, e).and_then(|(cst, res)| if res { None } else { Some(cst) })
}
-/// Creates a `ConstEvalLateContext` from the given `LateContext` and `TypeckTables`
+/// Creates a `ConstEvalLateContext` from the given `LateContext` and `TypeckTables`.
pub fn constant_context<'c, 'cc>(
- lcx: &LateContext<'c, 'cc>,
+ lcx: &'c LateContext<'c, 'cc>,
tables: &'c ty::TypeckTables<'cc>,
) -> ConstEvalLateContext<'c, 'cc> {
ConstEvalLateContext {
- tcx: lcx.tcx,
+ lcx,
tables,
param_env: lcx.param_env,
needed_resolution: false,
}
pub struct ConstEvalLateContext<'a, 'tcx: 'a> {
- tcx: TyCtxt<'a, 'tcx, 'tcx>,
+ lcx: &'a LateContext<'a, 'tcx>,
tables: &'a ty::TypeckTables<'tcx>,
param_env: ty::ParamEnv<'tcx>,
needed_resolution: bool,
- substs: &'tcx Substs<'tcx>,
+ substs: SubstsRef<'tcx>,
}
impl<'c, 'cc> ConstEvalLateContext<'c, 'cc> {
- /// simple constant folding: Insert an expression, get a constant or none.
+ /// Simple constant folding: Insert an expression, get a constant or none.
pub fn expr(&mut self, e: &Expr) -> Option<Constant> {
+ if let Some((ref cond, ref then, otherwise)) = higher::if_block(&e) {
+ return self.ifthenelse(cond, then, otherwise);
+ }
match e.node {
ExprKind::Path(ref qpath) => self.fetch_path(qpath, e.hir_id),
ExprKind::Block(ref block, _) => self.block(block),
- ExprKind::If(ref cond, ref then, ref otherwise) => self.ifthenelse(cond, then, otherwise),
ExprKind::Lit(ref lit) => Some(lit_to_constant(&lit.node, self.tables.expr_ty(e))),
ExprKind::Array(ref vec) => self.multi(vec).map(Constant::Vec),
ExprKind::Tup(ref tup) => self.multi(tup).map(Constant::Tuple),
ExprKind::Repeat(ref value, _) => {
let n = match self.tables.expr_ty(e).sty {
- ty::Array(_, n) => n.assert_usize(self.tcx).expect("array length"),
+ ty::Array(_, n) => n.assert_usize(self.lcx.tcx).expect("array length"),
_ => span_bug!(e.span, "typeck error"),
};
self.expr(value).map(|v| Constant::Repeat(Box::new(v), n))
UnDeref => Some(o),
}),
ExprKind::Binary(op, ref left, ref right) => self.binop(op, left, right),
- // TODO: add other expressions
+ ExprKind::Call(ref callee, ref args) => {
+ // We only handle a few const functions for now.
+ if_chain! {
+ if args.is_empty();
+ if let ExprKind::Path(qpath) = &callee.node;
+ let res = self.tables.qpath_res(qpath, callee.hir_id);
+ if let Some(def_id) = res.opt_def_id();
+ let def_path = self.lcx.get_def_path(def_id)
+ .iter()
+ .map(LocalInternedString::get)
+ .collect::<Vec<_>>();
+ if let &["core", "num", impl_ty, "max_value"] = &def_path[..];
+ then {
+ let value = match impl_ty {
+ "<impl i8>" => i8::max_value() as u128,
+ "<impl i16>" => i16::max_value() as u128,
+ "<impl i32>" => i32::max_value() as u128,
+ "<impl i64>" => i64::max_value() as u128,
+ "<impl i128>" => i128::max_value() as u128,
+ _ => return None,
+ };
+ Some(Constant::Int(value))
+ }
+ else {
+ None
+ }
+ }
+ },
+ // TODO: add other expressions.
_ => None,
}
}
#[allow(clippy::cast_possible_wrap)]
- fn constant_not(&self, o: &Constant, ty: ty::Ty<'_>) -> Option<Constant> {
+ fn constant_not(&self, o: &Constant, ty: Ty<'_>) -> Option<Constant> {
use self::Constant::*;
match *o {
Bool(b) => Some(Bool(!b)),
Int(value) => {
let value = !value;
match ty.sty {
- ty::Int(ity) => Some(Int(unsext(self.tcx, value as i128, ity))),
- ty::Uint(ity) => Some(Int(clip(self.tcx, value, ity))),
+ ty::Int(ity) => Some(Int(unsext(self.lcx.tcx, value as i128, ity))),
+ ty::Uint(ity) => Some(Int(clip(self.lcx.tcx, value, ity))),
_ => None,
}
},
}
}
- fn constant_negate(&self, o: &Constant, ty: ty::Ty<'_>) -> Option<Constant> {
+ fn constant_negate(&self, o: &Constant, ty: Ty<'_>) -> Option<Constant> {
use self::Constant::*;
match *o {
Int(value) => {
_ => return None,
};
// sign extend
- let value = sext(self.tcx, value, ity);
+ let value = sext(self.lcx.tcx, value, ity);
let value = value.checked_neg()?;
// clear unused bits
- Some(Int(unsext(self.tcx, value, ity)))
+ Some(Int(unsext(self.lcx.tcx, value, ity)))
},
F32(f) => Some(F32(-f)),
F64(f) => Some(F64(-f)),
}
}
- /// create `Some(Vec![..])` of all constants, unless there is any
- /// non-constant part
+ /// Create `Some(Vec![..])` of all constants, unless there is any
+ /// non-constant part.
fn multi(&mut self, vec: &[Expr]) -> Option<Vec<Constant>> {
vec.iter().map(|elem| self.expr(elem)).collect::<Option<_>>()
}
- /// lookup a possibly constant expression from a ExprKind::Path
+ /// Lookup a possibly constant expression from a ExprKind::Path.
fn fetch_path(&mut self, qpath: &QPath, id: HirId) -> Option<Constant> {
use rustc::mir::interpret::GlobalId;
- let def = self.tables.qpath_def(qpath, id);
- match def {
- Def::Const(def_id) | Def::AssociatedConst(def_id) => {
+ let res = self.tables.qpath_res(qpath, id);
+ match res {
+ Res::Def(DefKind::Const, def_id) | Res::Def(DefKind::AssociatedConst, def_id) => {
let substs = self.tables.node_substs(id);
let substs = if self.substs.is_empty() {
substs
} else {
- substs.subst(self.tcx, self.substs)
+ substs.subst(self.lcx.tcx, self.substs)
};
- let instance = Instance::resolve(self.tcx, self.param_env, def_id, substs)?;
+ let instance = Instance::resolve(self.lcx.tcx, self.param_env, def_id, substs)?;
let gid = GlobalId {
instance,
promoted: None,
};
- let result = self.tcx.const_eval(self.param_env.and(gid)).ok()?;
- let ret = miri_to_const(self.tcx, result);
- if ret.is_some() {
+ let result = self.lcx.tcx.const_eval(self.param_env.and(gid)).ok()?;
+ let result = miri_to_const(self.lcx.tcx, &result);
+ if result.is_some() {
self.needed_resolution = true;
}
- return ret;
+ result
},
- _ => {},
+ // FIXME: cover all usable cases.
+ _ => None,
}
- None
}
- /// A block can only yield a constant if it only has one constant expression
+ /// A block can only yield a constant if it only has one constant expression.
fn block(&mut self, block: &Block) -> Option<Constant> {
if block.stmts.is_empty() {
block.expr.as_ref().and_then(|b| self.expr(b))
}
}
- fn ifthenelse(&mut self, cond: &Expr, then: &P<Expr>, otherwise: &Option<P<Expr>>) -> Option<Constant> {
+ fn ifthenelse(&mut self, cond: &Expr, then: &Expr, otherwise: Option<&Expr>) -> Option<Constant> {
if let Some(Constant::Bool(b)) = self.expr(cond) {
if b {
- self.expr(&**then)
+ self.expr(&*then)
} else {
otherwise.as_ref().and_then(|expr| self.expr(expr))
}
match (l, r) {
(Constant::Int(l), Some(Constant::Int(r))) => match self.tables.expr_ty(left).sty {
ty::Int(ity) => {
- let l = sext(self.tcx, l, ity);
- let r = sext(self.tcx, r, ity);
- let zext = |n: i128| Constant::Int(unsext(self.tcx, n, ity));
+ let l = sext(self.lcx.tcx, l, ity);
+ let r = sext(self.lcx.tcx, r, ity);
+ let zext = |n: i128| Constant::Int(unsext(self.lcx.tcx, n, ity));
match op.node {
BinOpKind::Add => l.checked_add(r).map(zext),
BinOpKind::Sub => l.checked_sub(r).map(zext),
ty::Float(FloatTy::F64) => Some(Constant::F64(f64::from_bits(
b.try_into().expect("invalid f64 bit representation"),
))),
- // FIXME: implement other conversion
+ ty::RawPtr(type_and_mut) => {
+ if let ty::Uint(_) = type_and_mut.ty.sty {
+ return Some(Constant::RawPtr(b));
+ }
+ None
+ },
+ // FIXME: implement other conversions.
_ => None,
},
- ConstValue::ScalarPair(Scalar::Ptr(ptr), Scalar::Bits { bits: n, .. }) => match result.ty.sty {
+ ConstValue::Slice(Scalar::Ptr(ptr), n) => match result.ty.sty {
ty::Ref(_, tam, _) => match tam.sty {
ty::Str => {
let alloc = tcx.alloc_map.lock().unwrap_memory(ptr.alloc_id);
let offset = ptr.offset.bytes().try_into().expect("too-large pointer offset");
- let n = n as usize;
+ let n = usize::try_from(n).unwrap();
String::from_utf8(alloc.bytes[offset..(offset + n)].to_owned())
.ok()
.map(Constant::Str)
},
_ => None,
},
- // FIXME: implement other conversions
+ // FIXME: implement other conversions.
_ => None,
}
}
projects / rust.git / blobdiff