1 // Copyright 2018 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 #![allow(unknown_lints)]
13 use ty::layout::{HasDataLayout, Size};
14 use ty::subst::Substs;
15 use hir::def_id::DefId;
17 use super::{EvalResult, Pointer, PointerArithmetic, Allocation, AllocId, sign_extend, truncate};
19 /// Represents a constant value in Rust. Scalar and ScalarPair are optimizations which
20 /// matches the LocalValue optimizations for easy conversions between Value and ConstValue.
21 #[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord, RustcEncodable, RustcDecodable, Hash)]
22 pub enum ConstValue<'tcx> {
23 /// Never returned from the `const_eval` query, but the HIR contains these frequently in order
24 /// to allow HIR creation to happen for everything before needing to be able to run constant
26 Unevaluated(DefId, &'tcx Substs<'tcx>),
28 /// Used only for types with layout::abi::Scalar ABI and ZSTs
30 /// Not using the enum `Value` to encode that this must not be `Undef`
33 /// Used only for *fat pointers* with layout::abi::ScalarPair
35 /// Needed for pattern matching code related to slices and strings.
36 ScalarPair(Scalar, Scalar),
38 /// An allocation + offset into the allocation.
39 /// Invariant: The AllocId matches the allocation.
40 ByRef(AllocId, &'tcx Allocation, Size),
43 impl<'tcx> ConstValue<'tcx> {
45 pub fn try_to_scalar(&self) -> Option<Scalar> {
47 ConstValue::Unevaluated(..) |
48 ConstValue::ByRef(..) |
49 ConstValue::ScalarPair(..) => None,
50 ConstValue::Scalar(val) => Some(val),
55 pub fn try_to_bits(&self, size: Size) -> Option<u128> {
56 self.try_to_scalar()?.to_bits(size).ok()
60 pub fn try_to_ptr(&self) -> Option<Pointer> {
61 self.try_to_scalar()?.to_ptr().ok()
68 cx: impl HasDataLayout
70 ConstValue::ScalarPair(val, Scalar::Bits {
72 size: cx.data_layout().pointer_size.bytes() as u8,
77 pub fn new_dyn_trait(val: Scalar, vtable: Pointer) -> Self {
78 ConstValue::ScalarPair(val, Scalar::Ptr(vtable))
82 /// A `Scalar` represents an immediate, primitive value existing outside of a
83 /// `memory::Allocation`. It is in many ways like a small chunk of a `Allocation`, up to 8 bytes in
84 /// size. Like a range of bytes in an `Allocation`, a `Scalar` can either represent the raw bytes
85 /// of a simple value or a pointer into another `Allocation`
86 #[derive(Clone, Copy, Debug, Eq, PartialEq, Ord, PartialOrd, RustcEncodable, RustcDecodable, Hash)]
87 pub enum Scalar<Tag=(), Id=AllocId> {
88 /// The raw bytes of a simple value.
90 /// The first `size` bytes are the value.
91 /// Do not try to read less or more bytes that that. The remaining bytes must be 0.
96 /// A pointer into an `Allocation`. An `Allocation` in the `memory` module has a list of
97 /// relocations, but a `Scalar` is only large enough to contain one, so we just represent the
98 /// relocation and its associated offset together as a `Pointer` here.
99 Ptr(Pointer<Tag, Id>),
102 impl<'tcx> Scalar<()> {
104 pub fn with_default_tag<Tag>(self) -> Scalar<Tag>
108 Scalar::Ptr(ptr) => Scalar::Ptr(ptr.with_default_tag()),
109 Scalar::Bits { bits, size } => Scalar::Bits { bits, size },
114 impl<'tcx, Tag> Scalar<Tag> {
116 pub fn erase_tag(self) -> Scalar {
118 Scalar::Ptr(ptr) => Scalar::Ptr(ptr.erase_tag()),
119 Scalar::Bits { bits, size } => Scalar::Bits { bits, size },
124 pub fn ptr_null(cx: impl HasDataLayout) -> Self {
127 size: cx.data_layout().pointer_size.bytes() as u8,
132 pub fn zst() -> Self {
133 Scalar::Bits { bits: 0, size: 0 }
137 pub fn ptr_signed_offset(self, i: i64, cx: impl HasDataLayout) -> EvalResult<'tcx, Self> {
138 let layout = cx.data_layout();
140 Scalar::Bits { bits, size } => {
141 assert_eq!(size as u64, layout.pointer_size.bytes());
143 bits: layout.signed_offset(bits as u64, i)? as u128,
147 Scalar::Ptr(ptr) => ptr.signed_offset(i, layout).map(Scalar::Ptr),
152 pub fn ptr_offset(self, i: Size, cx: impl HasDataLayout) -> EvalResult<'tcx, Self> {
153 let layout = cx.data_layout();
155 Scalar::Bits { bits, size } => {
156 assert_eq!(size as u64, layout.pointer_size.bytes());
158 bits: layout.offset(bits as u64, i.bytes())? as u128,
162 Scalar::Ptr(ptr) => ptr.offset(i, layout).map(Scalar::Ptr),
167 pub fn ptr_wrapping_signed_offset(self, i: i64, cx: impl HasDataLayout) -> Self {
168 let layout = cx.data_layout();
170 Scalar::Bits { bits, size } => {
171 assert_eq!(size as u64, layout.pointer_size.bytes());
173 bits: layout.wrapping_signed_offset(bits as u64, i) as u128,
177 Scalar::Ptr(ptr) => Scalar::Ptr(ptr.wrapping_signed_offset(i, layout)),
182 pub fn is_null_ptr(self, cx: impl HasDataLayout) -> bool {
184 Scalar::Bits { bits, size } => {
185 assert_eq!(size as u64, cx.data_layout().pointer_size.bytes());
188 Scalar::Ptr(_) => false,
193 pub fn from_bool(b: bool) -> Self {
194 Scalar::Bits { bits: b as u128, size: 1 }
198 pub fn from_char(c: char) -> Self {
199 Scalar::Bits { bits: c as u128, size: 4 }
203 pub fn from_uint(i: impl Into<u128>, size: Size) -> Self {
205 debug_assert_eq!(truncate(i, size), i,
206 "Unsigned value {} does not fit in {} bits", i, size.bits());
207 Scalar::Bits { bits: i, size: size.bytes() as u8 }
211 pub fn from_int(i: impl Into<i128>, size: Size) -> Self {
213 // `into` performed sign extension, we have to truncate
214 let truncated = truncate(i as u128, size);
215 debug_assert_eq!(sign_extend(truncated, size) as i128, i,
216 "Signed value {} does not fit in {} bits", i, size.bits());
217 Scalar::Bits { bits: truncated, size: size.bytes() as u8 }
221 pub fn from_f32(f: f32) -> Self {
222 Scalar::Bits { bits: f.to_bits() as u128, size: 4 }
226 pub fn from_f64(f: f64) -> Self {
227 Scalar::Bits { bits: f.to_bits() as u128, size: 8 }
231 pub fn to_bits(self, target_size: Size) -> EvalResult<'tcx, u128> {
233 Scalar::Bits { bits, size } => {
234 assert_eq!(target_size.bytes(), size as u64);
235 assert_ne!(size, 0, "to_bits cannot be used with zsts");
238 Scalar::Ptr(_) => err!(ReadPointerAsBytes),
243 pub fn to_ptr(self) -> EvalResult<'tcx, Pointer<Tag>> {
245 Scalar::Bits { bits: 0, .. } => err!(InvalidNullPointerUsage),
246 Scalar::Bits { .. } => err!(ReadBytesAsPointer),
247 Scalar::Ptr(p) => Ok(p),
252 pub fn is_bits(self) -> bool {
254 Scalar::Bits { .. } => true,
260 pub fn is_ptr(self) -> bool {
262 Scalar::Ptr(_) => true,
267 pub fn to_bool(self) -> EvalResult<'tcx, bool> {
269 Scalar::Bits { bits: 0, size: 1 } => Ok(false),
270 Scalar::Bits { bits: 1, size: 1 } => Ok(true),
271 _ => err!(InvalidBool),
275 pub fn to_char(self) -> EvalResult<'tcx, char> {
276 let val = self.to_u32()?;
277 match ::std::char::from_u32(val) {
279 None => err!(InvalidChar(val as u128)),
283 pub fn to_u8(self) -> EvalResult<'static, u8> {
284 let sz = Size::from_bits(8);
285 let b = self.to_bits(sz)?;
286 assert_eq!(b as u8 as u128, b);
290 pub fn to_u32(self) -> EvalResult<'static, u32> {
291 let sz = Size::from_bits(32);
292 let b = self.to_bits(sz)?;
293 assert_eq!(b as u32 as u128, b);
297 pub fn to_u64(self) -> EvalResult<'static, u64> {
298 let sz = Size::from_bits(64);
299 let b = self.to_bits(sz)?;
300 assert_eq!(b as u64 as u128, b);
304 pub fn to_usize(self, cx: impl HasDataLayout) -> EvalResult<'static, u64> {
305 let b = self.to_bits(cx.data_layout().pointer_size)?;
306 assert_eq!(b as u64 as u128, b);
310 pub fn to_i8(self) -> EvalResult<'static, i8> {
311 let sz = Size::from_bits(8);
312 let b = self.to_bits(sz)?;
313 let b = sign_extend(b, sz) as i128;
314 assert_eq!(b as i8 as i128, b);
318 pub fn to_i32(self) -> EvalResult<'static, i32> {
319 let sz = Size::from_bits(32);
320 let b = self.to_bits(sz)?;
321 let b = sign_extend(b, sz) as i128;
322 assert_eq!(b as i32 as i128, b);
326 pub fn to_i64(self) -> EvalResult<'static, i64> {
327 let sz = Size::from_bits(64);
328 let b = self.to_bits(sz)?;
329 let b = sign_extend(b, sz) as i128;
330 assert_eq!(b as i64 as i128, b);
334 pub fn to_isize(self, cx: impl HasDataLayout) -> EvalResult<'static, i64> {
335 let b = self.to_bits(cx.data_layout().pointer_size)?;
336 let b = sign_extend(b, cx.data_layout().pointer_size) as i128;
337 assert_eq!(b as i64 as i128, b);
342 pub fn to_f32(self) -> EvalResult<'static, f32> {
343 Ok(f32::from_bits(self.to_u32()?))
347 pub fn to_f64(self) -> EvalResult<'static, f64> {
348 Ok(f64::from_bits(self.to_u64()?))
352 impl<Tag> From<Pointer<Tag>> for Scalar<Tag> {
354 fn from(ptr: Pointer<Tag>) -> Self {