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Commit | Line | Data |
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e9174d1e SL |
1 | //! See docs in build/expr/mod.rs |
2 | ||
923072b8 | 3 | use crate::build::{parse_float_into_constval, Builder}; |
04454e1e | 4 | use rustc_ast as ast; |
5e7ed085 | 5 | use rustc_hir::def_id::DefId; |
923072b8 FG |
6 | use rustc_middle::mir::interpret::{ |
7 | Allocation, ConstValue, LitToConstError, LitToConstInput, Scalar, | |
8 | }; | |
ba9703b0 | 9 | use rustc_middle::mir::*; |
17df50a5 | 10 | use rustc_middle::thir::*; |
5e7ed085 FG |
11 | use rustc_middle::ty::subst::SubstsRef; |
12 | use rustc_middle::ty::{self, CanonicalUserTypeAnnotation, Ty, TyCtxt}; | |
13 | use rustc_target::abi::Size; | |
e9174d1e | 14 | |
dc9dc135 | 15 | impl<'a, 'tcx> Builder<'a, 'tcx> { |
e9174d1e SL |
16 | /// Compile `expr`, yielding a compile-time constant. Assumes that |
17 | /// `expr` is a valid compile-time constant! | |
923072b8 | 18 | pub(crate) fn as_constant(&mut self, expr: &Expr<'tcx>) -> Constant<'tcx> { |
5e7ed085 FG |
19 | let create_uneval_from_def_id = |
20 | |tcx: TyCtxt<'tcx>, def_id: DefId, ty: Ty<'tcx>, substs: SubstsRef<'tcx>| { | |
21 | let uneval = ty::Unevaluated::new(ty::WithOptConstParam::unknown(def_id), substs); | |
923072b8 | 22 | tcx.mk_const(ty::ConstS { kind: ty::ConstKind::Unevaluated(uneval), ty }) |
5e7ed085 FG |
23 | }; |
24 | ||
e9174d1e | 25 | let this = self; |
5e7ed085 | 26 | let tcx = this.tcx; |
6a06907d XL |
27 | let Expr { ty, temp_lifetime: _, span, ref kind } = *expr; |
28 | match *kind { | |
17df50a5 XL |
29 | ExprKind::Scope { region_scope: _, lint_level: _, value } => { |
30 | this.as_constant(&this.thir[value]) | |
31 | } | |
5e7ed085 FG |
32 | ExprKind::Literal { lit, neg } => { |
33 | let literal = | |
04454e1e | 34 | match lit_to_mir_constant(tcx, LitToConstInput { lit: &lit.node, ty, neg }) { |
5e7ed085 FG |
35 | Ok(c) => c, |
36 | Err(LitToConstError::Reported) => ConstantKind::Ty(tcx.const_error(ty)), | |
37 | Err(LitToConstError::TypeError) => { | |
04454e1e | 38 | bug!("encountered type error in `lit_to_mir_constant") |
5e7ed085 FG |
39 | } |
40 | }; | |
41 | ||
04454e1e | 42 | Constant { span, user_ty: None, literal } |
5e7ed085 FG |
43 | } |
44 | ExprKind::NonHirLiteral { lit, user_ty } => { | |
9fa01778 XL |
45 | let user_ty = user_ty.map(|user_ty| { |
46 | this.canonical_user_type_annotations.push(CanonicalUserTypeAnnotation { | |
47 | span, | |
48 | user_ty, | |
49 | inferred_ty: ty, | |
50 | }) | |
0731742a | 51 | }); |
5e7ed085 FG |
52 | |
53 | let literal = ConstantKind::Val(ConstValue::Scalar(Scalar::Int(lit)), ty); | |
54 | ||
55 | Constant { span, user_ty: user_ty, literal } | |
56 | } | |
57 | ExprKind::NamedConst { def_id, substs, user_ty } => { | |
58 | let user_ty = user_ty.map(|user_ty| { | |
59 | this.canonical_user_type_annotations.push(CanonicalUserTypeAnnotation { | |
60 | span, | |
61 | user_ty, | |
62 | inferred_ty: ty, | |
63 | }) | |
64 | }); | |
65 | let literal = ConstantKind::Ty(create_uneval_from_def_id(tcx, def_id, ty, substs)); | |
66 | ||
67 | Constant { user_ty, span, literal } | |
68 | } | |
69 | ExprKind::ConstParam { param, def_id: _ } => { | |
70 | let const_param = | |
923072b8 | 71 | tcx.mk_const(ty::ConstS { kind: ty::ConstKind::Param(param), ty: expr.ty }); |
5e7ed085 FG |
72 | let literal = ConstantKind::Ty(const_param); |
73 | ||
74 | Constant { user_ty: None, span, literal } | |
75 | } | |
76 | ExprKind::ConstBlock { did: def_id, substs } => { | |
77 | let literal = ConstantKind::Ty(create_uneval_from_def_id(tcx, def_id, ty, substs)); | |
78 | ||
79 | Constant { user_ty: None, span, literal } | |
6a06907d | 80 | } |
5099ac24 | 81 | ExprKind::StaticRef { alloc_id, ty, .. } => { |
5e7ed085 | 82 | let const_val = ConstValue::Scalar(Scalar::from_pointer(alloc_id.into(), &tcx)); |
5099ac24 FG |
83 | let literal = ConstantKind::Val(const_val, ty); |
84 | ||
85 | Constant { span, user_ty: None, literal } | |
6a06907d | 86 | } |
b7449926 | 87 | _ => span_bug!(span, "expression is not a valid constant {:?}", kind), |
b039eaaf | 88 | } |
e9174d1e SL |
89 | } |
90 | } | |
5e7ed085 | 91 | |
04454e1e | 92 | #[instrument(skip(tcx, lit_input))] |
923072b8 | 93 | pub(crate) fn lit_to_mir_constant<'tcx>( |
5e7ed085 FG |
94 | tcx: TyCtxt<'tcx>, |
95 | lit_input: LitToConstInput<'tcx>, | |
96 | ) -> Result<ConstantKind<'tcx>, LitToConstError> { | |
97 | let LitToConstInput { lit, ty, neg } = lit_input; | |
98 | let trunc = |n| { | |
99 | let param_ty = ty::ParamEnv::reveal_all().and(ty); | |
100 | let width = tcx.layout_of(param_ty).map_err(|_| LitToConstError::Reported)?.size; | |
101 | trace!("trunc {} with size {} and shift {}", n, width.bits(), 128 - width.bits()); | |
102 | let result = width.truncate(n); | |
103 | trace!("trunc result: {}", result); | |
104 | Ok(ConstValue::Scalar(Scalar::from_uint(result, width))) | |
105 | }; | |
106 | ||
107 | let value = match (lit, &ty.kind()) { | |
108 | (ast::LitKind::Str(s, _), ty::Ref(_, inner_ty, _)) if inner_ty.is_str() => { | |
109 | let s = s.as_str(); | |
110 | let allocation = Allocation::from_bytes_byte_aligned_immutable(s.as_bytes()); | |
111 | let allocation = tcx.intern_const_alloc(allocation); | |
112 | ConstValue::Slice { data: allocation, start: 0, end: s.len() } | |
113 | } | |
114 | (ast::LitKind::ByteStr(data), ty::Ref(_, inner_ty, _)) | |
115 | if matches!(inner_ty.kind(), ty::Slice(_)) => | |
116 | { | |
117 | let allocation = Allocation::from_bytes_byte_aligned_immutable(data as &[u8]); | |
118 | let allocation = tcx.intern_const_alloc(allocation); | |
119 | ConstValue::Slice { data: allocation, start: 0, end: data.len() } | |
120 | } | |
121 | (ast::LitKind::ByteStr(data), ty::Ref(_, inner_ty, _)) if inner_ty.is_array() => { | |
122 | let id = tcx.allocate_bytes(data); | |
123 | ConstValue::Scalar(Scalar::from_pointer(id.into(), &tcx)) | |
124 | } | |
125 | (ast::LitKind::Byte(n), ty::Uint(ty::UintTy::U8)) => { | |
126 | ConstValue::Scalar(Scalar::from_uint(*n, Size::from_bytes(1))) | |
127 | } | |
128 | (ast::LitKind::Int(n, _), ty::Uint(_)) | (ast::LitKind::Int(n, _), ty::Int(_)) => { | |
129 | trunc(if neg { (*n as i128).overflowing_neg().0 as u128 } else { *n })? | |
130 | } | |
131 | (ast::LitKind::Float(n, _), ty::Float(fty)) => { | |
923072b8 | 132 | parse_float_into_constval(*n, *fty, neg).ok_or(LitToConstError::Reported)? |
5e7ed085 FG |
133 | } |
134 | (ast::LitKind::Bool(b), ty::Bool) => ConstValue::Scalar(Scalar::from_bool(*b)), | |
135 | (ast::LitKind::Char(c), ty::Char) => ConstValue::Scalar(Scalar::from_char(*c)), | |
136 | (ast::LitKind::Err(_), _) => return Err(LitToConstError::Reported), | |
137 | _ => return Err(LitToConstError::TypeError), | |
138 | }; | |
139 | ||
140 | Ok(ConstantKind::Val(value, ty)) | |
141 | } |