bjoernager/rust
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rebase and use ty::Const in patterns again

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This commit is contained in:
b-naber 2022-03-25 10:06:10 +01:00
parent ac60db231c
commit 0078e54185
13 changed files with 73 additions and 144 deletions
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64
compiler/rustc_mir_build/src/build/expr/as_constant.rs
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@ -1,17 +1,12 @@
//! See docs in build/expr/mod.rs
use crate::build::Builder;
use crate::thir::constant::parse_float;
use rustc_ast::ast;
use rustc_hir::def_id::DefId;
use rustc_middle::mir::interpret::{
Allocation, ConstValue, LitToConstError, LitToConstInput, Scalar,
};
use rustc_middle::mir::interpret::{ConstValue, LitToConstError, LitToConstInput, Scalar};
use rustc_middle::mir::*;
use rustc_middle::thir::*;
use rustc_middle::ty::subst::SubstsRef;
use rustc_middle::ty::{self, CanonicalUserTypeAnnotation, Ty, TyCtxt};
use rustc_target::abi::Size;
impl<'a, 'tcx> Builder<'a, 'tcx> {
/// Compile `expr`, yielding a compile-time constant. Assumes that
@ -32,11 +27,11 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
}
ExprKind::Literal { lit, neg } => {
let literal =
match lit_to_constant(tcx, LitToConstInput { lit: &lit.node, ty, neg }) {
match tcx.lit_to_mir_constant(LitToConstInput { lit: &lit.node, ty, neg }) {
Ok(c) => c,
Err(LitToConstError::Reported) => ConstantKind::Ty(tcx.const_error(ty)),
Err(LitToConstError::TypeError) => {
bug!("encountered type error in `lit_to_constant")
bug!("encountered type error in `lit_to_mir_constant")
}
};
@ -85,60 +80,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
Constant { span, user_ty: None, literal }
}
ExprKind::ConstBlock { value } => {
Constant { span: span, user_ty: None, literal: value }
}
_ => span_bug!(span, "expression is not a valid constant {:?}", kind),
}
}
}
crate fn lit_to_constant<'tcx>(
tcx: TyCtxt<'tcx>,
lit_input: LitToConstInput<'tcx>,
) -> Result<ConstantKind<'tcx>, LitToConstError> {
let LitToConstInput { lit, ty, neg } = lit_input;
let trunc = |n| {
let param_ty = ty::ParamEnv::reveal_all().and(ty);
let width = tcx.layout_of(param_ty).map_err(|_| LitToConstError::Reported)?.size;
trace!("trunc {} with size {} and shift {}", n, width.bits(), 128 - width.bits());
let result = width.truncate(n);
trace!("trunc result: {}", result);
Ok(ConstValue::Scalar(Scalar::from_uint(result, width)))
};
let value = match (lit, &ty.kind()) {
(ast::LitKind::Str(s, _), ty::Ref(_, inner_ty, _)) if inner_ty.is_str() => {
let s = s.as_str();
let allocation = Allocation::from_bytes_byte_aligned_immutable(s.as_bytes());
let allocation = tcx.intern_const_alloc(allocation);
ConstValue::Slice { data: allocation, start: 0, end: s.len() }
}
(ast::LitKind::ByteStr(data), ty::Ref(_, inner_ty, _))
if matches!(inner_ty.kind(), ty::Slice(_)) =>
{
let allocation = Allocation::from_bytes_byte_aligned_immutable(data as &[u8]);
let allocation = tcx.intern_const_alloc(allocation);
ConstValue::Slice { data: allocation, start: 0, end: data.len() }
}
(ast::LitKind::ByteStr(data), ty::Ref(_, inner_ty, _)) if inner_ty.is_array() => {
let id = tcx.allocate_bytes(data);
ConstValue::Scalar(Scalar::from_pointer(id.into(), &tcx))
}
(ast::LitKind::Byte(n), ty::Uint(ty::UintTy::U8)) => {
ConstValue::Scalar(Scalar::from_uint(*n, Size::from_bytes(1)))
}
(ast::LitKind::Int(n, _), ty::Uint(_)) | (ast::LitKind::Int(n, _), ty::Int(_)) => {
trunc(if neg { (*n as i128).overflowing_neg().0 as u128 } else { *n })?
}
(ast::LitKind::Float(n, _), ty::Float(fty)) => {
parse_float(*n, *fty, neg).ok_or(LitToConstError::Reported)?
}
(ast::LitKind::Bool(b), ty::Bool) => ConstValue::Scalar(Scalar::from_bool(*b)),
(ast::LitKind::Char(c), ty::Char) => ConstValue::Scalar(Scalar::from_char(*c)),
(ast::LitKind::Err(_), _) => return Err(LitToConstError::Reported),
_ => return Err(LitToConstError::TypeError),
};
Ok(ConstantKind::Val(value, ty))
}