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// Not in interpret to make sure we do not use private implementation details
use std::convert::TryFrom;
use rustc_hir::Mutability;
use rustc_middle::mir;
use rustc_middle::ty::{self, TyCtxt};
use rustc_span::{source_map::DUMMY_SP, symbol::Symbol};
use crate::interpret::{
intern_const_alloc_recursive, ConstValue, InternKind, InterpCx, MemPlaceMeta, Scalar,
};
mod error;
mod eval_queries;
mod fn_queries;
mod machine;
pub use error::*;
pub use eval_queries::*;
pub use fn_queries::*;
pub use machine::*;
pub(crate) fn const_caller_location(
tcx: TyCtxt<'tcx>,
(file, line, col): (Symbol, u32, u32),
) -> ConstValue<'tcx> {
trace!("const_caller_location: {}:{}:{}", file, line, col);
let mut ecx = mk_eval_cx(tcx, DUMMY_SP, ty::ParamEnv::reveal_all(), false);
let loc_place = ecx.alloc_caller_location(file, line, col);
intern_const_alloc_recursive(&mut ecx, InternKind::Constant, loc_place, false);
ConstValue::Scalar(loc_place.ptr)
}
/// This function uses `unwrap` copiously, because an already validated constant
/// must have valid fields and can thus never fail outside of compiler bugs. However, it is
/// invoked from the pretty printer, where it can receive enums with no variants and e.g.
/// `read_discriminant` needs to be able to handle that.
pub(crate) fn destructure_const<'tcx>(
tcx: TyCtxt<'tcx>,
param_env: ty::ParamEnv<'tcx>,
val: &'tcx ty::Const<'tcx>,
) -> mir::DestructuredConst<'tcx> {
trace!("destructure_const: {:?}", val);
let ecx = mk_eval_cx(tcx, DUMMY_SP, param_env, false);
let op = ecx.const_to_op(val, None).unwrap();
// We go to `usize` as we cannot allocate anything bigger anyway.
let (field_count, variant, down) = match val.ty.kind() {
ty::Array(_, len) => (usize::try_from(len.eval_usize(tcx, param_env)).unwrap(), None, op),
ty::Adt(def, _) if def.variants.is_empty() => {
return mir::DestructuredConst { variant: None, fields: tcx.arena.alloc_slice(&[]) };
}
ty::Adt(def, _) => {
let variant = ecx.read_discriminant(op).unwrap().1;
let down = ecx.operand_downcast(op, variant).unwrap();
(def.variants[variant].fields.len(), Some(variant), down)
}
ty::Tuple(substs) => (substs.len(), None, op),
_ => bug!("cannot destructure constant {:?}", val),
};
let fields_iter = (0..field_count).map(|i| {
let field_op = ecx.operand_field(down, i).unwrap();
let val = op_to_const(&ecx, field_op);
ty::Const::from_value(tcx, val, field_op.layout.ty)
});
let fields = tcx.arena.alloc_from_iter(fields_iter);
mir::DestructuredConst { variant, fields }
}
pub(crate) fn deref_const<'tcx>(
tcx: TyCtxt<'tcx>,
param_env: ty::ParamEnv<'tcx>,
val: &'tcx ty::Const<'tcx>,
) -> &'tcx ty::Const<'tcx> {
trace!("deref_const: {:?}", val);
let ecx = mk_eval_cx(tcx, DUMMY_SP, param_env, false);
let op = ecx.const_to_op(val, None).unwrap();
let mplace = ecx.deref_operand(op).unwrap();
if let Scalar::Ptr(ptr) = mplace.ptr {
assert_eq!(
ecx.memory.get_raw(ptr.alloc_id).unwrap().mutability,
Mutability::Not,
"deref_const cannot be used with mutable allocations as \
that could allow pattern matching to observe mutable statics",
);
}
let ty = match mplace.meta {
MemPlaceMeta::None => mplace.layout.ty,
MemPlaceMeta::Poison => bug!("poison metadata in `deref_const`: {:#?}", mplace),
// In case of unsized types, figure out the real type behind.
MemPlaceMeta::Meta(scalar) => match mplace.layout.ty.kind() {
ty::Str => bug!("there's no sized equivalent of a `str`"),
ty::Slice(elem_ty) => tcx.mk_array(elem_ty, scalar.to_machine_usize(&tcx).unwrap()),
_ => bug!(
"type {} should not have metadata, but had {:?}",
mplace.layout.ty,
mplace.meta
),
},
};
tcx.mk_const(ty::Const { val: ty::ConstKind::Value(op_to_const(&ecx, mplace.into())), ty })
}
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