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use GlobalId in eval_to_valtree query and introduce query for valtree_to_const_val

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This commit is contained in:
b-naber
2022-04-12 18:14:28 +02:00
parent 56d540e057
commit 96b36d6eb2
27 changed files with 541 additions and 245 deletions
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145
compiler/rustc_const_eval/src/const_eval/valtrees.rs
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@@ -1,33 +1,16 @@
use super::eval_queries::{mk_eval_cx, op_to_const};
use super::machine::CompileTimeEvalContext;
use super::{ValTreeCreationError, ValTreeCreationResult, VALTREE_MAX_NODES};
use crate::interpret::{
intern_const_alloc_recursive, ConstValue, ImmTy, Immediate, InternKind, MemPlaceMeta,
MemoryKind, PlaceTy, Scalar, ScalarMaybeUninit,
};
use rustc_middle::mir::interpret::ConstAlloc;
use rustc_middle::ty::{self, ScalarInt, Ty, TyCtxt};
use rustc_span::source_map::DUMMY_SP;
use rustc_target::abi::{Align, VariantIdx};
use crate::interpret::MPlaceTy;
use crate::interpret::Value;
/// Convert an evaluated constant to a type level constant
#[instrument(skip(tcx), level = "debug")]
pub(crate) fn const_to_valtree<'tcx>(
tcx: TyCtxt<'tcx>,
param_env: ty::ParamEnv<'tcx>,
raw: ConstAlloc<'tcx>,
) -> Option<ty::ValTree<'tcx>> {
let ecx = mk_eval_cx(
tcx, DUMMY_SP, param_env,
// It is absolutely crucial for soundness that
// we do not read from static items or other mutable memory.
false,
);
let place = ecx.raw_const_to_mplace(raw).unwrap();
const_to_valtree_inner(&ecx, &place)
}
use rustc_middle::ty::{self, ScalarInt, Ty, TyCtxt};
#[instrument(skip(ecx), level = "debug")]
fn branches<'tcx>(
@@ -35,7 +18,8 @@ fn branches<'tcx>(
place: &MPlaceTy<'tcx>,
n: usize,
variant: Option<VariantIdx>,
) -> Option<ty::ValTree<'tcx>> {
num_nodes: &mut usize,
) -> ValTreeCreationResult<'tcx> {
let place = match variant {
Some(variant) => ecx.mplace_downcast(&place, variant).unwrap(),
None => *place,
@@ -43,82 +27,116 @@ fn branches<'tcx>(
let variant = variant.map(|variant| Some(ty::ValTree::Leaf(ScalarInt::from(variant.as_u32()))));
debug!(?place, ?variant);
let fields = (0..n).map(|i| {
let mut fields = Vec::with_capacity(n);
for i in 0..n {
let field = ecx.mplace_field(&place, i).unwrap();
const_to_valtree_inner(ecx, &field)
});
// For enums, we preped their variant index before the variant's fields so we can figure out
let valtree = const_to_valtree_inner(ecx, &field, num_nodes)?;
fields.push(Some(valtree));
}
// For enums, we prepend their variant index before the variant's fields so we can figure out
// the variant again when just seeing a valtree.
let branches = variant.into_iter().chain(fields);
Some(ty::ValTree::Branch(ecx.tcx.arena.alloc_from_iter(branches.collect::<Option<Vec<_>>>()?)))
let branches = variant
.into_iter()
.chain(fields.into_iter())
.collect::<Option<Vec<_>>>()
.expect("should have already checked for errors in ValTree creation");
// Have to account for ZSTs here
if branches.len() == 0 {
*num_nodes += 1;
}
Ok(ty::ValTree::Branch(ecx.tcx.arena.alloc_from_iter(branches)))
}
#[instrument(skip(ecx), level = "debug")]
fn slice_branches<'tcx>(
ecx: &CompileTimeEvalContext<'tcx, 'tcx>,
place: &MPlaceTy<'tcx>,
) -> Option<ty::ValTree<'tcx>> {
num_nodes: &mut usize,
) -> ValTreeCreationResult<'tcx> {
let n = place
.len(&ecx.tcx.tcx)
.unwrap_or_else(|_| panic!("expected to use len of place {:?}", place));
let branches = (0..n).map(|i| {
let place_elem = ecx.mplace_index(place, i).unwrap();
const_to_valtree_inner(ecx, &place_elem)
});
Some(ty::ValTree::Branch(ecx.tcx.arena.alloc_from_iter(branches.collect::<Option<Vec<_>>>()?)))
let mut elems = Vec::with_capacity(n as usize);
for i in 0..n {
let place_elem = ecx.mplace_index(place, i).unwrap();
let valtree = const_to_valtree_inner(ecx, &place_elem, num_nodes)?;
elems.push(valtree);
}
Ok(ty::ValTree::Branch(ecx.tcx.arena.alloc_from_iter(elems)))
}
#[instrument(skip(ecx), level = "debug")]
fn const_to_valtree_inner<'tcx>(
pub(crate) fn const_to_valtree_inner<'tcx>(
ecx: &CompileTimeEvalContext<'tcx, 'tcx>,
place: &MPlaceTy<'tcx>,
) -> Option<ty::ValTree<'tcx>> {
match place.layout.ty.kind() {
ty::FnDef(..) => Some(ty::ValTree::zst()),
num_nodes: &mut usize,
) -> ValTreeCreationResult<'tcx> {
if *num_nodes >= VALTREE_MAX_NODES {
return Err(ValTreeCreationError::NodesOverflow);
}
let ty = place.layout.ty;
debug!("ty kind: {:?}", ty.kind());
match ty.kind() {
ty::FnDef(..) => {
*num_nodes += 1;
Ok(ty::ValTree::zst())
}
ty::Bool | ty::Int(_) | ty::Uint(_) | ty::Float(_) | ty::Char => {
let val = ecx.read_immediate(&place.into()).unwrap();
let Ok(val) = ecx.read_immediate(&place.into()) else {
return Err(ValTreeCreationError::Other);
};
let val = val.to_scalar().unwrap();
Some(ty::ValTree::Leaf(val.assert_int()))
*num_nodes += 1;
Ok(ty::ValTree::Leaf(val.assert_int()))
}
// Raw pointers are not allowed in type level constants, as we cannot properly test them for
// equality at compile-time (see `ptr_guaranteed_eq`/`_ne`).
// Technically we could allow function pointers (represented as `ty::Instance`), but this is not guaranteed to
// agree with runtime equality tests.
ty::FnPtr(_) | ty::RawPtr(_) => None,
ty::FnPtr(_) | ty::RawPtr(_) => Err(ValTreeCreationError::NonSupportedType),
ty::Ref(_, _, _) => {
let derefd_place = ecx.deref_operand(&place.into()).unwrap_or_else(|e| bug!("couldn't deref {:?}, error: {:?}", place, e));
let Ok(derefd_place)= ecx.deref_operand(&place.into()) else {
return Err(ValTreeCreationError::Other);
};
debug!(?derefd_place);
const_to_valtree_inner(ecx, &derefd_place)
const_to_valtree_inner(ecx, &derefd_place, num_nodes)
}
ty::Str | ty::Slice(_) | ty::Array(_, _) => {
let valtree = slice_branches(ecx, place);
debug!(?valtree);
valtree
slice_branches(ecx, place, num_nodes)
}
// Trait objects are not allowed in type level constants, as we have no concept for
// resolving their backing type, even if we can do that at const eval time. We may
// hypothetically be able to allow `dyn StructuralEq` trait objects in the future,
// but it is unclear if this is useful.
ty::Dynamic(..) => None,
ty::Dynamic(..) => Err(ValTreeCreationError::NonSupportedType),
ty::Tuple(substs) => branches(ecx, place, substs.len(), None),
ty::Tuple(elem_tys) => {
branches(ecx, place, elem_tys.len(), None, num_nodes)
}
ty::Adt(def, _) => {
if def.is_union() {
return None
return Err(ValTreeCreationError::NonSupportedType);
} else if def.variants().is_empty() {
bug!("uninhabited types should have errored and never gotten converted to valtree")
}
let variant = ecx.read_discriminant(&place.into()).unwrap().1;
branches(ecx, place, def.variant(variant).fields.len(), def.is_enum().then_some(variant))
let Ok((_, variant)) = ecx.read_discriminant(&place.into()) else {
return Err(ValTreeCreationError::Other);
};
branches(ecx, place, def.variant(variant).fields.len(), def.is_enum().then_some(variant), num_nodes)
}
ty::Never
@@ -136,7 +154,7 @@ fn const_to_valtree_inner<'tcx>(
// FIXME(oli-obk): we can probably encode closures just like structs
| ty::Closure(..)
| ty::Generator(..)
| ty::GeneratorWitness(..) => None,
| ty::GeneratorWitness(..) => Err(ValTreeCreationError::NonSupportedType),
}
}
@@ -225,8 +243,11 @@ fn create_pointee_place<'tcx>(
.unwrap();
debug!(?ptr);
let mut place = MPlaceTy::from_aligned_ptr(ptr.into(), layout);
place.meta = MemPlaceMeta::Meta(Scalar::from_u64(num_elems as u64));
let place = MPlaceTy::from_aligned_ptr_with_meta(
ptr.into(),
layout,
MemPlaceMeta::Meta(Scalar::from_u64(num_elems as u64)),
);
debug!(?place);
place
@@ -237,11 +258,11 @@ fn create_pointee_place<'tcx>(
/// Converts a `ValTree` to a `ConstValue`, which is needed after mir
/// construction has finished.
// FIXME Merge `valtree_to_const_value` and `fill_place_recursively` into one function
// FIXME Merge `valtree_to_const_value` and `valtree_into_mplace` into one function
#[instrument(skip(tcx), level = "debug")]
pub fn valtree_to_const_value<'tcx>(
tcx: TyCtxt<'tcx>,
param_env_ty: ty::ParamEnvAnd<'tcx, Ty<'tcx>>,
ty: Ty<'tcx>,
valtree: ty::ValTree<'tcx>,
) -> ConstValue<'tcx> {
// Basic idea: We directly construct `Scalar` values from trivial `ValTree`s
@@ -251,8 +272,8 @@ pub fn valtree_to_const_value<'tcx>(
// create inner `MPlace`s which are filled recursively.
// FIXME Does this need an example?
let (param_env, ty) = param_env_ty.into_parts();
let mut ecx = mk_eval_cx(tcx, DUMMY_SP, param_env, false);
let mut ecx = mk_eval_cx(tcx, DUMMY_SP, ty::ParamEnv::empty(), false);
let param_env_ty = ty::ParamEnv::empty().and(ty);
match ty.kind() {
ty::FnDef(..) => {
@@ -275,7 +296,7 @@ pub fn valtree_to_const_value<'tcx>(
};
debug!(?place);
fill_place_recursively(&mut ecx, &mut place, valtree);
valtree_into_mplace(&mut ecx, &mut place, valtree);
dump_place(&ecx, place.into());
intern_const_alloc_recursive(&mut ecx, InternKind::Constant, &place).unwrap();
@@ -317,7 +338,7 @@ pub fn valtree_to_const_value<'tcx>(
// FIXME Needs a better/correct name
#[instrument(skip(ecx), level = "debug")]
fn fill_place_recursively<'tcx>(
fn valtree_into_mplace<'tcx>(
ecx: &mut CompileTimeEvalContext<'tcx, 'tcx>,
place: &mut MPlaceTy<'tcx>,
valtree: ty::ValTree<'tcx>,
@@ -349,7 +370,7 @@ fn fill_place_recursively<'tcx>(
let mut pointee_place = create_pointee_place(ecx, *inner_ty, valtree);
debug!(?pointee_place);
fill_place_recursively(ecx, &mut pointee_place, valtree);
valtree_into_mplace(ecx, &mut pointee_place, valtree);
dump_place(ecx, pointee_place.into());
intern_const_alloc_recursive(ecx, InternKind::Constant, &pointee_place).unwrap();
@@ -437,7 +458,7 @@ fn fill_place_recursively<'tcx>(
};
debug!(?place_inner);
fill_place_recursively(ecx, &mut place_inner, *inner_valtree);
valtree_into_mplace(ecx, &mut place_inner, *inner_valtree);
dump_place(&ecx, place_inner.into());
}