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Auto merge of #95976 - b-naber:valtree-constval-conversion, r=oli-obk

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Implement Valtree to ConstValue conversion

Once we start to use `ValTree`s in the type system we will need to be able to convert them into `ConstValue` instances, which we want to continue to use after MIR construction.

r? `@oli-obk`

cc `@RalfJung`
This commit is contained in:
bors 2022-04-28 13:18:22 +00:00
commit b2c2a32870
15 changed files with 667 additions and 162 deletions
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38
compiler/rustc_const_eval/src/const_eval/eval_queries.rs
View file

@ -106,6 +106,7 @@ pub(super) fn mk_eval_cx<'mir, 'tcx>(
/// This function converts an interpreter value into a constant that is meant for use in the
/// type system.
#[instrument(skip(ecx), level = "debug")]
pub(super) fn op_to_const<'tcx>(
ecx: &CompileTimeEvalContext<'_, 'tcx>,
op: &OpTy<'tcx>,
@ -140,21 +141,26 @@ pub(super) fn op_to_const<'tcx>(
op.try_as_mplace()
};
debug!(?immediate);
// We know `offset` is relative to the allocation, so we can use `into_parts`.
let to_const_value = |mplace: &MPlaceTy<'_>| match mplace.ptr.into_parts() {
(Some(alloc_id), offset) => {
let alloc = ecx.tcx.global_alloc(alloc_id).unwrap_memory();
ConstValue::ByRef { alloc, offset }
}
(None, offset) => {
assert!(mplace.layout.is_zst());
assert_eq!(
offset.bytes() % mplace.layout.align.abi.bytes(),
0,
"this MPlaceTy must come from a validated constant, thus we can assume the \
let to_const_value = |mplace: &MPlaceTy<'_>| {
debug!("to_const_value(mplace: {:?})", mplace);
match mplace.ptr.into_parts() {
(Some(alloc_id), offset) => {
let alloc = ecx.tcx.global_alloc(alloc_id).unwrap_memory();
ConstValue::ByRef { alloc, offset }
}
(None, offset) => {
assert!(mplace.layout.is_zst());
assert_eq!(
offset.bytes() % mplace.layout.align.abi.bytes(),
0,
"this MPlaceTy must come from a validated constant, thus we can assume the \
alignment is correct",
);
ConstValue::Scalar(Scalar::ZST)
);
ConstValue::Scalar(Scalar::ZST)
}
}
};
match immediate {
@ -166,6 +172,7 @@ pub(super) fn op_to_const<'tcx>(
ScalarMaybeUninit::Uninit => to_const_value(&op.assert_mem_place()),
},
Immediate::ScalarPair(a, b) => {
debug!("ScalarPair(a: {:?}, b: {:?})", a, b);
// We know `offset` is relative to the allocation, so we can use `into_parts`.
let (data, start) =
match ecx.scalar_to_ptr(a.check_init().unwrap()).unwrap().into_parts() {
@ -209,7 +216,10 @@ fn turn_into_const_value<'tcx>(
);
// Turn this into a proper constant.
op_to_const(&ecx, &mplace.into())
let const_val = op_to_const(&ecx, &mplace.into());
debug!(?const_val);
const_val
}
pub fn eval_to_const_value_raw_provider<'tcx>(

136
compiler/rustc_const_eval/src/const_eval/mod.rs
View file

@ -3,29 +3,26 @@
use std::convert::TryFrom;
use rustc_hir::Mutability;
use rustc_middle::ty::layout::HasTyCtxt;
use rustc_middle::mir;
use rustc_middle::ty::{self, TyCtxt};
use rustc_middle::{
mir::{self, interpret::ConstAlloc},
ty::ScalarInt,
};
use rustc_span::{source_map::DUMMY_SP, symbol::Symbol};
use rustc_target::abi::VariantIdx;
use crate::interpret::{
intern_const_alloc_recursive, ConstValue, InternKind, InterpCx, InterpResult, MPlaceTy,
MemPlaceMeta, Scalar,
intern_const_alloc_recursive, ConstValue, InternKind, InterpCx, InterpResult, MemPlaceMeta,
Scalar,
};
mod error;
mod eval_queries;
mod fn_queries;
mod machine;
mod valtrees;
pub use error::*;
pub use eval_queries::*;
pub use fn_queries::*;
pub use machine::*;
pub(crate) use valtrees::{const_to_valtree, valtree_to_const_value};
pub(crate) fn const_caller_location(
tcx: TyCtxt<'_>,
@ -41,128 +38,6 @@ pub(crate) fn const_caller_location(
ConstValue::Scalar(Scalar::from_maybe_pointer(loc_place.ptr, &tcx))
}
/// Convert an evaluated constant to a type level constant
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)
}
#[instrument(skip(ecx), level = "debug")]
fn branches<'tcx>(
ecx: &CompileTimeEvalContext<'tcx, 'tcx>,
place: &MPlaceTy<'tcx>,
n: usize,
variant: Option<VariantIdx>,
) -> Option<ty::ValTree<'tcx>> {
let place = match variant {
Some(variant) => ecx.mplace_downcast(&place, variant).unwrap(),
None => *place,
};
let variant = variant.map(|variant| Some(ty::ValTree::Leaf(ScalarInt::from(variant.as_u32()))));
debug!(?place, ?variant);
let fields = (0..n).map(|i| {
let field = ecx.mplace_field(&place, i).unwrap();
const_to_valtree_inner(ecx, &field)
});
// 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<_>>>()?)))
}
fn slice_branches<'tcx>(
ecx: &CompileTimeEvalContext<'tcx, 'tcx>,
place: &MPlaceTy<'tcx>,
) -> Option<ty::ValTree<'tcx>> {
let n = place.len(&ecx.tcx()).expect(&format!("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<_>>>()?)))
}
#[instrument(skip(ecx), level = "debug")]
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()),
ty::Bool | ty::Int(_) | ty::Uint(_) | ty::Float(_) | ty::Char => {
let val = ecx.read_immediate(&place.into()).unwrap();
let val = val.to_scalar().unwrap();
Some(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::Ref(_, _, _) => {
let derefd_place = ecx.deref_operand(&place.into()).unwrap_or_else(|e| bug!("couldn't deref {:?}, error: {:?}", place, e));
debug!(?derefd_place);
const_to_valtree_inner(ecx, &derefd_place)
}
ty::Str | ty::Slice(_) | ty::Array(_, _) => {
let valtree = slice_branches(ecx, place);
debug!(?valtree);
valtree
}
// 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::Tuple(substs) => branches(ecx, place, substs.len(), None),
ty::Adt(def, _) => {
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))
}
ty::Never
| ty::Error(_)
| ty::Foreign(..)
| ty::Infer(ty::FreshIntTy(_))
| ty::Infer(ty::FreshFloatTy(_))
| ty::Projection(..)
| ty::Param(_)
| ty::Bound(..)
| ty::Placeholder(..)
// FIXME(oli-obk): we could look behind opaque types
| ty::Opaque(..)
| ty::Infer(_)
// FIXME(oli-obk): we can probably encode closures just like structs
| ty::Closure(..)
| ty::Generator(..)
| ty::GeneratorWitness(..) => None,
}
}
/// This function should never fail for validated constants. However, it is also invoked from the
/// pretty printer which might attempt to format invalid constants and in that case it might fail.
pub(crate) fn try_destructure_const<'tcx>(
@ -202,6 +77,7 @@ pub(crate) fn try_destructure_const<'tcx>(
Ok(mir::DestructuredConst { variant, fields })
}
#[instrument(skip(tcx), level = "debug")]
pub(crate) fn deref_const<'tcx>(
tcx: TyCtxt<'tcx>,
param_env: ty::ParamEnv<'tcx>,

459
compiler/rustc_const_eval/src/const_eval/valtrees.rs Normal file
View file

@ -0,0 +1,459 @@
use super::eval_queries::{mk_eval_cx, op_to_const};
use super::machine::CompileTimeEvalContext;
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)
}
#[instrument(skip(ecx), level = "debug")]
fn branches<'tcx>(
ecx: &CompileTimeEvalContext<'tcx, 'tcx>,
place: &MPlaceTy<'tcx>,
n: usize,
variant: Option<VariantIdx>,
) -> Option<ty::ValTree<'tcx>> {
let place = match variant {
Some(variant) => ecx.mplace_downcast(&place, variant).unwrap(),
None => *place,
};
let variant = variant.map(|variant| Some(ty::ValTree::Leaf(ScalarInt::from(variant.as_u32()))));
debug!(?place, ?variant);
let fields = (0..n).map(|i| {
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
// 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<_>>>()?)))
}
#[instrument(skip(ecx), level = "debug")]
fn slice_branches<'tcx>(
ecx: &CompileTimeEvalContext<'tcx, 'tcx>,
place: &MPlaceTy<'tcx>,
) -> Option<ty::ValTree<'tcx>> {
let n = place.len(&ecx.tcx.tcx).expect(&format!("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<_>>>()?)))
}
#[instrument(skip(ecx), level = "debug")]
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()),
ty::Bool | ty::Int(_) | ty::Uint(_) | ty::Float(_) | ty::Char => {
let val = ecx.read_immediate(&place.into()).unwrap();
let val = val.to_scalar().unwrap();
Some(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::Ref(_, _, _) => {
let derefd_place = ecx.deref_operand(&place.into()).unwrap_or_else(|e| bug!("couldn't deref {:?}, error: {:?}", place, e));
debug!(?derefd_place);
const_to_valtree_inner(ecx, &derefd_place)
}
ty::Str | ty::Slice(_) | ty::Array(_, _) => {
let valtree = slice_branches(ecx, place);
debug!(?valtree);
valtree
}
// 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::Tuple(substs) => branches(ecx, place, substs.len(), None),
ty::Adt(def, _) => {
if def.is_union() {
return None
} 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))
}
ty::Never
| ty::Error(_)
| ty::Foreign(..)
| ty::Infer(ty::FreshIntTy(_))
| ty::Infer(ty::FreshFloatTy(_))
| ty::Projection(..)
| ty::Param(_)
| ty::Bound(..)
| ty::Placeholder(..)
// FIXME(oli-obk): we could look behind opaque types
| ty::Opaque(..)
| ty::Infer(_)
// FIXME(oli-obk): we can probably encode closures just like structs
| ty::Closure(..)
| ty::Generator(..)
| ty::GeneratorWitness(..) => None,
}
}
#[instrument(skip(ecx), level = "debug")]
fn create_mplace_from_layout<'tcx>(
ecx: &mut CompileTimeEvalContext<'tcx, 'tcx>,
ty: Ty<'tcx>,
) -> MPlaceTy<'tcx> {
let tcx = ecx.tcx;
let param_env = ecx.param_env;
let layout = tcx.layout_of(param_env.and(ty)).unwrap();
debug!(?layout);
ecx.allocate(layout, MemoryKind::Stack).unwrap()
}
// Walks custom DSTs and gets the type of the unsized field and the number of elements
// in the unsized field.
fn get_info_on_unsized_field<'tcx>(
ty: Ty<'tcx>,
valtree: ty::ValTree<'tcx>,
tcx: TyCtxt<'tcx>,
) -> (Ty<'tcx>, usize) {
let mut last_valtree = valtree;
let tail = tcx.struct_tail_with_normalize(
ty,
|ty| ty,
|| {
let branches = last_valtree.unwrap_branch();
last_valtree = branches[branches.len() - 1];
debug!(?branches, ?last_valtree);
},
);
let unsized_inner_ty = match tail.kind() {
ty::Slice(t) => *t,
ty::Str => tail,
_ => bug!("expected Slice or Str"),
};
// Have to adjust type for ty::Str
let unsized_inner_ty = match unsized_inner_ty.kind() {
ty::Str => tcx.mk_ty(ty::Uint(ty::UintTy::U8)),
_ => unsized_inner_ty,
};
// Get the number of elements in the unsized field
let num_elems = last_valtree.unwrap_branch().len();
(unsized_inner_ty, num_elems)
}
#[instrument(skip(ecx), level = "debug")]
fn create_pointee_place<'tcx>(
ecx: &mut CompileTimeEvalContext<'tcx, 'tcx>,
ty: Ty<'tcx>,
valtree: ty::ValTree<'tcx>,
) -> MPlaceTy<'tcx> {
let tcx = ecx.tcx.tcx;
if !ty.is_sized(ecx.tcx, ty::ParamEnv::empty()) {
// We need to create `Allocation`s for custom DSTs
let (unsized_inner_ty, num_elems) = get_info_on_unsized_field(ty, valtree, tcx);
let unsized_inner_ty = match unsized_inner_ty.kind() {
ty::Str => tcx.mk_ty(ty::Uint(ty::UintTy::U8)),
_ => unsized_inner_ty,
};
let unsized_inner_ty_size =
tcx.layout_of(ty::ParamEnv::empty().and(unsized_inner_ty)).unwrap().layout.size();
debug!(?unsized_inner_ty, ?unsized_inner_ty_size, ?num_elems);
// for custom DSTs only the last field/element is unsized, but we need to also allocate
// space for the other fields/elements
let layout = tcx.layout_of(ty::ParamEnv::empty().and(ty)).unwrap();
let size_of_sized_part = layout.layout.size();
// Get the size of the memory behind the DST
let dst_size = unsized_inner_ty_size.checked_mul(num_elems as u64, &tcx).unwrap();
let ptr = ecx
.allocate_ptr(
size_of_sized_part.checked_add(dst_size, &tcx).unwrap(),
Align::from_bytes(1).unwrap(),
MemoryKind::Stack,
)
.unwrap();
debug!(?ptr);
let mut place = MPlaceTy::from_aligned_ptr(ptr.into(), layout);
place.meta = MemPlaceMeta::Meta(Scalar::from_u64(num_elems as u64));
debug!(?place);
place
} else {
create_mplace_from_layout(ecx, ty)
}
}
/// 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
#[instrument(skip(tcx), level = "debug")]
pub fn valtree_to_const_value<'tcx>(
tcx: TyCtxt<'tcx>,
param_env_ty: ty::ParamEnvAnd<'tcx, Ty<'tcx>>,
valtree: ty::ValTree<'tcx>,
) -> ConstValue<'tcx> {
// Basic idea: We directly construct `Scalar` values from trivial `ValTree`s
// (those for constants with type bool, int, uint, float or char).
// For all other types we create an `MPlace` and fill that by walking
// the `ValTree` and using `place_projection` and `place_field` to
// 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);
match ty.kind() {
ty::FnDef(..) => {
assert!(valtree.unwrap_branch().is_empty());
ConstValue::Scalar(Scalar::ZST)
}
ty::Bool | ty::Int(_) | ty::Uint(_) | ty::Float(_) | ty::Char => match valtree {
ty::ValTree::Leaf(scalar_int) => ConstValue::Scalar(Scalar::Int(scalar_int)),
ty::ValTree::Branch(_) => bug!(
"ValTrees for Bool, Int, Uint, Float or Char should have the form ValTree::Leaf"
),
},
ty::Ref(_, _, _) | ty::Tuple(_) | ty::Array(_, _) | ty::Adt(..) => {
let mut place = match ty.kind() {
ty::Ref(_, inner_ty, _) => {
// Need to create a place for the pointee to fill for Refs
create_pointee_place(&mut ecx, *inner_ty, valtree)
}
_ => create_mplace_from_layout(&mut ecx, ty),
};
debug!(?place);
fill_place_recursively(&mut ecx, &mut place, valtree);
dump_place(&ecx, place.into());
intern_const_alloc_recursive(&mut ecx, InternKind::Constant, &place).unwrap();
let const_val = match ty.kind() {
ty::Ref(_, _, _) => {
let ref_place = place.to_ref(&tcx);
let imm =
ImmTy::from_immediate(ref_place, tcx.layout_of(param_env_ty).unwrap());
op_to_const(&ecx, &imm.into())
}
_ => op_to_const(&ecx, &place.into()),
};
debug!(?const_val);
const_val
}
ty::Never
| ty::Error(_)
| ty::Foreign(..)
| ty::Infer(ty::FreshIntTy(_))
| ty::Infer(ty::FreshFloatTy(_))
| ty::Projection(..)
| ty::Param(_)
| ty::Bound(..)
| ty::Placeholder(..)
| ty::Opaque(..)
| ty::Infer(_)
| ty::Closure(..)
| ty::Generator(..)
| ty::GeneratorWitness(..)
| ty::FnPtr(_)
| ty::RawPtr(_)
| ty::Str
| ty::Slice(_)
| ty::Dynamic(..) => bug!("no ValTree should have been created for type {:?}", ty.kind()),
}
}
// FIXME Needs a better/correct name
#[instrument(skip(ecx), level = "debug")]
fn fill_place_recursively<'tcx>(
ecx: &mut CompileTimeEvalContext<'tcx, 'tcx>,
place: &mut MPlaceTy<'tcx>,
valtree: ty::ValTree<'tcx>,
) {
// This will match on valtree and write the value(s) corresponding to the ValTree
// inside the place recursively.
let tcx = ecx.tcx.tcx;
let ty = place.layout.ty;
match ty.kind() {
ty::FnDef(_, _) => {
ecx.write_immediate(
Immediate::Scalar(ScalarMaybeUninit::Scalar(Scalar::ZST)),
&(*place).into(),
)
.unwrap();
}
ty::Bool | ty::Int(_) | ty::Uint(_) | ty::Float(_) | ty::Char => {
let scalar_int = valtree.unwrap_leaf();
debug!("writing trivial valtree {:?} to place {:?}", scalar_int, place);
ecx.write_immediate(
Immediate::Scalar(ScalarMaybeUninit::Scalar(scalar_int.into())),
&(*place).into(),
)
.unwrap();
}
ty::Ref(_, inner_ty, _) => {
let mut pointee_place = create_pointee_place(ecx, *inner_ty, valtree);
debug!(?pointee_place);
fill_place_recursively(ecx, &mut pointee_place, valtree);
dump_place(ecx, pointee_place.into());
intern_const_alloc_recursive(ecx, InternKind::Constant, &pointee_place).unwrap();
let imm = match inner_ty.kind() {
ty::Slice(_) | ty::Str => {
let len = valtree.unwrap_branch().len();
let len_scalar = ScalarMaybeUninit::Scalar(Scalar::from_u64(len as u64));
Immediate::ScalarPair(
ScalarMaybeUninit::from_maybe_pointer((*pointee_place).ptr, &tcx),
len_scalar,
)
}
_ => pointee_place.to_ref(&tcx),
};
debug!(?imm);
ecx.write_immediate(imm, &(*place).into()).unwrap();
}
ty::Adt(_, _) | ty::Tuple(_) | ty::Array(_, _) | ty::Str | ty::Slice(_) => {
let branches = valtree.unwrap_branch();
// Need to downcast place for enums
let (place_adjusted, branches, variant_idx) = match ty.kind() {
ty::Adt(def, _) if def.is_enum() => {
// First element of valtree corresponds to variant
let scalar_int = branches[0].unwrap_leaf();
let variant_idx = VariantIdx::from_u32(scalar_int.try_to_u32().unwrap());
let variant = def.variant(variant_idx);
debug!(?variant);
(
place.project_downcast(ecx, variant_idx).unwrap(),
&branches[1..],
Some(variant_idx),
)
}
_ => (*place, branches, None),
};
debug!(?place_adjusted, ?branches);
// Create the places (by indexing into `place`) for the fields and fill
// them recursively
for (i, inner_valtree) in branches.iter().enumerate() {
debug!(?i, ?inner_valtree);
let mut place_inner = match ty.kind() {
ty::Str | ty::Slice(_) => ecx.mplace_index(&place, i as u64).unwrap(),
_ if !ty.is_sized(ecx.tcx, ty::ParamEnv::empty())
&& i == branches.len() - 1 =>
{
// Note: For custom DSTs we need to manually process the last unsized field.
// We created a `Pointer` for the `Allocation` of the complete sized version of
// the Adt in `create_pointee_place` and now we fill that `Allocation` with the
// values in the ValTree. For the unsized field we have to additionally add the meta
// data.
let (unsized_inner_ty, num_elems) =
get_info_on_unsized_field(ty, valtree, tcx);
debug!(?unsized_inner_ty);
let inner_ty = match ty.kind() {
ty::Adt(def, substs) => {
def.variant(VariantIdx::from_u32(0)).fields[i].ty(tcx, substs)
}
ty::Tuple(inner_tys) => inner_tys[i],
_ => bug!("unexpected unsized type {:?}", ty),
};
let inner_layout =
tcx.layout_of(ty::ParamEnv::empty().and(inner_ty)).unwrap();
debug!(?inner_layout);
let offset = place_adjusted.layout.fields.offset(i);
place
.offset(
offset,
MemPlaceMeta::Meta(Scalar::from_u64(num_elems as u64)),
inner_layout,
&tcx,
)
.unwrap()
}
_ => ecx.mplace_field(&place_adjusted, i).unwrap(),
};
debug!(?place_inner);
fill_place_recursively(ecx, &mut place_inner, *inner_valtree);
dump_place(&ecx, place_inner.into());
}
debug!("dump of place_adjusted:");
dump_place(ecx, place_adjusted.into());
if let Some(variant_idx) = variant_idx {
// don't forget filling the place with the discriminant of the enum
ecx.write_discriminant(variant_idx, &(*place).into()).unwrap();
}
debug!("dump of place after writing discriminant:");
dump_place(ecx, (*place).into());
}
_ => bug!("shouldn't have created a ValTree for {:?}", ty),
}
}
fn dump_place<'tcx>(ecx: &CompileTimeEvalContext<'tcx, 'tcx>, place: PlaceTy<'tcx>) {
trace!("{:?}", ecx.dump_place(*place));
}

2
compiler/rustc_const_eval/src/interpret/mod.rs
View file

@ -27,7 +27,7 @@ pub use self::memory::{AllocCheck, AllocRef, AllocRefMut, FnVal, Memory, MemoryK
pub use self::operand::{ImmTy, Immediate, OpTy, Operand};
pub use self::place::{MPlaceTy, MemPlace, MemPlaceMeta, Place, PlaceTy};
pub use self::validity::{CtfeValidationMode, RefTracking};
pub use self::visitor::{MutValueVisitor, ValueVisitor};
pub use self::visitor::{MutValueVisitor, Value, ValueVisitor};
crate use self::intrinsics::eval_nullary_intrinsic;
use eval_context::{from_known_layout, mir_assign_valid_types};

1
compiler/rustc_const_eval/src/interpret/operand.rs
View file

@ -424,6 +424,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
})
}
#[instrument(skip(self), level = "debug")]
pub fn operand_projection(
&self,
base: &OpTy<'tcx, M::PointerTag>,

17
compiler/rustc_const_eval/src/interpret/place.rs
View file

@ -115,6 +115,12 @@ impl<'tcx, Tag: Provenance> std::ops::Deref for MPlaceTy<'tcx, Tag> {
}
}
impl<'tcx, Tag: Provenance> std::ops::DerefMut for MPlaceTy<'tcx, Tag> {
fn deref_mut(&mut self) -> &mut Self::Target {
&mut self.mplace
}
}
impl<'tcx, Tag: Provenance> From<MPlaceTy<'tcx, Tag>> for PlaceTy<'tcx, Tag> {
#[inline(always)]
fn from(mplace: MPlaceTy<'tcx, Tag>) -> Self {
@ -294,6 +300,7 @@ where
/// Take an operand, representing a pointer, and dereference it to a place -- that
/// will always be a MemPlace. Lives in `place.rs` because it creates a place.
#[instrument(skip(self), level = "debug")]
pub fn deref_operand(
&self,
src: &OpTy<'tcx, M::PointerTag>,
@ -487,7 +494,8 @@ where
}
/// Project into an mplace
pub(super) fn mplace_projection(
#[instrument(skip(self), level = "debug")]
pub(crate) fn mplace_projection(
&self,
base: &MPlaceTy<'tcx, M::PointerTag>,
proj_elem: mir::PlaceElem<'tcx>,
@ -548,6 +556,7 @@ where
/// Just a convenience function, but used quite a bit.
/// This is the only projection that might have a side-effect: We cannot project
/// into the field of a local `ScalarPair`, we have to first allocate it.
#[instrument(skip(self), level = "debug")]
pub fn place_field(
&mut self,
base: &PlaceTy<'tcx, M::PointerTag>,
@ -617,6 +626,7 @@ where
/// Computes a place. You should only use this if you intend to write into this
/// place; for reading, a more efficient alternative is `eval_place_for_read`.
#[instrument(skip(self), level = "debug")]
pub fn eval_place(
&mut self,
place: mir::Place<'tcx>,
@ -646,6 +656,7 @@ where
/// Write an immediate to a place
#[inline(always)]
#[instrument(skip(self), level = "debug")]
pub fn write_immediate(
&mut self,
src: Immediate<M::PointerTag>,
@ -830,6 +841,7 @@ where
/// Copies the data from an operand to a place. This does not support transmuting!
/// Use `copy_op_transmute` if the layouts could disagree.
#[inline(always)]
#[instrument(skip(self), level = "debug")]
pub fn copy_op(
&mut self,
src: &OpTy<'tcx, M::PointerTag>,
@ -849,6 +861,7 @@ where
/// Use `copy_op_transmute` if the layouts could disagree.
/// Also, if you use this you are responsible for validating that things get copied at the
/// right type.
#[instrument(skip(self), level = "debug")]
fn copy_op_no_validate(
&mut self,
src: &OpTy<'tcx, M::PointerTag>,
@ -955,6 +968,7 @@ where
/// This supports unsized types and returns the computed size to avoid some
/// redundant computation when copying; use `force_allocation` for a simpler, sized-only
/// version.
#[instrument(skip(self), level = "debug")]
pub fn force_allocation_maybe_sized(
&mut self,
place: &PlaceTy<'tcx, M::PointerTag>,
@ -1037,6 +1051,7 @@ where
}
/// Writes the discriminant of the given variant.
#[instrument(skip(self), level = "debug")]
pub fn write_discriminant(
&mut self,
variant_index: VariantIdx,

4
compiler/rustc_const_eval/src/lib.rs
View file

@ -35,6 +35,7 @@ pub mod transform;
pub mod util;
use rustc_middle::ty::query::Providers;
use rustc_middle::ty::ParamEnv;
pub fn provide(providers: &mut Providers) {
const_eval::provide(providers);
@ -49,6 +50,9 @@ pub fn provide(providers: &mut Providers) {
let (param_env, raw) = param_env_and_value.into_parts();
const_eval::const_to_valtree(tcx, param_env, raw)
};
providers.valtree_to_const_val = |tcx, (ty, valtree)| {
const_eval::valtree_to_const_value(tcx, ParamEnv::empty().and(ty), valtree)
};
providers.deref_const = |tcx, param_env_and_value| {
let (param_env, value) = param_env_and_value.into_parts();
const_eval::deref_const(tcx, param_env, value)