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Auto merge of #115804 - RalfJung:valtree-to-const-val, r=oli-obk

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consistently pass ty::Const through valtrees

Some drive-by things extracted from https://github.com/rust-lang/rust/pull/115748.
This commit is contained in:
bors 2023-09-14 15:34:31 +00:00
commit e437e57954
4 changed files with 78 additions and 106 deletions
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103
compiler/rustc_const_eval/src/const_eval/valtrees.rs
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@ -7,7 +7,7 @@ use crate::interpret::{
intern_const_alloc_recursive, ConstValue, ImmTy, Immediate, InternKind, MemPlaceMeta,
MemoryKind, PlaceTy, Projectable, Scalar,
};
use rustc_middle::ty::layout::{LayoutOf, TyAndLayout};
use rustc_middle::ty::layout::{LayoutCx, LayoutOf, TyAndLayout};
use rustc_middle::ty::{self, ScalarInt, Ty, TyCtxt};
use rustc_span::source_map::DUMMY_SP;
use rustc_target::abi::VariantIdx;
@ -189,12 +189,11 @@ fn reconstruct_place_meta<'tcx>(
}
#[instrument(skip(ecx), level = "debug", ret)]
fn create_pointee_place<'tcx>(
fn create_valtree_place<'tcx>(
ecx: &mut CompileTimeEvalContext<'tcx, 'tcx>,
ty: Ty<'tcx>,
layout: TyAndLayout<'tcx>,
valtree: ty::ValTree<'tcx>,
) -> MPlaceTy<'tcx> {
let layout = ecx.layout_of(ty).unwrap();
let meta = reconstruct_place_meta(layout, valtree, ecx.tcx.tcx);
ecx.allocate_dyn(layout, MemoryKind::Stack, meta).unwrap()
}
@ -216,11 +215,6 @@ pub fn valtree_to_const_value<'tcx>(
// FIXME Does this need an example?
let (param_env, ty) = param_env_ty.into_parts();
let mut ecx: crate::interpret::InterpCx<
'_,
'_,
crate::const_eval::CompileTimeInterpreter<'_, '_>,
> = mk_eval_cx(tcx, DUMMY_SP, param_env, CanAccessStatics::No);
match ty.kind() {
ty::FnDef(..) => {
@ -233,33 +227,44 @@ pub fn valtree_to_const_value<'tcx>(
"ValTrees for Bool, Int, Uint, Float or Char should have the form ValTree::Leaf"
),
},
ty::Ref(_, _, _) | ty::Tuple(_) | ty::Array(_, _) | ty::Adt(..) => {
let place = match ty.kind() {
ty::Ref(_, inner_ty, _) => {
// Need to create a place for the pointee (the reference itself will be an immediate)
create_pointee_place(&mut ecx, *inner_ty, valtree)
ty::Ref(_, inner_ty, _) => {
let mut ecx = mk_eval_cx(tcx, DUMMY_SP, param_env, CanAccessStatics::No);
let imm = valtree_to_ref(&mut ecx, valtree, *inner_ty);
let imm = ImmTy::from_immediate(imm, tcx.layout_of(param_env_ty).unwrap());
op_to_const(&ecx, &imm.into())
}
ty::Tuple(_) | ty::Array(_, _) | ty::Adt(..) => {
let layout = tcx.layout_of(param_env_ty).unwrap();
if layout.is_zst() {
// Fast path to avoid some allocations.
return ConstValue::ZeroSized;
}
if layout.abi.is_scalar()
&& (matches!(ty.kind(), ty::Tuple(_))
|| matches!(ty.kind(), ty::Adt(def, _) if def.is_struct()))
{
// A Scalar tuple/struct; we can avoid creating an allocation.
let branches = valtree.unwrap_branch();
// Find the non-ZST field. (There can be aligned ZST!)
for (i, &inner_valtree) in branches.iter().enumerate() {
let field = layout.field(&LayoutCx { tcx, param_env }, i);
if !field.is_zst() {
return valtree_to_const_value(tcx, param_env.and(field.ty), inner_valtree);
}
}
_ => {
// Need to create a place for this valtree.
create_pointee_place(&mut ecx, ty, valtree)
}
};
debug!(?place);
bug!("could not find non-ZST field during in {layout:#?}");
}
let mut ecx = mk_eval_cx(tcx, DUMMY_SP, param_env, CanAccessStatics::No);
// Need to create a place for this valtree.
let place = create_valtree_place(&mut ecx, layout, valtree);
valtree_into_mplace(&mut ecx, &place, valtree);
dump_place(&ecx, &place);
intern_const_alloc_recursive(&mut ecx, InternKind::Constant, &place).unwrap();
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()),
}
op_to_const(&ecx, &place.into())
}
ty::Never
| ty::Error(_)
@ -283,6 +288,22 @@ pub fn valtree_to_const_value<'tcx>(
}
}
/// Put a valtree into memory and return a reference to that.
fn valtree_to_ref<'tcx>(
ecx: &mut CompileTimeEvalContext<'tcx, 'tcx>,
valtree: ty::ValTree<'tcx>,
pointee_ty: Ty<'tcx>,
) -> Immediate {
let pointee_place = create_valtree_place(ecx, ecx.layout_of(pointee_ty).unwrap(), valtree);
debug!(?pointee_place);
valtree_into_mplace(ecx, &pointee_place, valtree);
dump_place(ecx, &pointee_place);
intern_const_alloc_recursive(ecx, InternKind::Constant, &pointee_place).unwrap();
pointee_place.to_ref(&ecx.tcx)
}
#[instrument(skip(ecx), level = "debug")]
fn valtree_into_mplace<'tcx>(
ecx: &mut CompileTimeEvalContext<'tcx, 'tcx>,
@ -292,7 +313,6 @@ fn valtree_into_mplace<'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() {
@ -305,27 +325,8 @@ fn valtree_into_mplace<'tcx>(
ecx.write_immediate(Immediate::Scalar(scalar_int.into()), place).unwrap();
}
ty::Ref(_, inner_ty, _) => {
let pointee_place = create_pointee_place(ecx, *inner_ty, valtree);
debug!(?pointee_place);
valtree_into_mplace(ecx, &pointee_place, valtree);
dump_place(ecx, &pointee_place);
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 = Scalar::from_target_usize(len as u64, &tcx);
Immediate::ScalarPair(
Scalar::from_maybe_pointer(pointee_place.ptr(), &tcx),
len_scalar,
)
}
_ => pointee_place.to_ref(&tcx),
};
let imm = valtree_to_ref(ecx, valtree, *inner_ty);
debug!(?imm);
ecx.write_immediate(imm, place).unwrap();
}
ty::Adt(_, _) | ty::Tuple(_) | ty::Array(_, _) | ty::Str | ty::Slice(_) => {