create leafs for slices

rust-lang · Apr 8, 2022 · 82217a6 · 82217a6
1 parent fcc4d8c
commit 82217a6
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Showing 6 changed files with 64 additions and 145 deletions.
diff --git a/compiler/rustc_const_eval/src/const_eval/eval_queries.rs b/compiler/rustc_const_eval/src/const_eval/eval_queries.rs
@@ -188,6 +188,7 @@ pub(super) fn op_to_const<'tcx>(
     }
 }
 
+#[instrument(skip(tcx), level = "debug")]
 fn turn_into_const_value<'tcx>(
     tcx: TyCtxt<'tcx>,
     constant: ConstAlloc<'tcx>,
@@ -206,6 +207,7 @@ fn turn_into_const_value<'tcx>(
         !is_static || cid.promoted.is_some(),
         "the `eval_to_const_value_raw` query should not be used for statics, use `eval_to_allocation` instead"
     );
+
     // Turn this into a proper constant.
     op_to_const(&ecx, &mplace.into())
 }

diff --git a/compiler/rustc_const_eval/src/const_eval/mod.rs b/compiler/rustc_const_eval/src/const_eval/mod.rs
@@ -6,14 +6,14 @@ use rustc_hir::Mutability;
 use rustc_middle::ty::{self, TyCtxt};
 use rustc_middle::{
     mir::{self, interpret::ConstAlloc},
-    ty::{ScalarInt, Ty},
+    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, Immediate, InternKind, InterpCx, InterpResult,
+    MPlaceTy, MemPlaceMeta, Scalar,
 };
 
 mod error;
@@ -80,19 +80,28 @@ fn branches<'tcx>(
     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>,
+    n: u64,
+) -> Option<ty::ValTree<'tcx>> {
+    let elems = (0..n).map(|i| {
+        let place_elem = ecx.mplace_index(place, i).unwrap();
+        const_to_valtree_inner(ecx, &place_elem)
+    });
+
+    // Need `len` for the ValTree -> ConstValue conversion
+    let len = Some(Some(ty::ValTree::Leaf(ScalarInt::from(n))));
+    let branches = len.into_iter().chain(elems);
+
+    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>> {
-    // We only want to use raw bytes in ValTrees for string slices or &[<integer_ty>]
-    let use_bytes_for_ref = |ty: Ty<'tcx>| -> bool {
-        match ty.kind() {
-            ty::Str | ty::Char | ty::Uint(_) | ty::Int(_) | ty::Bool => true,
-            _ => false,
-        }
-    };
-
     match place.layout.ty.kind() {
         ty::FnDef(..) => Some(ty::ValTree::zst()),
         ty::Bool | ty::Int(_) | ty::Uint(_) | ty::Float(_) | ty::Char => {
@@ -107,75 +116,52 @@ fn const_to_valtree_inner<'tcx>(
         // agree with runtime equality tests.
         ty::FnPtr(_) | ty::RawPtr(_) => None,
 
-        ty::Ref(_, ref_ty, _) if place.layout.ty.is_slice() => {
-            match ecx.try_read_immediate_from_mplace(&place) {
-                Ok(Some(imm)) => {
-                    // `imm` is a ScalarPair. We try to get the underlying bytes behind that
-                    // fat pointer for string slices and slices of integer types. For any other
-                    // slice types we use `branches` to recursively construct the Valtree.
-
-                    if use_bytes_for_ref(*ref_ty) {
-                        let (alloc, range) = ecx.get_alloc_from_imm_scalar_pair(imm);
-                        let alloc_bytes = match alloc.get_bytes(&ecx.tcx, range) {
-                            Ok(bytes) => bytes,
-                            Err(_e) => return None,
-                        };
-                        debug!(?alloc_bytes);
-
-                        let bytes = ecx.tcx.arena.alloc_slice(alloc_bytes);
-                        let len = bytes.len();
-                        debug!(?bytes, ?len);
-
-                        let slice = ty::ValSlice { bytes};
-
-                        Some(ty::ValTree::SliceOrStr(slice))
-                    } else {
-                        let derefd = ecx.deref_operand(&imm.into()).expect(&format!("couldnt deref {:?}", imm));
-                        debug!("derefd: {:?}", derefd);
-
-                        let derefd_imm = match ecx.try_read_immediate_from_mplace(&derefd) {
-                            Ok(Some(imm)) => imm,
-                            _ => return None,
-                        };
-                        debug!(?derefd_imm);
-
-                        let tcx = ecx.tcx.tcx;
-                        let scalar_len= derefd.meta.unwrap_meta();
-                        let len = match scalar_len {
-                            Scalar::Int(int) => {
-                                int.try_to_machine_usize(tcx).expect(&format!("Expected a valid ScalarInt in {:?}", scalar_len))
-                            }
-                            _ => bug!("expected a ScalarInt in meta data for {:?}", place),
-                        };
-                        debug!(?len);
-
-                        let valtree = branches(ecx, place, len.try_into().expect("BLA"), None);
-                        debug!(?valtree);
-
-                        valtree
+        ty::Ref(_, inner_ty, _)  => {
+            match inner_ty.kind() {
+                ty::Slice(_) | ty::Str => {
+                    match ecx.try_read_immediate_from_mplace(&place) {
+                        Ok(Some(imm)) => {
+                            let mplace_ref = ecx.ref_to_mplace(&imm).unwrap();
+                            let derefd = ecx.deref_operand(&place.into()).expect(&format!("couldnt deref {:?}", imm));
+                            debug!(?mplace_ref, ?derefd);
+
+                            let len = match imm.imm {
+                                Immediate::ScalarPair(_, b) => {
+                                    let len = b.to_machine_usize(&ecx.tcx.tcx).unwrap();
+                                    len
+                                }
+                                _ => bug!("expected ScalarPair for &[T] or &str"),
+                            };
+                            debug!(?len);
+
+                            let valtree = slice_branches(ecx, &derefd, len);
+                            debug!(?valtree);
+
+                            valtree
+                        }
+                        _ => {
+                            None
+                        }
                     }
                 }
                 _ => {
-                    None
-                }
-            }
-        }
+                    let imm = ecx.try_read_immediate_from_mplace(&place).unwrap_or_else(|e| bug!("couldnt read immediate from {:?}, error: {:?}", place, e));
 
-        ty::Ref(_, inner_ty, _) => {
-            debug!("Ref with inner_ty: {:?}", inner_ty);
-            let imm = ecx.try_read_immediate_from_mplace(&place).unwrap_or_else(|e| bug!("couldnt read immediate from {:?}, error: {:?}", place, e));
-            match imm {
-                Some(imm) => {
-                    debug!(?imm);
+                    match imm {
+                        Some(imm) => {
+                            debug!(?imm);
 
-                    let derefd_place = ecx.deref_mplace(place).unwrap_or_else(|e| bug!("couldn't deref {:?}, error: {:?}", place, e));
-                    debug!(?derefd_place);
+                            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)
+                            const_to_valtree_inner(ecx, &derefd_place)
+                        }
+                        None => bug!("couldn't read immediate from {:?}", place),
+                    }
                 }
-                None => None,
             }
         }
+
         ty::Str => {
             bug!("ty::Str should have been handled in ty::Ref branch that uses raw bytes");
         }

diff --git a/compiler/rustc_const_eval/src/interpret/operand.rs b/compiler/rustc_const_eval/src/interpret/operand.rs
@@ -14,9 +14,9 @@ use rustc_target::abi::{Abi, HasDataLayout, Size, TagEncoding};
 use rustc_target::abi::{VariantIdx, Variants};
 
 use super::{
-    alloc_range, from_known_layout, mir_assign_valid_types, AllocId, AllocRange, Allocation,
-    ConstValue, GlobalId, InterpCx, InterpResult, MPlaceTy, Machine, MemPlace, Place, PlaceTy,
-    Pointer, Provenance, Scalar, ScalarMaybeUninit,
+    alloc_range, from_known_layout, mir_assign_valid_types, AllocId, ConstValue, GlobalId,
+    InterpCx, InterpResult, MPlaceTy, Machine, MemPlace, Place, PlaceTy, Pointer, Provenance,
+    Scalar, ScalarMaybeUninit,
 };
 
 /// An `Immediate` represents a single immediate self-contained Rust value.
@@ -98,7 +98,7 @@ impl<'tcx, Tag: Provenance> Immediate<Tag> {
 // as input for binary and cast operations.
 #[derive(Copy, Clone, Debug)]
 pub struct ImmTy<'tcx, Tag: Provenance = AllocId> {
-    imm: Immediate<Tag>,
+    pub(crate) imm: Immediate<Tag>,
     pub layout: TyAndLayout<'tcx>,
 }
 
@@ -777,32 +777,3 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         })
     }
 }
-
-impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx, PointerTag = AllocId>> InterpCx<'mir, 'tcx, M> {
-    pub fn get_alloc_from_imm_scalar_pair(
-        &self,
-        imm: ImmTy<'tcx, M::PointerTag>,
-    ) -> (&Allocation, AllocRange) {
-        match imm.imm {
-            Immediate::ScalarPair(a, b) => {
-                // We know `offset` is relative to the allocation, so we can use `into_parts`.
-                let (data, start) = match self.scalar_to_ptr(a.check_init().unwrap()).into_parts() {
-                    (Some(alloc_id), offset) => {
-                        (self.tcx.global_alloc(alloc_id).unwrap_memory(), offset.bytes())
-                    }
-                    (None, _offset) => (
-                        self.tcx.intern_const_alloc(Allocation::from_bytes_byte_aligned_immutable(
-                            b"" as &[u8],
-                        )),
-                        0,
-                    ),
-                };
-                let len = b.to_machine_usize(self).unwrap();
-                let size = Size::from_bytes(len);
-                let start = Size::from_bytes(start);
-                (data.inner(), AllocRange { start, size })
-            }
-            _ => bug!("{:?} not a ScalarPair", imm),
-        }
-    }
-}
diff --git a/compiler/rustc_const_eval/src/interpret/place.rs b/compiler/rustc_const_eval/src/interpret/place.rs
@@ -305,18 +305,6 @@ where
         Ok(mplace)
     }
 
-    #[instrument(skip(self), level = "debug")]
-    pub fn deref_mplace(
-        &self,
-        src: &MPlaceTy<'tcx, M::PointerTag>,
-    ) -> InterpResult<'tcx, MPlaceTy<'tcx, M::PointerTag>> {
-        let val = self.try_read_immediate_from_mplace(src)?;
-        let mplace = self.ref_to_mplace(&val.unwrap())?;
-        self.check_mplace_access(mplace, CheckInAllocMsg::DerefTest)?;
-
-        Ok(mplace)
-    }
-
     #[inline]
     pub(super) fn get_alloc(
         &self,

diff --git a/compiler/rustc_middle/src/ty/consts/valtree.rs b/compiler/rustc_middle/src/ty/consts/valtree.rs
@@ -1,7 +1,5 @@
 use super::ScalarInt;
-use crate::ty::codec::TyDecoder;
 use rustc_macros::{HashStable, TyDecodable, TyEncodable};
-use rustc_serialize::{Decodable, Encodable, Encoder};
 
 #[derive(Copy, Clone, Debug, Hash, TyEncodable, TyDecodable, Eq, PartialEq, Ord, PartialOrd)]
 #[derive(HashStable)]
@@ -22,7 +20,6 @@ pub enum ValTree<'tcx> {
     /// See the `ScalarInt` documentation for how `ScalarInt` guarantees that equal values
     /// of these types have the same representation.
     Leaf(ScalarInt),
-    SliceOrStr(ValSlice<'tcx>),
     /// The fields of any kind of aggregate. Structs, tuples and arrays are represented by
     /// listing their fields' values in order.
     /// Enums are represented by storing their discriminant as a field, followed by all
@@ -35,28 +32,3 @@ impl<'tcx> ValTree<'tcx> {
         Self::Branch(&[])
     }
 }
-
-#[derive(Copy, Clone, Debug, HashStable, Hash, Eq, PartialEq, PartialOrd, Ord)]
-pub struct ValSlice<'tcx> {
-    pub bytes: &'tcx [u8],
-}
-
-impl<'tcx, S: Encoder> Encodable<S> for ValSlice<'tcx> {
-    fn encode(&self, s: &mut S) -> Result<(), S::Error> {
-        s.emit_usize(self.bytes.len())?;
-        s.emit_raw_bytes(self.bytes)?;
-
-        Ok(())
-    }
-}
-
-impl<'tcx, D: TyDecoder<'tcx>> Decodable<D> for ValSlice<'tcx> {
-    fn decode(d: &mut D) -> Self {
-        let tcx = d.tcx();
-        let len = d.read_usize();
-        let bytes_raw = d.read_raw_bytes(len);
-        let bytes = tcx.arena.alloc_slice(&bytes_raw[..]);
-
-        ValSlice { bytes }
-    }
-}
diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs
@@ -62,7 +62,7 @@ pub use self::closure::{
     CAPTURE_STRUCT_LOCAL,
 };
 pub use self::consts::{
-    Const, ConstInt, ConstKind, ConstS, InferConst, ScalarInt, Unevaluated, ValSlice, ValTree,
+    Const, ConstInt, ConstKind, ConstS, InferConst, ScalarInt, Unevaluated, ValTree,
 };
 pub use self::context::{
     tls, CanonicalUserType, CanonicalUserTypeAnnotation, CanonicalUserTypeAnnotations,