diff options
Diffstat (limited to 'compiler/rustc_const_eval/src/interpret/operand.rs')
| -rw-r--r-- | compiler/rustc_const_eval/src/interpret/operand.rs | 198 |
1 files changed, 30 insertions, 168 deletions
diff --git a/compiler/rustc_const_eval/src/interpret/operand.rs b/compiler/rustc_const_eval/src/interpret/operand.rs index befc0928f..5310ef0bb 100644 --- a/compiler/rustc_const_eval/src/interpret/operand.rs +++ b/compiler/rustc_const_eval/src/interpret/operand.rs @@ -4,13 +4,12 @@ use either::{Either, Left, Right}; use rustc_hir::def::Namespace; -use rustc_middle::ty::layout::{LayoutOf, PrimitiveExt, TyAndLayout}; +use rustc_middle::ty::layout::{LayoutOf, TyAndLayout}; use rustc_middle::ty::print::{FmtPrinter, PrettyPrinter}; use rustc_middle::ty::{ConstInt, Ty, ValTree}; use rustc_middle::{mir, ty}; use rustc_span::Span; -use rustc_target::abi::{self, Abi, Align, HasDataLayout, Size, TagEncoding}; -use rustc_target::abi::{VariantIdx, Variants}; +use rustc_target::abi::{self, Abi, Align, HasDataLayout, Size}; use super::{ alloc_range, from_known_layout, mir_assign_valid_types, AllocId, ConstValue, Frame, GlobalId, @@ -53,7 +52,7 @@ impl<Prov: Provenance> Immediate<Prov> { } pub fn new_slice(val: Scalar<Prov>, len: u64, cx: &impl HasDataLayout) -> Self { - Immediate::ScalarPair(val, Scalar::from_machine_usize(len, cx)) + Immediate::ScalarPair(val, Scalar::from_target_usize(len, cx)) } pub fn new_dyn_trait( @@ -256,7 +255,22 @@ impl<'tcx, Prov: Provenance> OpTy<'tcx, Prov> { } } - pub fn offset_with_meta( + /// Replace the layout of this operand. There's basically no sanity check that this makes sense, + /// you better know what you are doing! If this is an immediate, applying the wrong layout can + /// not just lead to invalid data, it can actually *shift the data around* since the offsets of + /// a ScalarPair are entirely determined by the layout, not the data. + pub fn transmute(&self, layout: TyAndLayout<'tcx>) -> Self { + assert_eq!( + self.layout.size, layout.size, + "transmuting with a size change, that doesn't seem right" + ); + OpTy { layout, ..*self } + } + + /// Offset the operand in memory (if possible) and change its metadata. + /// + /// This can go wrong very easily if you give the wrong layout for the new place! + pub(super) fn offset_with_meta( &self, offset: Size, meta: MemPlaceMeta<Prov>, @@ -277,6 +291,9 @@ impl<'tcx, Prov: Provenance> OpTy<'tcx, Prov> { } } + /// Offset the operand in memory (if possible). + /// + /// This can go wrong very easily if you give the wrong layout for the new place! pub fn offset( &self, offset: Size, @@ -319,7 +336,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> { assert_eq!(size, mplace.layout.size, "abi::Scalar size does not match layout size"); let scalar = alloc.read_scalar( alloc_range(Size::ZERO, size), - /*read_provenance*/ s.is_ptr(), + /*read_provenance*/ matches!(s, abi::Pointer(_)), )?; Some(ImmTy { imm: scalar.into(), layout: mplace.layout }) } @@ -335,11 +352,11 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> { assert!(b_offset.bytes() > 0); // in `operand_field` we use the offset to tell apart the fields let a_val = alloc.read_scalar( alloc_range(Size::ZERO, a_size), - /*read_provenance*/ a.is_ptr(), + /*read_provenance*/ matches!(a, abi::Pointer(_)), )?; let b_val = alloc.read_scalar( alloc_range(b_offset, b_size), - /*read_provenance*/ b.is_ptr(), + /*read_provenance*/ matches!(b, abi::Pointer(_)), )?; Some(ImmTy { imm: Immediate::ScalarPair(a_val, b_val), layout: mplace.layout }) } @@ -415,12 +432,12 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> { self.read_scalar(op)?.to_pointer(self) } /// Read a pointer-sized unsigned integer from a place. - pub fn read_machine_usize(&self, op: &OpTy<'tcx, M::Provenance>) -> InterpResult<'tcx, u64> { - self.read_scalar(op)?.to_machine_usize(self) + pub fn read_target_usize(&self, op: &OpTy<'tcx, M::Provenance>) -> InterpResult<'tcx, u64> { + self.read_scalar(op)?.to_target_usize(self) } /// Read a pointer-sized signed integer from a place. - pub fn read_machine_isize(&self, op: &OpTy<'tcx, M::Provenance>) -> InterpResult<'tcx, i64> { - self.read_scalar(op)?.to_machine_isize(self) + pub fn read_target_isize(&self, op: &OpTy<'tcx, M::Provenance>) -> InterpResult<'tcx, i64> { + self.read_scalar(op)?.to_target_isize(self) } /// Turn the wide MPlace into a string (must already be dereferenced!) @@ -595,14 +612,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> { span: Option<Span>, layout: Option<TyAndLayout<'tcx>>, ) -> InterpResult<'tcx, OpTy<'tcx, M::Provenance>> { - // FIXME(const_prop): normalization needed b/c const prop lint in - // `mir_drops_elaborated_and_const_checked`, which happens before - // optimized MIR. Only after optimizing the MIR can we guarantee - // that the `RevealAll` pass has happened and that the body's consts - // are normalized, so any call to resolve before that needs to be - // manually normalized. - let val = self.tcx.normalize_erasing_regions(self.param_env, *val); - match val { + match *val { mir::ConstantKind::Ty(ct) => { let ty = ct.ty(); let valtree = self.eval_ty_constant(ct, span)?; @@ -657,154 +667,6 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> { }; Ok(OpTy { op, layout, align: Some(layout.align.abi) }) } - - /// Read discriminant, return the runtime value as well as the variant index. - /// Can also legally be called on non-enums (e.g. through the discriminant_value intrinsic)! - pub fn read_discriminant( - &self, - op: &OpTy<'tcx, M::Provenance>, - ) -> InterpResult<'tcx, (Scalar<M::Provenance>, VariantIdx)> { - trace!("read_discriminant_value {:#?}", op.layout); - // Get type and layout of the discriminant. - let discr_layout = self.layout_of(op.layout.ty.discriminant_ty(*self.tcx))?; - trace!("discriminant type: {:?}", discr_layout.ty); - - // We use "discriminant" to refer to the value associated with a particular enum variant. - // This is not to be confused with its "variant index", which is just determining its position in the - // declared list of variants -- they can differ with explicitly assigned discriminants. - // We use "tag" to refer to how the discriminant is encoded in memory, which can be either - // straight-forward (`TagEncoding::Direct`) or with a niche (`TagEncoding::Niche`). - let (tag_scalar_layout, tag_encoding, tag_field) = match op.layout.variants { - Variants::Single { index } => { - let discr = match op.layout.ty.discriminant_for_variant(*self.tcx, index) { - Some(discr) => { - // This type actually has discriminants. - assert_eq!(discr.ty, discr_layout.ty); - Scalar::from_uint(discr.val, discr_layout.size) - } - None => { - // On a type without actual discriminants, variant is 0. - assert_eq!(index.as_u32(), 0); - Scalar::from_uint(index.as_u32(), discr_layout.size) - } - }; - return Ok((discr, index)); - } - Variants::Multiple { tag, ref tag_encoding, tag_field, .. } => { - (tag, tag_encoding, tag_field) - } - }; - - // There are *three* layouts that come into play here: - // - The discriminant has a type for typechecking. This is `discr_layout`, and is used for - // the `Scalar` we return. - // - The tag (encoded discriminant) has layout `tag_layout`. This is always an integer type, - // and used to interpret the value we read from the tag field. - // For the return value, a cast to `discr_layout` is performed. - // - The field storing the tag has a layout, which is very similar to `tag_layout` but - // may be a pointer. This is `tag_val.layout`; we just use it for sanity checks. - - // Get layout for tag. - let tag_layout = self.layout_of(tag_scalar_layout.primitive().to_int_ty(*self.tcx))?; - - // Read tag and sanity-check `tag_layout`. - let tag_val = self.read_immediate(&self.operand_field(op, tag_field)?)?; - assert_eq!(tag_layout.size, tag_val.layout.size); - assert_eq!(tag_layout.abi.is_signed(), tag_val.layout.abi.is_signed()); - trace!("tag value: {}", tag_val); - - // Figure out which discriminant and variant this corresponds to. - Ok(match *tag_encoding { - TagEncoding::Direct => { - let scalar = tag_val.to_scalar(); - // Generate a specific error if `tag_val` is not an integer. - // (`tag_bits` itself is only used for error messages below.) - let tag_bits = scalar - .try_to_int() - .map_err(|dbg_val| err_ub!(InvalidTag(dbg_val)))? - .assert_bits(tag_layout.size); - // Cast bits from tag layout to discriminant layout. - // After the checks we did above, this cannot fail, as - // discriminants are int-like. - let discr_val = - self.cast_from_int_like(scalar, tag_val.layout, discr_layout.ty).unwrap(); - let discr_bits = discr_val.assert_bits(discr_layout.size); - // Convert discriminant to variant index, and catch invalid discriminants. - let index = match *op.layout.ty.kind() { - ty::Adt(adt, _) => { - adt.discriminants(*self.tcx).find(|(_, var)| var.val == discr_bits) - } - ty::Generator(def_id, substs, _) => { - let substs = substs.as_generator(); - substs - .discriminants(def_id, *self.tcx) - .find(|(_, var)| var.val == discr_bits) - } - _ => span_bug!(self.cur_span(), "tagged layout for non-adt non-generator"), - } - .ok_or_else(|| err_ub!(InvalidTag(Scalar::from_uint(tag_bits, tag_layout.size))))?; - // Return the cast value, and the index. - (discr_val, index.0) - } - TagEncoding::Niche { untagged_variant, ref niche_variants, niche_start } => { - let tag_val = tag_val.to_scalar(); - // Compute the variant this niche value/"tag" corresponds to. With niche layout, - // discriminant (encoded in niche/tag) and variant index are the same. - let variants_start = niche_variants.start().as_u32(); - let variants_end = niche_variants.end().as_u32(); - let variant = match tag_val.try_to_int() { - Err(dbg_val) => { - // So this is a pointer then, and casting to an int failed. - // Can only happen during CTFE. - // The niche must be just 0, and the ptr not null, then we know this is - // okay. Everything else, we conservatively reject. - let ptr_valid = niche_start == 0 - && variants_start == variants_end - && !self.scalar_may_be_null(tag_val)?; - if !ptr_valid { - throw_ub!(InvalidTag(dbg_val)) - } - untagged_variant - } - Ok(tag_bits) => { - let tag_bits = tag_bits.assert_bits(tag_layout.size); - // We need to use machine arithmetic to get the relative variant idx: - // variant_index_relative = tag_val - niche_start_val - let tag_val = ImmTy::from_uint(tag_bits, tag_layout); - let niche_start_val = ImmTy::from_uint(niche_start, tag_layout); - let variant_index_relative_val = - self.binary_op(mir::BinOp::Sub, &tag_val, &niche_start_val)?; - let variant_index_relative = - variant_index_relative_val.to_scalar().assert_bits(tag_val.layout.size); - // Check if this is in the range that indicates an actual discriminant. - if variant_index_relative <= u128::from(variants_end - variants_start) { - let variant_index_relative = u32::try_from(variant_index_relative) - .expect("we checked that this fits into a u32"); - // Then computing the absolute variant idx should not overflow any more. - let variant_index = variants_start - .checked_add(variant_index_relative) - .expect("overflow computing absolute variant idx"); - let variants_len = op - .layout - .ty - .ty_adt_def() - .expect("tagged layout for non adt") - .variants() - .len(); - assert!(usize::try_from(variant_index).unwrap() < variants_len); - VariantIdx::from_u32(variant_index) - } else { - untagged_variant - } - } - }; - // Compute the size of the scalar we need to return. - // No need to cast, because the variant index directly serves as discriminant and is - // encoded in the tag. - (Scalar::from_uint(variant.as_u32(), discr_layout.size), variant) - } - }) - } } // Some nodes are used a lot. Make sure they don't unintentionally get bigger. |