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interpret: more consistently use ImmTy in operators and casts #116010

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Sep 21, 2023
Merged

interpret: more consistently use ImmTy in operators and casts #116010

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da08a3f
interpret: more consistently use ImmTy in operators and casts
RalfJung Sep 20, 2023
bdbf545
interpret: less debug-printing of types
RalfJung Sep 20, 2023
23fd286
stronger consistency check in ImmTy::from_immediate
RalfJung Sep 20, 2023
0eff07b
try to avoid some layout_of calls
RalfJung Sep 21, 2023
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4 changes: 2 additions & 2 deletions compiler/rustc_const_eval/src/const_eval/machine.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,7 @@ use rustc_hir::{LangItem, CRATE_HIR_ID};
use rustc_middle::mir;
use rustc_middle::mir::interpret::PointerArithmetic;
use rustc_middle::ty::layout::{FnAbiOf, TyAndLayout};
use rustc_middle::ty::{self, Ty, TyCtxt};
use rustc_middle::ty::{self, TyCtxt};
use rustc_session::lint::builtin::INVALID_ALIGNMENT;
use std::borrow::Borrow;
use std::hash::Hash;
Expand Down Expand Up @@ -596,7 +596,7 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter<'mir,
_bin_op: mir::BinOp,
_left: &ImmTy<'tcx>,
_right: &ImmTy<'tcx>,
) -> InterpResult<'tcx, (Scalar, bool, Ty<'tcx>)> {
) -> InterpResult<'tcx, (ImmTy<'tcx>, bool)> {
throw_unsup_format!("pointer arithmetic or comparison is not supported at compile-time");
}

Expand Down
109 changes: 56 additions & 53 deletions compiler/rustc_const_eval/src/interpret/cast.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -24,41 +24,44 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
cast_ty: Ty<'tcx>,
dest: &PlaceTy<'tcx, M::Provenance>,
) -> InterpResult<'tcx> {
// `cast_ty` will often be the same as `dest.ty`, but not always, since subtyping is still
// possible.
let cast_layout =
if cast_ty == dest.layout.ty { dest.layout } else { self.layout_of(cast_ty)? };
// FIXME: In which cases should we trigger UB when the source is uninit?
match cast_kind {
CastKind::PointerCoercion(PointerCoercion::Unsize) => {
let cast_ty = self.layout_of(cast_ty)?;
self.unsize_into(src, cast_ty, dest)?;
self.unsize_into(src, cast_layout, dest)?;
}

CastKind::PointerExposeAddress => {
let src = self.read_immediate(src)?;
let res = self.pointer_expose_address_cast(&src, cast_ty)?;
self.write_immediate(res, dest)?;
let res = self.pointer_expose_address_cast(&src, cast_layout)?;
self.write_immediate(*res, dest)?;
}

CastKind::PointerFromExposedAddress => {
let src = self.read_immediate(src)?;
let res = self.pointer_from_exposed_address_cast(&src, cast_ty)?;
self.write_immediate(res, dest)?;
let res = self.pointer_from_exposed_address_cast(&src, cast_layout)?;
self.write_immediate(*res, dest)?;
}

CastKind::IntToInt | CastKind::IntToFloat => {
let src = self.read_immediate(src)?;
let res = self.int_to_int_or_float(&src, cast_ty)?;
self.write_immediate(res, dest)?;
let res = self.int_to_int_or_float(&src, cast_layout)?;
self.write_immediate(*res, dest)?;
}

CastKind::FloatToFloat | CastKind::FloatToInt => {
let src = self.read_immediate(src)?;
let res = self.float_to_float_or_int(&src, cast_ty)?;
self.write_immediate(res, dest)?;
let res = self.float_to_float_or_int(&src, cast_layout)?;
self.write_immediate(*res, dest)?;
}

CastKind::FnPtrToPtr | CastKind::PtrToPtr => {
let src = self.read_immediate(src)?;
let res = self.ptr_to_ptr(&src, cast_ty)?;
self.write_immediate(res, dest)?;
let res = self.ptr_to_ptr(&src, cast_layout)?;
self.write_immediate(*res, dest)?;
}

CastKind::PointerCoercion(
Expand Down Expand Up @@ -87,7 +90,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
let fn_ptr = self.fn_ptr(FnVal::Instance(instance));
self.write_pointer(fn_ptr, dest)?;
}
_ => span_bug!(self.cur_span(), "reify fn pointer on {:?}", src.layout.ty),
_ => span_bug!(self.cur_span(), "reify fn pointer on {}", src.layout.ty),
}
}

Expand All @@ -98,7 +101,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
// No change to value
self.write_immediate(*src, dest)?;
}
_ => span_bug!(self.cur_span(), "fn to unsafe fn cast on {:?}", cast_ty),
_ => span_bug!(self.cur_span(), "fn to unsafe fn cast on {}", cast_ty),
}
}

Expand All @@ -119,7 +122,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
let fn_ptr = self.fn_ptr(FnVal::Instance(instance));
self.write_pointer(fn_ptr, dest)?;
}
_ => span_bug!(self.cur_span(), "closure fn pointer on {:?}", src.layout.ty),
_ => span_bug!(self.cur_span(), "closure fn pointer on {}", src.layout.ty),
}
}

Expand All @@ -140,6 +143,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
CastKind::Transmute => {
assert!(src.layout.is_sized());
assert!(dest.layout.is_sized());
assert_eq!(cast_ty, dest.layout.ty); // we otherwise ignore `cast_ty` enirely...
if src.layout.size != dest.layout.size {
let src_bytes = src.layout.size.bytes();
let dest_bytes = dest.layout.size.bytes();
Expand All @@ -164,62 +168,61 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
pub fn int_to_int_or_float(
&self,
src: &ImmTy<'tcx, M::Provenance>,
cast_ty: Ty<'tcx>,
) -> InterpResult<'tcx, Immediate<M::Provenance>> {
cast_to: TyAndLayout<'tcx>,
) -> InterpResult<'tcx, ImmTy<'tcx, M::Provenance>> {
assert!(src.layout.ty.is_integral() || src.layout.ty.is_char() || src.layout.ty.is_bool());
assert!(cast_ty.is_floating_point() || cast_ty.is_integral() || cast_ty.is_char());
assert!(cast_to.ty.is_floating_point() || cast_to.ty.is_integral() || cast_to.ty.is_char());

Ok(self.cast_from_int_like(src.to_scalar(), src.layout, cast_ty)?.into())
Ok(ImmTy::from_scalar(
self.cast_from_int_like(src.to_scalar(), src.layout, cast_to.ty)?,
cast_to,
))
}

/// Handles 'FloatToFloat' and 'FloatToInt' casts.
pub fn float_to_float_or_int(
&self,
src: &ImmTy<'tcx, M::Provenance>,
cast_ty: Ty<'tcx>,
) -> InterpResult<'tcx, Immediate<M::Provenance>> {
cast_to: TyAndLayout<'tcx>,
) -> InterpResult<'tcx, ImmTy<'tcx, M::Provenance>> {
use rustc_type_ir::sty::TyKind::*;

match src.layout.ty.kind() {
let val = match src.layout.ty.kind() {
// Floating point
Float(FloatTy::F32) => {
return Ok(self.cast_from_float(src.to_scalar().to_f32()?, cast_ty).into());
}
Float(FloatTy::F64) => {
return Ok(self.cast_from_float(src.to_scalar().to_f64()?, cast_ty).into());
}
Float(FloatTy::F32) => self.cast_from_float(src.to_scalar().to_f32()?, cast_to.ty),
Float(FloatTy::F64) => self.cast_from_float(src.to_scalar().to_f64()?, cast_to.ty),
_ => {
bug!("Can't cast 'Float' type into {:?}", cast_ty);
bug!("Can't cast 'Float' type into {}", cast_to.ty);
}
}
};
Ok(ImmTy::from_scalar(val, cast_to))
}

/// Handles 'FnPtrToPtr' and 'PtrToPtr' casts.
pub fn ptr_to_ptr(
&self,
src: &ImmTy<'tcx, M::Provenance>,
cast_ty: Ty<'tcx>,
) -> InterpResult<'tcx, Immediate<M::Provenance>> {
cast_to: TyAndLayout<'tcx>,
) -> InterpResult<'tcx, ImmTy<'tcx, M::Provenance>> {
assert!(src.layout.ty.is_any_ptr());
assert!(cast_ty.is_unsafe_ptr());
assert!(cast_to.ty.is_unsafe_ptr());
// Handle casting any ptr to raw ptr (might be a fat ptr).
let dest_layout = self.layout_of(cast_ty)?;
if dest_layout.size == src.layout.size {
if cast_to.size == src.layout.size {
// Thin or fat pointer that just hast the ptr kind of target type changed.
return Ok(**src);
return Ok(ImmTy::from_immediate(**src, cast_to));
} else {
// Casting the metadata away from a fat ptr.
assert_eq!(src.layout.size, 2 * self.pointer_size());
assert_eq!(dest_layout.size, self.pointer_size());
assert_eq!(cast_to.size, self.pointer_size());
assert!(src.layout.ty.is_unsafe_ptr());
return match **src {
Immediate::ScalarPair(data, _) => Ok(data.into()),
Immediate::ScalarPair(data, _) => Ok(ImmTy::from_scalar(data, cast_to)),
Immediate::Scalar(..) => span_bug!(
self.cur_span(),
"{:?} input to a fat-to-thin cast ({:?} -> {:?})",
"{:?} input to a fat-to-thin cast ({} -> {})",
*src,
src.layout.ty,
cast_ty
cast_to.ty
),
Immediate::Uninit => throw_ub!(InvalidUninitBytes(None)),
};
Expand All @@ -229,27 +232,27 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
pub fn pointer_expose_address_cast(
&mut self,
src: &ImmTy<'tcx, M::Provenance>,
cast_ty: Ty<'tcx>,
) -> InterpResult<'tcx, Immediate<M::Provenance>> {
cast_to: TyAndLayout<'tcx>,
) -> InterpResult<'tcx, ImmTy<'tcx, M::Provenance>> {
assert_matches!(src.layout.ty.kind(), ty::RawPtr(_) | ty::FnPtr(_));
assert!(cast_ty.is_integral());
assert!(cast_to.ty.is_integral());

let scalar = src.to_scalar();
let ptr = scalar.to_pointer(self)?;
match ptr.into_pointer_or_addr() {
Ok(ptr) => M::expose_ptr(self, ptr)?,
Err(_) => {} // Do nothing, exposing an invalid pointer (`None` provenance) is a NOP.
};
Ok(self.cast_from_int_like(scalar, src.layout, cast_ty)?.into())
Ok(ImmTy::from_scalar(self.cast_from_int_like(scalar, src.layout, cast_to.ty)?, cast_to))
}

pub fn pointer_from_exposed_address_cast(
&self,
src: &ImmTy<'tcx, M::Provenance>,
cast_ty: Ty<'tcx>,
) -> InterpResult<'tcx, Immediate<M::Provenance>> {
cast_to: TyAndLayout<'tcx>,
) -> InterpResult<'tcx, ImmTy<'tcx, M::Provenance>> {
assert!(src.layout.ty.is_integral());
assert_matches!(cast_ty.kind(), ty::RawPtr(_));
assert_matches!(cast_to.ty.kind(), ty::RawPtr(_));

// First cast to usize.
let scalar = src.to_scalar();
Expand All @@ -258,12 +261,12 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {

// Then turn address into pointer.
let ptr = M::ptr_from_addr_cast(&self, addr)?;
Ok(Scalar::from_maybe_pointer(ptr, self).into())
Ok(ImmTy::from_scalar(Scalar::from_maybe_pointer(ptr, self), cast_to))
}

/// Low-level cast helper function. This works directly on scalars and can take 'int-like' input
/// type (basically everything with a scalar layout) to int/float/char types.
pub fn cast_from_int_like(
fn cast_from_int_like(
&self,
scalar: Scalar<M::Provenance>, // input value (there is no ScalarTy so we separate data+layout)
src_layout: TyAndLayout<'tcx>,
Expand Down Expand Up @@ -298,7 +301,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
}

// Casts to bool are not permitted by rustc, no need to handle them here.
_ => span_bug!(self.cur_span(), "invalid int to {:?} cast", cast_ty),
_ => span_bug!(self.cur_span(), "invalid int to {} cast", cast_ty),
})
}

Expand Down Expand Up @@ -331,7 +334,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
// float -> f64
Float(FloatTy::F64) => Scalar::from_f64(f.convert(&mut false).value),
// That's it.
_ => span_bug!(self.cur_span(), "invalid float to {:?} cast", dest_ty),
_ => span_bug!(self.cur_span(), "invalid float to {} cast", dest_ty),
}
}

Expand Down Expand Up @@ -389,7 +392,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {

span_bug!(
self.cur_span(),
"invalid pointer unsizing {:?} -> {:?}",
"invalid pointer unsizing {} -> {}",
src.layout.ty,
cast_ty
)
Expand All @@ -403,7 +406,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
cast_ty: TyAndLayout<'tcx>,
dest: &PlaceTy<'tcx, M::Provenance>,
) -> InterpResult<'tcx> {
trace!("Unsizing {:?} of type {} into {:?}", *src, src.layout.ty, cast_ty.ty);
trace!("Unsizing {:?} of type {} into {}", *src, src.layout.ty, cast_ty.ty);
match (&src.layout.ty.kind(), &cast_ty.ty.kind()) {
(&ty::Ref(_, s, _), &ty::Ref(_, c, _) | &ty::RawPtr(TypeAndMut { ty: c, .. }))
| (&ty::RawPtr(TypeAndMut { ty: s, .. }), &ty::RawPtr(TypeAndMut { ty: c, .. })) => {
Expand Down
13 changes: 6 additions & 7 deletions compiler/rustc_const_eval/src/interpret/discriminant.rs
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Expand Up @@ -76,7 +76,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
let niche_start_val = ImmTy::from_uint(niche_start, tag_layout);
let variant_index_relative_val =
ImmTy::from_uint(variant_index_relative, tag_layout);
let tag_val = self.binary_op(
let tag_val = self.wrapping_binary_op(
mir::BinOp::Add,
&variant_index_relative_val,
&niche_start_val,
Expand Down Expand Up @@ -153,19 +153,18 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
// Figure out which discriminant and variant this corresponds to.
let index = 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
let tag_bits = tag_val
.to_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);
let discr_val = self.int_to_int_or_float(&tag_val, discr_layout).unwrap();
let discr_bits = discr_val.to_scalar().assert_bits(discr_layout.size);
// Convert discriminant to variant index, and catch invalid discriminants.
let index = match *ty.kind() {
ty::Adt(adt, _) => {
Expand Down Expand Up @@ -208,7 +207,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
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)?;
self.wrapping_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.
Expand Down
6 changes: 3 additions & 3 deletions compiler/rustc_const_eval/src/interpret/eval_context.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -416,7 +416,7 @@ pub(super) fn from_known_layout<'tcx>(
if !mir_assign_valid_types(tcx.tcx, param_env, check_layout, known_layout) {
span_bug!(
tcx.span,
"expected type differs from actual type.\nexpected: {:?}\nactual: {:?}",
"expected type differs from actual type.\nexpected: {}\nactual: {}",
known_layout.ty,
check_layout.ty,
);
Expand Down Expand Up @@ -712,7 +712,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {

ty::Foreign(_) => Ok(None),

_ => span_bug!(self.cur_span(), "size_and_align_of::<{:?}> not supported", layout.ty),
_ => span_bug!(self.cur_span(), "size_and_align_of::<{}> not supported", layout.ty),
}
}
#[inline]
Expand Down Expand Up @@ -982,7 +982,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {

ty::Bound(..)
| ty::Infer(ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => {
bug!("`is_very_trivially_sized` applied to unexpected type: {:?}", ty)
bug!("`is_very_trivially_sized` applied to unexpected type: {}", ty)
}
}
}
Expand Down