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Remove misc_cast and validate types when casting #103122

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Oct 25, 2022
Merged

Remove misc_cast and validate types when casting #103122

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63 changes: 43 additions & 20 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 @@ -42,10 +42,22 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
let res = self.pointer_from_exposed_address_cast(&src, cast_ty)?;
self.write_immediate(res, dest)?;
}
// FIXME: We shouldn't use `misc_cast` for these but handle them separately.
IntToInt | FloatToInt | FloatToFloat | IntToFloat | FnPtrToPtr | PtrToPtr => {

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

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

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

Expand Down Expand Up @@ -126,13 +138,27 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
Ok(())
}

pub fn misc_cast(
pub fn int_to_int_or_float(
&mut self,
src: &ImmTy<'tcx, M::Provenance>,
cast_ty: Ty<'tcx>,
) -> InterpResult<'tcx, Immediate<M::Provenance>> {
if (src.layout.ty.is_integral() || src.layout.ty.is_char() || src.layout.ty.is_bool())
&& (cast_ty.is_floating_point() || cast_ty.is_integral() || cast_ty.is_char())
{
let scalar = src.to_scalar();
Ok(self.cast_from_int_like(scalar, src.layout, cast_ty)?.into())
} else {
bug!("Unexpected cast from type {:?}", src.layout.ty)
}
}

pub fn float_to_float_or_int(
&mut self,
src: &ImmTy<'tcx, M::Provenance>,
cast_ty: Ty<'tcx>,
) -> InterpResult<'tcx, Immediate<M::Provenance>> {
use rustc_type_ir::sty::TyKind::*;
trace!("Casting {:?}: {:?} to {:?}", *src, src.layout.ty, cast_ty);

match src.layout.ty.kind() {
// Floating point
Expand All @@ -142,19 +168,18 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
Float(FloatTy::F64) => {
return Ok(self.cast_from_float(src.to_scalar().to_f64()?, cast_ty).into());
}
// The rest is integer/pointer-"like", including fn ptr casts
_ => assert!(
src.layout.ty.is_bool()
|| src.layout.ty.is_char()
|| src.layout.ty.is_integral()
|| src.layout.ty.is_any_ptr(),
"Unexpected cast from type {:?}",
src.layout.ty
),
_ => {
bug!("Can't cast 'Float' type into {:?}", cast_ty);
}
}
}

// # First handle non-scalar source values.

/// Handles 'FnPtrToPtr' and 'PtrToPtr' casts.
pub fn ptr_to_ptr(
&mut self,
src: &ImmTy<'tcx, M::Provenance>,
cast_ty: Ty<'tcx>,
) -> InterpResult<'tcx, Immediate<M::Provenance>> {
// Handle casting any ptr to raw ptr (might be a fat ptr).
if src.layout.ty.is_any_ptr() && cast_ty.is_unsafe_ptr() {
let dest_layout = self.layout_of(cast_ty)?;
Expand All @@ -178,11 +203,9 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
Immediate::Uninit => throw_ub!(InvalidUninitBytes(None)),
};
}
} else {
bug!("Can't cast 'Ptr' or 'FnPtr' into {:?}", cast_ty);
}

// # The remaining source values are scalar and "int-like".
let scalar = src.to_scalar();
Ok(self.cast_from_int_like(scalar, src.layout, cast_ty)?.into())
}

pub fn pointer_expose_address_cast(
Expand Down
25 changes: 20 additions & 5 deletions compiler/rustc_const_eval/src/transform/validate.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -556,21 +556,36 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
check_kinds!(a, "Cannot shallow init type {:?}", ty::RawPtr(..));
}
Rvalue::Cast(kind, operand, target_type) => {
let op_ty = operand.ty(self.body, self.tcx);
match kind {
CastKind::DynStar => {
// FIXME(dyn-star): make sure nothing needs to be done here.
}
// Nothing to check here
// FIXME: Add Checks for these
CastKind::PointerFromExposedAddress
| CastKind::PointerExposeAddress
| CastKind::Pointer(_) => {}
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_ => {
let op_ty = operand.ty(self.body, self.tcx);
if op_ty.is_enum() {
CastKind::IntToInt | CastKind::IntToFloat => {
let input_valid = op_ty.is_integral() || op_ty.is_char() || op_ty.is_bool();
let target_valid = target_type.is_numeric() || target_type.is_char();
if !input_valid || !target_valid {
self.fail(
location,
format!("Wrong cast kind {kind:?} for the type {op_ty}",),
);
}
}
CastKind::FnPtrToPtr | CastKind::PtrToPtr => {
if !(op_ty.is_any_ptr() && target_type.is_unsafe_ptr()) {
self.fail(location, "Can't cast {op_ty} into 'Ptr'");
}
}
CastKind::FloatToFloat | CastKind::FloatToInt => {
if !op_ty.is_floating_point() || !target_type.is_numeric() {
self.fail(
location,
format!(
"enum -> int casts should go through `Rvalue::Discriminant`: {operand:?}:{op_ty} as {target_type}",
"Trying to cast non 'Float' as {kind:?} into {target_type:?}"
),
);
}
Expand Down
6 changes: 3 additions & 3 deletions src/tools/miri/src/shims/intrinsics/simd.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -437,13 +437,13 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
let val = match (op.layout.ty.kind(), dest.layout.ty.kind()) {
// Int-to-(int|float): always safe
(ty::Int(_) | ty::Uint(_), ty::Int(_) | ty::Uint(_) | ty::Float(_)) =>
this.misc_cast(&op, dest.layout.ty)?,
this.int_to_int_or_float(&op, dest.layout.ty)?,
// Float-to-float: always safe
(ty::Float(_), ty::Float(_)) =>
this.misc_cast(&op, dest.layout.ty)?,
this.float_to_float_or_int(&op, dest.layout.ty)?,
// Float-to-int in safe mode
(ty::Float(_), ty::Int(_) | ty::Uint(_)) if safe_cast =>
this.misc_cast(&op, dest.layout.ty)?,
this.float_to_float_or_int(&op, dest.layout.ty)?,
// Float-to-int in unchecked mode
(ty::Float(FloatTy::F32), ty::Int(_) | ty::Uint(_)) if !safe_cast =>
this.float_to_int_unchecked(op.to_scalar().to_f32()?, dest.layout.ty)?.into(),
Expand Down