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turn cast_immediate into its own function

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This commit is contained in:
Ralf Jung 2019-07-24 19:01:12 +02:00
parent 48b87c6f27
commit ec1e71895a
2 changed files with 54 additions and 35 deletions
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75
src/librustc_mir/interpret/cast.rs
View File

@ -11,7 +11,7 @@ use rustc::mir::interpret::{
};
use rustc::mir::CastKind;
use super::{InterpCx, Machine, PlaceTy, OpTy, Immediate, FnVal};
use super::{InterpCx, Machine, PlaceTy, OpTy, ImmTy, Immediate, FnVal};
impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
fn type_is_fat_ptr(&self, ty: Ty<'tcx>) -> bool {
@ -37,40 +37,8 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
Misc | Pointer(PointerCast::MutToConstPointer) => {
let src = self.read_immediate(src)?;
if self.type_is_fat_ptr(src.layout.ty) {
match (*src, self.type_is_fat_ptr(dest.layout.ty)) {
// pointers to extern types
(Immediate::Scalar(_),_) |
// slices and trait objects to other slices/trait objects
(Immediate::ScalarPair(..), true) => {
// No change to immediate
self.write_immediate(*src, dest)?;
}
// slices and trait objects to thin pointers (dropping the metadata)
(Immediate::ScalarPair(data, _), false) => {
self.write_scalar(data, dest)?;
}
}
} else {
match src.layout.variants {
layout::Variants::Single { index } => {
if let Some(discr) =
src.layout.ty.discriminant_for_variant(*self.tcx, index)
{
// Cast from a univariant enum
assert!(src.layout.is_zst());
return self.write_scalar(
Scalar::from_uint(discr.val, dest.layout.size),
dest);
}
}
layout::Variants::Multiple { .. } => {},
}
let dest_val = self.cast_scalar(src.to_scalar()?, src.layout, dest.layout)?;
self.write_scalar(dest_val, dest)?;
}
let res = self.cast_immediate(src, dest.layout)?;
self.write_immediate(res, dest)?;
}
Pointer(PointerCast::ReifyFnPointer) => {
@ -126,6 +94,43 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
Ok(())
}
fn cast_immediate(
&self,
src: ImmTy<'tcx, M::PointerTag>,
dest_layout: TyLayout<'tcx>,
) -> InterpResult<'tcx, Immediate<M::PointerTag>> {
if self.type_is_fat_ptr(src.layout.ty) {
return match (*src, self.type_is_fat_ptr(dest_layout.ty)) {
// pointers to extern types
(Immediate::Scalar(_),_) |
// slices and trait objects to other slices/trait objects
(Immediate::ScalarPair(..), true) => {
// No change to immediate
Ok(*src)
}
// slices and trait objects to thin pointers (dropping the metadata)
(Immediate::ScalarPair(data, _), false) => {
Ok(data.into())
}
};
} else {
match src.layout.variants {
layout::Variants::Single { index } => {
if let Some(discr) =
src.layout.ty.discriminant_for_variant(*self.tcx, index)
{
// Cast from a univariant enum
assert!(src.layout.is_zst());
return Ok(Scalar::from_uint(discr.val, dest_layout.size).into());
}
}
layout::Variants::Multiple { .. } => {},
}
return Ok(self.cast_scalar(src.to_scalar()?, src.layout, dest_layout)?.into());
}
}
fn cast_scalar(
&self,
val: Scalar<M::PointerTag>,

14
src/librustc_mir/interpret/operand.rs
View File

@ -32,6 +32,20 @@ pub enum Immediate<Tag=(), Id=AllocId> {
ScalarPair(ScalarMaybeUndef<Tag, Id>, ScalarMaybeUndef<Tag, Id>),
}
impl<Tag> From<ScalarMaybeUndef<Tag>> for Immediate<Tag> {
#[inline(always)]
fn from(val: ScalarMaybeUndef<Tag>) -> Self {
Immediate::Scalar(val)
}
}
impl<Tag> From<Scalar<Tag>> for Immediate<Tag> {
#[inline(always)]
fn from(val: Scalar<Tag>) -> Self {
Immediate::Scalar(val.into())
}
}
impl<'tcx, Tag> Immediate<Tag> {
#[inline]
pub fn from_scalar(val: Scalar<Tag>) -> Self {