mikros/rust
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

get rid of some remaining type-based dispatching in cast code

Browse Source
This commit is contained in:
Ralf Jung 2019-07-25 00:22:05 +02:00
parent 7885fac7e9
commit 144e5e99b5
1 changed files with 34 additions and 54 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

88
src/librustc_mir/interpret/cast.rs
View File

@ -7,7 +7,7 @@
use rustc_apfloat::ieee::{Single, Double};
use rustc_apfloat::{Float, FloatConvert};
use rustc::mir::interpret::{
Scalar, InterpResult, Pointer, PointerArithmetic,
Scalar, InterpResult, PointerArithmetic,
};
use rustc::mir::CastKind;
@ -111,32 +111,6 @@ fn cast_immediate(
)
}
// Handle casting the metadata away from a fat pointer.
if src.layout.ty.is_unsafe_ptr() && dest_layout.ty.is_unsafe_ptr() &&
dest_layout.size != src.layout.size
{
assert_eq!(src.layout.size, 2*self.memory.pointer_size());
assert_eq!(dest_layout.size, self.memory.pointer_size());
assert!(dest_layout.ty.is_unsafe_ptr());
return match *src {
Immediate::ScalarPair(data, _) => Ok(data.into()),
Immediate::Scalar(..) =>
bug!(
"{:?} input to a fat-to-thin cast ({:?} -> {:?})",
*src, src.layout.ty, dest_layout.ty
),
};
}
// Handle casting reference to raw ptr or raw to other raw (might be a fat ptr).
if (src.layout.ty.is_region_ptr() || src.layout.ty.is_unsafe_ptr()) &&
dest_layout.ty.is_unsafe_ptr()
{
// The only possible size-unequal case was handled above.
assert_eq!(src.layout.size, dest_layout.size);
return Ok(*src);
}
// Handle cast from a univariant (ZST) enum
match src.layout.variants {
layout::Variants::Single { index } => {
@ -150,12 +124,39 @@ fn cast_immediate(
layout::Variants::Multiple { .. } => {},
}
// Handle all the rest.
let val = src.to_scalar()?;
Ok(match val.to_bits_or_ptr(src.layout.size, self) {
Err(ptr) => self.cast_from_ptr(ptr, src.layout, dest_layout)?,
Ok(data) => self.cast_from_int(data, src.layout, dest_layout)?,
}.into())
// Handle casting the metadata away from a fat pointer.
if src.layout.ty.is_unsafe_ptr() && dest_layout.ty.is_unsafe_ptr() &&
dest_layout.size != src.layout.size
{
assert_eq!(src.layout.size, 2*self.memory.pointer_size());
assert_eq!(dest_layout.size, self.memory.pointer_size());
assert!(dest_layout.ty.is_unsafe_ptr());
match *src {
Immediate::ScalarPair(data, _) =>
return Ok(data.into()),
Immediate::Scalar(..) =>
bug!(
"{:?} input to a fat-to-thin cast ({:?} -> {:?})",
*src, src.layout.ty, dest_layout.ty
),
};
}
// Handle casting any ptr to raw ptr (might be a fat ptr).
if (src.layout.ty.is_region_ptr() || src.layout.ty.is_unsafe_ptr() || src.layout.ty.is_fn_ptr()) &&
dest_layout.ty.is_unsafe_ptr()
{
// The only possible size-unequal case was handled above.
assert_eq!(src.layout.size, dest_layout.size);
return Ok(*src);
}
// For all remaining casts, we either
// (a) cast a raw ptr to usize, or
// (b) cast from an integer-like (including bool, char, enums).
// In both cases we want the bits.
let bits = self.force_bits(src.to_scalar()?, src.layout.size)?;
Ok(self.cast_from_int(bits, src.layout, dest_layout)?.into())
}
fn cast_from_int(
@ -236,27 +237,6 @@ fn cast_from_float<F>(
}
}
fn cast_from_ptr(
&self,
ptr: Pointer<M::PointerTag>,
src_layout: TyLayout<'tcx>,
dest_layout: TyLayout<'tcx>,
) -> InterpResult<'tcx, Scalar<M::PointerTag>> {
use rustc::ty::TyKind::*;
match dest_layout.ty.sty {
// Casting to a reference or fn pointer is not permitted by rustc,
// no need to support it here.
RawPtr(_) => Ok(ptr.into()),
Int(_) | Uint(_) => {
let size = self.memory.pointer_size();
let bits = self.force_bits(Scalar::Ptr(ptr), size)?;
self.cast_from_int(bits, src_layout, dest_layout)
}
_ => bug!("invalid MIR: ptr to {:?} cast", dest_layout.ty)
}
}
fn unsize_into_ptr(
&mut self,
src: OpTy<'tcx, M::PointerTag>,