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Move the const casting code into its dedicated file
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@oli-obk
oli-obk committed Jul 18, 2018
1 parent fb5b268 commit 1f4e210
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Showing 2 changed files with 145 additions and 131 deletions.
146 changes: 143 additions & 3 deletions src/librustc_mir/interpret/cast.rs
View file
Original file line number Diff line number Diff line change
@@ -1,13 +1,153 @@
use rustc::ty::Ty;
use rustc::ty::layout::LayoutOf;
use rustc::ty::{self, Ty};
use rustc::ty::layout::{self, LayoutOf};
use syntax::ast::{FloatTy, IntTy, UintTy};

use rustc_apfloat::ieee::{Single, Double};
use super::{EvalContext, Machine};
use rustc::mir::interpret::{Scalar, EvalResult, Pointer, PointerArithmetic};
use rustc::mir::interpret::{Scalar, EvalResult, Pointer, PointerArithmetic, Value, EvalErrorKind};
use rustc::mir::CastKind;
use rustc_apfloat::Float;
use interpret::eval_context::ValTy;
use interpret::Place;

impl<'a, 'mir, 'tcx, M: Machine<'mir, 'tcx>> EvalContext<'a, 'mir, 'tcx, M> {
crate fn cast(
&mut self,
src: ValTy<'tcx>,
kind: CastKind,
dest_ty: Ty<'tcx>,
dest: Place,
) -> EvalResult<'tcx> {
use rustc::mir::CastKind::*;
match kind {
Unsize => {
let src_layout = self.layout_of(src.ty)?;
let dst_layout = self.layout_of(dest_ty)?;
self.unsize_into(src.value, src_layout, dest, dst_layout)?;
}

Misc => {
if self.type_is_fat_ptr(src.ty) {
match (src.value, self.type_is_fat_ptr(dest_ty)) {
(Value::ByRef { .. }, _) |
// pointers to extern types
(Value::Scalar(_),_) |
// slices and trait objects to other slices/trait objects
(Value::ScalarPair(..), true) => {
let valty = ValTy {
value: src.value,
ty: dest_ty,
};
self.write_value(valty, dest)?;
}
// slices and trait objects to thin pointers (dropping the metadata)
(Value::ScalarPair(data, _), false) => {
let valty = ValTy {
value: Value::Scalar(data),
ty: dest_ty,
};
self.write_value(valty, dest)?;
}
}
} else {
let src_layout = self.layout_of(src.ty)?;
match src_layout.variants {
layout::Variants::Single { index } => {
if let Some(def) = src.ty.ty_adt_def() {
let discr_val = def
.discriminant_for_variant(*self.tcx, index)
.val;
let defined = self
.layout_of(dest_ty)
.unwrap()
.size
.bits() as u8;
return self.write_scalar(
dest,
Scalar::Bits {
bits: discr_val,
defined,
},
dest_ty);
}
}
layout::Variants::Tagged { .. } |
layout::Variants::NicheFilling { .. } => {},
}

let src_val = self.value_to_scalar(src)?;
let dest_val = self.cast_scalar(src_val, src.ty, dest_ty)?;
let valty = ValTy {
value: Value::Scalar(dest_val),
ty: dest_ty,
};
self.write_value(valty, dest)?;
}
}

ReifyFnPointer => {
match src.ty.sty {
ty::TyFnDef(def_id, substs) => {
if self.tcx.has_attr(def_id, "rustc_args_required_const") {
bug!("reifying a fn ptr that requires \
const arguments");
}
let instance: EvalResult<'tcx, _> = ty::Instance::resolve(
*self.tcx,
self.param_env,
def_id,
substs,
).ok_or_else(|| EvalErrorKind::TooGeneric.into());
let fn_ptr = self.memory.create_fn_alloc(instance?);
let valty = ValTy {
value: Value::Scalar(fn_ptr.into()),
ty: dest_ty,
};
self.write_value(valty, dest)?;
}
ref other => bug!("reify fn pointer on {:?}", other),
}
}

UnsafeFnPointer => {
match dest_ty.sty {
ty::TyFnPtr(_) => {
let mut src = src;
src.ty = dest_ty;
self.write_value(src, dest)?;
}
ref other => bug!("fn to unsafe fn cast on {:?}", other),
}
}

ClosureFnPointer => {
match src.ty.sty {
ty::TyClosure(def_id, substs) => {
let substs = self.tcx.subst_and_normalize_erasing_regions(
self.substs(),
ty::ParamEnv::reveal_all(),
&substs,
);
let instance = ty::Instance::resolve_closure(
*self.tcx,
def_id,
substs,
ty::ClosureKind::FnOnce,
);
let fn_ptr = self.memory.create_fn_alloc(instance);
let valty = ValTy {
value: Value::Scalar(fn_ptr.into()),
ty: dest_ty,
};
self.write_value(valty, dest)?;
}
ref other => bug!("closure fn pointer on {:?}", other),
}
}
}
Ok(())
}

pub(super) fn cast_scalar(
&self,
val: Scalar,
Expand Down
130 changes: 2 additions & 128 deletions src/librustc_mir/interpret/eval_context.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -770,134 +770,8 @@ impl<'a, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> EvalContext<'a, 'mir, 'tcx, M

Cast(kind, ref operand, cast_ty) => {
debug_assert_eq!(self.monomorphize(cast_ty, self.substs()), dest_ty);
use rustc::mir::CastKind::*;
let src = self.eval_operand(operand)?;
match kind {
Unsize => {
let src_layout = self.layout_of(src.ty)?;
let dst_layout = self.layout_of(dest_ty)?;
self.unsize_into(src.value, src_layout, dest, dst_layout)?;
}

Misc => {
if self.type_is_fat_ptr(src.ty) {
match (src.value, self.type_is_fat_ptr(dest_ty)) {
(Value::ByRef { .. }, _) |
// pointers to extern types
(Value::Scalar(_),_) |
// slices and trait objects to other slices/trait objects
(Value::ScalarPair(..), true) => {
let valty = ValTy {
value: src.value,
ty: dest_ty,
};
self.write_value(valty, dest)?;
}
// slices and trait objects to thin pointers (dropping the metadata)
(Value::ScalarPair(data, _), false) => {
let valty = ValTy {
value: Value::Scalar(data),
ty: dest_ty,
};
self.write_value(valty, dest)?;
}
}
} else {
let src_layout = self.layout_of(src.ty)?;
match src_layout.variants {
layout::Variants::Single { index } => {
if let Some(def) = src.ty.ty_adt_def() {
let discr_val = def
.discriminant_for_variant(*self.tcx, index)
.val;
let defined = self
.layout_of(dest_ty)
.unwrap()
.size
.bits() as u8;
return self.write_scalar(
dest,
Scalar::Bits {
bits: discr_val,
defined,
},
dest_ty);
}
}
layout::Variants::Tagged { .. } |
layout::Variants::NicheFilling { .. } => {},
}

let src_val = self.value_to_scalar(src)?;
let dest_val = self.cast_scalar(src_val, src.ty, dest_ty)?;
let valty = ValTy {
value: Value::Scalar(dest_val),
ty: dest_ty,
};
self.write_value(valty, dest)?;
}
}

ReifyFnPointer => {
match src.ty.sty {
ty::TyFnDef(def_id, substs) => {
if self.tcx.has_attr(def_id, "rustc_args_required_const") {
bug!("reifying a fn ptr that requires \
const arguments");
}
let instance: EvalResult<'tcx, _> = ty::Instance::resolve(
*self.tcx,
self.param_env,
def_id,
substs,
).ok_or_else(|| EvalErrorKind::TooGeneric.into());
let fn_ptr = self.memory.create_fn_alloc(instance?);
let valty = ValTy {
value: Value::Scalar(fn_ptr.into()),
ty: dest_ty,
};
self.write_value(valty, dest)?;
}
ref other => bug!("reify fn pointer on {:?}", other),
}
}

UnsafeFnPointer => {
match dest_ty.sty {
ty::TyFnPtr(_) => {
let mut src = src;
src.ty = dest_ty;
self.write_value(src, dest)?;
}
ref other => bug!("fn to unsafe fn cast on {:?}", other),
}
}

ClosureFnPointer => {
match src.ty.sty {
ty::TyClosure(def_id, substs) => {
let substs = self.tcx.subst_and_normalize_erasing_regions(
self.substs(),
ty::ParamEnv::reveal_all(),
&substs,
);
let instance = ty::Instance::resolve_closure(
*self.tcx,
def_id,
substs,
ty::ClosureKind::FnOnce,
);
let fn_ptr = self.memory.create_fn_alloc(instance);
let valty = ValTy {
value: Value::Scalar(fn_ptr.into()),
ty: dest_ty,
};
self.write_value(valty, dest)?;
}
ref other => bug!("closure fn pointer on {:?}", other),
}
}
}
self.cast(src, kind, dest_ty, dest)?;
}

Discriminant(ref place) => {
Expand Down Expand Up @@ -1564,7 +1438,7 @@ impl<'a, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> EvalContext<'a, 'mir, 'tcx, M
}
}

fn unsize_into(
crate fn unsize_into(
&mut self,
src: Value,
src_layout: TyLayout<'tcx>,
Expand Down

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