nordic-dev.net/rust
nordic-dev.net/rust
2
0
Fork 0
mirror of https://github.com/rust-lang/rust.git synced 2024-12-11 16:15:03 +00:00
Code Issues Packages Projects Releases Wiki Activity

erase the tag on casts involving (raw) pointers

Browse Source
This commit is contained in:
Ralf Jung 2018-11-17 09:08:30 +01:00
parent e4d03f82b5
commit a7b312f825
1 changed files with 13 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
src/librustc_mir/interpret/cast.rs
View File

@ -44,16 +44,22 @@ impl<'a, 'mir, 'tcx, M: Machine<'a, 'mir, 'tcx>> EvalContext<'a, 'mir, 'tcx, M>
}
Misc => {
let src_layout = src.layout;
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)) {
// There are no casts to references
assert!(!dest.layout.ty.is_region_ptr());
// Hence we make all casts erase the tag
let src = src.erase_tag().with_default_tag();
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)?;
self.write_immediate(src, dest)?;
}
// slices and trait objects to thin pointers (dropping the metadata)
(Immediate::ScalarPair(data, _), false) => {
@ -61,11 +67,11 @@ impl<'a, 'mir, 'tcx, M: Machine<'a, 'mir, 'tcx>> EvalContext<'a, 'mir, 'tcx, M>
}
}
} else {
match src.layout.variants {
match src_layout.variants {
layout::Variants::Single { index } => {
if let Some(def) = src.layout.ty.ty_adt_def() {
if let Some(def) = src_layout.ty.ty_adt_def() {
// Cast from a univariant enum
assert!(src.layout.is_zst());
assert!(src_layout.is_zst());
let discr_val = def
.discriminant_for_variant(*self.tcx, index)
.val;
@ -78,7 +84,7 @@ impl<'a, 'mir, 'tcx, M: Machine<'a, 'mir, 'tcx>> EvalContext<'a, 'mir, 'tcx, M>
layout::Variants::NicheFilling { .. } => {},
}
let dest_val = self.cast_scalar(src.to_scalar()?, src.layout, dest.layout)?;
let dest_val = self.cast_scalar(src.to_scalar()?, src_layout, dest.layout)?;
self.write_scalar(dest_val, dest)?;
}
}