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Add allocate_bytes and refactor allocate_str in InterpCx for raw byte allocation

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Signed-off-by: shamb0 <r.raajey@gmail.com>
This commit is contained in:
shamb0 2024-12-04 21:09:50 +05:30
parent cdb89d6b15
commit 9b07e75055
1 changed files with 33 additions and 14 deletions
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47
compiler/rustc_const_eval/src/interpret/place.rs
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@ -1018,29 +1018,48 @@ where
self.allocate_dyn(layout, kind, MemPlaceMeta::None)
}
/// Returns a wide MPlace of type `str` to a new 1-aligned allocation.
/// Immutable strings are deduplicated and stored in global memory.
/// Allocates a sequence of bytes in the interpreter's memory.
/// For immutable allocations, uses deduplication to reuse existing memory.
/// For mutable allocations, creates a new unique allocation.
pub fn allocate_bytes(
&mut self,
bytes: &[u8],
align: Align,
kind: MemoryKind<M::MemoryKind>,
mutbl: Mutability,
) -> InterpResult<'tcx, Pointer<M::Provenance>> {
// Use cache for immutable strings.
if mutbl.is_not() {
// Use dedup'd allocation function.
let salt = M::get_global_alloc_salt(self, None);
let id = self.tcx.allocate_bytes_dedup(bytes, salt);
// Turn untagged "global" pointers (obtained via `tcx`) into the machine pointer to the allocation.
M::adjust_alloc_root_pointer(&self, Pointer::from(id), Some(kind))
} else {
// Allocate new memory for mutable data.
self.allocate_bytes_ptr(bytes, align, kind, mutbl)
}
}
/// Allocates a string in the interpreter's memory with metadata for length.
/// Uses `allocate_bytes` internally but adds string-specific metadata handling.
pub fn allocate_str(
&mut self,
str: &str,
kind: MemoryKind<M::MemoryKind>,
mutbl: Mutability,
) -> InterpResult<'tcx, MPlaceTy<'tcx, M::Provenance>> {
let tcx = self.tcx.tcx;
let bytes = str.as_bytes();
let ptr = self.allocate_bytes(bytes, Align::ONE, kind, mutbl)?;
// Use cache for immutable strings.
let ptr = if mutbl.is_not() {
// Use dedup'd allocation function.
let salt = M::get_global_alloc_salt(self, None);
let id = tcx.allocate_bytes_dedup(str.as_bytes(), salt);
// Create length metadata for the string.
let meta = Scalar::from_target_usize(u64::try_from(bytes.len()).unwrap(), self);
// Turn untagged "global" pointers (obtained via `tcx`) into the machine pointer to the allocation.
M::adjust_alloc_root_pointer(&self, Pointer::from(id), Some(kind))?
} else {
self.allocate_bytes_ptr(str.as_bytes(), Align::ONE, kind, mutbl)?
};
let meta = Scalar::from_target_usize(u64::try_from(str.len()).unwrap(), self);
// Get layout for Rust's str type.
let layout = self.layout_of(self.tcx.types.str_).unwrap();
// Combine pointer and metadata into a wide pointer.
interp_ok(self.ptr_with_meta_to_mplace(
ptr.into(),
MemPlaceMeta::Meta(meta),