Module borrow_array 

Codegen for prelude borrow array operations.

A borrow_array<n, T> is lowered to a fat pointer {ptr, mask_ptr, usize} that is allocated to at least n * sizeof(T) bytes. The second pointer is a bit-packed mask storing which array elements have been borrowed (1=borrowed, 0=available). It should be allocated to at least ceil(n / sizeof(usize)) * sizeof(usize) bytes. The extra usize is an offset pointing to the first element, i.e. the first element is at address ptr + offset * sizeof(T).

The rationale behind the additional offset is the pop_left operation which bumps the offset instead of mutating the pointer. This way, we can still free the original pointer when the array is discarded after a pop.

We provide utility functions barray_fat_pointer_ty, build_barray_fat_pointer, and decompose_barray_fat_pointer to work with borrow-array fat pointers.

The DefaultBorrowArrayCodegen extension allocates all arrays on the heap using the standard libc malloc and free functions. This behaviour can be customised by providing a different implementation for BorrowArrayCodegen::emit_allocate_array and BorrowArrayCodegen::emit_free_array.

Structs

BArrayFatPtrComponents

BorrowArrayCodegenExtension

DefaultBorrowArrayCodegen

A trivial implementation of BorrowArrayCodegen which passes all methods through to their default implementations.

Traits

BorrowArrayCodegen

A helper trait for customising the lowering of borrow_array, including its types, hugr_core::ops::constant::CustomConsts, and ops.

Functions

barray_fat_pointer_ty

Returns the LLVM representation of a borrow array value as a fat pointer.

build_all_borrowed_check

Emits a check that all array elements have been borrowed.

build_barray_alloc

Helper function to allocate a fat borrow array pointer.

build_barray_fat_pointer

Constructs a borrow array fat pointer value.

build_bounds_check

Emits a check that a specified (unsigned) index is less than the size of the array

build_is_borrowed_bit

Emits a check that returns whether a specific array element is borrowed (true) or not (false).

build_none_borrowed_check

Emits a check that no array elements have been borrowed.

decompose_barray_fat_pointer

Returns the underlying pointer, mask and offset stored in a fat borrow array pointer.

emit_barray_discard

Emits an BArrayDiscard op.

emit_barray_op

Emits an BArrayOp.

emit_barray_unsafe_op

Emits an BArrayUnsafeOp.

emit_barray_value

Emits an borrow_array::BArrayValue.

emit_clone_op

Emits an BArrayClone op.

emit_from_array_op

Emits an BArrayFromArray op.

emit_repeat_op

Emits an BArrayRepeat op.

emit_scan_op

Emits an BArrayScan op.

emit_to_array_op

Emits an BArrayToArray op.