memref

Memref is a memory reference type used in MLIR (Multi-Level Intermediate Representation) to model a region of memory that stores elements of a given type. A memref value encodes the element type, rank, and the extents of each dimension, and it may include dynamic dimensions indicated by a placeholder such as ?. The layout information, including strides and an optional offset, describes how elements are laid out in memory. The memory space qualifier, if present, specifies which memory resource owns the buffer.

Memref values are distinct from tensor values in MLIR: memrefs carry memory reference semantics, enabling allocation, deallocation, and in-place updates, while tensors are values without identity in memory.

Common operations in the Memref domain include allocation and deallocation (alloc and dealloc), element access via load and store, and viewing or sub-reference via subview, which creates a new memref that references a subset of the original memory. There are casting and reshaping operations to reinterpret memory without copying.

Memref is a central type in MLIR for representing function arguments and buffers used by optimizers and code generators. It provides a stable interface for analyses and transforms that operate on memory layouts, and it integrates with LLVM when lowering to the LLVM dialect. In practice, memref is used to implement multi-dimensional arrays in high-performance computing and numerical computing pipelines within the MLIR ecosystem.