'dlti' Dialect

The Data Layout and Target Information (DLTI) dialect is intended to hold attributes and other components pertaining to descriptions of in-memory data layout and compilation targets.

Attributes ¶

DataLayoutEntryAttr ¶

An attribute to represent an entry of a data layout specification.

A data layout entry attribute is a key-value pair where the key is a type or an identifier and the value is another attribute. These entries form a data layout specification.

Parameters: ¶

DataLayoutSpecAttr ¶

An attribute to represent a data layout specification.

A data layout specification is a list of entries that specify (partial) data layout information. It is expected to be attached to operations that serve as scopes for data layout requests.

Parameters: ¶

MapAttr ¶

A mapping of DLTI-information by way of key-value pairs

Syntax:

#dlti.map<
  ::llvm::ArrayRef<DataLayoutEntryInterface>   # entries
>

A Data Layout and Target Information map is a list of entries effectively encoding a dictionary, mapping DLTI-related keys to DLTI-related values.

This attribute’s main purpose is to facilate querying IR for arbitrary key-value associations that encode DLTI. Facility functions exist to perform recursive lookups on nested DLTI-map/query interface-implementing attributes.

Consider the following flat encoding of a single-key dictionary

#dlti.map<#dlti.dl_entry<"CPU::cache::L1::size_in_bytes", 65536 : i32>>

versus nested maps, which make it possible to obtain sub-dictionaries of related information (with the following example making use of other attributes that also implement the DLTIQueryInterface):

#dlti.target_system_spec<"CPU":
  #dlti.target_device_spec<#dlti.dl_entry<"cache",
    #dlti.map<#dlti.dl_entry<"L1",
      #dlti.map<#dlti.dl_entry<"size_in_bytes", 65536 : i32>>>,
              #dlti.dl_entry<"L1d",
      #dlti.map<#dlti.dl_entry<"size_in_bytes", 32768 : i32>>> >>>>

With the flat encoding, the implied structure of the key is ignored, that is the only successful query (as expressed in the Transform Dialect) is: transform.dlti.query ["CPU::cache::L1::size_in_bytes"] at %op, where %op is a handle to an operation which associates the flat-encoding #dlti.map attribute.

For querying nested dictionaries, the relevant keys need to be separately provided. That is, if %op is an handle to an op which has the nesting #dlti.target_system_spec-attribute from above attached, then transform.dlti.query ["CPU","cache","L1","size_in_bytes"] at %op gives back the first leaf value contained. To access the other leaf, we need to do transform.dlti.query ["CPU","cache","L1d","size_in_bytes"] at %op.

#### Parameters:

| Parameter | C++ type | Description |
| :-------: | :-------: | ----------- |
| entries | `::llvm::ArrayRef<DataLayoutEntryInterface>` |  |

### TargetDeviceSpecAttr

An attribute to represent target device specification.

Syntax:

#dlti.target_device_spec< ::llvm::ArrayRef # entries

Each device specification describes a single device and its
hardware properties. Each device specification can contain any number
of optional hardware properties (e.g., max_vector_op_width below).

Example:

#dlti.target_device_spec< #dlti.dl_entry<“dlti.max_vector_op_width”, 64 : ui32»

#### Parameters:

| Parameter | C++ type | Description |
| :-------: | :-------: | ----------- |
| entries | `::llvm::ArrayRef<DataLayoutEntryInterface>` |  |

### TargetSystemSpecAttr

An attribute to represent target system specification.

Syntax:

#dlti.target_system_spec< ::llvm::ArrayRef # entries

A system specification describes the overall system containing
multiple devices, with each device having a unique ID (string)
and its corresponding TargetDeviceSpec object.

Example:

dlti.target_system_spec = #dlti.target_system_spec< “CPU”: #dlti.target_device_spec< #dlti.dl_entry<“dlti.L1_cache_size_in_bytes”, 4096: ui32», “GPU”: #dlti.target_device_spec< #dlti.dl_entry<“dlti.max_vector_op_width”, 64 : ui32», “XPU”: #dlti.target_device_spec< #dlti.dl_entry<“dlti.max_vector_op_width”, 4096 : ui32»>

#### Parameters:

| Parameter | C++ type | Description |
| :-------: | :-------: | ----------- |
| entries | `::llvm::ArrayRef<DeviceIDTargetDeviceSpecPair>` |  |