'esi' Dialect

The Elastic Silicon Interconnect dialect aims to aid in accelerator system construction.

WARNING: The ESI dialect has evolved significantly since its inception while these documents have not. As such, large parts are significantly out-of-date.

Application channels

The main component of ESI are point-to-point, typed channels that allow designers to connect modules to each other and software, then communicate by sending messages. Channels largely abstract away the details of message communication from the designer, though the designer can declaratively specify how to implement the channel.

Messages have types: ints, structs, arrays, unions, and variable-length lists. The width of a channel is not necessarily the same width as the message. ESI “windows” can be used to break up a message into a series of “frames”. IP blocks can emit / absorb “windowed” messages or full-sized messages, which can be automatically broken up to save wire area at the cost of bandwidth.

Any channel which is exposed to the host will have a platform-agnostic software API constructed for it based on the type of the channel. The software application merely has to connect to the accelerator then invoke a method to send or receive messages from the accelerator system.

ChannelBundleType

a bundle of channels

Syntax:

!esi.bundle<
  ::llvm::ArrayRef<BundledChannel>,   # channels
  ::mlir::UnitAttr   # resettable
>

A channel bundle (sometimes referred to as just “bundle”) is a set of channels of associated signals, along with per-channel names and directions. The prototypical example for a bundle is a request-response channel pair.

The direction terminology is a bit confusing. Let us designate the module which is outputting the bundle as the “sender” module and a module which has a bundle as an input as the “receiver”. The directions “from” and “to” are from the senders perspective. So, the “to” direction means that channel is transmitting messages from the sender to the receiver. Then, “from” means that the sender is getting messages from the receiver (typically responses).

When requesting a bundle from a service, the service is always considered the sender; so, “to” means the service is sending messages to the client and “from” means the service is receiving messages from the client.

Parameters:

ChannelType

An ESI-compatible channel port

Syntax:

!esi.channel<
  Type,   # inner
  ::circt::esi::ChannelSignaling,   # signaling
  uint64_t   # dataDelay
>

An ESI port kind which models a latency-insensitive, unidirectional, point-to-point data stream. Channels are typed (like all of ESI). Said type can be any MLIR type, but must be lowered to something a backend knows how to output (i.e. something emitVerilog knows about).

Parameters: signaling: the style of the control signals (valid/ready vs FIFO). dataDelay: the number of cycles data takes to arrive after the control indicates a transaction has occured. For instance, on a FIFO without read ahead, this would be 1. Defaults to 0.

Example:

hw.module.extern @Sender() -> (%x: !esi.channel<i1>)
hw.module @Reciever(%a: !esi.channel<hw.array<5xi16>>) { }

Parameters:

ClockType

A type for clock-carrying wires

Syntax: !seq.clock

The !seq.clock type represents signals which can be used to drive the clock input of sequential operations.

ListType

a runtime-variably sized list

Syntax:

!esi.list<
  Type   # elementType
>

In software, a chunk of memory with runtime-specified length. In hardware, a stream of runtime-specified amount of data transmitted over many cycles in compile-time specified specified windows (chunks).

Parameters:

WindowType

a data window

Syntax:

!esi.window<
  StringAttr,   # name
  mlir::Type,   # into
  ::llvm::ArrayRef<WindowFrameType>   # frames
>

A ‘data window’ allows designers to break up large messages into multiple frames (aka phits) spread across multiple cycles. Windows are specified in terms of a mapping of struct fields to frames. The width of a window is the maximum frame size + the union tag (log2(#frames)).

A data window does NOT imply an ESI channel.

Current restrictions:

• A field may only appear once.
• Fields may only be re-ordered (wrt the original message) within a frame.
• Array fields whose array length is not evenly divisible by ’numItems’ will have an implicit frame inserted directly after containing the leftover array items.
• Array fields with an array length MUST be in their own frame.

Parameters:

FirMemType

A FIRRTL-flavored memory

Syntax:

!seq.firmem<
  uint64_t,   # depth
  uint32_t,   # width
  std::optional<uint32_t>   # maskWidth
>

The !seq.firmem type represents a FIRRTL-flavored memory declared by a seq.firmem operation. It captures the parameters of the memory that are relevant to the read, write, and read-write ports, such as width and depth.

Parameters:

HLMemType

Multi-dimensional memory type

Syntax:

hlmem-type ::== `hlmem` `<` dim-list element-type `>`

The HLMemType represents the type of an addressable memory structure. The type is inherently multidimensional. Dimensions must be known integer values.

Note: unidimensional memories are represented as <1x{element type}> - <{element type}> is illegal.

Parameters:

ImmutableType

Value type that is immutable after initialization

Syntax:

!seq.immutable<
  ::mlir::Type   # innerType
>

Parameters:

WindowFieldType

a field-in-frame specifier

Syntax:

!esi.window.field<
  StringAttr,   # fieldName
  uint64_t   # numItems
>

Specify that a field should appear within the enclosing frame.

Parameters:

WindowFrameType

Declare a data window frame

Syntax:

!esi.window.frame<
  StringAttr,   # name
  ::llvm::ArrayRef<WindowFieldType>   # members
>

A named list of fields which should appear in a given frame.

Parameters:

ListType

a runtime-variably sized list

Syntax:

!esi.list<
  Type   # elementType
>

In software, a chunk of memory with runtime-specified length. In hardware, a stream of runtime-specified amount of data transmitted over many cycles in compile-time specified specified windows (chunks).

Parameters:

esi.buffer (::circt::esi::ChannelBufferOp)

Control options for an ESI channel.

A channel buffer (buffer) is essentially a set of options on a channel. It always adds at least one cycle of latency (pipeline stage) to the channel, but this is configurable.

This operation is inserted on an ESI dataflow edge. It must exist previous to SystemVerilog emission but can be added in a lowering pass.

A stages attribute may be provided to specify a specific number of cycles (pipeline stages) to use on this channel. Must be greater than 0.

A name attribute may be provided to assigned a name to a buffered connection.

Example:

%esiChan = hw.instance "sender" @Sender () : () -> (!esi.channel<i1>)
// Allow automatic selection of options.
%bufferedChan = esi.buffer %esiChan : i1
hw.instance "recv" @Reciever (%bufferedChan) : (!esi.channel<i1>) -> ()

// Alternatively, specify the number of stages.
%fourStageBufferedChan = esi.buffer %esiChan { stages = 4 } : i1

Traits: AlwaysSpeculatableImplTrait

Interfaces: ChannelOpInterface, ConditionallySpeculatable, NoMemoryEffect (MemoryEffectOpInterface)

Effects: MemoryEffects::Effect{}

Attributes:

Operands:

Results:

esi.cosim.from_host (::circt::esi::CosimFromHostEndpointOp)

Co-simulation endpoint receiving data from the host

Syntax:

operation ::= `esi.cosim.from_host` $clk `,` $rst `,` $id attr-dict `:` qualified(type($fromHost))

A co-simulation endpoint is a connection from the simulation to some outside process, usually a software application responsible for driving the simulation (driver).

It is uni-directional, in this case receiving data from the host for the simulation.

NOTE: $id MUST be unique across all endpoints at simulation runtime.

Attributes:

Operands:

Results:

esi.cosim.to_host (::circt::esi::CosimToHostEndpointOp)

Co-simulation endpoint sending data to the host.

Syntax:

operation ::= `esi.cosim.to_host` $clk `,` $rst `,` $toHost`,` $id attr-dict `:` qualified(type($toHost))

A co-simulation endpoint is a connection from the simulation to some outside process, usually a software application responsible for driving the simulation (driver).

It is uni-directional, in this case sending data from the simulation to the host.

NOTE: $id MUST be unique across all endpoints at simulation runtime.

Attributes:

Operands:

esi.fifo (::circt::esi::FIFOOp)

A FIFO with ESI channel connections

Syntax:

operation ::= `esi.fifo` `in` $input `clk` $clk `rst` $rst `depth` $depth attr-dict
              `:` type($input) `->` type($output)

A FIFO is a first-in-first-out buffer. This operation is a simple FIFO which can be used to connect two ESI channels. The ESI channels MUST have FIFO signaling semantics.

Attributes:

Operands:

Results:

esi.null (::circt::esi::NullSourceOp)

An op which never produces messages.

Syntax:

operation ::= `esi.null` attr-dict `:` qualified(type($out))

Traits: AlwaysSpeculatableImplTrait

Interfaces: ConditionallySpeculatable, NoMemoryEffect (MemoryEffectOpInterface)

Effects: MemoryEffects::Effect{}

Results:

esi.bundle.pack (::circt::esi::PackBundleOp)

Pack channels into a bundle

Syntax:

operation ::= `esi.bundle.pack` $toChannels attr-dict `:` custom<UnPackBundleType>(
              type($toChannels), type($fromChannels), type($bundle))

Interfaces: OpAsmOpInterface

Operands:

Results:

esi.stage (::circt::esi::PipelineStageOp)

An elastic buffer stage.

An individual elastic pipeline register. Generally lowered to from a ChannelBuffer (‘buffer’), though can be inserted anywhere to add an additional pipeline stage. Adding individually could be useful for late-pass latency balancing.

Traits: AlwaysSpeculatableImplTrait

Interfaces: ChannelOpInterface, ConditionallySpeculatable, NoMemoryEffect (MemoryEffectOpInterface)

Effects: MemoryEffects::Effect{}

Operands:

Results:

esi.bundle.unpack (::circt::esi::UnpackBundleOp)

Unpack channels from a bundle

Syntax:

operation ::= `esi.bundle.unpack` $fromChannels `from` $bundle attr-dict `:` custom<UnPackBundleType>(
              type($toChannels), type($fromChannels), type($bundle))

Interfaces: OpAsmOpInterface

Operands:

Results:

esi.unwrap.fifo (::circt::esi::UnwrapFIFOOp)

Unwrap a value from an ESI port into a FIFO interface

Syntax:

operation ::= `esi.unwrap.fifo` $chanInput `,` $rden attr-dict `:` qualified(type($chanInput))

Interfaces: ChannelOpInterface, InferTypeOpInterface

Operands:

Results:

esi.unwrap.iface (::circt::esi::UnwrapSVInterfaceOp)

Unwrap an SV interface from an ESI port

Syntax:

operation ::= `esi.unwrap.iface` $chanInput `into` $interfaceSource attr-dict `:` `(` qualified(type($chanInput)) `,` qualified(type($interfaceSource)) `)`

Unwrap an ESI channel into a SystemVerilog interface containing valid, ready, and data signals.

Interfaces: ChannelOpInterface

Operands:

esi.unwrap.vr (::circt::esi::UnwrapValidReadyOp)

Unwrap a value from an ESI port

Unwrapping a value allows operations on the contained value. Unwrap the channel along with a ready signal that you generate. Result is the data along with a valid signal.

Interfaces: ChannelOpInterface

Operands:

Results:

esi.window.unwrap (::circt::esi::UnwrapWindow)

Unwrap a data window into a union

Syntax:

operation ::= `esi.window.unwrap` $window attr-dict `:` qualified(type($window))

Traits: AlwaysSpeculatableImplTrait

Interfaces: ConditionallySpeculatable, InferTypeOpInterface, NoMemoryEffect (MemoryEffectOpInterface)

Effects: MemoryEffects::Effect{}

Operands:

Results:

esi.wrap.fifo (::circt::esi::WrapFIFOOp)

Wrap a value into an ESI port with FIFO signaling

Syntax:

operation ::= `esi.wrap.fifo` $data `,` $empty attr-dict `:`
              custom<WrapFIFOType>(type($data), type($chanOutput))

Interfaces: ChannelOpInterface

Operands:

Results:

esi.wrap.iface (::circt::esi::WrapSVInterfaceOp)

Wrap an SV interface into an ESI port

Syntax:

operation ::= `esi.wrap.iface` $interfaceSink attr-dict `:` qualified(type($interfaceSink)) `->` qualified(type($output))

Wrap a SystemVerilog interface into an ESI channel. Interface MUST look like an interface produced by ESI meaning it MUST contain valid, ready, and data signals. Any other signals will be discarded.

Interfaces: ChannelOpInterface

Operands:

Results:

esi.wrap.vr (::circt::esi::WrapValidReadyOp)

Wrap a value into an ESI port

Wrapping a value into an ESI port type allows modules to send values down an ESI port. Wrap data with valid bit, result is the ESI channel and the ready signal from the other end of the channel.

Interfaces: ChannelOpInterface

Operands:

Results:

esi.window.wrap (::circt::esi::WrapWindow)

Wrap a union into a data window

Syntax:

operation ::= `esi.window.wrap` $frame attr-dict `:` custom<InferWindowRet>(type($frame), type($window))

Traits: AlwaysSpeculatableImplTrait

Interfaces: ConditionallySpeculatable, NoMemoryEffect (MemoryEffectOpInterface)

Effects: MemoryEffects::Effect{}

Operands:

Results:

Services

ESI “services” provide device-wide connectivity and arbitration for shared resources, which can be requested from any IP block (service “client”). Standard services will include DRAM, clock/reset, statistical counter reporting, and debug.

esi.manifest.hier_node (::circt::esi::AppIDHierNodeOp)

A node in the AppID hierarchy

Syntax:

operation ::= `esi.manifest.hier_node` qualified($appID) `mod` $moduleRef attr-dict-with-keyword $children

Traits: HasParent<circt::esi::AppIDHierRootOp, circt::esi::AppIDHierNodeOp>, NoTerminator, SingleBlock

Attributes:

esi.manifest.hier_root (::circt::esi::AppIDHierRootOp)

The root of an appid instance hierarchy

Syntax:

operation ::= `esi.manifest.hier_root` $topModuleRef attr-dict-with-keyword $children

Traits: HasParent<mlir::ModuleOp>, NoTerminator, SingleBlock

Attributes:

esi.buffer (::circt::esi::ChannelBufferOp)

Control options for an ESI channel.

A channel buffer (buffer) is essentially a set of options on a channel. It always adds at least one cycle of latency (pipeline stage) to the channel, but this is configurable.

This operation is inserted on an ESI dataflow edge. It must exist previous to SystemVerilog emission but can be added in a lowering pass.

A stages attribute may be provided to specify a specific number of cycles (pipeline stages) to use on this channel. Must be greater than 0.

A name attribute may be provided to assigned a name to a buffered connection.

Example:

%esiChan = hw.instance "sender" @Sender () : () -> (!esi.channel<i1>)
// Allow automatic selection of options.
%bufferedChan = esi.buffer %esiChan : i1
hw.instance "recv" @Reciever (%bufferedChan) : (!esi.channel<i1>) -> ()

// Alternatively, specify the number of stages.
%fourStageBufferedChan = esi.buffer %esiChan { stages = 4 } : i1

Traits: AlwaysSpeculatableImplTrait

Interfaces: ChannelOpInterface, ConditionallySpeculatable, NoMemoryEffect (MemoryEffectOpInterface)

Effects: MemoryEffects::Effect{}

Attributes:

Operands:

Results:

esi.manifest.compressed (::circt::esi::CompressedManifestOp)

A zlib-compressed JSON manifest

Syntax:

operation ::= `esi.manifest.compressed` $compressedManifest attr-dict

Attributes:

esi.cosim.from_host (::circt::esi::CosimFromHostEndpointOp)

Co-simulation endpoint receiving data from the host

Syntax:

operation ::= `esi.cosim.from_host` $clk `,` $rst `,` $id attr-dict `:` qualified(type($fromHost))

A co-simulation endpoint is a connection from the simulation to some outside process, usually a software application responsible for driving the simulation (driver).

It is uni-directional, in this case receiving data from the host for the simulation.

NOTE: $id MUST be unique across all endpoints at simulation runtime.

Attributes:

Operands:

Results:

esi.cosim.to_host (::circt::esi::CosimToHostEndpointOp)

Co-simulation endpoint sending data to the host.

Syntax:

operation ::= `esi.cosim.to_host` $clk `,` $rst `,` $toHost`,` $id attr-dict `:` qualified(type($toHost))

A co-simulation endpoint is a connection from the simulation to some outside process, usually a software application responsible for driving the simulation (driver).

It is uni-directional, in this case sending data from the simulation to the host.

NOTE: $id MUST be unique across all endpoints at simulation runtime.

Attributes:

Operands:

esi.service.decl (::circt::esi::CustomServiceDeclOp)

An ESI service interface declaration

Syntax:

operation ::= `esi.service.decl` $sym_name $ports attr-dict

A declaration of an ESI service interface. Defines a contract between a service provider and its clients.

Example:

esi.service.decl @HostComms {
  esi.service.port send : !esi.bundle<[!esi.any from "send"]>
  esi.service.port recieve : !esi.channel<[i8 to "recv"]>
}

Traits: HasParent<::mlir::ModuleOp>, NoTerminator, SingleBlock

Interfaces: ServiceDeclOpInterface, Symbol

Attributes:

esi.fifo (::circt::esi::FIFOOp)

A FIFO with ESI channel connections

Syntax:

operation ::= `esi.fifo` `in` $input `clk` $clk `rst` $rst `depth` $depth attr-dict
              `:` type($input) `->` type($output)

A FIFO is a first-in-first-out buffer. This operation is a simple FIFO which can be used to connect two ESI channels. The ESI channels MUST have FIFO signaling semantics.

Attributes:

Operands:

Results:

esi.null (::circt::esi::NullSourceOp)

An op which never produces messages.

Syntax:

operation ::= `esi.null` attr-dict `:` qualified(type($out))

Traits: AlwaysSpeculatableImplTrait

Interfaces: ConditionallySpeculatable, NoMemoryEffect (MemoryEffectOpInterface)

Effects: MemoryEffects::Effect{}

Results:

esi.bundle.pack (::circt::esi::PackBundleOp)

Pack channels into a bundle

Syntax:

operation ::= `esi.bundle.pack` $toChannels attr-dict `:` custom<UnPackBundleType>(
              type($toChannels), type($fromChannels), type($bundle))

Interfaces: OpAsmOpInterface

Operands:

Results:

esi.stage (::circt::esi::PipelineStageOp)

An elastic buffer stage.

An individual elastic pipeline register. Generally lowered to from a ChannelBuffer (‘buffer’), though can be inserted anywhere to add an additional pipeline stage. Adding individually could be useful for late-pass latency balancing.

Traits: AlwaysSpeculatableImplTrait

Interfaces: ChannelOpInterface, ConditionallySpeculatable, NoMemoryEffect (MemoryEffectOpInterface)

Effects: MemoryEffects::Effect{}

Operands:

Results:

esi.service.req (::circt::esi::RequestConnectionOp)

Request a connection to receive data

Syntax:

operation ::= `esi.service.req` $servicePort `(` qualified($appID) `)`
              attr-dict `:` qualified(type($toClient))

Interfaces: HasAppID, SymbolUserOpInterface

Attributes:

Results:

esi.service.port (::circt::esi::ServiceDeclPortOp)

An ESI service bundle being received by the client

Syntax:

operation ::= `esi.service.port` $inner_sym  attr-dict `:` $toClientType

Traits: HasParent<::circt::esi::CustomServiceDeclOp>

Attributes:

esi.manifest.impl_conn (::circt::esi::ServiceImplClientRecordOp)

Details of a service implementation client connection

Syntax:

operation ::= `esi.manifest.impl_conn` $relAppIDPath `req` $servicePort `(` $typeID `)`
              (`channels` $channelAssignments^)? (`with` $implDetails^)? attr-dict

A record containing all the necessary details of how to connect to a client which the parent service record is servicing. Emitted on a per-client bundle basis. There shall be at most on of these records in the entire manifest for a particular client.

Traits: HasParent<ServiceImplRecordOp>

Interfaces: IsManifestData

Attributes:

esi.manifest.service_impl (::circt::esi::ServiceImplRecordOp)

Record of a service implementation

Syntax:

operation ::= `esi.manifest.service_impl` qualified($appID) (`svc` $service^)? (`std` $stdService^)?
              `by` $serviceImplName `with` $implDetails
              attr-dict-with-keyword custom<ServiceImplRecordReqDetails>($reqDetails)

A record of a service implementation. Optionally emitted by the service implementation. Contains information necessary to connect to the service and service clients.

Traits: NoTerminator

Interfaces: HasAppID, IsManifestData

Attributes:

esi.service.impl_req.req (::circt::esi::ServiceImplementConnReqOp)

The canonical form of a connection request

Syntax:

operation ::= `esi.service.impl_req.req` $servicePort `(` $relativeAppIDPath `)`
              attr-dict `:` qualified(type($toClient))

Interfaces: SymbolUserOpInterface

Attributes:

Results:

esi.service.impl_req (::circt::esi::ServiceImplementReqOp)

Request for a service to be implemented

Syntax:

operation ::= `esi.service.impl_req` qualified($appID) (`svc` $service_symbol^)? `impl` `as` $impl_type
              (`std` $stdService^)? (`opts` $impl_opts^)? `(` $inputs `)`
              attr-dict `:` functional-type($inputs, results)
              $portReqs

The connect services pass replaces service.instances with this op. The portReqs region is the set of connection requests which need to be implemented for this service instance. Channels to/from the requests have been added to the operands/results of this op and consumers/producers have been redirected.

Some other pass or frontend is expected to replace this op with an actual implementation.

Traits: NoTerminator

Interfaces: HasAppID

Attributes:

Operands:

Results:

esi.service.instance (::circt::esi::ServiceInstanceOp)

Instantiate a server module

Syntax:

operation ::= `esi.service.instance` qualified($appID) (`svc` $service_symbol^)? `impl` `as` $impl_type
              (`opts` $impl_opts^)? `(` $inputs `)`
              attr-dict `:` functional-type($inputs, results)

Instantiate a service adhering to a service declaration interface.

A pass collects all of the connection requests to the service this op implements from the containing modules’ descendants (in the instance hierarchy). It bubbles them all up to the module containing this op, creating the necessary ESI channel ports, groups them appropriately, then replaces this op with a service.impl_req.

If ‘service_symbol’ isn’t specified, this instance will be used to implement all of the service requests which get surfaced to here. This option is generally used at the top level to specify host connectivity.

Since implementing the server will usually need “normal” I/O, inputs and results act like normal hw.instance ports.

$identifier is used by frontends to specify or remember the type of implementation to use for this service.

Interfaces: HasAppID

Attributes:

Operands:

Results:

esi.manifest.req (::circt::esi::ServiceRequestRecordOp)

Record of a service request

Syntax:

operation ::= `esi.manifest.req` qualified($requestor) `,` $servicePort (`std` $stdService^)?
              `,` $typeID attr-dict

A record of a service request, including the requestor, the service requested, and the parameters of the request. Emitted before connecting the service to preserve metadata about the original request.

Interfaces: HasAppID, IsManifestData

Attributes:

esi.manifest.constants (::circt::esi::SymbolConstantsOp)

Constant values associated with a symbol

Syntax:

operation ::= `esi.manifest.constants` $symbolRef $constants attr-dict

Interfaces: IsManifestData

Attributes:

esi.manifest.sym (::circt::esi::SymbolMetadataOp)

Metadata about a symbol

Syntax:

operation ::= `esi.manifest.sym` $symbolRef
              (`name` $name^)?
              (`repo` $repo^)?
              (`commit` $commitHash^)?
              (`version` $version^)?
              (`summary` $summary^)?
              attr-dict

Metadata about a symbol, including its name, repository, commit hash, version, and summary. All are optional, but strongly encouraged. Any additional metadata which users wish to attach should go as discardable attributes.

Interfaces: IsManifestData

Attributes:

esi.bundle.unpack (::circt::esi::UnpackBundleOp)

Unpack channels from a bundle

Syntax:

operation ::= `esi.bundle.unpack` $fromChannels `from` $bundle attr-dict `:` custom<UnPackBundleType>(
              type($toChannels), type($fromChannels), type($bundle))

Interfaces: OpAsmOpInterface

Operands:

Results:

esi.unwrap.fifo (::circt::esi::UnwrapFIFOOp)

Unwrap a value from an ESI port into a FIFO interface

Syntax:

operation ::= `esi.unwrap.fifo` $chanInput `,` $rden attr-dict `:` qualified(type($chanInput))

Interfaces: ChannelOpInterface, InferTypeOpInterface

Operands:

Results:

esi.unwrap.iface (::circt::esi::UnwrapSVInterfaceOp)

Unwrap an SV interface from an ESI port

Syntax:

operation ::= `esi.unwrap.iface` $chanInput `into` $interfaceSource attr-dict `:` `(` qualified(type($chanInput)) `,` qualified(type($interfaceSource)) `)`

Unwrap an ESI channel into a SystemVerilog interface containing valid, ready, and data signals.

Interfaces: ChannelOpInterface

Operands:

esi.unwrap.vr (::circt::esi::UnwrapValidReadyOp)

Unwrap a value from an ESI port

Unwrapping a value allows operations on the contained value. Unwrap the channel along with a ready signal that you generate. Result is the data along with a valid signal.

Interfaces: ChannelOpInterface

Operands:

Results:

esi.window.unwrap (::circt::esi::UnwrapWindow)

Unwrap a data window into a union

Syntax:

operation ::= `esi.window.unwrap` $window attr-dict `:` qualified(type($window))

Traits: AlwaysSpeculatableImplTrait

Interfaces: ConditionallySpeculatable, InferTypeOpInterface, NoMemoryEffect (MemoryEffectOpInterface)

Effects: MemoryEffects::Effect{}

Operands:

Results:

esi.wrap.fifo (::circt::esi::WrapFIFOOp)

Wrap a value into an ESI port with FIFO signaling

Syntax:

operation ::= `esi.wrap.fifo` $data `,` $empty attr-dict `:`
              custom<WrapFIFOType>(type($data), type($chanOutput))

Interfaces: ChannelOpInterface

Operands:

Results:

esi.wrap.iface (::circt::esi::WrapSVInterfaceOp)

Wrap an SV interface into an ESI port

Syntax:

operation ::= `esi.wrap.iface` $interfaceSink attr-dict `:` qualified(type($interfaceSink)) `->` qualified(type($output))

Wrap a SystemVerilog interface into an ESI channel. Interface MUST look like an interface produced by ESI meaning it MUST contain valid, ready, and data signals. Any other signals will be discarded.

Interfaces: ChannelOpInterface

Operands:

Results:

esi.wrap.vr (::circt::esi::WrapValidReadyOp)

Wrap a value into an ESI port

Wrapping a value into an ESI port type allows modules to send values down an ESI port. Wrap data with valid bit, result is the ESI channel and the ready signal from the other end of the channel.

Interfaces: ChannelOpInterface

Operands:

Results:

esi.window.wrap (::circt::esi::WrapWindow)

Wrap a union into a data window

Syntax:

operation ::= `esi.window.wrap` $frame attr-dict `:` custom<InferWindowRet>(type($frame), type($window))

Traits: AlwaysSpeculatableImplTrait

Interfaces: ConditionallySpeculatable, NoMemoryEffect (MemoryEffectOpInterface)

Effects: MemoryEffects::Effect{}

Operands:

Results:

esi.manifest.hier_node (::circt::esi::AppIDHierNodeOp)

A node in the AppID hierarchy

Syntax:

operation ::= `esi.manifest.hier_node` qualified($appID) `mod` $moduleRef attr-dict-with-keyword $children

Traits: HasParent<circt::esi::AppIDHierRootOp, circt::esi::AppIDHierNodeOp>, NoTerminator, SingleBlock

Attributes:

esi.manifest.hier_root (::circt::esi::AppIDHierRootOp)

The root of an appid instance hierarchy

Syntax:

operation ::= `esi.manifest.hier_root` $topModuleRef attr-dict-with-keyword $children

Traits: HasParent<mlir::ModuleOp>, NoTerminator, SingleBlock

Attributes:

esi.service.std.call (::circt::esi::CallServiceDeclOp)

Service against which hardware can call into software

Syntax:

operation ::= `esi.service.std.call` $sym_name attr-dict

Traits: HasParent<::mlir::ModuleOp>, NoTerminator, SingleBlock

Interfaces: ServiceDeclOpInterface, Symbol

Attributes:

esi.buffer (::circt::esi::ChannelBufferOp)

Control options for an ESI channel.

A channel buffer (buffer) is essentially a set of options on a channel. It always adds at least one cycle of latency (pipeline stage) to the channel, but this is configurable.

This operation is inserted on an ESI dataflow edge. It must exist previous to SystemVerilog emission but can be added in a lowering pass.

A stages attribute may be provided to specify a specific number of cycles (pipeline stages) to use on this channel. Must be greater than 0.

A name attribute may be provided to assigned a name to a buffered connection.

Example:

%esiChan = hw.instance "sender" @Sender () : () -> (!esi.channel<i1>)
// Allow automatic selection of options.
%bufferedChan = esi.buffer %esiChan : i1
hw.instance "recv" @Reciever (%bufferedChan) : (!esi.channel<i1>) -> ()

// Alternatively, specify the number of stages.
%fourStageBufferedChan = esi.buffer %esiChan { stages = 4 } : i1

Traits: AlwaysSpeculatableImplTrait

Interfaces: ChannelOpInterface, ConditionallySpeculatable, NoMemoryEffect (MemoryEffectOpInterface)

Effects: MemoryEffects::Effect{}

Attributes:

Operands:

Results:

esi.manifest.compressed (::circt::esi::CompressedManifestOp)

A zlib-compressed JSON manifest

Syntax:

operation ::= `esi.manifest.compressed` $compressedManifest attr-dict

Attributes:

esi.cosim.from_host (::circt::esi::CosimFromHostEndpointOp)

Co-simulation endpoint receiving data from the host

Syntax:

operation ::= `esi.cosim.from_host` $clk `,` $rst `,` $id attr-dict `:` qualified(type($fromHost))

A co-simulation endpoint is a connection from the simulation to some outside process, usually a software application responsible for driving the simulation (driver).

It is uni-directional, in this case receiving data from the host for the simulation.

NOTE: $id MUST be unique across all endpoints at simulation runtime.

Attributes:

Operands:

Results:

esi.cosim.to_host (::circt::esi::CosimToHostEndpointOp)

Co-simulation endpoint sending data to the host.

Syntax:

operation ::= `esi.cosim.to_host` $clk `,` $rst `,` $toHost`,` $id attr-dict `:` qualified(type($toHost))

A co-simulation endpoint is a connection from the simulation to some outside process, usually a software application responsible for driving the simulation (driver).

It is uni-directional, in this case sending data from the simulation to the host.

NOTE: $id MUST be unique across all endpoints at simulation runtime.

Attributes:

Operands:

esi.service.decl (::circt::esi::CustomServiceDeclOp)

An ESI service interface declaration

Syntax:

operation ::= `esi.service.decl` $sym_name $ports attr-dict

A declaration of an ESI service interface. Defines a contract between a service provider and its clients.

Example:

esi.service.decl @HostComms {
  esi.service.port send : !esi.bundle<[!esi.any from "send"]>
  esi.service.port recieve : !esi.channel<[i8 to "recv"]>
}

Traits: HasParent<::mlir::ModuleOp>, NoTerminator, SingleBlock

Interfaces: ServiceDeclOpInterface, Symbol

Attributes:

esi.fifo (::circt::esi::FIFOOp)

A FIFO with ESI channel connections

Syntax:

operation ::= `esi.fifo` `in` $input `clk` $clk `rst` $rst `depth` $depth attr-dict
              `:` type($input) `->` type($output)

A FIFO is a first-in-first-out buffer. This operation is a simple FIFO which can be used to connect two ESI channels. The ESI channels MUST have FIFO signaling semantics.

Attributes:

Operands:

Results:

esi.service.std.func (::circt::esi::FuncServiceDeclOp)

Function service

Syntax:

operation ::= `esi.service.std.func` $sym_name attr-dict

Declares a service which provides a function call interface to a client.

Ports: to_client call(args: any) -> result: any Client exposes a function call interface to the user and does not allow out-of-order returns.

TODO: ports for out-of-order returns

Traits: HasParent<::mlir::ModuleOp>, NoTerminator, SingleBlock

Interfaces: ServiceDeclOpInterface, Symbol

Attributes:

esi.service.std.hostmem (::circt::esi::HostMemServiceDeclOp)

Host memory service

Syntax:

operation ::= `esi.service.std.hostmem` $sym_name attr-dict

Declares a service to read/write host memory. Used for DMA services. Must be implemented by a BSP.

Traits: HasParent<::mlir::ModuleOp>

Interfaces: ServiceDeclOpInterface, Symbol

Attributes:

esi.service.std.mmio (::circt::esi::MMIOServiceDeclOp)

MMIO service

Syntax:

operation ::= `esi.service.std.mmio` $sym_name attr-dict

Declares a service to be backed by a MMIO interface, which is platform dependent. Must be implemented by a BSP.

Traits: HasParent<::mlir::ModuleOp>

Interfaces: ServiceDeclOpInterface, Symbol

Attributes:

esi.null (::circt::esi::NullSourceOp)

An op which never produces messages.

Syntax:

operation ::= `esi.null` attr-dict `:` qualified(type($out))

Traits: AlwaysSpeculatableImplTrait

Interfaces: ConditionallySpeculatable, NoMemoryEffect (MemoryEffectOpInterface)

Effects: MemoryEffects::Effect{}

Results:

esi.bundle.pack (::circt::esi::PackBundleOp)

Pack channels into a bundle

Syntax:

operation ::= `esi.bundle.pack` $toChannels attr-dict `:` custom<UnPackBundleType>(
              type($toChannels), type($fromChannels), type($bundle))

Interfaces: OpAsmOpInterface

Operands:

Results:

esi.stage (::circt::esi::PipelineStageOp)

An elastic buffer stage.

An individual elastic pipeline register. Generally lowered to from a ChannelBuffer (‘buffer’), though can be inserted anywhere to add an additional pipeline stage. Adding individually could be useful for late-pass latency balancing.

Traits: AlwaysSpeculatableImplTrait

Interfaces: ChannelOpInterface, ConditionallySpeculatable, NoMemoryEffect (MemoryEffectOpInterface)

Effects: MemoryEffects::Effect{}

Operands:

Results:

esi.mem.ram (::circt::esi::RandomAccessMemoryDeclOp)

Random access memory service

Syntax:

operation ::= `esi.mem.ram` $sym_name $innerType `x` $depth attr-dict

Declares a service which is backed by a memory of some sort. Allows random access of the inner elements.

Ports: read(address: clog2(depth)) -> data: innerType write({address: clog2(depth), data: innerType}) -> done: i0

Users can ensure R/W ordering by waiting for the write “done” message before issuing a potentially dependant read. Ordering of R/W messages in flight is undefined.

Traits: HasParent<::mlir::ModuleOp>, NoTerminator, SingleBlock

Interfaces: ServiceDeclOpInterface, Symbol

Attributes:

esi.service.req (::circt::esi::RequestConnectionOp)

Request a connection to receive data

Syntax:

operation ::= `esi.service.req` $servicePort `(` qualified($appID) `)`
              attr-dict `:` qualified(type($toClient))

Interfaces: HasAppID, SymbolUserOpInterface

Attributes:

Results:

esi.service.port (::circt::esi::ServiceDeclPortOp)

An ESI service bundle being received by the client

Syntax:

operation ::= `esi.service.port` $inner_sym  attr-dict `:` $toClientType

Traits: HasParent<::circt::esi::CustomServiceDeclOp>

Attributes:

esi.manifest.impl_conn (::circt::esi::ServiceImplClientRecordOp)

Details of a service implementation client connection

Syntax:

operation ::= `esi.manifest.impl_conn` $relAppIDPath `req` $servicePort `(` $typeID `)`
              (`channels` $channelAssignments^)? (`with` $implDetails^)? attr-dict

A record containing all the necessary details of how to connect to a client which the parent service record is servicing. Emitted on a per-client bundle basis. There shall be at most on of these records in the entire manifest for a particular client.

Traits: HasParent<ServiceImplRecordOp>

Interfaces: IsManifestData

Attributes:

esi.manifest.service_impl (::circt::esi::ServiceImplRecordOp)

Record of a service implementation

Syntax:

operation ::= `esi.manifest.service_impl` qualified($appID) (`svc` $service^)? (`std` $stdService^)?
              `by` $serviceImplName `with` $implDetails
              attr-dict-with-keyword custom<ServiceImplRecordReqDetails>($reqDetails)

A record of a service implementation. Optionally emitted by the service implementation. Contains information necessary to connect to the service and service clients.

Traits: NoTerminator

Interfaces: HasAppID, IsManifestData

Attributes:

esi.service.impl_req.req (::circt::esi::ServiceImplementConnReqOp)

The canonical form of a connection request

Syntax:

operation ::= `esi.service.impl_req.req` $servicePort `(` $relativeAppIDPath `)`
              attr-dict `:` qualified(type($toClient))

Interfaces: SymbolUserOpInterface

Attributes:

Results:

esi.service.impl_req (::circt::esi::ServiceImplementReqOp)

Request for a service to be implemented

Syntax:

operation ::= `esi.service.impl_req` qualified($appID) (`svc` $service_symbol^)? `impl` `as` $impl_type
              (`std` $stdService^)? (`opts` $impl_opts^)? `(` $inputs `)`
              attr-dict `:` functional-type($inputs, results)
              $portReqs

The connect services pass replaces service.instances with this op. The portReqs region is the set of connection requests which need to be implemented for this service instance. Channels to/from the requests have been added to the operands/results of this op and consumers/producers have been redirected.

Some other pass or frontend is expected to replace this op with an actual implementation.

Traits: NoTerminator

Interfaces: HasAppID

Attributes:

Operands:

Results:

esi.service.instance (::circt::esi::ServiceInstanceOp)

Instantiate a server module

Syntax:

operation ::= `esi.service.instance` qualified($appID) (`svc` $service_symbol^)? `impl` `as` $impl_type
              (`opts` $impl_opts^)? `(` $inputs `)`
              attr-dict `:` functional-type($inputs, results)

Instantiate a service adhering to a service declaration interface.

A pass collects all of the connection requests to the service this op implements from the containing modules’ descendants (in the instance hierarchy). It bubbles them all up to the module containing this op, creating the necessary ESI channel ports, groups them appropriately, then replaces this op with a service.impl_req.

If ‘service_symbol’ isn’t specified, this instance will be used to implement all of the service requests which get surfaced to here. This option is generally used at the top level to specify host connectivity.

Since implementing the server will usually need “normal” I/O, inputs and results act like normal hw.instance ports.

$identifier is used by frontends to specify or remember the type of implementation to use for this service.

Interfaces: HasAppID

Attributes:

Operands:

Results:

esi.manifest.req (::circt::esi::ServiceRequestRecordOp)

Record of a service request

Syntax:

operation ::= `esi.manifest.req` qualified($requestor) `,` $servicePort (`std` $stdService^)?
              `,` $typeID attr-dict

A record of a service request, including the requestor, the service requested, and the parameters of the request. Emitted before connecting the service to preserve metadata about the original request.

Interfaces: HasAppID, IsManifestData

Attributes:

esi.manifest.constants (::circt::esi::SymbolConstantsOp)

Constant values associated with a symbol

Syntax:

operation ::= `esi.manifest.constants` $symbolRef $constants attr-dict

Interfaces: IsManifestData

Attributes:

esi.manifest.sym (::circt::esi::SymbolMetadataOp)

Metadata about a symbol

Syntax:

operation ::= `esi.manifest.sym` $symbolRef
              (`name` $name^)?
              (`repo` $repo^)?
              (`commit` $commitHash^)?
              (`version` $version^)?
              (`summary` $summary^)?
              attr-dict

Metadata about a symbol, including its name, repository, commit hash, version, and summary. All are optional, but strongly encouraged. Any additional metadata which users wish to attach should go as discardable attributes.

Interfaces: IsManifestData

Attributes:

esi.bundle.unpack (::circt::esi::UnpackBundleOp)

Unpack channels from a bundle

Syntax:

operation ::= `esi.bundle.unpack` $fromChannels `from` $bundle attr-dict `:` custom<UnPackBundleType>(
              type($toChannels), type($fromChannels), type($bundle))

Interfaces: OpAsmOpInterface

Operands:

Results:

esi.unwrap.fifo (::circt::esi::UnwrapFIFOOp)

Unwrap a value from an ESI port into a FIFO interface

Syntax:

operation ::= `esi.unwrap.fifo` $chanInput `,` $rden attr-dict `:` qualified(type($chanInput))

Interfaces: ChannelOpInterface, InferTypeOpInterface

Operands:

Results:

esi.unwrap.iface (::circt::esi::UnwrapSVInterfaceOp)

Unwrap an SV interface from an ESI port

Syntax:

operation ::= `esi.unwrap.iface` $chanInput `into` $interfaceSource attr-dict `:` `(` qualified(type($chanInput)) `,` qualified(type($interfaceSource)) `)`

Unwrap an ESI channel into a SystemVerilog interface containing valid, ready, and data signals.

Interfaces: ChannelOpInterface

Operands:

esi.unwrap.vr (::circt::esi::UnwrapValidReadyOp)

Unwrap a value from an ESI port

Unwrapping a value allows operations on the contained value. Unwrap the channel along with a ready signal that you generate. Result is the data along with a valid signal.

Interfaces: ChannelOpInterface

Operands:

Results:

esi.window.unwrap (::circt::esi::UnwrapWindow)

Unwrap a data window into a union

Syntax:

operation ::= `esi.window.unwrap` $window attr-dict `:` qualified(type($window))

Traits: AlwaysSpeculatableImplTrait

Interfaces: ConditionallySpeculatable, InferTypeOpInterface, NoMemoryEffect (MemoryEffectOpInterface)

Effects: MemoryEffects::Effect{}

Operands:

Results:

esi.wrap.fifo (::circt::esi::WrapFIFOOp)

Wrap a value into an ESI port with FIFO signaling

Syntax:

operation ::= `esi.wrap.fifo` $data `,` $empty attr-dict `:`
              custom<WrapFIFOType>(type($data), type($chanOutput))

Interfaces: ChannelOpInterface

Operands:

Results:

esi.wrap.iface (::circt::esi::WrapSVInterfaceOp)

Wrap an SV interface into an ESI port

Syntax:

operation ::= `esi.wrap.iface` $interfaceSink attr-dict `:` qualified(type($interfaceSink)) `->` qualified(type($output))

Wrap a SystemVerilog interface into an ESI channel. Interface MUST look like an interface produced by ESI meaning it MUST contain valid, ready, and data signals. Any other signals will be discarded.

Interfaces: ChannelOpInterface

Operands:

Results:

esi.wrap.vr (::circt::esi::WrapValidReadyOp)

Wrap a value into an ESI port

Wrapping a value into an ESI port type allows modules to send values down an ESI port. Wrap data with valid bit, result is the ESI channel and the ready signal from the other end of the channel.

Interfaces: ChannelOpInterface

Operands:

Results:

esi.window.wrap (::circt::esi::WrapWindow)

Wrap a union into a data window

Syntax:

operation ::= `esi.window.wrap` $frame attr-dict `:` custom<InferWindowRet>(type($frame), type($window))

Traits: AlwaysSpeculatableImplTrait

Interfaces: ConditionallySpeculatable, NoMemoryEffect (MemoryEffectOpInterface)

Effects: MemoryEffects::Effect{}

Operands:

Results:

Structural

ESI has a special module which doesn’t expose ports. All external interactions are expected to be done through services.

esi.pure_module.input (::circt::esi::ESIPureModuleInputOp)

Inputs become input ports when the module is lowered

Syntax:

operation ::= `esi.pure_module.input` $name attr-dict `:` type($value)

To create input ports when lowering a pure module op into an HWModuleOp, use this op. This op is typically created by a service implementation generator.

If two ‘input’ ops exist in the same block, the names match, and the type matches they’ll become one port during lowering. Two or more may not exist with the same name and different types. Useful for ‘clk’ and ‘rst’.

Traits: HasParent<ESIPureModuleOp>

Attributes:

Results:

esi.pure_module (::circt::esi::ESIPureModuleOp)

ESI pure module

Syntax:

operation ::= `esi.pure_module` $sym_name attr-dict-with-keyword $body

A module containing only ESI channels and modules with only ESI ports. All non-local connectivity is done through ESI services. If this module is the top level in the design, then the design’s actual top level ports are defined by a BSP.

Useful on its own for simulation and BSPs which don’t define a top-level.

Traits: HasParent<mlir::ModuleOp>, NoRegionArguments, NoTerminator, SingleBlock

Interfaces: HWModuleLike, InstanceGraphModuleOpInterface, PortList, RegionKindInterface, Symbol

Attributes:

esi.pure_module.output (::circt::esi::ESIPureModuleOutputOp)

Outputs become output ports when the module is lowered

Syntax:

operation ::= `esi.pure_module.output` $name `,` $value attr-dict `:` type($value)

To create output ports when lowering a pure module op into an HWModuleOp, use this op. This op is typically created by a service implementation generator.

Two ‘output’ ops with the same name cannot exist in the same block.

Traits: HasParent<ESIPureModuleOp>

Attributes:

Operands:

esi.pure_module.param (::circt::esi::ESIPureModuleParamOp)

Params become module parameters when the module is lowered

Syntax:

operation ::= `esi.pure_module.param` $name `:` $type attr-dict

Allows attaching parameters to modules which become HW module parameters when lowering. Currently, they are ignored. Some low-level BSPs instantiate modules with parameters. This allows the modules produced to accept parameters so those BSPs can instantiate them.

Traits: HasParent<ESIPureModuleOp>

Attributes:

Interfaces

Misc CIRCT interfaces.

ChannelOpInterface (ChannelOpInterface)

“An interface for operations which carries channel semantics.”

Methods:

channelType

circt::esi::ChannelType channelType();

“Returns the channel type of this operation.”

NOTE: This method must be implemented by the user.

innerType

mlir::Type innerType();

“Returns the inner type of this channel. This will be the type of the data value of the channel, if the channel carries data semantics. Else, return NoneType.”

NOTE: This method must be implemented by the user.

HasAppID (HasAppIDOpInterface)

Op can be identified by an AppID.

Methods:

getAppID

::circt::esi::AppIDAttr getAppID();

Returns the AppID of this operation.

NOTE: This method must be implemented by the user.

IsManifestData (IsManifestData)

Op’s attributes should be represented in the manifest.

Methods:

getManifestClass

static StringRef getManifestClass();

Get the class name for this op.

NOTE: This method must be implemented by the user.

getSymbolRefAttr

FlatSymbolRefAttr getSymbolRefAttr();

Get the symbol to which this manifest data is referring, if any.

NOTE: This method must be implemented by the user.

getDetails

void getDetails(SmallVectorImpl<NamedAttribute>&results);

Populate results with the manifest data.

NOTE: This method must be implemented by the user.

getDetailsAsDict

DictionaryAttr getDetailsAsDict();

Get the manifest data from this op as an attribute.

NOTE: This method must be implemented by the user.

ServiceDeclOpInterface (ServiceDeclOpInterface)

Any op which represents a service declaration should implement this interface.

Methods:

getPortList

void getPortList(llvm::SmallVectorImpl<ServicePortInfo>&ports);

Returns the list of interface ports for this service interface.

NOTE: This method must be implemented by the user.

getTypeName

std::optional<StringRef> getTypeName();

Return a well-known name for this service type.

NOTE: This method must be implemented by the user.

getPortInfo

FailureOr<ServicePortInfo> getPortInfo(StringAttr portName);

Get info on a particular port.

NOTE: This method must be implemented by the user.

'esi' Dialect Docs

• ESI data types and communication types
• ESI Global Services
• ESI Software APIs
• Miscellaneous Notes
• The Elastic Silicon Interconnect dialect