hpvm-c.md

HPVM-C Language Specification

An HPVM program is a combination of host code and one or more data flow graphs (DFG) at the IR level. We provide C function declarations representing the HPVM intrinsics that allow creating, querying, and interacting with the DFGs. More details about the HPVM IR intrinsics can be found in the HPVM IR Specification..

An HPVM-C program contains both the host and the DFG code. Each HPVM kernel, represented by a leaf node in the DFG, can be compiled to multiple different targets (e.g. CPU and GPU) as described below.

This document describes all the API calls that can be used in an HPVM-C program.

Host API

void __hpvm__init()
Used before all other HPVM calls to initialize the HPVM runtime.

void __hpvm__cleanup()
Used at the end of HPVM program to clean up all remaining runtime-created HPVM objects.

void llvm_hpvm_track_mem(void* ptr, size_t sz)
Insert memory starting at ptr of size sz in the memory tracker of HPVM runtime.

void llvm_hpvm_untrack_mem(void* ptr)
Stop tracking the memory object identified by ptr.

void llvm_hpvm_request_mem(void* ptr, size_t sz)
If the memory object identified by ptr is not in host memory, copy it to host memory.

void* __hpvm__launch(unsigned isStream, void* rootGraph, void* args)
Launches the execution of the dataflow graph with node function rootGraph. args is a pointer to a packed struct, containing one field per argument of the RootGraph function, consecutively. For non-streaming DFGs with a non empty result type, args must contain an additional field of the type RootGraph.returnTy, where the result of the graph will be returned. isStream chooses between a non streaming (0) or streaming (1) graph execution. Returns a handle to the executing graph.

void __hpvm__wait(void* G)
Waits for completion of execution of the dataflow graph with handle G.

void __hpvm__push(void* G, void* args)
Push set of input data items, args, (same as type included in launch) to streaming DFG with handle G.

void* __hpvm__pop(void* G)
Pop and return data produced from one execution of streaming DFG with handle G. The return type is a struct containing a field for every output of DFG.

Internal Node API

void* __hpvm__createNodeND(unsigned dims, void* F, ...)
Creates a static dataflow node replicated in dims dimensions (0 to 3), each executing node function F. The arguments following F are the size of each dimension, respectively, passed in as a size_t. Returns a handle to the created dataflow node.

void* __hpvm__edge(void* src, void* dst, unsigned replType, unsigned sp, unsigned dp, unsigned isStream)
Creates an edge from output sp of node src to input dp of node dst. If replType is 0, the edge is a one-to-one edge, otherwise it is an all-to-all edge. isStream defines whether or not the edge is streaming. Returns a handle to the created edge.

void __hpvm__bindIn(void* N, unsigned ip, unsigned ic, unsigned isStream)
Binds the input ip of the current node to input ic of child node function N. isStream defines whether or not the input bind is streaming.

void __hpvm__bindOut(void* N, unsigned op, unsigned oc, unsigned isStream)
Binds the output op of the current node to output oc of child node function N. isStream defines whether or not the output bind is streaming.

void __hpvm__hint(enum Target target) (C)
void __hpvm__hint(hpvm::Target target) (C++)
Must be called once in each node function. Indicates which hardware target the current function should run in.