Working with DPCTLSyclInterface library

The DPCLSyclInterface library is a C-API library which provides select C++ functions for casting from C opaque pointers to pointers to corresponding C++ classes.

This document explains the memory ownership model adopted by DPCTLSyclInterface.

Function declarations are decorated with tokens such as __dpctl_keep, __dpctl_take, and __dpctl_give. Use of these tokens in declarations serves to self-document memory ownership semantics.

Token __dpctl_give indicates that the function makes a new allocation and delegates responsibility to free it to the caller. Creation functions, such as DCPTLDevice_Create(), belong to category of such functions.

The token __dpctl_take indicates that the library deletes the allocation associated with the object to which the token applies. Deletion functions, such as DPCTLDevice_Delete(), represent set of such functions.

The token __dpctl_keep indicates that the library does not alter allocation associated with the object to which the token applies. Functions to query integral device descriptors, such as DPCTLDevice_GetMaxComputeUnits(), are examples of such functions.

Example: Example of use of DPCTLSyclInterface functions

// filename: example_syclinterface.c
#include "stdint.h"
#include "stdio.h"
#include "dpctl_sycl_interface.h"

int main(void) {
    // we own memory allocation associated DRef object
    DPCTLSyclDeviceRef DRef = DPCTLDevice_Create();

    // we own memory allocation associated with char array
    const char* name = DPCTLDevice_GetName(DRef);
    uint32_t cu = DPCTLDevice_GetMaxComputeUnits(DRef);

    // Free allocations associated with DRef
    DPCTLDevice_Delete(DRef);

    printf("Device %s has %d compute units\n", name, cu);

    // Free memory allocate for device name
    DPCTLCString_Delete(name);

    return 0;
}

Building the example:

Building the example into an executable

icx example_syclinterface.c -fsanitize=address                 \
    $(python -m dpctl --includes) $(python -m dpctl --library) \
    -o example

Running the example displays the following output without errors:

Execution of the executable and its output

$ ./a.x
Device Intel(R) Graphics [0x9a49] has 96 compute units