OpenCL Device.addressBits uses CL_DEVICE_TYPE (0x1000) instead of CL_DEVICE_ADDRESS_BITS (0x100D)

[niy-ati]

Summary

In the OpenCL device info wrapper, Device.Info.addressBits is annotated with the wrong cl_device_info value, so device.addressBits does not query address width.

Location

source/dcompute/driver/ocl/device.d (current master):

@(0x100C) uint maxClockFrequency;
@(0x1000) uint addressBits;   // <-- wrong
@(0x100E) uint maxReadImageArgs;

type already correctly uses @(0x1000) a few lines above:

@(0x1000) Type type;

So addressBits reuses CL_DEVICE_TYPE and skips the constant that belongs between 0x100C and 0x100E.

Reference

From the OpenCL C headers (Khronos OpenCL-Headers CL/cl.h):

Constant	Value	Meaning
CL_DEVICE_TYPE	0x1000	device type bitfield
CL_DEVICE_MAX_CLOCK_FREQUENCY	0x100C	clock frequency
CL_DEVICE_ADDRESS_BITS	0x100D	address bits (cl_uint)
CL_DEVICE_MAX_READ_IMAGE_ARGS	0x100E	max read image args

addressBits should use 0x100D, not 0x1000.

The generated getter (via generateGetInfo / clGetDeviceInfo) passes that UDA value as param_name, so the wrong query is what runs at runtime.

How this was found

While reviewing Device.Info UDA values against cl.h (after looking at the related size fix in #84 , #85, which corrected enum base types but did not change this attribute), the sequence 0x100C -> 0x1000 -> 0x100E stood out: 0x100D is missing and 0x1000 is already used for type.

Expected

device.addressBits should call clGetDeviceInfo(..., CL_DEVICE_ADDRESS_BITS, ...) and return the device address width (commonly 32 or 64).

Actual

device.addressBits calls clGetDeviceInfo(..., CL_DEVICE_TYPE, ...) with a uint-sized buffer. That is not the address-bits query; the returned value is not meaningful as address width.

How to reproduce

On any machine with a working OpenCL ICD and dcompute’s OCL driver:

import std.stdio;
import std.experimental.allocator;
import dcompute.driver.ocl;

void main()
{
    Platform.initialise();
    auto platforms = Platform.getPlatforms(theAllocator);
    auto devices = platforms[0].getDevices(theAllocator);
    auto d = devices[0];

    writefln("name: %s", d.name);
    writefln("type: %s (%s)", d.type, cast(ulong)d.type);
    writefln("addressBits: %s", d.addressBits);
}

Compare addressBits with a direct query (or clinfo):

cl_uint bits;
clGetDeviceInfo(device, CL_DEVICE_ADDRESS_BITS, sizeof(bits), &bits, NULL);

You should see a mismatch: dcompute’s addressBits does not match CL_DEVICE_ADDRESS_BITS from clinfo / the direct call. (Exact wrong numeric value depends on the device and how the truncated CL_DEVICE_TYPE read lands in a uint.)

Proposed fix

Change the attribute only:

@(0x100D) uint addressBits;

Note on related work

#84 / #85 fixed OpenCL enum base type sizes so fields like type are read with the correct sizeof. That is separate from this bug, which is a wrong param_name constant on addressBits.