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[Offload] Add MAX_WORK_GROUP_SIZE device info query #143718

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[Offload] Add MAX_WORK_GROUP_SIZE device info query #143718

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91bfce2
[Offload] Add `MAX_WORK_GROUP_SIZE` device info query
RossBrunton Jun 11, 2025
95a5f19
Small fixes
RossBrunton Jun 11, 2025
872264a
Return Error from GetInfoXYZ
RossBrunton Jun 25, 2025
1efb174
Put on same line
RossBrunton Jun 25, 2025
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3 changes: 2 additions & 1 deletion offload/liboffload/API/Device.td
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Original file line number Diff line number Diff line change
Expand Up @@ -31,7 +31,8 @@ def : Enum {
TaggedEtor<"PLATFORM", "ol_platform_handle_t", "the platform associated with the device">,
TaggedEtor<"NAME", "char[]", "Device name">,
TaggedEtor<"VENDOR", "char[]", "Device vendor">,
TaggedEtor<"DRIVER_VERSION", "char[]", "Driver version">
TaggedEtor<"DRIVER_VERSION", "char[]", "Driver version">,
TaggedEtor<"MAX_WORK_GROUP_SIZE", "ol_dimensions_t", "Maximum work group size in each dimension">,
];
}

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35 changes: 35 additions & 0 deletions offload/liboffload/src/OffloadImpl.cpp
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Expand Up @@ -13,6 +13,7 @@

#include "OffloadImpl.hpp"
#include "Helpers.hpp"
#include "OffloadPrint.hpp" // Required for operator<< implementation of ol_device_info_t
#include "PluginManager.h"
#include "llvm/Support/FormatVariadic.h"
#include <OffloadAPI.h>
Expand Down Expand Up @@ -264,6 +265,37 @@ Error olGetDeviceInfoImplDetail(ol_device_handle_t Device,

return "";
};
auto GetInfoXyz = [&](std::vector<std::string> Names) -> Error {
if (Device == OffloadContext::get().HostDevice())
return ReturnValue(ol_dimensions_t{0u, 0u, 0u});
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What's ReturnValue used for? Isn't this was Expected is supposed to be used for?

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ReturnValue is a helper object with an operator() that automatically writes the value to PropValue and PropSizeRet as appropriate (as well as doing some validation checks).

If this were to return Expected<ol_dimensions_t>, then the callers would have to do the Error unwrapping themselves.

@callumfare For the sake of clarity, do you mind if (in a separate patch) I rename this to something like SetOutput?

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That seems like a weird way to work around just using Expected<T>.

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@RossBrunton Yeah I'm happy if that gets renamed. I think the naming is a little inconsistent with the info functions as well ('info' vs 'prop' etc).

@jhuber6 I think the wrappers are helpful to have since the code to output the value and underlying size is a little verbose - https://github.com/llvm/llvm-project/blob/main/offload/liboffload/src/Helpers.hpp

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Unless I'm missing an easier way, that would result in code like this:

case OL_DEVICE_INFO_NAME:
  auto Res = GetInfoWhatever(...);
  if (Res) {
    return ReturnValue(*Res);
  } else {
    return Res.takeError();
  }

For every device info that uses this interface, which feels unnecessarily verbose.

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Because that function also doesn't use Expected<T>, it would just be a return otherwise and then you unpack the value at the bottom (Where we actually set the result.)

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What would be the value of T?


assert(Device->Device &&
"liboffload device handle contains a null plugin device");

auto Info = Device->Device->obtainInfoImpl();
if (auto Err = Info.takeError())
return Err;

for (auto Name : Names) {
if (auto Entry = Info->get(Name)) {
auto Node = *Entry;
ol_dimensions_t Out{0, 0, 0};

if (auto X = Node->get("x"))
Out.x = std::get<size_t>((*X)->Value);
if (auto Y = Node->get("y"))
Out.y = std::get<size_t>((*Y)->Value);
if (auto Z = Node->get("z"))
Out.z = std::get<size_t>((*Z)->Value);
return ReturnValue(Out);
}
}

std::string ErrBuffer;
llvm::raw_string_ostream(ErrBuffer)
<< "plugin did not provide information for " << PropName;
return Plugin::error(ErrorCode::UNIMPLEMENTED, ErrBuffer.c_str());
};

switch (PropName) {
case OL_DEVICE_INFO_PLATFORM:
Expand All @@ -279,6 +311,9 @@ Error olGetDeviceInfoImplDetail(ol_device_handle_t Device,
case OL_DEVICE_INFO_DRIVER_VERSION:
return ReturnValue(
GetInfoString({"CUDA Driver Version", "HSA Runtime Version"}));
case OL_DEVICE_INFO_MAX_WORK_GROUP_SIZE:
return GetInfoXyz({"Workgroup Max Size per Dimension" /*AMD*/,
"Maximum Block Dimensions" /*CUDA*/});
default:
return createOffloadError(ErrorCode::INVALID_ENUMERATION,
"getDeviceInfo enum '%i' is invalid", PropName);
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5 changes: 5 additions & 0 deletions offload/tools/offload-tblgen/PrintGen.cpp
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Expand Up @@ -213,6 +213,11 @@ template <typename T> inline void printTagged(llvm::raw_ostream &os, const void
"enum {0} value);\n",
EnumRec{R}.getName());
}
for (auto *R : Records.getAllDerivedDefinitions("Struct")) {
OS << formatv("inline llvm::raw_ostream &operator<<(llvm::raw_ostream &os, "
"const struct {0} param);\n",
StructRec{R}.getName());
}
OS << "\n";

// Create definitions
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9 changes: 9 additions & 0 deletions offload/unittests/OffloadAPI/device/olGetDeviceInfo.cpp
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Expand Up @@ -77,6 +77,15 @@ TEST_P(olGetDeviceInfoTest, SuccessDriverVersion) {
ASSERT_EQ(std::strlen(DriverVersion.data()), Size - 1);
}

TEST_P(olGetDeviceInfoTest, SuccessMaxWorkGroupSize) {
ol_dimensions_t Value{0, 0, 0};
ASSERT_SUCCESS(olGetDeviceInfo(Device, OL_DEVICE_INFO_MAX_WORK_GROUP_SIZE,
sizeof(Value), &Value));
ASSERT_GT(Value.x, 0u);
ASSERT_GT(Value.y, 0u);
ASSERT_GT(Value.z, 0u);
}

TEST_P(olGetDeviceInfoTest, InvalidNullHandleDevice) {
ol_device_type_t DeviceType;
ASSERT_ERROR(OL_ERRC_INVALID_NULL_HANDLE,
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8 changes: 8 additions & 0 deletions offload/unittests/OffloadAPI/device/olGetDeviceInfoSize.cpp
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Expand Up @@ -44,6 +44,14 @@ TEST_P(olGetDeviceInfoSizeTest, SuccessDriverVersion) {
ASSERT_NE(Size, 0ul);
}

TEST_P(olGetDeviceInfoSizeTest, SuccessMaxWorkGroupSize) {
size_t Size = 0;
ASSERT_SUCCESS(
olGetDeviceInfoSize(Device, OL_DEVICE_INFO_MAX_WORK_GROUP_SIZE, &Size));
ASSERT_EQ(Size, sizeof(ol_dimensions_t));
ASSERT_EQ(Size, sizeof(uint32_t) * 3);
}

TEST_P(olGetDeviceInfoSizeTest, InvalidNullHandle) {
size_t Size = 0;
ASSERT_ERROR(OL_ERRC_INVALID_NULL_HANDLE,
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