[llvm] [Offload] Add `MAX_WORK_GROUP_SIZE` device info query (PR #143718)

Ross Brunton via llvm-commits llvm-commits at lists.llvm.org
Wed Jun 25 05:56:18 PDT 2025


https://github.com/RossBrunton updated https://github.com/llvm/llvm-project/pull/143718

>From 91bfce23596991746e08d42c5c26807e6e97fd20 Mon Sep 17 00:00:00 2001
From: Ross Brunton <ross at codeplay.com>
Date: Wed, 11 Jun 2025 15:55:09 +0100
Subject: [PATCH 1/4] [Offload] Add `MAX_WORK_GROUP_SIZE` device info query

This adds a new device info query for the maximum workgroup/block size
for each dimension. Since this returns three values, a new `ol_range_t`
type was added as an `{x, y, z}` triplet. Device info handling and
struct printing was also updated to handle it.
---
 offload/liboffload/API/Device.td              |  3 +-
 offload/liboffload/src/OffloadImpl.cpp        | 28 +++++++++++++++++++
 offload/tools/offload-tblgen/PrintGen.cpp     |  5 ++++
 .../OffloadAPI/device/olGetDeviceInfo.cpp     |  9 ++++++
 .../OffloadAPI/device/olGetDeviceInfoSize.cpp |  8 ++++++
 5 files changed, 52 insertions(+), 1 deletion(-)

diff --git a/offload/liboffload/API/Device.td b/offload/liboffload/API/Device.td
index 4abc24f3ba27f..94bd6cbf0e5be 100644
--- a/offload/liboffload/API/Device.td
+++ b/offload/liboffload/API/Device.td
@@ -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">,
   ];
 }
 
diff --git a/offload/liboffload/src/OffloadImpl.cpp b/offload/liboffload/src/OffloadImpl.cpp
index da2101529ffec..139af2f9a9616 100644
--- a/offload/liboffload/src/OffloadImpl.cpp
+++ b/offload/liboffload/src/OffloadImpl.cpp
@@ -264,6 +264,31 @@ Error olGetDeviceInfoImplDetail(ol_device_handle_t Device,
 
     return "";
   };
+  auto GetInfoXyz = [&](std::vector<std::string> Names) {
+    if (!Device->Device)
+      return ol_dimensions_t{0, 0, 0};
+
+    auto Info = Device->Device->obtainInfoImpl();
+    if (auto Err = Info.takeError())
+      return ol_dimensions_t{0, 0, 0};
+
+    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 Out;
+      }
+    }
+
+    return ol_dimensions_t{0, 0, 0};
+  };
 
   switch (PropName) {
   case OL_DEVICE_INFO_PLATFORM:
@@ -279,6 +304,9 @@ 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 ReturnValue(GetInfoXyz({"Workgroup Max Size per Dimension" /*AMD*/,
+                                   "Maximum Block Dimensions" /*CUDA*/}));
   default:
     return createOffloadError(ErrorCode::INVALID_ENUMERATION,
                               "getDeviceInfo enum '%i' is invalid", PropName);
diff --git a/offload/tools/offload-tblgen/PrintGen.cpp b/offload/tools/offload-tblgen/PrintGen.cpp
index a964ff09d0f6e..d1189688a90a3 100644
--- a/offload/tools/offload-tblgen/PrintGen.cpp
+++ b/offload/tools/offload-tblgen/PrintGen.cpp
@@ -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
diff --git a/offload/unittests/OffloadAPI/device/olGetDeviceInfo.cpp b/offload/unittests/OffloadAPI/device/olGetDeviceInfo.cpp
index 0247744911eaa..a6f0145ab39b4 100644
--- a/offload/unittests/OffloadAPI/device/olGetDeviceInfo.cpp
+++ b/offload/unittests/OffloadAPI/device/olGetDeviceInfo.cpp
@@ -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, 0);
+  ASSERT_GT(Value.y, 0);
+  ASSERT_GT(Value.z, 0);
+}
+
 TEST_P(olGetDeviceInfoTest, InvalidNullHandleDevice) {
   ol_device_type_t DeviceType;
   ASSERT_ERROR(OL_ERRC_INVALID_NULL_HANDLE,
diff --git a/offload/unittests/OffloadAPI/device/olGetDeviceInfoSize.cpp b/offload/unittests/OffloadAPI/device/olGetDeviceInfoSize.cpp
index edd2704a722dd..a908078a25211 100644
--- a/offload/unittests/OffloadAPI/device/olGetDeviceInfoSize.cpp
+++ b/offload/unittests/OffloadAPI/device/olGetDeviceInfoSize.cpp
@@ -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,

>From 95a5f197469fc5b151629980c3f2bca4de5ebcf3 Mon Sep 17 00:00:00 2001
From: Ross Brunton <ross at codeplay.com>
Date: Wed, 11 Jun 2025 16:43:12 +0100
Subject: [PATCH 2/4] Small fixes

---
 offload/unittests/OffloadAPI/device/olGetDeviceInfo.cpp | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/offload/unittests/OffloadAPI/device/olGetDeviceInfo.cpp b/offload/unittests/OffloadAPI/device/olGetDeviceInfo.cpp
index a6f0145ab39b4..c534c45205993 100644
--- a/offload/unittests/OffloadAPI/device/olGetDeviceInfo.cpp
+++ b/offload/unittests/OffloadAPI/device/olGetDeviceInfo.cpp
@@ -81,9 +81,9 @@ 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, 0);
-  ASSERT_GT(Value.y, 0);
-  ASSERT_GT(Value.z, 0);
+  ASSERT_GT(Value.x, 0u);
+  ASSERT_GT(Value.y, 0u);
+  ASSERT_GT(Value.z, 0u);
 }
 
 TEST_P(olGetDeviceInfoTest, InvalidNullHandleDevice) {

>From 872264af641a4cc5f822c3598c3a2d2fd9586102 Mon Sep 17 00:00:00 2001
From: Ross Brunton <ross at codeplay.com>
Date: Wed, 25 Jun 2025 13:40:39 +0100
Subject: [PATCH 3/4] Return Error from GetInfoXYZ

---
 offload/liboffload/src/OffloadImpl.cpp | 24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/offload/liboffload/src/OffloadImpl.cpp b/offload/liboffload/src/OffloadImpl.cpp
index 139af2f9a9616..5d83017ffc258 100644
--- a/offload/liboffload/src/OffloadImpl.cpp
+++ b/offload/liboffload/src/OffloadImpl.cpp
@@ -13,6 +13,8 @@
 
 #include "OffloadImpl.hpp"
 #include "Helpers.hpp"
+// Required for operator<< implementation of ol_device_info_t
+#include "OffloadPrint.hpp"
 #include "PluginManager.h"
 #include "llvm/Support/FormatVariadic.h"
 #include <OffloadAPI.h>
@@ -264,13 +266,16 @@ Error olGetDeviceInfoImplDetail(ol_device_handle_t Device,
 
     return "";
   };
-  auto GetInfoXyz = [&](std::vector<std::string> Names) {
-    if (!Device->Device)
-      return ol_dimensions_t{0, 0, 0};
+  auto GetInfoXyz = [&](std::vector<std::string> Names) -> Error {
+    if (Device == OffloadContext::get().HostDevice())
+      return ReturnValue(ol_dimensions_t{0u, 0u, 0u});
+
+    assert(Device->Device &&
+           "liboffload device handle contains a null plugin device");
 
     auto Info = Device->Device->obtainInfoImpl();
     if (auto Err = Info.takeError())
-      return ol_dimensions_t{0, 0, 0};
+      return Err;
 
     for (auto Name : Names) {
       if (auto Entry = Info->get(Name)) {
@@ -283,11 +288,14 @@ Error olGetDeviceInfoImplDetail(ol_device_handle_t Device,
           Out.y = std::get<size_t>((*Y)->Value);
         if (auto Z = Node->get("z"))
           Out.z = std::get<size_t>((*Z)->Value);
-        return Out;
+        return ReturnValue(Out);
       }
     }
 
-    return ol_dimensions_t{0, 0, 0};
+    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) {
@@ -305,8 +313,8 @@ Error olGetDeviceInfoImplDetail(ol_device_handle_t Device,
     return ReturnValue(
         GetInfoString({"CUDA Driver Version", "HSA Runtime Version"}));
   case OL_DEVICE_INFO_MAX_WORK_GROUP_SIZE:
-    return ReturnValue(GetInfoXyz({"Workgroup Max Size per Dimension" /*AMD*/,
-                                   "Maximum Block Dimensions" /*CUDA*/}));
+    return GetInfoXyz({"Workgroup Max Size per Dimension" /*AMD*/,
+                       "Maximum Block Dimensions" /*CUDA*/});
   default:
     return createOffloadError(ErrorCode::INVALID_ENUMERATION,
                               "getDeviceInfo enum '%i' is invalid", PropName);

>From 1efb1746db9aa2ff93710bfe161c2f523c62d4b5 Mon Sep 17 00:00:00 2001
From: Ross Brunton <ross at codeplay.com>
Date: Wed, 25 Jun 2025 13:56:04 +0100
Subject: [PATCH 4/4] Put on same line

---
 offload/liboffload/src/OffloadImpl.cpp | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/offload/liboffload/src/OffloadImpl.cpp b/offload/liboffload/src/OffloadImpl.cpp
index 5d83017ffc258..84f8c82a909a0 100644
--- a/offload/liboffload/src/OffloadImpl.cpp
+++ b/offload/liboffload/src/OffloadImpl.cpp
@@ -13,8 +13,7 @@
 
 #include "OffloadImpl.hpp"
 #include "Helpers.hpp"
-// Required for operator<< implementation of ol_device_info_t
-#include "OffloadPrint.hpp"
+#include "OffloadPrint.hpp" // Required for operator<< implementation of ol_device_info_t
 #include "PluginManager.h"
 #include "llvm/Support/FormatVariadic.h"
 #include <OffloadAPI.h>



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