[llvm] [Offload] Add specifier for the host type (PR #141635)

[Joseph Huber via llvm-commits]

https://github.com/jhuber6 created https://github.com/llvm/llvm-project/pull/141635

Summary:
We use this sepcial type to indicate a host value, this will be refined
later but for now it's used as a stand-in device for transfers and
queues. It needs a special kind because it is not a device target as the
other ones so we need to differentiate it between a CPU and GPU type.

Fixes: https://github.com/llvm/llvm-project/issues/141436


>From 0be9fbffc03bda6562a6e4d5c14e8f8d410d28de Mon Sep 17 00:00:00 2001
From: Joseph Huber <huberjn at outlook.com>
Date: Tue, 27 May 2025 12:14:44 -0500
Subject: [PATCH] [Offload] Add specifier for the host type

Summary:
We use this sepcial type to indicate a host value, this will be refined
later but for now it's used as a stand-in device for transfers and
queues. It needs a special kind because it is not a device target as the
other ones so we need to differentiate it between a CPU and GPU type.

Fixes: https://github.com/llvm/llvm-project/issues/141436
---
 offload/liboffload/API/Device.td                        | 1 +
 offload/liboffload/include/generated/OffloadAPI.h       | 2 ++
 offload/liboffload/include/generated/OffloadPrint.hpp   | 3 +++
 offload/liboffload/src/OffloadImpl.cpp                  | 3 ++-
 offload/unittests/OffloadAPI/device/olGetDeviceInfo.cpp | 7 +++++++
 5 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/offload/liboffload/API/Device.td b/offload/liboffload/API/Device.td
index 28c96bb5d2910..4abc24f3ba27f 100644
--- a/offload/liboffload/API/Device.td
+++ b/offload/liboffload/API/Device.td
@@ -18,6 +18,7 @@ def : Enum {
     Etor<"ALL", "Devices of all types">,
     Etor<"GPU", "GPU device type">,
     Etor<"CPU", "CPU device type">,
+    Etor<"Host", "Host device type">,
   ];
 }
 
diff --git a/offload/liboffload/include/generated/OffloadAPI.h b/offload/liboffload/include/generated/OffloadAPI.h
index f7ec749f6efa3..a1d7540519e32 100644
--- a/offload/liboffload/include/generated/OffloadAPI.h
+++ b/offload/liboffload/include/generated/OffloadAPI.h
@@ -320,6 +320,8 @@ typedef enum ol_device_type_t {
   OL_DEVICE_TYPE_GPU = 2,
   /// CPU device type
   OL_DEVICE_TYPE_CPU = 3,
+  /// Host device type
+  OL_DEVICE_TYPE_HOST = 4,
   /// @cond
   OL_DEVICE_TYPE_FORCE_UINT32 = 0x7fffffff
   /// @endcond
diff --git a/offload/liboffload/include/generated/OffloadPrint.hpp b/offload/liboffload/include/generated/OffloadPrint.hpp
index 9b916543eec0d..3aad6223d4dea 100644
--- a/offload/liboffload/include/generated/OffloadPrint.hpp
+++ b/offload/liboffload/include/generated/OffloadPrint.hpp
@@ -224,6 +224,9 @@ inline llvm::raw_ostream &operator<<(llvm::raw_ostream &os,
   case OL_DEVICE_TYPE_CPU:
     os << "OL_DEVICE_TYPE_CPU";
     break;
+  case OL_DEVICE_TYPE_HOST:
+    os << "OL_DEVICE_TYPE_HOST";
+    break;
   default:
     os << "unknown enumerator";
     break;
diff --git a/offload/liboffload/src/OffloadImpl.cpp b/offload/liboffload/src/OffloadImpl.cpp
index ea65282e3ba52..d311251ee088f 100644
--- a/offload/liboffload/src/OffloadImpl.cpp
+++ b/offload/liboffload/src/OffloadImpl.cpp
@@ -252,7 +252,8 @@ ol_impl_result_t olGetDeviceInfoImplDetail(ol_device_handle_t Device,
   case OL_DEVICE_INFO_PLATFORM:
     return ReturnValue(Device->Platform);
   case OL_DEVICE_INFO_TYPE:
-    return ReturnValue(OL_DEVICE_TYPE_GPU);
+    return Device == HostDevice() ? ReturnValue(OL_DEVICE_TYPE_HOST)
+                                  : ReturnValue(OL_DEVICE_TYPE_GPU);
   case OL_DEVICE_INFO_NAME:
     return ReturnValue(GetInfo({"Device Name"}).c_str());
   case OL_DEVICE_INFO_VENDOR:
diff --git a/offload/unittests/OffloadAPI/device/olGetDeviceInfo.cpp b/offload/unittests/OffloadAPI/device/olGetDeviceInfo.cpp
index 46ed622fa8b81..243bedddea6fe 100644
--- a/offload/unittests/OffloadAPI/device/olGetDeviceInfo.cpp
+++ b/offload/unittests/OffloadAPI/device/olGetDeviceInfo.cpp
@@ -19,6 +19,13 @@ TEST_P(olGetDeviceInfoTest, SuccessType) {
                                  sizeof(ol_device_type_t), &DeviceType));
 }
 
+TEST_P(olGetDeviceInfoTest, HostSuccessType) {
+  ol_device_type_t DeviceType;
+  ASSERT_SUCCESS(olGetDeviceInfo(Host, OL_DEVICE_INFO_TYPE,
+                                 sizeof(ol_device_type_t), &DeviceType));
+  ASSERT_EQ(DeviceType, OL_DEVICE_TYPE_HOST);
+}
+
 TEST_P(olGetDeviceInfoTest, SuccessPlatform) {
   ol_platform_handle_t Platform = nullptr;
   ASSERT_SUCCESS(olGetDeviceInfo(Device, OL_DEVICE_INFO_PLATFORM,