[llvm] [Offload] Fix segfault when looking for host device name (PR #141632)

[Joseph Huber via llvm-commits]

https://github.com/jhuber6 created https://github.com/llvm/llvm-project/pull/141632

Summary:
This is done using the generic device into pointe, but no such thing
exists for the host device, leading to a segfault. This patch fixes that
for now, but in the future we should probably be more careful in general
handling the possibility that the handle is null everywhere.

Fixes: https://github.com/llvm/llvm-project/issues/141434


>From 880de292d1ee71ef3d738127df7fc5a498ab36ac Mon Sep 17 00:00:00 2001
From: Joseph Huber <huberjn at outlook.com>
Date: Tue, 27 May 2025 11:52:25 -0500
Subject: [PATCH] [Offload] Fix segfault when looking for host device name

Summary:
This is done using the generic device into pointe, but no such thing
exists for the host device, leading to a segfault. This patch fixes that
for now, but in the future we should probably be more careful in general
handling the possibility that the handle is null everywhere.

Fixes: https://github.com/llvm/llvm-project/issues/141434
---
 offload/liboffload/src/OffloadImpl.cpp                 |  6 ++++++
 .../unittests/OffloadAPI/device/olGetDeviceInfo.cpp    | 10 ++++++++++
 2 files changed, 16 insertions(+)

diff --git a/offload/liboffload/src/OffloadImpl.cpp b/offload/liboffload/src/OffloadImpl.cpp
index ea65282e3ba52..ac2ca20601cae 100644
--- a/offload/liboffload/src/OffloadImpl.cpp
+++ b/offload/liboffload/src/OffloadImpl.cpp
@@ -230,6 +230,12 @@ ol_impl_result_t olGetDeviceInfoImplDetail(ol_device_handle_t Device,
   // Find the info if it exists under any of the given names
   auto GetInfo = [&](std::vector<std::string> Names) {
     InfoQueueTy DevInfo;
+    if (Device == HostDevice())
+      return std::string("Host");
+
+    if (!Device->Device)
+      return std::string("");
+
     if (auto Err = Device->Device->obtainInfoImpl(DevInfo))
       return std::string("");
 
diff --git a/offload/unittests/OffloadAPI/device/olGetDeviceInfo.cpp b/offload/unittests/OffloadAPI/device/olGetDeviceInfo.cpp
index 46ed622fa8b81..1240f219813e2 100644
--- a/offload/unittests/OffloadAPI/device/olGetDeviceInfo.cpp
+++ b/offload/unittests/OffloadAPI/device/olGetDeviceInfo.cpp
@@ -37,6 +37,16 @@ TEST_P(olGetDeviceInfoTest, SuccessName) {
   ASSERT_EQ(std::strlen(Name.data()), Size - 1);
 }
 
+TEST_P(olGetDeviceInfoTest, HostName) {
+  size_t Size = 0;
+  ASSERT_SUCCESS(olGetDeviceInfoSize(Host, OL_DEVICE_INFO_NAME, &Size));
+  ASSERT_GT(Size, 0ul);
+  std::vector<char> Name;
+  Name.resize(Size);
+  ASSERT_SUCCESS(olGetDeviceInfo(Host, OL_DEVICE_INFO_NAME, Size, Name.data()));
+  ASSERT_EQ(std::strlen(Name.data()), Size - 1);
+}
+
 TEST_P(olGetDeviceInfoTest, SuccessVendor) {
   size_t Size = 0;
   ASSERT_SUCCESS(olGetDeviceInfoSize(Device, OL_DEVICE_INFO_VENDOR, &Size));