From 53ead32bfabaf78b250b78a34f9db6826c665207 Mon Sep 17 00:00:00 2001
From: Marijn Suijten <marijn@traverseresearch.nl>
Date: Mon, 30 Mar 2026 15:07:27 +0200
Subject: [PATCH] api-query: Continue device initialization when a backend
 fails

Device::initialize() returns early when any backend fails to initialize,
preventing subsequent backends from being discovered. For example, a
Vulkan initialization failure (e.g. VK_ERROR_INCOMPATIBLE_DRIVER when
MoltenVK is not installed) blocks Metal device discovery on macOS.

Collect backend initialization errors with joinErrors() and return them
together instead. Also make lit.cfg.py resilient to an empty device list
from api-query.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
---
 lib/API/Device.cpp | 24 +++++++++++++++++-------
 test/lit.cfg.py    |  2 +-
 2 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/lib/API/Device.cpp b/lib/API/Device.cpp
index fc1044884..c1be35d15 100644
--- a/lib/API/Device.cpp
+++ b/lib/API/Device.cpp
@@ -14,8 +14,8 @@
 #include "Config.h"
 
 #include "llvm/Support/Error.h"
+#include "llvm/Support/raw_ostream.h"
 
-#include <cstdlib>
 #include <memory>
 
 using namespace offloadtest;
@@ -27,21 +27,31 @@ Device::~Device() {}
 llvm::Expected<llvm::SmallVector<std::unique_ptr<Device>>>
 offloadtest::initializeDevices(const DeviceConfig Config) {
   llvm::SmallVector<std::unique_ptr<Device>> Devices;
+  llvm::Error Err = llvm::Error::success();
 
 #ifdef OFFLOADTEST_ENABLE_D3D12
-  if (auto Err = initializeDX12Devices(Config, Devices))
-    return Err;
+  if (auto E = initializeDX12Devices(Config, Devices))
+    Err = llvm::joinErrors(std::move(Err), std::move(E));
 #endif
 
 #ifdef OFFLOADTEST_ENABLE_VULKAN
-  if (auto Err = initializeVulkanDevices(Config, Devices))
-    return Err;
+  if (auto E = initializeVulkanDevices(Config, Devices))
+    Err = llvm::joinErrors(std::move(Err), std::move(E));
 #endif
 
 #ifdef OFFLOADTEST_ENABLE_METAL
-  if (auto Err = initializeMetalDevices(Config, Devices))
-    return Err;
+  if (auto E = initializeMetalDevices(Config, Devices))
+    Err = llvm::joinErrors(std::move(Err), std::move(E));
 #endif
 
+  if (Devices.empty()) {
+    if (Err)
+      return std::move(Err);
+    return llvm::createStringError(std::errc::no_such_device,
+                                   "No GPU devices found.");
+  }
+  // Log errors from backends that failed while others succeeded.
+  if (Err)
+    llvm::logAllUnhandledErrors(std::move(Err), llvm::errs());
   return Devices;
 }
diff --git a/test/lit.cfg.py b/test/lit.cfg.py
index 35e8f2ba5..029953e74 100644
--- a/test/lit.cfg.py
+++ b/test/lit.cfg.py
@@ -241,7 +241,7 @@ def setDeviceFeatures(config, device, compiler):
 target_device = None
 # Find the right device to configure against
 pattern = re.compile(GPUName, re.IGNORECASE)
-for device in devices["Devices"]:
+for device in devices.get("Devices", []):
     is_warp = "Microsoft Basic Render Driver" in device["Description"]
     is_gpu_name_match = bool(pattern.search(device["Description"]))
     if device["API"] == "DirectX" and config.offloadtest_enable_d3d12: