From ba8132345cbae5b749b4a01deda732ad6f8251a0 Mon Sep 17 00:00:00 2001
From: Gangzheng Tong <tonggangzheng@gmail.com>
Date: Mon, 22 Sep 2025 15:46:42 -0700
Subject: Add RHI Device Caching and Test Prefix Exclusion (#8448)

# Add RHI Device Caching and Test Prefix Exclusion

## Summary

This PR introduces two key improvements to the Slang test
infrastructure:

1. **RHI Device Caching**: Implements device caching to significantly
speed up test execution by reusing graphics devices across tests, **RHI
Device Caching reduces slang-test execution time from ~15 minutes to ~5
minutes in Windows release builds**
2. **Test Prefix Exclusion**: Adds `-exclude-prefix` option to skip
tests matching specified path prefixes

## Changes

### RHI Device Caching
- **New `DeviceCache` class** (`slang-test-device-cache.h/cpp`):
Thread-safe device cache with LRU eviction (max 10 devices)
- **Cache control option**: `-cache-rhi-device` flag in both
`slang-test` and `render-test`
- Default: **enabled** in slang-test, **disabled** in render-test when
run standalone
  - Automatically skips caching for CUDA devices (due to driver issues)
- **Performance benefit**: Eliminates expensive device
creation/destruction cycles, especially beneficial for Vulkan on Tegra
platforms

### Test Prefix Exclusion
- **New `-exclude-prefix <prefix>` option** in slang-test
- Allows excluding entire test directories or patterns from execution
- Complements existing `-category` and individual test filtering options

### Usage Examples
```bash
# Enable device caching (default)
slang-test

# Disable device caching
slang-test -cache-rhi-device false

# Exclude tests from specific directories
slang-test -exclude-prefix tests/problematic/
slang-test -exclude-prefix tests/slow/ -exclude-prefix tests/experimental/
```

This change should significantly improve test execution performance,
particularly in CI environments with frequent device operations. This is
needed for running the GPU test in aarch64, where repeated device
creation/destroy is causing driver issues.

Needed by: https://github.com/shader-slang/slang/issues/8346

---------

Co-authored-by: slangbot <ellieh+slangbot@nvidia.com>
Co-authored-by: slangbot <186143334+slangbot@users.noreply.github.com>
---
 tools/render-test/slang-test-device-cache.h | 97 +++++++++++++++++++++++++++++
 1 file changed, 97 insertions(+)
 create mode 100644 tools/render-test/slang-test-device-cache.h

(limited to 'tools/render-test/slang-test-device-cache.h')

diff --git a/tools/render-test/slang-test-device-cache.h b/tools/render-test/slang-test-device-cache.h
new file mode 100644
index 000000000..752d03ff1
--- /dev/null
+++ b/tools/render-test/slang-test-device-cache.h
@@ -0,0 +1,97 @@
+#pragma once
+
+#include <mutex>
+#include <slang-rhi.h>
+#include <string>
+#include <unordered_map>
+#include <vector>
+
+// Device Cache for preventing NVIDIA Tegra driver state corruption
+// This cache reuses Vulkan instances and devices to avoid the VK_ERROR_INCOMPATIBLE_DRIVER
+// issue that occurs after ~19 device creation/destruction cycles on Tegra platforms.
+// Uses ComPtr for automatic device lifecycle management - devices are released when removed from
+// cache.
+class DeviceCache
+{
+public:
+    struct DeviceCacheKey
+    {
+        rhi::DeviceType deviceType;
+        bool enableValidation;
+        bool enableRayTracingValidation;
+        std::string profileName;
+        std::vector<std::string> requiredFeatures;
+
+        bool operator==(const DeviceCacheKey& other) const;
+    };
+
+    struct DeviceCacheKeyHash
+    {
+        std::size_t operator()(const DeviceCacheKey& key) const;
+    };
+
+    struct CachedDevice
+    {
+        Slang::ComPtr<rhi::IDevice> device;
+        uint64_t creationOrder;
+
+        CachedDevice();
+    };
+
+private:
+    static constexpr int MAX_CACHED_DEVICES = 10;
+
+    // Use function-local statics to control destruction order (Meyer's singleton pattern)
+    static std::mutex& getMutex();
+    static std::unordered_map<DeviceCacheKey, CachedDevice, DeviceCacheKeyHash>& getDeviceCache();
+    static uint64_t& getNextCreationOrder();
+
+    static void evictOldestDeviceIfNeeded();
+
+public:
+    static SlangResult acquireDevice(const rhi::DeviceDesc& desc, rhi::IDevice** outDevice);
+    static void cleanCache();
+};
+
+// RAII wrapper for cached devices to ensure proper cleanup
+class CachedDeviceWrapper
+{
+private:
+    Slang::ComPtr<rhi::IDevice> m_device;
+
+public:
+    CachedDeviceWrapper() = default;
+
+    CachedDeviceWrapper(Slang::ComPtr<rhi::IDevice> device)
+        : m_device(device)
+    {
+    }
+
+    ~CachedDeviceWrapper() {}
+
+    // Move constructor
+    CachedDeviceWrapper(CachedDeviceWrapper&& other) noexcept
+        : m_device(std::move(other.m_device))
+    {
+    }
+
+    // Move assignment
+    CachedDeviceWrapper& operator=(CachedDeviceWrapper&& other) noexcept
+    {
+        if (this != &other)
+        {
+            m_device = std::move(other.m_device);
+        }
+        return *this;
+    }
+
+    // Delete copy constructor and assignment
+    CachedDeviceWrapper(const CachedDeviceWrapper&) = delete;
+    CachedDeviceWrapper& operator=(const CachedDeviceWrapper&) = delete;
+
+    rhi::IDevice* get() const { return m_device.get(); }
+    rhi::IDevice* operator->() const { return m_device.get(); }
+    operator bool() const { return m_device != nullptr; }
+
+    Slang::ComPtr<rhi::IDevice>& getComPtr() { return m_device; }
+};
-- 
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