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      1 /*
      2  * Copyright 2016 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 // The API layer of the loader defines Vulkan API and manages layers.  The
     18 // entrypoints are generated and defined in api_dispatch.cpp.  Most of them
     19 // simply find the dispatch table and jump.
     20 //
     21 // There are a few of them requiring manual code for things such as layer
     22 // discovery or chaining.  They call into functions defined in this file.
     23 
     24 #include <stdlib.h>
     25 #include <string.h>
     26 #include <algorithm>
     27 #include <mutex>
     28 #include <new>
     29 #include <utility>
     30 #include <cutils/properties.h>
     31 #include <log/log.h>
     32 
     33 #include <vulkan/vk_layer_interface.h>
     34 #include "api.h"
     35 #include "driver.h"
     36 #include "layers_extensions.h"
     37 
     38 namespace vulkan {
     39 namespace api {
     40 
     41 namespace {
     42 
     43 // Provide overridden layer names when there are implicit layers.  No effect
     44 // otherwise.
     45 class OverrideLayerNames {
     46    public:
     47     OverrideLayerNames(bool is_instance, const VkAllocationCallbacks& allocator)
     48         : is_instance_(is_instance),
     49           allocator_(allocator),
     50           scope_(VK_SYSTEM_ALLOCATION_SCOPE_COMMAND),
     51           names_(nullptr),
     52           name_count_(0),
     53           implicit_layers_() {
     54         implicit_layers_.result = VK_SUCCESS;
     55     }
     56 
     57     ~OverrideLayerNames() {
     58         allocator_.pfnFree(allocator_.pUserData, names_);
     59         allocator_.pfnFree(allocator_.pUserData, implicit_layers_.elements);
     60         allocator_.pfnFree(allocator_.pUserData, implicit_layers_.name_pool);
     61     }
     62 
     63     VkResult Parse(const char* const* names, uint32_t count) {
     64         AddImplicitLayers();
     65 
     66         const auto& arr = implicit_layers_;
     67         if (arr.result != VK_SUCCESS)
     68             return arr.result;
     69 
     70         // no need to override when there is no implicit layer
     71         if (!arr.count)
     72             return VK_SUCCESS;
     73 
     74         names_ = AllocateNameArray(arr.count + count);
     75         if (!names_)
     76             return VK_ERROR_OUT_OF_HOST_MEMORY;
     77 
     78         // add implicit layer names
     79         for (uint32_t i = 0; i < arr.count; i++)
     80             names_[i] = GetImplicitLayerName(i);
     81 
     82         name_count_ = arr.count;
     83 
     84         // add explicit layer names
     85         for (uint32_t i = 0; i < count; i++) {
     86             // ignore explicit layers that are also implicit
     87             if (IsImplicitLayer(names[i]))
     88                 continue;
     89 
     90             names_[name_count_++] = names[i];
     91         }
     92 
     93         return VK_SUCCESS;
     94     }
     95 
     96     const char* const* Names() const { return names_; }
     97 
     98     uint32_t Count() const { return name_count_; }
     99 
    100    private:
    101     struct ImplicitLayer {
    102         int priority;
    103         size_t name_offset;
    104     };
    105 
    106     struct ImplicitLayerArray {
    107         ImplicitLayer* elements;
    108         uint32_t max_count;
    109         uint32_t count;
    110 
    111         char* name_pool;
    112         size_t max_pool_size;
    113         size_t pool_size;
    114 
    115         VkResult result;
    116     };
    117 
    118     void AddImplicitLayers() {
    119         if (!is_instance_ || !driver::Debuggable())
    120             return;
    121 
    122         ParseDebugVulkanLayers();
    123         property_list(ParseDebugVulkanLayer, this);
    124 
    125         // sort by priorities
    126         auto& arr = implicit_layers_;
    127         std::sort(arr.elements, arr.elements + arr.count,
    128                   [](const ImplicitLayer& a, const ImplicitLayer& b) {
    129                       return (a.priority < b.priority);
    130                   });
    131     }
    132 
    133     void ParseDebugVulkanLayers() {
    134         // debug.vulkan.layers specifies colon-separated layer names
    135         char prop[PROPERTY_VALUE_MAX];
    136         if (!property_get("debug.vulkan.layers", prop, ""))
    137             return;
    138 
    139         // assign negative/high priorities to them
    140         int prio = -PROPERTY_VALUE_MAX;
    141 
    142         const char* p = prop;
    143         const char* delim;
    144         while ((delim = strchr(p, ':'))) {
    145             if (delim > p)
    146                 AddImplicitLayer(prio, p, static_cast<size_t>(delim - p));
    147 
    148             prio++;
    149             p = delim + 1;
    150         }
    151 
    152         if (p[0] != '\0')
    153             AddImplicitLayer(prio, p, strlen(p));
    154     }
    155 
    156     static void ParseDebugVulkanLayer(const char* key,
    157                                       const char* val,
    158                                       void* user_data) {
    159         static const char prefix[] = "debug.vulkan.layer.";
    160         const size_t prefix_len = sizeof(prefix) - 1;
    161 
    162         if (strncmp(key, prefix, prefix_len) || val[0] == '\0')
    163             return;
    164         key += prefix_len;
    165 
    166         // debug.vulkan.layer.<priority>
    167         int priority = -1;
    168         if (key[0] >= '0' && key[0] <= '9')
    169             priority = atoi(key);
    170 
    171         if (priority < 0) {
    172             ALOGW("Ignored implicit layer %s with invalid priority %s", val,
    173                   key);
    174             return;
    175         }
    176 
    177         OverrideLayerNames& override_layers =
    178             *reinterpret_cast<OverrideLayerNames*>(user_data);
    179         override_layers.AddImplicitLayer(priority, val, strlen(val));
    180     }
    181 
    182     void AddImplicitLayer(int priority, const char* name, size_t len) {
    183         if (!GrowImplicitLayerArray(1, 0))
    184             return;
    185 
    186         auto& arr = implicit_layers_;
    187         auto& layer = arr.elements[arr.count++];
    188 
    189         layer.priority = priority;
    190         layer.name_offset = AddImplicitLayerName(name, len);
    191 
    192         ALOGV("Added implicit layer %s", GetImplicitLayerName(arr.count - 1));
    193     }
    194 
    195     size_t AddImplicitLayerName(const char* name, size_t len) {
    196         if (!GrowImplicitLayerArray(0, len + 1))
    197             return 0;
    198 
    199         // add the name to the pool
    200         auto& arr = implicit_layers_;
    201         size_t offset = arr.pool_size;
    202         char* dst = arr.name_pool + offset;
    203 
    204         std::copy(name, name + len, dst);
    205         dst[len] = '\0';
    206 
    207         arr.pool_size += len + 1;
    208 
    209         return offset;
    210     }
    211 
    212     bool GrowImplicitLayerArray(uint32_t layer_count, size_t name_size) {
    213         const uint32_t initial_max_count = 16;
    214         const size_t initial_max_pool_size = 512;
    215 
    216         auto& arr = implicit_layers_;
    217 
    218         // grow the element array if needed
    219         while (arr.count + layer_count > arr.max_count) {
    220             uint32_t new_max_count =
    221                 (arr.max_count) ? (arr.max_count << 1) : initial_max_count;
    222             void* new_mem = nullptr;
    223 
    224             if (new_max_count > arr.max_count) {
    225                 new_mem = allocator_.pfnReallocation(
    226                     allocator_.pUserData, arr.elements,
    227                     sizeof(ImplicitLayer) * new_max_count,
    228                     alignof(ImplicitLayer), scope_);
    229             }
    230 
    231             if (!new_mem) {
    232                 arr.result = VK_ERROR_OUT_OF_HOST_MEMORY;
    233                 arr.count = 0;
    234                 return false;
    235             }
    236 
    237             arr.elements = reinterpret_cast<ImplicitLayer*>(new_mem);
    238             arr.max_count = new_max_count;
    239         }
    240 
    241         // grow the name pool if needed
    242         while (arr.pool_size + name_size > arr.max_pool_size) {
    243             size_t new_max_pool_size = (arr.max_pool_size)
    244                                            ? (arr.max_pool_size << 1)
    245                                            : initial_max_pool_size;
    246             void* new_mem = nullptr;
    247 
    248             if (new_max_pool_size > arr.max_pool_size) {
    249                 new_mem = allocator_.pfnReallocation(
    250                     allocator_.pUserData, arr.name_pool, new_max_pool_size,
    251                     alignof(char), scope_);
    252             }
    253 
    254             if (!new_mem) {
    255                 arr.result = VK_ERROR_OUT_OF_HOST_MEMORY;
    256                 arr.pool_size = 0;
    257                 return false;
    258             }
    259 
    260             arr.name_pool = reinterpret_cast<char*>(new_mem);
    261             arr.max_pool_size = new_max_pool_size;
    262         }
    263 
    264         return true;
    265     }
    266 
    267     const char* GetImplicitLayerName(uint32_t index) const {
    268         const auto& arr = implicit_layers_;
    269 
    270         // this may return nullptr when arr.result is not VK_SUCCESS
    271         return implicit_layers_.name_pool + arr.elements[index].name_offset;
    272     }
    273 
    274     bool IsImplicitLayer(const char* name) const {
    275         const auto& arr = implicit_layers_;
    276 
    277         for (uint32_t i = 0; i < arr.count; i++) {
    278             if (strcmp(name, GetImplicitLayerName(i)) == 0)
    279                 return true;
    280         }
    281 
    282         return false;
    283     }
    284 
    285     const char** AllocateNameArray(uint32_t count) const {
    286         return reinterpret_cast<const char**>(allocator_.pfnAllocation(
    287             allocator_.pUserData, sizeof(const char*) * count,
    288             alignof(const char*), scope_));
    289     }
    290 
    291     const bool is_instance_;
    292     const VkAllocationCallbacks& allocator_;
    293     const VkSystemAllocationScope scope_;
    294 
    295     const char** names_;
    296     uint32_t name_count_;
    297 
    298     ImplicitLayerArray implicit_layers_;
    299 };
    300 
    301 // Provide overridden extension names when there are implicit extensions.
    302 // No effect otherwise.
    303 //
    304 // This is used only to enable VK_EXT_debug_report.
    305 class OverrideExtensionNames {
    306    public:
    307     OverrideExtensionNames(bool is_instance,
    308                            const VkAllocationCallbacks& allocator)
    309         : is_instance_(is_instance),
    310           allocator_(allocator),
    311           scope_(VK_SYSTEM_ALLOCATION_SCOPE_COMMAND),
    312           names_(nullptr),
    313           name_count_(0),
    314           install_debug_callback_(false) {}
    315 
    316     ~OverrideExtensionNames() {
    317         allocator_.pfnFree(allocator_.pUserData, names_);
    318     }
    319 
    320     VkResult Parse(const char* const* names, uint32_t count) {
    321         // this is only for debug.vulkan.enable_callback
    322         if (!EnableDebugCallback())
    323             return VK_SUCCESS;
    324 
    325         names_ = AllocateNameArray(count + 1);
    326         if (!names_)
    327             return VK_ERROR_OUT_OF_HOST_MEMORY;
    328 
    329         std::copy(names, names + count, names_);
    330 
    331         name_count_ = count;
    332         names_[name_count_++] = "VK_EXT_debug_report";
    333 
    334         install_debug_callback_ = true;
    335 
    336         return VK_SUCCESS;
    337     }
    338 
    339     const char* const* Names() const { return names_; }
    340 
    341     uint32_t Count() const { return name_count_; }
    342 
    343     bool InstallDebugCallback() const { return install_debug_callback_; }
    344 
    345    private:
    346     bool EnableDebugCallback() const {
    347         return (is_instance_ && driver::Debuggable() &&
    348                 property_get_bool("debug.vulkan.enable_callback", false));
    349     }
    350 
    351     const char** AllocateNameArray(uint32_t count) const {
    352         return reinterpret_cast<const char**>(allocator_.pfnAllocation(
    353             allocator_.pUserData, sizeof(const char*) * count,
    354             alignof(const char*), scope_));
    355     }
    356 
    357     const bool is_instance_;
    358     const VkAllocationCallbacks& allocator_;
    359     const VkSystemAllocationScope scope_;
    360 
    361     const char** names_;
    362     uint32_t name_count_;
    363     bool install_debug_callback_;
    364 };
    365 
    366 // vkCreateInstance and vkCreateDevice helpers with support for layer
    367 // chaining.
    368 class LayerChain {
    369    public:
    370     struct ActiveLayer {
    371         LayerRef ref;
    372         union {
    373             VkLayerInstanceLink instance_link;
    374             VkLayerDeviceLink device_link;
    375         };
    376     };
    377 
    378     static VkResult CreateInstance(const VkInstanceCreateInfo* create_info,
    379                                    const VkAllocationCallbacks* allocator,
    380                                    VkInstance* instance_out);
    381 
    382     static VkResult CreateDevice(VkPhysicalDevice physical_dev,
    383                                  const VkDeviceCreateInfo* create_info,
    384                                  const VkAllocationCallbacks* allocator,
    385                                  VkDevice* dev_out);
    386 
    387     static void DestroyInstance(VkInstance instance,
    388                                 const VkAllocationCallbacks* allocator);
    389 
    390     static void DestroyDevice(VkDevice dev,
    391                               const VkAllocationCallbacks* allocator);
    392 
    393     static const ActiveLayer* GetActiveLayers(VkPhysicalDevice physical_dev,
    394                                               uint32_t& count);
    395 
    396    private:
    397     LayerChain(bool is_instance,
    398                const driver::DebugReportLogger& logger,
    399                const VkAllocationCallbacks& allocator);
    400     ~LayerChain();
    401 
    402     VkResult ActivateLayers(const char* const* layer_names,
    403                             uint32_t layer_count,
    404                             const char* const* extension_names,
    405                             uint32_t extension_count);
    406     VkResult ActivateLayers(VkPhysicalDevice physical_dev,
    407                             const char* const* layer_names,
    408                             uint32_t layer_count,
    409                             const char* const* extension_names,
    410                             uint32_t extension_count);
    411     ActiveLayer* AllocateLayerArray(uint32_t count) const;
    412     VkResult LoadLayer(ActiveLayer& layer, const char* name);
    413     void SetupLayerLinks();
    414 
    415     bool Empty() const;
    416     void ModifyCreateInfo(VkInstanceCreateInfo& info);
    417     void ModifyCreateInfo(VkDeviceCreateInfo& info);
    418 
    419     VkResult Create(const VkInstanceCreateInfo* create_info,
    420                     const VkAllocationCallbacks* allocator,
    421                     VkInstance* instance_out);
    422 
    423     VkResult Create(VkPhysicalDevice physical_dev,
    424                     const VkDeviceCreateInfo* create_info,
    425                     const VkAllocationCallbacks* allocator,
    426                     VkDevice* dev_out);
    427 
    428     VkResult ValidateExtensions(const char* const* extension_names,
    429                                 uint32_t extension_count);
    430     VkResult ValidateExtensions(VkPhysicalDevice physical_dev,
    431                                 const char* const* extension_names,
    432                                 uint32_t extension_count);
    433     VkExtensionProperties* AllocateDriverExtensionArray(uint32_t count) const;
    434     bool IsLayerExtension(const char* name) const;
    435     bool IsDriverExtension(const char* name) const;
    436 
    437     template <typename DataType>
    438     void StealLayers(DataType& data);
    439 
    440     static void DestroyLayers(ActiveLayer* layers,
    441                               uint32_t count,
    442                               const VkAllocationCallbacks& allocator);
    443 
    444     static VKAPI_ATTR VkResult SetInstanceLoaderData(VkInstance instance,
    445                                                      void* object);
    446     static VKAPI_ATTR VkResult SetDeviceLoaderData(VkDevice device,
    447                                                    void* object);
    448 
    449     static VKAPI_ATTR VkBool32
    450     DebugReportCallback(VkDebugReportFlagsEXT flags,
    451                         VkDebugReportObjectTypeEXT obj_type,
    452                         uint64_t obj,
    453                         size_t location,
    454                         int32_t msg_code,
    455                         const char* layer_prefix,
    456                         const char* msg,
    457                         void* user_data);
    458 
    459     const bool is_instance_;
    460     const driver::DebugReportLogger& logger_;
    461     const VkAllocationCallbacks& allocator_;
    462 
    463     OverrideLayerNames override_layers_;
    464     OverrideExtensionNames override_extensions_;
    465 
    466     ActiveLayer* layers_;
    467     uint32_t layer_count_;
    468 
    469     PFN_vkGetInstanceProcAddr get_instance_proc_addr_;
    470     PFN_vkGetDeviceProcAddr get_device_proc_addr_;
    471 
    472     union {
    473         VkLayerInstanceCreateInfo instance_chain_info_[2];
    474         VkLayerDeviceCreateInfo device_chain_info_[2];
    475     };
    476 
    477     VkExtensionProperties* driver_extensions_;
    478     uint32_t driver_extension_count_;
    479     std::bitset<driver::ProcHook::EXTENSION_COUNT> enabled_extensions_;
    480 };
    481 
    482 LayerChain::LayerChain(bool is_instance,
    483                        const driver::DebugReportLogger& logger,
    484                        const VkAllocationCallbacks& allocator)
    485     : is_instance_(is_instance),
    486       logger_(logger),
    487       allocator_(allocator),
    488       override_layers_(is_instance, allocator),
    489       override_extensions_(is_instance, allocator),
    490       layers_(nullptr),
    491       layer_count_(0),
    492       get_instance_proc_addr_(nullptr),
    493       get_device_proc_addr_(nullptr),
    494       driver_extensions_(nullptr),
    495       driver_extension_count_(0) {
    496     enabled_extensions_.set(driver::ProcHook::EXTENSION_CORE);
    497 }
    498 
    499 LayerChain::~LayerChain() {
    500     allocator_.pfnFree(allocator_.pUserData, driver_extensions_);
    501     DestroyLayers(layers_, layer_count_, allocator_);
    502 }
    503 
    504 VkResult LayerChain::ActivateLayers(const char* const* layer_names,
    505                                     uint32_t layer_count,
    506                                     const char* const* extension_names,
    507                                     uint32_t extension_count) {
    508     VkResult result = override_layers_.Parse(layer_names, layer_count);
    509     if (result != VK_SUCCESS)
    510         return result;
    511 
    512     result = override_extensions_.Parse(extension_names, extension_count);
    513     if (result != VK_SUCCESS)
    514         return result;
    515 
    516     if (override_layers_.Count()) {
    517         layer_names = override_layers_.Names();
    518         layer_count = override_layers_.Count();
    519     }
    520 
    521     if (!layer_count) {
    522         // point head of chain to the driver
    523         get_instance_proc_addr_ = driver::GetInstanceProcAddr;
    524 
    525         return VK_SUCCESS;
    526     }
    527 
    528     layers_ = AllocateLayerArray(layer_count);
    529     if (!layers_)
    530         return VK_ERROR_OUT_OF_HOST_MEMORY;
    531 
    532     // load layers
    533     for (uint32_t i = 0; i < layer_count; i++) {
    534         result = LoadLayer(layers_[i], layer_names[i]);
    535         if (result != VK_SUCCESS)
    536             return result;
    537 
    538         // count loaded layers for proper destructions on errors
    539         layer_count_++;
    540     }
    541 
    542     SetupLayerLinks();
    543 
    544     return VK_SUCCESS;
    545 }
    546 
    547 VkResult LayerChain::ActivateLayers(VkPhysicalDevice physical_dev,
    548                                     const char* const* layer_names,
    549                                     uint32_t layer_count,
    550                                     const char* const* extension_names,
    551                                     uint32_t extension_count) {
    552     uint32_t instance_layer_count;
    553     const ActiveLayer* instance_layers =
    554         GetActiveLayers(physical_dev, instance_layer_count);
    555 
    556     // log a message if the application device layer array is not empty nor an
    557     // exact match of the instance layer array.
    558     if (layer_count) {
    559         bool exact_match = (instance_layer_count == layer_count);
    560         if (exact_match) {
    561             for (uint32_t i = 0; i < instance_layer_count; i++) {
    562                 const Layer& l = *instance_layers[i].ref;
    563                 if (strcmp(GetLayerProperties(l).layerName, layer_names[i])) {
    564                     exact_match = false;
    565                     break;
    566                 }
    567             }
    568         }
    569 
    570         if (!exact_match) {
    571             logger_.Warn(physical_dev,
    572                          "Device layers disagree with instance layers and are "
    573                          "overridden by instance layers");
    574         }
    575     }
    576 
    577     VkResult result =
    578         override_extensions_.Parse(extension_names, extension_count);
    579     if (result != VK_SUCCESS)
    580         return result;
    581 
    582     if (!instance_layer_count) {
    583         // point head of chain to the driver
    584         get_instance_proc_addr_ = driver::GetInstanceProcAddr;
    585         get_device_proc_addr_ = driver::GetDeviceProcAddr;
    586 
    587         return VK_SUCCESS;
    588     }
    589 
    590     layers_ = AllocateLayerArray(instance_layer_count);
    591     if (!layers_)
    592         return VK_ERROR_OUT_OF_HOST_MEMORY;
    593 
    594     for (uint32_t i = 0; i < instance_layer_count; i++) {
    595         const Layer& l = *instance_layers[i].ref;
    596 
    597         // no need to and cannot chain non-global layers
    598         if (!IsLayerGlobal(l))
    599             continue;
    600 
    601         // this never fails
    602         new (&layers_[layer_count_++]) ActiveLayer{GetLayerRef(l), {}};
    603     }
    604 
    605     // this may happen when all layers are non-global ones
    606     if (!layer_count_) {
    607         get_instance_proc_addr_ = driver::GetInstanceProcAddr;
    608         get_device_proc_addr_ = driver::GetDeviceProcAddr;
    609         return VK_SUCCESS;
    610     }
    611 
    612     SetupLayerLinks();
    613 
    614     return VK_SUCCESS;
    615 }
    616 
    617 LayerChain::ActiveLayer* LayerChain::AllocateLayerArray(uint32_t count) const {
    618     VkSystemAllocationScope scope = (is_instance_)
    619                                         ? VK_SYSTEM_ALLOCATION_SCOPE_INSTANCE
    620                                         : VK_SYSTEM_ALLOCATION_SCOPE_COMMAND;
    621 
    622     return reinterpret_cast<ActiveLayer*>(allocator_.pfnAllocation(
    623         allocator_.pUserData, sizeof(ActiveLayer) * count, alignof(ActiveLayer),
    624         scope));
    625 }
    626 
    627 VkResult LayerChain::LoadLayer(ActiveLayer& layer, const char* name) {
    628     const Layer* l = FindLayer(name);
    629     if (!l) {
    630         logger_.Err(VK_NULL_HANDLE, "Failed to find layer %s", name);
    631         return VK_ERROR_LAYER_NOT_PRESENT;
    632     }
    633 
    634     new (&layer) ActiveLayer{GetLayerRef(*l), {}};
    635     if (!layer.ref) {
    636         ALOGW("Failed to open layer %s", name);
    637         layer.ref.~LayerRef();
    638         return VK_ERROR_LAYER_NOT_PRESENT;
    639     }
    640 
    641     ALOGI("Loaded layer %s", name);
    642 
    643     return VK_SUCCESS;
    644 }
    645 
    646 void LayerChain::SetupLayerLinks() {
    647     if (is_instance_) {
    648         for (uint32_t i = 0; i < layer_count_; i++) {
    649             ActiveLayer& layer = layers_[i];
    650 
    651             // point head of chain to the first layer
    652             if (i == 0)
    653                 get_instance_proc_addr_ = layer.ref.GetGetInstanceProcAddr();
    654 
    655             // point tail of chain to the driver
    656             if (i == layer_count_ - 1) {
    657                 layer.instance_link.pNext = nullptr;
    658                 layer.instance_link.pfnNextGetInstanceProcAddr =
    659                     driver::GetInstanceProcAddr;
    660                 break;
    661             }
    662 
    663             const ActiveLayer& next = layers_[i + 1];
    664 
    665             // const_cast as some naughty layers want to modify our links!
    666             layer.instance_link.pNext =
    667                 const_cast<VkLayerInstanceLink*>(&next.instance_link);
    668             layer.instance_link.pfnNextGetInstanceProcAddr =
    669                 next.ref.GetGetInstanceProcAddr();
    670         }
    671     } else {
    672         for (uint32_t i = 0; i < layer_count_; i++) {
    673             ActiveLayer& layer = layers_[i];
    674 
    675             // point head of chain to the first layer
    676             if (i == 0) {
    677                 get_instance_proc_addr_ = layer.ref.GetGetInstanceProcAddr();
    678                 get_device_proc_addr_ = layer.ref.GetGetDeviceProcAddr();
    679             }
    680 
    681             // point tail of chain to the driver
    682             if (i == layer_count_ - 1) {
    683                 layer.device_link.pNext = nullptr;
    684                 layer.device_link.pfnNextGetInstanceProcAddr =
    685                     driver::GetInstanceProcAddr;
    686                 layer.device_link.pfnNextGetDeviceProcAddr =
    687                     driver::GetDeviceProcAddr;
    688                 break;
    689             }
    690 
    691             const ActiveLayer& next = layers_[i + 1];
    692 
    693             // const_cast as some naughty layers want to modify our links!
    694             layer.device_link.pNext =
    695                 const_cast<VkLayerDeviceLink*>(&next.device_link);
    696             layer.device_link.pfnNextGetInstanceProcAddr =
    697                 next.ref.GetGetInstanceProcAddr();
    698             layer.device_link.pfnNextGetDeviceProcAddr =
    699                 next.ref.GetGetDeviceProcAddr();
    700         }
    701     }
    702 }
    703 
    704 bool LayerChain::Empty() const {
    705     return (!layer_count_ && !override_layers_.Count() &&
    706             !override_extensions_.Count());
    707 }
    708 
    709 void LayerChain::ModifyCreateInfo(VkInstanceCreateInfo& info) {
    710     if (layer_count_) {
    711         auto& link_info = instance_chain_info_[1];
    712         link_info.sType = VK_STRUCTURE_TYPE_LOADER_INSTANCE_CREATE_INFO;
    713         link_info.pNext = info.pNext;
    714         link_info.function = VK_LAYER_FUNCTION_LINK;
    715         link_info.u.pLayerInfo = &layers_[0].instance_link;
    716 
    717         auto& cb_info = instance_chain_info_[0];
    718         cb_info.sType = VK_STRUCTURE_TYPE_LOADER_INSTANCE_CREATE_INFO;
    719         cb_info.pNext = &link_info;
    720         cb_info.function = VK_LAYER_FUNCTION_DATA_CALLBACK;
    721         cb_info.u.pfnSetInstanceLoaderData = SetInstanceLoaderData;
    722 
    723         info.pNext = &cb_info;
    724     }
    725 
    726     if (override_layers_.Count()) {
    727         info.enabledLayerCount = override_layers_.Count();
    728         info.ppEnabledLayerNames = override_layers_.Names();
    729     }
    730 
    731     if (override_extensions_.Count()) {
    732         info.enabledExtensionCount = override_extensions_.Count();
    733         info.ppEnabledExtensionNames = override_extensions_.Names();
    734     }
    735 }
    736 
    737 void LayerChain::ModifyCreateInfo(VkDeviceCreateInfo& info) {
    738     if (layer_count_) {
    739         auto& link_info = device_chain_info_[1];
    740         link_info.sType = VK_STRUCTURE_TYPE_LOADER_DEVICE_CREATE_INFO;
    741         link_info.pNext = info.pNext;
    742         link_info.function = VK_LAYER_FUNCTION_LINK;
    743         link_info.u.pLayerInfo = &layers_[0].device_link;
    744 
    745         auto& cb_info = device_chain_info_[0];
    746         cb_info.sType = VK_STRUCTURE_TYPE_LOADER_DEVICE_CREATE_INFO;
    747         cb_info.pNext = &link_info;
    748         cb_info.function = VK_LAYER_FUNCTION_DATA_CALLBACK;
    749         cb_info.u.pfnSetDeviceLoaderData = SetDeviceLoaderData;
    750 
    751         info.pNext = &cb_info;
    752     }
    753 
    754     if (override_layers_.Count()) {
    755         info.enabledLayerCount = override_layers_.Count();
    756         info.ppEnabledLayerNames = override_layers_.Names();
    757     }
    758 
    759     if (override_extensions_.Count()) {
    760         info.enabledExtensionCount = override_extensions_.Count();
    761         info.ppEnabledExtensionNames = override_extensions_.Names();
    762     }
    763 }
    764 
    765 VkResult LayerChain::Create(const VkInstanceCreateInfo* create_info,
    766                             const VkAllocationCallbacks* allocator,
    767                             VkInstance* instance_out) {
    768     VkResult result = ValidateExtensions(create_info->ppEnabledExtensionNames,
    769                                          create_info->enabledExtensionCount);
    770     if (result != VK_SUCCESS)
    771         return result;
    772 
    773     // call down the chain
    774     PFN_vkCreateInstance create_instance =
    775         reinterpret_cast<PFN_vkCreateInstance>(
    776             get_instance_proc_addr_(VK_NULL_HANDLE, "vkCreateInstance"));
    777     VkInstance instance;
    778     result = create_instance(create_info, allocator, &instance);
    779     if (result != VK_SUCCESS)
    780         return result;
    781 
    782     // initialize InstanceData
    783     InstanceData& data = GetData(instance);
    784 
    785     if (!InitDispatchTable(instance, get_instance_proc_addr_,
    786                            enabled_extensions_)) {
    787         if (data.dispatch.DestroyInstance)
    788             data.dispatch.DestroyInstance(instance, allocator);
    789 
    790         return VK_ERROR_INITIALIZATION_FAILED;
    791     }
    792 
    793     // install debug report callback
    794     if (override_extensions_.InstallDebugCallback()) {
    795         PFN_vkCreateDebugReportCallbackEXT create_debug_report_callback =
    796             reinterpret_cast<PFN_vkCreateDebugReportCallbackEXT>(
    797                 get_instance_proc_addr_(instance,
    798                                         "vkCreateDebugReportCallbackEXT"));
    799         data.destroy_debug_callback =
    800             reinterpret_cast<PFN_vkDestroyDebugReportCallbackEXT>(
    801                 get_instance_proc_addr_(instance,
    802                                         "vkDestroyDebugReportCallbackEXT"));
    803         if (!create_debug_report_callback || !data.destroy_debug_callback) {
    804             ALOGE("Broken VK_EXT_debug_report support");
    805             data.dispatch.DestroyInstance(instance, allocator);
    806             return VK_ERROR_INITIALIZATION_FAILED;
    807         }
    808 
    809         VkDebugReportCallbackCreateInfoEXT debug_callback_info = {};
    810         debug_callback_info.sType =
    811             VK_STRUCTURE_TYPE_DEBUG_REPORT_CREATE_INFO_EXT;
    812         debug_callback_info.flags =
    813             VK_DEBUG_REPORT_ERROR_BIT_EXT | VK_DEBUG_REPORT_WARNING_BIT_EXT;
    814         debug_callback_info.pfnCallback = DebugReportCallback;
    815 
    816         VkDebugReportCallbackEXT debug_callback;
    817         result = create_debug_report_callback(instance, &debug_callback_info,
    818                                               nullptr, &debug_callback);
    819         if (result != VK_SUCCESS) {
    820             ALOGE("Failed to install debug report callback");
    821             data.dispatch.DestroyInstance(instance, allocator);
    822             return VK_ERROR_INITIALIZATION_FAILED;
    823         }
    824 
    825         data.debug_callback = debug_callback;
    826 
    827         ALOGI("Installed debug report callback");
    828     }
    829 
    830     StealLayers(data);
    831 
    832     *instance_out = instance;
    833 
    834     return VK_SUCCESS;
    835 }
    836 
    837 VkResult LayerChain::Create(VkPhysicalDevice physical_dev,
    838                             const VkDeviceCreateInfo* create_info,
    839                             const VkAllocationCallbacks* allocator,
    840                             VkDevice* dev_out) {
    841     VkResult result =
    842         ValidateExtensions(physical_dev, create_info->ppEnabledExtensionNames,
    843                            create_info->enabledExtensionCount);
    844     if (result != VK_SUCCESS)
    845         return result;
    846 
    847     // call down the chain
    848     PFN_vkCreateDevice create_device =
    849         GetData(physical_dev).dispatch.CreateDevice;
    850     VkDevice dev;
    851     result = create_device(physical_dev, create_info, allocator, &dev);
    852     if (result != VK_SUCCESS)
    853         return result;
    854 
    855     // initialize DeviceData
    856     DeviceData& data = GetData(dev);
    857 
    858     if (!InitDispatchTable(dev, get_device_proc_addr_, enabled_extensions_)) {
    859         if (data.dispatch.DestroyDevice)
    860             data.dispatch.DestroyDevice(dev, allocator);
    861 
    862         return VK_ERROR_INITIALIZATION_FAILED;
    863     }
    864 
    865     // no StealLayers so that active layers are destroyed with this
    866     // LayerChain
    867     *dev_out = dev;
    868 
    869     return VK_SUCCESS;
    870 }
    871 
    872 VkResult LayerChain::ValidateExtensions(const char* const* extension_names,
    873                                         uint32_t extension_count) {
    874     if (!extension_count)
    875         return VK_SUCCESS;
    876 
    877     // query driver instance extensions
    878     uint32_t count;
    879     VkResult result =
    880         EnumerateInstanceExtensionProperties(nullptr, &count, nullptr);
    881     if (result == VK_SUCCESS && count) {
    882         driver_extensions_ = AllocateDriverExtensionArray(count);
    883         result = (driver_extensions_) ? EnumerateInstanceExtensionProperties(
    884                                             nullptr, &count, driver_extensions_)
    885                                       : VK_ERROR_OUT_OF_HOST_MEMORY;
    886     }
    887     if (result != VK_SUCCESS)
    888         return result;
    889 
    890     driver_extension_count_ = count;
    891 
    892     for (uint32_t i = 0; i < extension_count; i++) {
    893         const char* name = extension_names[i];
    894         if (!IsLayerExtension(name) && !IsDriverExtension(name)) {
    895             logger_.Err(VK_NULL_HANDLE,
    896                         "Failed to enable missing instance extension %s", name);
    897             return VK_ERROR_EXTENSION_NOT_PRESENT;
    898         }
    899 
    900         auto ext_bit = driver::GetProcHookExtension(name);
    901         if (ext_bit != driver::ProcHook::EXTENSION_UNKNOWN)
    902             enabled_extensions_.set(ext_bit);
    903     }
    904 
    905     return VK_SUCCESS;
    906 }
    907 
    908 VkResult LayerChain::ValidateExtensions(VkPhysicalDevice physical_dev,
    909                                         const char* const* extension_names,
    910                                         uint32_t extension_count) {
    911     if (!extension_count)
    912         return VK_SUCCESS;
    913 
    914     // query driver device extensions
    915     uint32_t count;
    916     VkResult result = EnumerateDeviceExtensionProperties(physical_dev, nullptr,
    917                                                          &count, nullptr);
    918     if (result == VK_SUCCESS && count) {
    919         driver_extensions_ = AllocateDriverExtensionArray(count);
    920         result = (driver_extensions_)
    921                      ? EnumerateDeviceExtensionProperties(
    922                            physical_dev, nullptr, &count, driver_extensions_)
    923                      : VK_ERROR_OUT_OF_HOST_MEMORY;
    924     }
    925     if (result != VK_SUCCESS)
    926         return result;
    927 
    928     driver_extension_count_ = count;
    929 
    930     for (uint32_t i = 0; i < extension_count; i++) {
    931         const char* name = extension_names[i];
    932         if (!IsLayerExtension(name) && !IsDriverExtension(name)) {
    933             logger_.Err(physical_dev,
    934                         "Failed to enable missing device extension %s", name);
    935             return VK_ERROR_EXTENSION_NOT_PRESENT;
    936         }
    937 
    938         auto ext_bit = driver::GetProcHookExtension(name);
    939         if (ext_bit != driver::ProcHook::EXTENSION_UNKNOWN)
    940             enabled_extensions_.set(ext_bit);
    941     }
    942 
    943     return VK_SUCCESS;
    944 }
    945 
    946 VkExtensionProperties* LayerChain::AllocateDriverExtensionArray(
    947     uint32_t count) const {
    948     return reinterpret_cast<VkExtensionProperties*>(allocator_.pfnAllocation(
    949         allocator_.pUserData, sizeof(VkExtensionProperties) * count,
    950         alignof(VkExtensionProperties), VK_SYSTEM_ALLOCATION_SCOPE_COMMAND));
    951 }
    952 
    953 bool LayerChain::IsLayerExtension(const char* name) const {
    954     if (is_instance_) {
    955         for (uint32_t i = 0; i < layer_count_; i++) {
    956             const ActiveLayer& layer = layers_[i];
    957             if (FindLayerInstanceExtension(*layer.ref, name))
    958                 return true;
    959         }
    960     } else {
    961         for (uint32_t i = 0; i < layer_count_; i++) {
    962             const ActiveLayer& layer = layers_[i];
    963             if (FindLayerDeviceExtension(*layer.ref, name))
    964                 return true;
    965         }
    966     }
    967 
    968     return false;
    969 }
    970 
    971 bool LayerChain::IsDriverExtension(const char* name) const {
    972     for (uint32_t i = 0; i < driver_extension_count_; i++) {
    973         if (strcmp(driver_extensions_[i].extensionName, name) == 0)
    974             return true;
    975     }
    976 
    977     return false;
    978 }
    979 
    980 template <typename DataType>
    981 void LayerChain::StealLayers(DataType& data) {
    982     data.layers = layers_;
    983     data.layer_count = layer_count_;
    984 
    985     layers_ = nullptr;
    986     layer_count_ = 0;
    987 }
    988 
    989 void LayerChain::DestroyLayers(ActiveLayer* layers,
    990                                uint32_t count,
    991                                const VkAllocationCallbacks& allocator) {
    992     for (uint32_t i = 0; i < count; i++)
    993         layers[i].ref.~LayerRef();
    994 
    995     allocator.pfnFree(allocator.pUserData, layers);
    996 }
    997 
    998 VkResult LayerChain::SetInstanceLoaderData(VkInstance instance, void* object) {
    999     driver::InstanceDispatchable dispatchable =
   1000         reinterpret_cast<driver::InstanceDispatchable>(object);
   1001 
   1002     return (driver::SetDataInternal(dispatchable, &driver::GetData(instance)))
   1003                ? VK_SUCCESS
   1004                : VK_ERROR_INITIALIZATION_FAILED;
   1005 }
   1006 
   1007 VkResult LayerChain::SetDeviceLoaderData(VkDevice device, void* object) {
   1008     driver::DeviceDispatchable dispatchable =
   1009         reinterpret_cast<driver::DeviceDispatchable>(object);
   1010 
   1011     return (driver::SetDataInternal(dispatchable, &driver::GetData(device)))
   1012                ? VK_SUCCESS
   1013                : VK_ERROR_INITIALIZATION_FAILED;
   1014 }
   1015 
   1016 VkBool32 LayerChain::DebugReportCallback(VkDebugReportFlagsEXT flags,
   1017                                          VkDebugReportObjectTypeEXT obj_type,
   1018                                          uint64_t obj,
   1019                                          size_t location,
   1020                                          int32_t msg_code,
   1021                                          const char* layer_prefix,
   1022                                          const char* msg,
   1023                                          void* user_data) {
   1024     int prio;
   1025 
   1026     if (flags & VK_DEBUG_REPORT_ERROR_BIT_EXT)
   1027         prio = ANDROID_LOG_ERROR;
   1028     else if (flags & (VK_DEBUG_REPORT_WARNING_BIT_EXT |
   1029                       VK_DEBUG_REPORT_PERFORMANCE_WARNING_BIT_EXT))
   1030         prio = ANDROID_LOG_WARN;
   1031     else if (flags & VK_DEBUG_REPORT_INFORMATION_BIT_EXT)
   1032         prio = ANDROID_LOG_INFO;
   1033     else if (flags & VK_DEBUG_REPORT_DEBUG_BIT_EXT)
   1034         prio = ANDROID_LOG_DEBUG;
   1035     else
   1036         prio = ANDROID_LOG_UNKNOWN;
   1037 
   1038     LOG_PRI(prio, LOG_TAG, "[%s] Code %d : %s", layer_prefix, msg_code, msg);
   1039 
   1040     (void)obj_type;
   1041     (void)obj;
   1042     (void)location;
   1043     (void)user_data;
   1044 
   1045     return false;
   1046 }
   1047 
   1048 VkResult LayerChain::CreateInstance(const VkInstanceCreateInfo* create_info,
   1049                                     const VkAllocationCallbacks* allocator,
   1050                                     VkInstance* instance_out) {
   1051     LayerChain chain(true, driver::DebugReportLogger(*create_info),
   1052                      (allocator) ? *allocator : driver::GetDefaultAllocator());
   1053 
   1054     VkResult result = chain.ActivateLayers(create_info->ppEnabledLayerNames,
   1055                                            create_info->enabledLayerCount,
   1056                                            create_info->ppEnabledExtensionNames,
   1057                                            create_info->enabledExtensionCount);
   1058     if (result != VK_SUCCESS)
   1059         return result;
   1060 
   1061     // use a local create info when the chain is not empty
   1062     VkInstanceCreateInfo local_create_info;
   1063     if (!chain.Empty()) {
   1064         local_create_info = *create_info;
   1065         chain.ModifyCreateInfo(local_create_info);
   1066         create_info = &local_create_info;
   1067     }
   1068 
   1069     return chain.Create(create_info, allocator, instance_out);
   1070 }
   1071 
   1072 VkResult LayerChain::CreateDevice(VkPhysicalDevice physical_dev,
   1073                                   const VkDeviceCreateInfo* create_info,
   1074                                   const VkAllocationCallbacks* allocator,
   1075                                   VkDevice* dev_out) {
   1076     LayerChain chain(
   1077         false, driver::Logger(physical_dev),
   1078         (allocator) ? *allocator : driver::GetData(physical_dev).allocator);
   1079 
   1080     VkResult result = chain.ActivateLayers(
   1081         physical_dev, create_info->ppEnabledLayerNames,
   1082         create_info->enabledLayerCount, create_info->ppEnabledExtensionNames,
   1083         create_info->enabledExtensionCount);
   1084     if (result != VK_SUCCESS)
   1085         return result;
   1086 
   1087     // use a local create info when the chain is not empty
   1088     VkDeviceCreateInfo local_create_info;
   1089     if (!chain.Empty()) {
   1090         local_create_info = *create_info;
   1091         chain.ModifyCreateInfo(local_create_info);
   1092         create_info = &local_create_info;
   1093     }
   1094 
   1095     return chain.Create(physical_dev, create_info, allocator, dev_out);
   1096 }
   1097 
   1098 void LayerChain::DestroyInstance(VkInstance instance,
   1099                                  const VkAllocationCallbacks* allocator) {
   1100     InstanceData& data = GetData(instance);
   1101 
   1102     if (data.debug_callback != VK_NULL_HANDLE)
   1103         data.destroy_debug_callback(instance, data.debug_callback, allocator);
   1104 
   1105     ActiveLayer* layers = reinterpret_cast<ActiveLayer*>(data.layers);
   1106     uint32_t layer_count = data.layer_count;
   1107 
   1108     VkAllocationCallbacks local_allocator;
   1109     if (!allocator)
   1110         local_allocator = driver::GetData(instance).allocator;
   1111 
   1112     // this also destroys InstanceData
   1113     data.dispatch.DestroyInstance(instance, allocator);
   1114 
   1115     DestroyLayers(layers, layer_count,
   1116                   (allocator) ? *allocator : local_allocator);
   1117 }
   1118 
   1119 void LayerChain::DestroyDevice(VkDevice device,
   1120                                const VkAllocationCallbacks* allocator) {
   1121     DeviceData& data = GetData(device);
   1122     // this also destroys DeviceData
   1123     data.dispatch.DestroyDevice(device, allocator);
   1124 }
   1125 
   1126 const LayerChain::ActiveLayer* LayerChain::GetActiveLayers(
   1127     VkPhysicalDevice physical_dev,
   1128     uint32_t& count) {
   1129     count = GetData(physical_dev).layer_count;
   1130     return reinterpret_cast<const ActiveLayer*>(GetData(physical_dev).layers);
   1131 }
   1132 
   1133 // ----------------------------------------------------------------------------
   1134 
   1135 bool EnsureInitialized() {
   1136     static std::once_flag once_flag;
   1137     static bool initialized;
   1138 
   1139     std::call_once(once_flag, []() {
   1140         if (driver::OpenHAL()) {
   1141             DiscoverLayers();
   1142             initialized = true;
   1143         }
   1144     });
   1145 
   1146     return initialized;
   1147 }
   1148 
   1149 }  // anonymous namespace
   1150 
   1151 VkResult CreateInstance(const VkInstanceCreateInfo* pCreateInfo,
   1152                         const VkAllocationCallbacks* pAllocator,
   1153                         VkInstance* pInstance) {
   1154     if (!EnsureInitialized())
   1155         return VK_ERROR_INITIALIZATION_FAILED;
   1156 
   1157     return LayerChain::CreateInstance(pCreateInfo, pAllocator, pInstance);
   1158 }
   1159 
   1160 void DestroyInstance(VkInstance instance,
   1161                      const VkAllocationCallbacks* pAllocator) {
   1162     if (instance != VK_NULL_HANDLE)
   1163         LayerChain::DestroyInstance(instance, pAllocator);
   1164 }
   1165 
   1166 VkResult CreateDevice(VkPhysicalDevice physicalDevice,
   1167                       const VkDeviceCreateInfo* pCreateInfo,
   1168                       const VkAllocationCallbacks* pAllocator,
   1169                       VkDevice* pDevice) {
   1170     return LayerChain::CreateDevice(physicalDevice, pCreateInfo, pAllocator,
   1171                                     pDevice);
   1172 }
   1173 
   1174 void DestroyDevice(VkDevice device, const VkAllocationCallbacks* pAllocator) {
   1175     if (device != VK_NULL_HANDLE)
   1176         LayerChain::DestroyDevice(device, pAllocator);
   1177 }
   1178 
   1179 VkResult EnumerateInstanceLayerProperties(uint32_t* pPropertyCount,
   1180                                           VkLayerProperties* pProperties) {
   1181     if (!EnsureInitialized())
   1182         return VK_ERROR_INITIALIZATION_FAILED;
   1183 
   1184     uint32_t count = GetLayerCount();
   1185 
   1186     if (!pProperties) {
   1187         *pPropertyCount = count;
   1188         return VK_SUCCESS;
   1189     }
   1190 
   1191     uint32_t copied = std::min(*pPropertyCount, count);
   1192     for (uint32_t i = 0; i < copied; i++)
   1193         pProperties[i] = GetLayerProperties(GetLayer(i));
   1194     *pPropertyCount = copied;
   1195 
   1196     return (copied == count) ? VK_SUCCESS : VK_INCOMPLETE;
   1197 }
   1198 
   1199 VkResult EnumerateInstanceExtensionProperties(
   1200     const char* pLayerName,
   1201     uint32_t* pPropertyCount,
   1202     VkExtensionProperties* pProperties) {
   1203     if (!EnsureInitialized())
   1204         return VK_ERROR_INITIALIZATION_FAILED;
   1205 
   1206     if (pLayerName) {
   1207         const Layer* layer = FindLayer(pLayerName);
   1208         if (!layer)
   1209             return VK_ERROR_LAYER_NOT_PRESENT;
   1210 
   1211         uint32_t count;
   1212         const VkExtensionProperties* props =
   1213             GetLayerInstanceExtensions(*layer, count);
   1214 
   1215         if (!pProperties || *pPropertyCount > count)
   1216             *pPropertyCount = count;
   1217         if (pProperties)
   1218             std::copy(props, props + *pPropertyCount, pProperties);
   1219 
   1220         return *pPropertyCount < count ? VK_INCOMPLETE : VK_SUCCESS;
   1221     }
   1222 
   1223     // TODO how about extensions from implicitly enabled layers?
   1224     return vulkan::driver::EnumerateInstanceExtensionProperties(
   1225         nullptr, pPropertyCount, pProperties);
   1226 }
   1227 
   1228 VkResult EnumerateDeviceLayerProperties(VkPhysicalDevice physicalDevice,
   1229                                         uint32_t* pPropertyCount,
   1230                                         VkLayerProperties* pProperties) {
   1231     uint32_t count;
   1232     const LayerChain::ActiveLayer* layers =
   1233         LayerChain::GetActiveLayers(physicalDevice, count);
   1234 
   1235     if (!pProperties) {
   1236         *pPropertyCount = count;
   1237         return VK_SUCCESS;
   1238     }
   1239 
   1240     uint32_t copied = std::min(*pPropertyCount, count);
   1241     for (uint32_t i = 0; i < copied; i++)
   1242         pProperties[i] = GetLayerProperties(*layers[i].ref);
   1243     *pPropertyCount = copied;
   1244 
   1245     return (copied == count) ? VK_SUCCESS : VK_INCOMPLETE;
   1246 }
   1247 
   1248 VkResult EnumerateDeviceExtensionProperties(
   1249     VkPhysicalDevice physicalDevice,
   1250     const char* pLayerName,
   1251     uint32_t* pPropertyCount,
   1252     VkExtensionProperties* pProperties) {
   1253     if (pLayerName) {
   1254         // EnumerateDeviceLayerProperties enumerates active layers for
   1255         // backward compatibility.  The extension query here should work for
   1256         // all layers.
   1257         const Layer* layer = FindLayer(pLayerName);
   1258         if (!layer)
   1259             return VK_ERROR_LAYER_NOT_PRESENT;
   1260 
   1261         uint32_t count;
   1262         const VkExtensionProperties* props =
   1263             GetLayerDeviceExtensions(*layer, count);
   1264 
   1265         if (!pProperties || *pPropertyCount > count)
   1266             *pPropertyCount = count;
   1267         if (pProperties)
   1268             std::copy(props, props + *pPropertyCount, pProperties);
   1269 
   1270         return *pPropertyCount < count ? VK_INCOMPLETE : VK_SUCCESS;
   1271     }
   1272 
   1273     // TODO how about extensions from implicitly enabled layers?
   1274     const InstanceData& data = GetData(physicalDevice);
   1275     return data.dispatch.EnumerateDeviceExtensionProperties(
   1276         physicalDevice, nullptr, pPropertyCount, pProperties);
   1277 }
   1278 
   1279 }  // namespace api
   1280 }  // namespace vulkan
   1281