loader: implement new layer init method

New layer init method requires the construction of
Link information for CreateInstance and CreateDevice
that is accessible to layers via the CreateInfo.pNext pointer.
The layer can then use the Get*ProcAddr from the Link
structure to initialize their dispatch table if the
call down the chain returns successfully.
This removes the need to do special initialization work
at Get*ProcAddr time.
Layer Get*ProcAddr now return their internal function
pointers regardless of the value of instance or device.
Only need to have valid instance & device when looking
up extensions or when passing the request down the chain.
This mechanism allows us to remove object wrapping used
by the loader previously. Also simplifies the dispatch table
setup.

Conflicts:
	layers/device_limits.cpp
	layers/draw_state.cpp
	loader/loader.c
	loader/trampoline.c

1 files changed, 39 insertions, 30 deletions

diff --git a/layers/screenshot.cpp b/layers/screenshot.cpp
index 521aedc6..32312897 100644
--- a/layers/screenshot.cpp
+++ b/layers/screenshot.cpp
@@ -406,21 +406,36 @@ VK_LAYER_EXPORT VKAPI_ATTR VkResult VKAPI_CALL vkCreateDevice(
     const VkAllocationCallbacks* pAllocator,
     VkDevice                 *pDevice)
 {
-    VkLayerDispatchTable *pDisp  = get_dispatch_table(screenshot_device_table_map, *pDevice);
-    VkResult result = pDisp->CreateDevice(gpu, pCreateInfo, pAllocator, pDevice);
-
-    if (result == VK_SUCCESS) {
-        init_screenshot();
-        createDeviceRegisterExtensions(pCreateInfo, *pDevice);
-        // Create a mapping from a device to a physicalDevice
-        if (deviceMap[*pDevice] == NULL)
-        {
-            DeviceMapStruct *deviceMapElem = new DeviceMapStruct;
-            deviceMap[*pDevice] = deviceMapElem;
-        }
-        deviceMap[*pDevice]->physicalDevice = gpu;
+    VkLayerDeviceCreateInfo *chain_info = get_chain_info(pCreateInfo, VK_LAYER_LINK_INFO);
+
+    assert(chain_info->u.pLayerInfo);
+    PFN_vkGetInstanceProcAddr fpGetInstanceProcAddr = chain_info->u.pLayerInfo->pfnNextGetInstanceProcAddr;
+    PFN_vkGetDeviceProcAddr fpGetDeviceProcAddr = chain_info->u.pLayerInfo->pfnNextGetDeviceProcAddr;
+    PFN_vkCreateDevice fpCreateDevice = (PFN_vkCreateDevice) fpGetInstanceProcAddr(NULL, "vkCreateDevice");
+    if (fpCreateDevice == NULL) {
+        return VK_ERROR_INITIALIZATION_FAILED;
     }
 
+    // Advance the link info for the next element on the chain
+    chain_info->u.pLayerInfo = chain_info->u.pLayerInfo->pNext;
+
+    VkResult result = fpCreateDevice(gpu, pCreateInfo, pAllocator, pDevice);
+    if (result != VK_SUCCESS) {
+        return result;
+    }
+
+    initDeviceTable(*pDevice, fpGetDeviceProcAddr, screenshot_device_table_map);
+
+    init_screenshot();
+    createDeviceRegisterExtensions(pCreateInfo, *pDevice);
+    // Create a mapping from a device to a physicalDevice
+    if (deviceMap[*pDevice] == NULL)
+    {
+        DeviceMapStruct *deviceMapElem = new DeviceMapStruct;
+        deviceMap[*pDevice] = deviceMapElem;
+    }
+    deviceMap[*pDevice]->physicalDevice = gpu;
+
     return result;
 }
 
@@ -743,17 +758,9 @@ VK_LAYER_EXPORT VKAPI_ATTR PFN_vkVoidFunction VKAPI_CALL vkGetDeviceProcAddr(
     VkDevice         dev,
     const char       *funcName)
 {
-    if (dev == NULL) {
-        return NULL;
-    }
-
-    /* loader uses this to force layer initialization; device object is wrapped */
     if (!strcmp(funcName, "vkGetDeviceProcAddr")) {
-        initDeviceTable(screenshot_device_table_map, (const VkBaseLayerObject *) dev);
         return (PFN_vkVoidFunction)vkGetDeviceProcAddr;
     }
-    if (!strcmp(funcName, "vkCreateDevice"))
-        return (PFN_vkVoidFunction) vkCreateDevice;
 
     if (!strcmp(funcName, "vkGetDeviceQueue"))
         return (PFN_vkVoidFunction) vkGetDeviceQueue;
@@ -761,6 +768,10 @@ VK_LAYER_EXPORT VKAPI_ATTR PFN_vkVoidFunction VKAPI_CALL vkGetDeviceProcAddr(
     if (!strcmp(funcName, "vkCreateCommandPool"))
         return (PFN_vkVoidFunction) vkCreateCommandPool;
 
+    if (dev == NULL) {
+        return NULL;
+    }
+
     VkLayerDispatchTable *pDisp =  get_dispatch_table(screenshot_device_table_map, dev);
     if (deviceExtMap.size() != 0 && deviceExtMap[pDisp].wsi_enabled)
     {
@@ -780,21 +791,19 @@ VK_LAYER_EXPORT VKAPI_ATTR PFN_vkVoidFunction VKAPI_CALL vkGetDeviceProcAddr(
 
 VK_LAYER_EXPORT VKAPI_ATTR PFN_vkVoidFunction VKAPI_CALL vkGetInstanceProcAddr(VkInstance instance, const char* funcName)
 {
-    if (instance == VK_NULL_HANDLE) {
-        return NULL;
-    }
-
-    /* loader uses this to force layer initialization; instance object is wrapped */
-    if (!strcmp("vkGetInstanceProcAddr", funcName)) {
-        initInstanceTable((const VkBaseLayerObject *) instance);
+    if (!strcmp("vkGetInstanceProcAddr", funcName))
         return (PFN_vkVoidFunction) vkGetInstanceProcAddr;
-    }
-
+    if (!strcmp(funcName, "vkCreateDevice"))
+        return (PFN_vkVoidFunction) vkCreateDevice;
     if (!strcmp(funcName, "vkEnumeratePhysicalDevices"))
 		return (PFN_vkVoidFunction)vkEnumeratePhysicalDevices;
     if (!strcmp(funcName, "vkEnumerateDeviceExtensionProperties"))
 		return (PFN_vkVoidFunction)vkEnumerateDeviceExtensionProperties;
 
+    if (instance == VK_NULL_HANDLE) {
+        return NULL;
+    }
+
     VkLayerInstanceDispatchTable* pTable = instance_dispatch_table(instance);
     if (pTable->GetInstanceProcAddr == NULL)
         return NULL;