[Mesa-dev] [PATCH 3/3] anv: Define trampolines as the weak functions

[Jason Ekstrand]

Instead of having weak references to the anv functions and separate
trampoline functions with their own dispatch table, just make the
trampoline functions weak.  This gets rid of a dispatch table and
potentially lets the compiler delete the unused weak function.  The
end result is a reduction in the .text section of 5.7K and a reduction
in the .data section of 1.4K.

Before:

   text	   data	    bss	    dec	    hex	filename
3190329	 282232	   8960	3481521	 351fb1	_install/lib64/libvulkan_intel.so

After:

   text	   data	    bss	    dec	    hex	filename
3184548	 280792	   8960	3474300	 35037c	_install/lib64/libvulkan_intel.so
---
 src/intel/vulkan/anv_device.c           |  5 +-
 src/intel/vulkan/anv_entrypoints_gen.py | 65 ++++++++-----------------
 2 files changed, 21 insertions(+), 49 deletions(-)

diff --git a/src/intel/vulkan/anv_device.c b/src/intel/vulkan/anv_device.c
index a2551452eb1..f68226217b4 100644
--- a/src/intel/vulkan/anv_device.c
+++ b/src/intel/vulkan/anv_device.c
@@ -653,12 +653,9 @@ VkResult anv_CreateInstance(
       if (!anv_device_entrypoint_is_enabled(i, instance->app_info.api_version,
                                             &instance->enabled_extensions, NULL)) {
          instance->device_dispatch.entrypoints[i] = NULL;
-      } else if (anv_device_dispatch_table.entrypoints[i] != NULL) {
-         instance->device_dispatch.entrypoints[i] =
-            anv_device_dispatch_table.entrypoints[i];
       } else {
          instance->device_dispatch.entrypoints[i] =
-            anv_tramp_device_dispatch_table.entrypoints[i];
+            anv_device_dispatch_table.entrypoints[i];
       }
    }
 
diff --git a/src/intel/vulkan/anv_entrypoints_gen.py b/src/intel/vulkan/anv_entrypoints_gen.py
index 25a532fd706..792e3b6c90c 100644
--- a/src/intel/vulkan/anv_entrypoints_gen.py
+++ b/src/intel/vulkan/anv_entrypoints_gen.py
@@ -92,7 +92,6 @@ extern const struct anv_instance_dispatch_table anv_instance_dispatch_table;
 %for layer in LAYERS:
 extern const struct anv_device_dispatch_table ${layer}_device_dispatch_table;
 %endfor
-extern const struct anv_device_dispatch_table anv_tramp_device_dispatch_table;
 
 % for e in instance_entrypoints:
   % if e.alias:
@@ -247,7 +246,26 @@ const struct anv_instance_dispatch_table anv_instance_dispatch_table = {
     % if e.guard is not None:
 #ifdef ${e.guard}
     % endif
-    ${e.return_type} ${e.prefixed_name(layer)}(${e.decl_params()}) __attribute__ ((weak));
+    % if layer == 'anv':
+      ${e.return_type} __attribute__ ((weak))
+      ${e.prefixed_name('anv')}(${e.decl_params()})
+      {
+        % if e.params[0].type == 'VkDevice':
+          ANV_FROM_HANDLE(anv_device, anv_device, ${e.params[0].name});
+          return anv_device->dispatch.${e.name}(${e.call_params()});
+        % elif e.params[0].type == 'VkCommandBuffer':
+          ANV_FROM_HANDLE(anv_cmd_buffer, anv_cmd_buffer, ${e.params[0].name});
+          return anv_cmd_buffer->device->dispatch.${e.name}(${e.call_params()});
+        % elif e.params[0].type == 'VkQueue':
+          ANV_FROM_HANDLE(anv_queue, anv_queue, ${e.params[0].name});
+          return anv_queue->device->dispatch.${e.name}(${e.call_params()});
+        % else:
+          assert(!"Unhandled device child trampoline case: ${e.params[0].type}");
+        % endif
+      }
+    % else:
+      ${e.return_type} ${e.prefixed_name(layer)}(${e.decl_params()}) __attribute__ ((weak));
+    % endif
     % if e.guard is not None:
 #endif // ${e.guard}
     % endif
@@ -267,49 +285,6 @@ const struct anv_instance_dispatch_table anv_instance_dispatch_table = {
 % endfor
 
 
-/** Trampoline entrypoints for all device functions */
-
-% for e in device_entrypoints:
-  % if e.alias:
-    <% continue %>
-  % endif
-  % if e.guard is not None:
-#ifdef ${e.guard}
-  % endif
-  static ${e.return_type}
-  ${e.prefixed_name('anv_tramp')}(${e.decl_params()})
-  {
-    % if e.params[0].type == 'VkDevice':
-      ANV_FROM_HANDLE(anv_device, anv_device, ${e.params[0].name});
-      return anv_device->dispatch.${e.name}(${e.call_params()});
-    % elif e.params[0].type == 'VkCommandBuffer':
-      ANV_FROM_HANDLE(anv_cmd_buffer, anv_cmd_buffer, ${e.params[0].name});
-      return anv_cmd_buffer->device->dispatch.${e.name}(${e.call_params()});
-    % elif e.params[0].type == 'VkQueue':
-      ANV_FROM_HANDLE(anv_queue, anv_queue, ${e.params[0].name});
-      return anv_queue->device->dispatch.${e.name}(${e.call_params()});
-    % else:
-      assert(!"Unhandled device child trampoline case: ${e.params[0].type}");
-    % endif
-  }
-  % if e.guard is not None:
-#endif // ${e.guard}
-  % endif
-% endfor
-
-const struct anv_device_dispatch_table anv_tramp_device_dispatch_table = {
-% for e in device_entrypoints:
-  % if e.guard is not None:
-#ifdef ${e.guard}
-  % endif
-    .${e.name} = ${e.prefixed_name('anv_tramp')},
-  % if e.guard is not None:
-#endif // ${e.guard}
-  % endif
-% endfor
-};
-
-
 /** Return true if the core version or extension in which the given entrypoint
  * is defined is enabled.
  *
-- 
2.19.1