gallium/dri: Add D3D12 software driver option

This lets you use GALLIUM_DRIVER=d3d12 to choose the d3d12
backend with a software winsys.

Reviewed-by: Erik Faye-Lund <erik.faye-lund@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7937>

src/gallium/auxiliary/target-helpers/inline_sw_helper.h

@@ -27,6 +27,10 @@
 #include "virgl/vtest/virgl_vtest_public.h"
 #endif
 
+#ifdef GALLIUM_D3D12
+#include "d3d12/d3d12_public.h"
+#endif
+
 static inline struct pipe_screen *
 sw_screen_create_named(struct sw_winsys *winsys, const char *driver)
 {
@@ -60,6 +64,11 @@ sw_screen_create_named(struct sw_winsys *winsys, const char *driver)
       screen = zink_create_screen(winsys);
 #endif
 
+#if defined(GALLIUM_D3D12)
+   if (screen == NULL && strcmp(driver, "d3d12") == 0)
+      screen = d3d12_create_dxcore_screen(winsys, NULL);
+#endif
+
    return screen;
 }
 
@@ -78,6 +87,8 @@ sw_screen_create(struct sw_winsys *winsys)
    default_driver = "swr";
 #elif defined(GALLIUM_ZINK)
    default_driver = "zink";
+#elif defined(GALLIUM_D3D12)
+   default_driver = "d3d12";
 #else
    default_driver = "";
 #endif

src/gallium/auxiliary/target-helpers/sw_helper.h

@@ -16,6 +16,10 @@
 #include "zink/zink_public.h"
 #endif
 
+#ifdef GALLIUM_D3D12
+#include "d3d12/d3d12_public.h"
+#endif
+
 #ifdef GALLIUM_SOFTPIPE
 #include "softpipe/sp_public.h"
 #endif
@@ -66,6 +70,11 @@ sw_screen_create_named(struct sw_winsys *winsys, const char *driver)
       screen = zink_create_screen(winsys);
 #endif
 
+#if defined(GALLIUM_D3D12)
+   if (screen == NULL && strcmp(driver, "d3d12") == 0)
+      screen = d3d12_create_dxcore_screen(winsys, NULL);
+#endif
+
    return screen;
 }
 
@@ -84,6 +93,8 @@ sw_screen_create(struct sw_winsys *winsys)
    default_driver = "swr";
 #elif defined(GALLIUM_ZINK)
    default_driver = "zink";
+#elif defined(GALLIUM_D3D12)
+   default_driver = "d3d12";
 #else
    default_driver = "";
 #endif

src/gallium/targets/dri/meson.build

@@ -57,7 +57,7 @@ libgallium_dri = shared_library(
     driver_swrast, driver_r300, driver_r600, driver_radeonsi, driver_nouveau,
     driver_kmsro, driver_v3d, driver_vc4, driver_freedreno, driver_etnaviv,
     driver_tegra, driver_i915, driver_svga, driver_virgl,
-    driver_swr, driver_panfrost, driver_iris, driver_lima, driver_zink
+    driver_swr, driver_panfrost, driver_iris, driver_lima, driver_zink, driver_d3d12
   ],
   # Will be deleted during installation, see install_megadrivers.py
   install : true,
@@ -104,7 +104,8 @@ foreach d : [[with_gallium_kmsro, [
              [with_gallium_svga, 'vmwgfx_dri.so'],
              [with_gallium_virgl, 'virtio_gpu_dri.so'],
              [with_gallium_lima, 'lima_dri.so'],
-             [with_gallium_zink, 'zink_dri.so']]
+             [with_gallium_zink, 'zink_dri.so'],
+             [with_gallium_d3d12, 'd3d12_dri.so']]
   if d[0]
     gallium_dri_drivers += d[1]
   endif

src/gallium/targets/dri/target.c

@@ -121,3 +121,7 @@ DEFINE_LOADER_DRM_ENTRYPOINT(lima)
 #if defined(GALLIUM_ZINK)
 DEFINE_LOADER_DRM_ENTRYPOINT(zink);
 #endif
+
+#if defined(GALLIUM_D3D12)
+DEFINE_LOADER_DRM_ENTRYPOINT(d3d12);
+#endif