i965: Build the driver into a shared mesa_dri_drivers.so .

Previously, we've split things such that mesa core is in libdricore,
exposing the whole Mesa core interface in the global namespace, and the
i965_dri.so code all links against that.  Along with polluting application
namespace terribly, it requires extra PLT indirections and prevents LTO.

Instead, we can build all of the driver contents into the same .so with
just a few symbols exposed to be referenced from the actual driver .so
file, allowing LTO and reducing our exposed symbol count massively.

FPS improvement on GLB2.7 with INTEL_NO_HW=1: 2.61061% +/- 1.16957% (n=50)
(without LTO, just the PLT reductions from this commit)

Note that the X Server requires commit
7ecfab47eb221dbb996ea6c033348b8eceaeb893 to successfully load this driver!

v2: Set a global driverAPI variable so loaders don't have to update to
    createNewScreen2() (though they may want to for thread safety).
v3: Drop AM_CPPFLAGS addition (Emil pointed out I'd missed some cflags
    that would be necessary, though only if we actually relied on them).
v4: Fix install with DESTDIR set.

Reviewed-by: Matt Turner <mattst88@gmail.com> (v1)
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com> (v2)

3 files changed, 22 insertions, 25 deletions

diff --git a/src/mesa/drivers/dri/i965/Makefile.am b/src/mesa/drivers/dri/i965/Makefile.am
index 71442dd..589a074 100644
--- a/src/mesa/drivers/dri/i965/Makefile.am
+++ b/src/mesa/drivers/dri/i965/Makefile.am
@@ -38,30 +38,19 @@ AM_CFLAGS = \
 
 AM_CXXFLAGS = $(AM_CFLAGS)
 
-dridir = $(DRI_DRIVER_INSTALL_DIR)
-
 noinst_LTLIBRARIES = libi965_dri.la
-dri_LTLIBRARIES = i965_dri.la
-
 libi965_dri_la_SOURCES = $(i965_FILES)
+libi965_dri_la_LIBADD = $(INTEL_LIBS)
 
-# list of libs to be linked against by i965_dri.so and i965 test programs.
-COMMON_LIBS = \
+TEST_LIBS = \
 	libi965_dri.la \
 	../common/libdricommon.la \
-	$(DRI_LIB_DEPS) \
-	$(INTEL_LIBS)
-
-TEST_LIBS = \
-	$(COMMON_LIBS) \
+	../common/libmegadriver_stub.la \
+	$(MEGADRIVER_DRI_LIB_DEPS) \
+        ../../../libmesa.la \
         -lrt \
 	../common/libdri_test_stubs.la
 
-i965_dri_la_SOURCES =
-nodist_EXTRA_i965_dri_la_SOURCES = dummy2.cpp
-i965_dri_la_LIBADD = $(COMMON_LIBS)
-i965_dri_la_LDFLAGS = $(DRI_DRIVER_LDFLAGS)
-
 TESTS = \
         test_eu_compact \
         test_vec4_register_coalesce
@@ -77,9 +66,3 @@ test_eu_compact_SOURCES = \
 	test_eu_compact.c
 nodist_EXTRA_test_eu_compact_SOURCES = dummy.cpp
 test_eu_compact_LDADD = $(TEST_LIBS)
-
-# Provide compatibility with scripts for the old Mesa build system for
-# a while by putting a link to the driver into /lib of the build tree.
-all-local: i965_dri.la
-	$(MKDIR_P) $(top_builddir)/$(LIB_DIR);
-	ln -f .libs/i965_dri.so $(top_builddir)/$(LIB_DIR)/i965_dri.so;
diff --git a/src/mesa/drivers/dri/i965/intel_screen.c b/src/mesa/drivers/dri/i965/intel_screen.c
index 6cec60e..eafafa2 100644
--- a/src/mesa/drivers/dri/i965/intel_screen.c
+++ b/src/mesa/drivers/dri/i965/intel_screen.c
@@ -1314,7 +1314,7 @@ intelReleaseBuffer(__DRIscreen *screen, __DRIbuffer *buffer)
 }
 
 
-const struct __DriverAPIRec driDriverAPI = {
+static const struct __DriverAPIRec brw_driver_api = {
    .InitScreen		 = intelInitScreen2,
    .DestroyScreen	 = intelDestroyScreen,
    .CreateContext	 = brwCreateContext,
@@ -1327,10 +1327,22 @@ const struct __DriverAPIRec driDriverAPI = {
    .ReleaseBuffer        = intelReleaseBuffer
 };
 
-/* This is the table of extensions that the loader will dlsym() for. */
-PUBLIC const __DRIextension *__driDriverExtensions[] = {
+static const struct __DRIDriverVtableExtensionRec brw_vtable = {
+   .base = { __DRI_DRIVER_VTABLE, 1 },
+   .vtable = &brw_driver_api,
+};
+
+static const __DRIextension *brw_driver_extensions[] = {
     &driCoreExtension.base,
     &driDRI2Extension.base,
+    &brw_vtable.base,
     &brw_config_options.base,
     NULL
 };
+
+PUBLIC const __DRIextension **__driDriverGetExtensions_i965(void)
+{
+   globalDriverAPI = &brw_driver_api;
+
+   return brw_driver_extensions;
+}
diff --git a/src/mesa/drivers/dri/i965/intel_screen.h b/src/mesa/drivers/dri/i965/intel_screen.h
index 0b75c6e..eb9bfca 100644
--- a/src/mesa/drivers/dri/i965/intel_screen.h
+++ b/src/mesa/drivers/dri/i965/intel_screen.h
@@ -67,6 +67,8 @@ extern void intelDestroyContext(__DRIcontext * driContextPriv);
 
 extern GLboolean intelUnbindContext(__DRIcontext * driContextPriv);
 
+PUBLIC const __DRIextension **__driDriverGetExtensions_i965(void);
+
 extern GLboolean
 intelMakeCurrent(__DRIcontext * driContextPriv,
                  __DRIdrawable * driDrawPriv,