glx: Move the GLX variable caching what GL context is current to dix.

GLX is trying to track whether the context it wants is current, to
avoid the glFlush() (and the rest of the overhead) that occurs on all
MakeCurrent calls.  However, its cache can be incorrect now that
glamor exists.  This is a step toward getting glamor to coordinate
with GLX.

Signed-off-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Michel Dänzer <michel.daenzer@amd.com>
Reviewed-by: Adam Jackson <ajax@redhat.com>

dix/dixutils.c

@@ -866,3 +866,28 @@ InitCallbackManager(void)
 {
     DeleteCallbackManager();
 }
+
+/**
+ * Coordinates the global GL context used by modules in the X Server
+ * doing rendering with OpenGL.
+ *
+ * When setting a GL context (glXMakeCurrent() or eglMakeCurrent()),
+ * there is an expensive implied glFlush() required by the GLX and EGL
+ * APIs, so modules don't want to have to do it on every request.  But
+ * the individual modules using GL also don't know about each other,
+ * so they have to coordinate who owns the current context.
+ *
+ * When you're about to do a MakeCurrent, you should set this variable
+ * to your context's address, and you can skip MakeCurrent if it's
+ * already set to yours.
+ *
+ * When you're about to do a DestroyContext, you should set this to
+ * NULL if it's set to your context.
+ *
+ * When you're about to do an unbindContext on a DRI driver, you
+ * should set this to NULL.  Despite the unbindContext interface
+ * sounding like it only unbinds the passed in context, it actually
+ * unconditionally clears the dispatch table even if the given
+ * context wasn't current.
+ */
+void *lastGLContext = NULL;

glx/glxcmds.c

@@ -188,7 +188,7 @@ validGlxDrawable(ClientPtr client, XID id, int type, int access_mode,
 void
 __glXContextDestroy(__GLXcontext * context)
 {
-    __glXFlushContextCache();
+    lastGLContext = NULL;
 }
 
 static void
@@ -434,9 +434,8 @@ static void
 StopUsingContext(__GLXcontext * glxc)
 {
     if (glxc) {
-        if (glxc == __glXLastContext) {
-            /* Tell server GL library */
-            __glXLastContext = 0;
+        if (glxc == lastGLContext) {
+            lastGLContext = NULL;
         }
         glxc->currentClient = NULL;
         if (!glxc->idExists) {
@@ -448,7 +447,7 @@ StopUsingContext(__GLXcontext * glxc)
 static void
 StartUsingContext(__GLXclientState * cl, __GLXcontext * glxc)
 {
-    __glXLastContext = glxc;
+    lastGLContext = glxc;
     glxc->currentClient = cl->client;
 }
 
@@ -627,7 +626,7 @@ DoMakeCurrent(__GLXclientState * cl,
         if (!(*prevglxc->loseCurrent) (prevglxc)) {
             return __glXError(GLXBadContext);
         }
-        __glXFlushContextCache();
+        lastGLContext = NULL;
         if (!prevglxc->isDirect) {
             prevglxc->drawPriv = NULL;
             prevglxc->readPriv = NULL;

glx/glxext.c

@@ -47,12 +47,6 @@
 #include "indirect_table.h"
 #include "indirect_util.h"
 
-/*
-** The last context used by the server.  It is the context that is current
-** from the server's perspective.
-*/
-__GLXcontext *__glXLastContext;
-
 /*
 ** X resources.
 */
@@ -79,7 +73,7 @@ static int __glXDispatch(ClientPtr);
 static void
 ResetExtension(ExtensionEntry * extEntry)
 {
-    __glXFlushContextCache();
+    lastGLContext = NULL;
 }
 
 /*
@@ -141,8 +135,8 @@ DrawableGone(__GLXdrawable * glxPriv, XID xid)
 		(c->drawPriv == glxPriv || c->readPriv == glxPriv)) {
             /* just force a re-bind the next time through */
             (*c->loseCurrent) (c);
-            if (c == __glXLastContext)
-                __glXFlushContextCache();
+            if (c == lastGLContext)
+                lastGLContext = NULL;
         }
         if (c->drawPriv == glxPriv)
             c->drawPriv = NULL;
@@ -203,8 +197,8 @@ __glXFreeContext(__GLXcontext * cx)
 
     free(cx->feedbackBuf);
     free(cx->selectBuf);
-    if (cx == __glXLastContext) {
-        __glXFlushContextCache();
+    if (cx == lastGLContext) {
+        lastGLContext = NULL;
     }
 
     /* We can get here through both regular dispatching from
@@ -406,12 +400,6 @@ GlxExtensionInit(void)
 
 /************************************************************************/
 
-void
-__glXFlushContextCache(void)
-{
-    __glXLastContext = 0;
-}
-
 /*
 ** Make a context the current one for the GL (in this implementation, there
 ** is only one instance of the GL, and we use it to serve all GL clients by
@@ -449,7 +437,7 @@ __glXForceCurrent(__GLXclientState * cl, GLXContextTag tag, int *error)
     if (cx->wait && (*cx->wait) (cx, cl, error))
         return NULL;
 
-    if (cx == __glXLastContext) {
+    if (cx == lastGLContext) {
         /* No need to re-bind */
         return cx;
     }
@@ -463,7 +451,7 @@ __glXForceCurrent(__GLXclientState * cl, GLXContextTag tag, int *error)
             return 0;
         }
     }
-    __glXLastContext = cx;
+    lastGLContext = cx;
     return cx;
 }
 

glx/glxserver.h

@@ -84,7 +84,6 @@ void __glXScreenInitVisuals(__GLXscreen * screen);
 /*
 ** The last context used (from the server's persective) is cached.
 */
-extern __GLXcontext *__glXLastContext;
 extern __GLXcontext *__glXForceCurrent(__GLXclientState *, GLXContextTag,
                                        int *);
 

include/dix.h

@@ -608,4 +608,6 @@ CorePointerProc(DeviceIntPtr dev, int what);
 extern _X_HIDDEN int
 CoreKeyboardProc(DeviceIntPtr dev, int what);
 
+extern _X_EXPORT void *lastGLContext;
+
 #endif                          /* DIX_H */