EXA: RENDER improvements.

Exclude bits that will be overwritten from migration.

Use exaGlyphs even when Composite can't be accelerated, to avoid PolyFillRect
roundtrip via offscreen memory.

Initialize mask pixmap in exaGlyphs in FB in addition to system if the driver
provides Composite hooks to avoid migration overhead.

Remove manual damage tracking where superfluous.

exa/exa_unaccel.c

@@ -23,6 +23,10 @@
 
 #include "exa_priv.h"
 
+#ifdef RENDER
+#include "mipict.h"
+#endif
+
 /*
  * These functions wrap the low-level fb rendering functions and
  * synchronize framebuffer/accelerated drawing by stalling until
@@ -319,9 +323,30 @@ ExaCheckComposite (CARD8      op,
                    CARD16     width,
                    CARD16     height)
 {
+    RegionRec region;
+    int xoff, yoff;
+
+    REGION_NULL(pScreen, &region);
+
+    if (!exaOpReadsDestination(op)) {
+	if (!miComputeCompositeRegion (&region, pSrc, pMask, pDst,
+				       xSrc, ySrc, xMask, yMask, xDst, yDst,
+				       width, height))
+	    return;
+
+	exaGetDrawableDeltas (pDst->pDrawable,
+			      exaGetDrawablePixmap(pDst->pDrawable),
+			      &xoff, &yoff);
+
+	REGION_TRANSLATE(pScreen, &region, xoff, yoff);
+
+	exaPrepareAccessReg (pDst->pDrawable, EXA_PREPARE_DEST, &region);
+    } else
+	exaPrepareAccess (pDst->pDrawable, EXA_PREPARE_DEST);
+
     EXA_FALLBACK(("from picts %p/%p to pict %p\n",
 		 pSrc, pMask, pDst));
-    exaPrepareAccess (pDst->pDrawable, EXA_PREPARE_DEST);
+
     if (pSrc->pDrawable != NULL)
 	exaPrepareAccess (pSrc->pDrawable, EXA_PREPARE_SRC);
     if (pMask && pMask->pDrawable != NULL)
@@ -343,6 +368,8 @@ ExaCheckComposite (CARD8      op,
     if (pSrc->pDrawable != NULL)
 	exaFinishAccess (pSrc->pDrawable, EXA_PREPARE_SRC);
     exaFinishAccess (pDst->pDrawable, EXA_PREPARE_DEST);
+
+    REGION_UNINIT(pScreen, &region);
 }
 
 /**