The XrSwToPMBlit is a blit which is used as a direct(unscaled) blit of the image in the memory to the pixmap. It tries to optimize the SrcOver composite in case of an opaque source image and use Src instead:

        if (CompositeType.SrcOverNoEa.equals(comp) && (src.getTransparency() == Transparency.OPAQUE)) {
            Blit opaqueSwToSurfaceBlit = Blit.getFromCache(src.getSurfaceType(), CompositeType.SrcNoEa, dst.getSurfaceType());
            opaqueSwToSurfaceBlit.Blit(src, dst, comp, clip, sx, sy, dx, dy, w, h);
        } else {

The code above does not work for two reasons:
- The check "CompositeType.SrcOverNoEa.equals(comp)" always fails because the comp is of type Composite(AlphaComposite/XORComposite/etc) not a CompositeType
 - This optimisation is applied already in the sun.java2d.pipe.DrawImage#blitSurfaceData:
https://github.com/openjdk/jdk/blob/master/src/java.desktop/share/classes/sun/java2d/pipe/DrawImage.java#L933