Apple's new 12.9-inch iPad Pro has a 12-core GPU inside its A9X processor, compared to only six GPU cores in the A9 chip used in the iPhone 6s and 6s Plus smartphones. This information was revealed in a new teardown of the A9X processor.
According to Anandtech:
We don't know the clockspeed of the GPU – this being somewhat problematic to determine within the iOS sandbox – but based on our earlier performance results it's likely that A9X's GPU is only clocked slightly higher than A9's. I say slightly higher because no GPU gets 100% performance scaling with additional cores, and with our GFXBench Manhattan scores being almost perfectly double that of A9's, it stands to reason that Apple had to add a bit more to the GPU clockspeed to get there.
One other interesting discovery in the teardown is that the A9X has no L3 cache:
The only cache to be found on A9X are the L1 and L2 caches for the CPU and GPU respectively, along with some even smaller amounts for cache for various other functional blocks.