Previously, Apple’s iPhones and iPads used PowerVR GPUs from Imagination Technologies for graphics. Based on our analysis, Apple has created a custom GPU that powers the A8, A9, and 10 processors, shipping in the iPhone 6 and later models, and some iPads. Using public documents, we demonstrate that the programmable shader cores inside Apple’s GPU are different from Imagination Technologies’ PowerVR and offer superior 16-bit floating-point performance and data conversion functions. We further believe that Apple has also developed a custom shader compiler and graphics driver. The proprietary design enables Apple to deliver best-in-class performance for graphics, and other tasks that use the GPU, such as image processing and machine learning.
Starting with the Maxwell GM20x architecture, Nvidia high-performance GPUs have borrowed techniques from low-power mobile graphics architectures. Specifically, Maxwell and Pascal use tile-based immediate-mode rasterizers that buffer pixel output, instead of conventional full-screen immediate-mode rasterizers. Using simple DirectX shaders, we demonstrate the tile-based rasterization in Nvidia’s Maxwell and Pascal GPUs and contrast this behavior to the immediate-mode rasterizer used by AMD.