[libre-riscv-dev] [isa-dev] Re: FP transcendentals (trigonometry, root/exp/log) proposal

Jacob Lifshay programmerjake at gmail.com
Sun Aug 11 18:36:26 BST 2019

On Sun, Aug 11, 2019, 10:34 Jacob Lifshay <programmerjake at gmail.com> wrote:

> Atif Zafar asked me to post the following observations:
I forgot to state that he wrote the following:

> A couple of observations reading the past set of emails:
>    1. Vulkan is the future of 3d graphics. It provides the lowest level
>    access to graphics hardware of any API
>    2. Much of the functionality of other APIs - WebGL, OpenGL, OpenGL/ES,
>    DirectX etc. can be built on top of Vulkan and there are efforts to this
>    regard.
>    3. High level features such as graphics pipeline commands - i.e.
>    single plane 3d clipping of triangles - need to be built in a higher level
>    API
> So I agree with you that we should look at SPIR-V and the Vulkan ISA
> seriously. Now that ISA is very complex and many of the instructions may
> possibly be reconstructed from simpler ones. We need to thus perhaps look
> at a "minimized" subset of the Vulkan ISA instructions that truly define
> the atomic operations from which the full ISA can be constructed. So the
> instruction decode hardware can implement this "higher-level ISA" - perhaps
> in microcode - from the "atomic ISA" at runtime while hardware support is
> only provided for the "atomic ISA".
> From the SIGGRAPH BOF it was clear there are competing interests. Some
> people wanted explicit texture mapping instructions while others wanted HPC
> type threaded vector extensions. Although each of these can be accommodated
> we need to adjudicate the location in the process pipeline where they
> belong - atomic ISA, higher-level ISA or higher-level graphics library.

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