[PATCH] D136968: [RISCV][docs] Add some wording around vendor extensions

[Philip Reames via Phabricator via llvm-commits]

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This adds an initial bit of policy around inclusion of vendor extensions.  My intention here is to leave all of the actual decision making to a case by case decision on the regular sync calls, but to spell out some of the pieces we've discussed and (I think) have general agreement on.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D136968

Files:
  llvm/docs/RISCVUsage.rst


Index: llvm/docs/RISCVUsage.rst
===================================================================
--- llvm/docs/RISCVUsage.rst
+++ llvm/docs/RISCVUsage.rst
@@ -145,6 +145,18 @@
 
 To use an experimental extension from `clang`, you must add `-menable-experimental-extensions` to the command line, and specify the exact version of the experimental extension you are using.  To use an experimental extension with LLVM's internal developer tools (e.g. `llc`, `llvm-objdump`, `llvm-mc`), you must prefix the extension name with `experimental-`.  Note that you don't need to specify the version with internal tools, and shouldn't include the `experimental-` prefix with `clang`.
 
+Vendor Extensions
+=================
+
+Vendor extensions are extensions which are not standardized by RVI, and are instead defined by a hardware vendor.  At the moment, LLVM does not support any vendor extensions for RISC-V, but we expect this to change in the future.
+
+The term vendor extension roughly parallels the definition of a `Non Standard` extension from Section 1.3 of the Volume I: RISC-V Unprivileged ISA specification.  In particular, we expect to eventually accept both `Custom` extensions and `Non-Conforming` extensions.
+
+Inclusion of a vendor extension will be considered on a case by case basis.  All proposals should be brought to the bi-weekly RISCV sync calls for discussion.  For a general idea of the factors likely to be considered, please see the `Clang documentation <https://clang.llvm.org/get_involved.html>`_.
+
+It is our intention to follow the naming conventions described in `riscv-non-isa/riscv-toolchain-conventions <https://github.com/riscv-non-isa/riscv-toolchain-conventions#conventions-for-vendor-extensions>`_.  Exceptions to this naming will need to be strongly motivated.
+
+
 Specification Documents
 =======================
 For ratified specifications, please refer to the `official RISC-V International


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