[clang] [AArch64][RISCV] Document option --print-supported-extensions (PR #98698)

[Jonathan Thackray via cfe-commits]

https://github.com/jthackray updated https://github.com/llvm/llvm-project/pull/98698

>From b5d6146b583f96c7e8cec9abd2d2fec51dd4a611 Mon Sep 17 00:00:00 2001
From: Jonathan Thackray <jonathan.thackray at arm.com>
Date: Fri, 12 Jul 2024 23:08:28 +0100
Subject: [PATCH] [AArch64][RISCV] Document option --print-supported-extensions

---
 clang/docs/CommandGuide/clang.rst | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/clang/docs/CommandGuide/clang.rst b/clang/docs/CommandGuide/clang.rst
index a348f3640c5eb..29154292dc7a5 100644
--- a/clang/docs/CommandGuide/clang.rst
+++ b/clang/docs/CommandGuide/clang.rst
@@ -400,6 +400,14 @@ number of cross compilers, or may only support a native target.
   option is only supported on AArch64 and RISC-V. On RISC-V, this option also
   prints out the ISA string of enabled extensions.
 
+.. option:: --print-supported-extensions
+
+  Prints the list of all extensions that are supported for every CPU target
+  for an architecture (specified through ``--target=<architecture>`` or
+  :option:`-arch` ``<architecture>``). If no target is specified, the system
+  default target will be used. Currently, this option is only supported on
+  AArch64 and RISC-V.
+
 Code Generation Options
 ~~~~~~~~~~~~~~~~~~~~~~~