[AArch64][RISCV] Document option --print-supported-extensions

[jthackray]

Add documentation for the --print-supported-extensions
option which appears to be missing at present.

[llvmbot]

@llvm/pr-subscribers-clang

Author: Jonathan Thackray (jthackray)

Changes

Add documentation for the --print-supported-extensions
option which appears to be missing at present.

---

Full diff: https://github.com/llvm/llvm-project/pull/98698.diff

1 Files Affected:

• (modified) clang/docs/CommandGuide/clang.rst (+8)

diff --git a/clang/docs/CommandGuide/clang.rst b/clang/docs/CommandGuide/clang.rst
index a348f3640c5eb..2def6ab41c70f 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 extensions that are supported for any possible CPU target
+  for the architecture specified by the combination of `--target`, `-march`,
+  and `-mcpu` values. Currently, this option is only supported on AArch64
+  and RISC-V. On RISC-V, this option also prints out the ISA string of
+  enabled extensions.
+
 Code Generation Options
 ~~~~~~~~~~~~~~~~~~~~~~~