https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109456
--- Comment #9 from Xi Ruoyao <xry111 at gcc dot gnu.org> ---
The easiest way is considering it a documentation issue and do:
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 0870f7aff93..c39880349d5 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -18635,8 +18635,8 @@ more efficient than other code generation strategies.
@opindex ffixed
@item -ffixed-@var{reg}
Treat the register named @var{reg} as a fixed register; generated code
-should never refer to it (except perhaps as a stack pointer, frame
-pointer or in some other fixed role).
+should never refer to it (except as a stack pointer, frame
+pointer, argument register or in some other fixed role).
@var{reg} must be the name of a register. The register names accepted
are machine-specific and are defined in the @code{REGISTER_NAMES}
