doc: Add doc for RISC-V Operand Modifiers

Document `z` and `i` operand modifiers, we have much more modifiers
other than those two, but they are the only two implement on both
GCC and LLVM, consider the compatibility I would like to document those
two first, and then review other modifiers later to see if any other should
expose and implement on RISC-V LLVM too.

gcc/ChangeLog:

	* doc/extend.texi (RISC-V Operand Modifiers): New.

diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index bfbc1d6cc9f8e3ff189429f3cf411792aeefa6d0..d88fd75e06e6bbeb6b9bef5707e075056801790a 100644 (file)
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -11533,6 +11533,16 @@ The list below describes the supported modifiers and their effects for LoongArch
 @item @code{z} @tab Print the operand in its unmodified form, followed by a comma.
 @end multitable
 
+@anchor{riscvOperandmodifiers}
+@subsubsection RISC-V Operand Modifiers
+
+The list below describes the supported modifiers and their effects for RISC-V.
+
+@multitable @columnfractions .10 .90
+@headitem Modifier @tab Description
+@item @code{z} @tab Print ''@code{zero}'' instead of 0 if the operand is an immediate with a value of zero.
+@item @code{i} @tab Print the character ''@code{i}'' if the operand is an immediate.
+@end multitable
 
 @lowersections
 @include md.texi