> It would be nice to add to the documentation that INSN_BASE_REG_CLASS,
> INSN_INDEX_REG_CLASS, and REGNO_OK_FOR_INSN_BASE_P if defined have
> priority over older corresponding macros as it is already documented for
> REGNO_MODE_CODE_OK_FOR_BASE_P relating to REGNO_OK_FOR_BASE_P. But this
> small issue can be addressed later.
>
Thanks, I would add the description like below when committing.
+@defmac INSN_BASE_REG_CLASS (@var{insn})
+A C expression whose value is the register class to which a valid
+base register for a specified @var{insn} must belong. This macro is
+used when some backend insns may have limited usage of base register
+compared with other insns. If you define this macro, the compiler will
+use it instead of all other defined macros that relate to
+BASE_REG_CLASS.
+@end defmac
+
+@defmac REGNO_OK_FOR_INSN_BASE_P (@var{num}, @var{insn})
+A C expression which is nonzero if register number @var{num} is
+suitable for use as a base register in operand addresses for a specified
+@var{insn}. This macro is used when some backend insn may have limited
+usage of base register compared with other insns. If you define this
+macro, the compiler will use it instead of all other defined macros
+that relate to REGNO_OK_FOR_BASE_P.
+@end defmac
+
+@defmac INSN_INDEX_REG_CLASS (@var{insn})
+A C expression whose value is the register class to which a valid
+index register for a specified @var{insn} must belong. This macro is
+used when some backend insns may have limited usage of index register
+compared with other insns. If you defined this macro, the compiler
+will use it instead of @code{INDEX_REG_CLASS}.
+@end defmac
+
