Re: [RTL, ColdFire 24/63] Add support for a MODE_INDEX_REG_CLASS macro

[Richard Sandiford <richard at codesourcery dot com>]

Jeffrey Law <law@redhat.com> writes:
> On Tue, 2007-02-27 at 19:12 +0000, Richard Sandiford wrote:
>> >
>> > Once you do that, there is no current need to make double_reg_address_ok
>> > an array of booleans, and doing so would just make the compiler slightly
>> > slower.  So although I agree we should it if some other port needs it
>> > (i.e. if some other port allows disp(base,index) addresses for some
>> > modes and allows only plain (base,index) address for others), I don't
>> > think we should otherwise.
>> 
>> And you haven't addressed that point.  Do you disagree that INDEX_REG_CLASS
>> is supposed to be NO_REGS if no index regs are allowed?
> The validity of indexing is mode dependent on your target.  For every
> mode that allows indexed addressing the set of valid index registers
> is the same.
>
>
>> 
>> > I haven't really tested the attached patch except to verify that 
>> > the provided testcase no longer aborts and that the reloads we
>> > generate for the problem insn look correct.  However, I feel its a
>> > much more correct solution than what you're trying to do.
>> 
>> I honestly don't understand why you think my patch is unreasonable.
> Because it's not fixing the problem, it's papering over the problem.

I disagree.  BASE_REG_CLASS is a guarantee from the backend that
any register in that class is a valid base register.  Reload relies
on that fact.  Why should INDEX_REG_CLASS by any different?

Richard