Feature request: Set the direction flag on x86/x64 register->register operations

[Stefan Dösinger]

First of all, thanks for your replies.

> >> Is this safe? So far I haven't run the gas testsuite yet
> 
> You'd have to prove it.
I ran the testsuite in the meantime and found a few bugs: I have an updated, but still imperfect patch attached(the modification of the tests and 16 bit movs).

> First of all you'd need to complete what you started: Your patch
> apparently
> only cares about 32- and 64-bit register operands at present, but
> should
> in particular also deal with 16-bit ones (i.e. it should be generalized,
> since
> if the command line option you propose is passed, the user ought to be
> allowed to expect that *all* code gets handled the alternative way).
I have to double check what I actually want in that case, and see how msvc handles these cases, and then think how to keep the behavior consistent. (Microsoft software doesn't always show consistent behavior unfortunately)

> Indeed, and it would seem to me the patch as is doesn't correctly deal
> with
> all cases (specifically, the early setting of found_reverse_match
> doesn't
> seem right if none of the opcodes matching the current insn have a D
> bit).
The testsuite agreed with you, and I've changed that.

> But using the testsuite *and* adding new tests properly covering at
> least
> all questionable cases would certainly show that.
The testsuite now seems to pass if I force the change on, of course if the opcodes that the patch intentionally changes are "fixed" in the testsuite. I'll add a new test instead of modifying the existing ones.

> >As you stated here, one may want one particular encoding. I'd like to
> see:
> >
> >1. Allow a suffix in mnemonic, like mov.dn, mov.db, mov.dd. mov.dw
> 
> I don't think this would help the author, as it would then need a
> compiler
> change, too (whereas in the current shape I don't think such would be
> needed).
Correct

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