x86: AT&T syntax operand size defaults

[Jan Beulich]

>>> On 16.11.17 at 12:48, <hjl.tools@gmail.com> wrote:
> Please remind me again what options we have for FPU instructions.

At present fisttp (and a few others, looks like all related to integer
operands, i.e. all fi*) default to the 's' suffix, which isn't in line with
the supposed defaulting to 'l'. The first proposed step here was to
make the disassembler properly emit 's'. Later on the assembler side,
together with the other addition of diagnostics (in the default case),
's' as a suffix would become mandatory for warning-free operation.

One thing you were concerned about is assembler input and
disassembler output going out of sync. There are examples of this
already, so I could see it being done either way. But if you tell me
I should change the testcase inputs as well, as that'll shrink the
size of one of the later patches.

The other option is to retain current behavior for fi*, by special
casing them in tc-i386.c. I dislike this option, though.

Jan