Re: [PATCH][ARM][gas] Make gas accept vcmp[e].f{32,64} <reg>, #0.0

[Kyrill Tkachov <kyrylo dot tkachov at arm dot com>]

On 04/08/14 11:08, Will Newton wrote:
> On 4 August 2014 10:34, Kyrill Tkachov <kyrylo.tkachov@arm.com> wrote:
>
> Hi Kyrill,
>
> > The ARM ARM says that the VFP compare with zero instructions (vcmp, vcmpe)
> > accept the zero in the form of a #0.0 immediate. However, gas currently only
> > accepts #0. This patch fixes that and some simple tests are added.
> >
> > The new parse_ifimm_zerofunction is rather simple and is modelled on the
> > parse_qfloat_immediate below it and didn't blow up in my testing.
> >
> >
> > make check on gas passes and a gcc testsuite run doesn't show any problems.
> >
> > Ok for trunk?
> >
> > Thanks,
> > Kyrill
> >
> > [gas/]
> > 2014-06-24  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
> >
> >      * config/tc-arm.c (parse_ifimm_zero): New function.
> >      (enum operand_parse_code): Add OP_RSVD_FI0 value.
> >      (parse_operands): Handle OP_RSVD_FI0.
> >      (asm_opcode_insns): Use RSVD_FI0 for second operand of vcmp, vcmpe.
> >
> > [gas/testsuite/]
> > 2014-06-24  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
> >
> >      * gas/arm/ual-vcmp.s: New file.
> >      * gas/arm/ual-vcmp.d: Likewise.
> Would it be possible to use my_get_expression or a similar parser for
> this?
Hi Will,

Thanks for the suggestion, but I'm struggling to figure out what 
my_get_expression is supposed to be doing. Is it supposed to be taking a 
string and parsing it into an expressionS?
I'm not very well versed in gas internal data types...

Kyrill

> It can be surprisingly tricky to get right, e.g. I think your
> code will accept #0.01 as zero for example. In any case it would be
> good to have a *-bad.s test which checks to make sure that invalid
> values are actually detected.