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

[Will Newton <will dot newton at linaro dot org>]

On 5 August 2014 14:11, Kyrill Tkachov <kyrylo.tkachov@arm.com> wrote:
>
> 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...

Yes, that's pretty much it. I think an integer will be type O_constant
with the value in X_add_number and a floating point value O_big with a
value in generic_floating_point_number. The expr.c code is not pretty
but it should be possible to make it do something approaching what's
reguired...

-- 
Will Newton
Toolchain Working Group, Linaro