[PATCH, AARCH64] support s2_<op1>_<Cn>_<Cm>_<op2> sys reg
Yufeng Zhang
Yufeng.Zhang@arm.com
Tue Nov 12 23:10:00 GMT 2013
Hi Zhenqiang,
On 11/12/13 06:12, Zhenqiang Chen wrote:
> Hi,
>
> Current parse_sys_reg only supports s3_<op1>_<Cn>_<Cm>_<op2>. But
> according to the document,
>
> integer sys_op0 = 2 + UInt(o0)
>
> o0 is bit-19.
>
> So sys_op0 can be 2 or 3.
>
> This patch changes GAS to to add s2_<op1>_<Cn>_<Cm>_<op2> support.
> OK for trunk?
For MSR/MRS instruction, it is correct that sys_op0 can be 2 or 3.
However, it doesn't necessarily mean that the encoding space of
sys_op0==2 contains reserved area for implementation defined system
registers.
The ARMARMv8 mentions in section C4.2.6 "Op0==0b11, Moves to and from
non-debug System registers and special-purpose registers" that:
"The instructions that move data to and from non-debug system registers
are encoded with Op0==0b11, except that some of this encoding space is
reserved for IMPLEMENTATION DEFINED functionality."
The document however doesn't mention about the implementation defined
functionality in section C4.2.5 "Op0==0b10, Moves to and from debug,
qtrace, and Execution environment System registers".
Is there any named system register in the op0==0b10 encoding space that
you would like to add support for, by extending the syntax?
Also if we go head with the patch, please also add some tests to
gas/testsuite/gas/aarch64/sysreg.[d|s].
Thanks,
Yufeng
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