[PATCH][AArch64] Enable access to the whole MRS/MSR system reg encoding space

[James Molloy]

Hi Tom,

Thanks for working on this. I can see this feature is very useful for
"power users" doing architectural exploration.

However, the change makes the production compiler less strict, and I don't
think that's right. This change should be enabled behind a flag so that a
user explicitly has to opt-in to it.

Cheers,

James

On 18 September 2014 14:57, Tom Coxon <tom.coxon at arm.com> wrote:

> Hi all,
>
> The attached patch enables access to the whole space of ARMv8-A system
> registers through the S<op0>_<op1>_<Cn>_<Cm>_<op2> syntax.
>
> This is useful to anyone needing to write assembly code supporting new
> system registers before the assembler has learned the official names for
> them.
>
> Although this is a real use case, it is niche and most users should still
> use the official system registers names. In order to avoid encouraging
> general use of this syntax, ARM is not planning to document this in the
> ARMARM.
>
> Regards,
> Tom
>
> Files changed:
>  lib/Target/AArch64/AArch64InstrFormats.td          |   12 +++----
>  .../AArch64/Disassembler/AArch64Disassembler.cpp   |   24 +++----------
>  .../AArch64/InstPrinter/AArch64InstPrinter.cpp     |   12 +++----
>  lib/Target/AArch64/Utils/AArch64BaseInfo.cpp       |   36
> +++++++-------------
>  lib/Target/AArch64/Utils/AArch64BaseInfo.h         |    2 +-
>  test/MC/AArch64/arm64-system-encoding.s            |    4 +++
>  test/MC/AArch64/basic-a64-diagnostics.s            |   16 ++++-----
>  test/MC/AArch64/basic-a64-instructions.s           |    8 +++--
>  8 files changed, 44 insertions(+), 70 deletions(-)
>
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