llvm dev - Apr 2019 - How to enable AArch64 V8.3A support in clang?

Hey:
Apple's version of Clang has support for ``-arch arm64e``which enables ARM
PAC support. IIRC a few years ago someone from Apple/ARM says they are planning
to merge the support back to upstream and judging by my very limited experience
with backend it seems to be the case. However I just couldn't get that part
to work. Directly using ``-arch arm64e`` doesn't seem to work and results in
a ``invalid arch name '-arch arm64e'``.


I then tried multiple combinations like ``-target arm64-apple-ios5.0.0
-march=armv8.3-a`` but has no effect. The binary still doesn't have any
V8.3A instructions. Am I missing something here?


Thanks




Zhang
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Hi Zhang,

On Tue, Apr 23, 2019 at 10:22 AM Zhang via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
>
> Hey:
> Apple's version of Clang has support for ``-arch arm64e``which enables
ARM PAC support. IIRC a few years ago someone from Apple/ARM says they are
planning to merge the support back to upstream and judging by my very limited
experience with backend it seems to be the case. However I just couldn't get
that part to work. Directly using ``-arch arm64e`` doesn't seem to work and
results in a ``invalid arch name '-arch arm64e'``.
>
> I then tried multiple combinations like ``-target arm64-apple-ios5.0.0
-march=armv8.3-a`` but has no effect. The binary still doesn't have any
V8.3A instructions. Am I missing something here?
arm64e is only supported by Apple Clang at this time.
Upstream LLVM/Clang has various bits and pieces, including: full
assembler/disassembler for v8.3a, some basic codegen (for return
address signing and v8.5a BTI), and minimal MachO object reading.

Let me know if you have any questions,
-Ahmed
>
> Thanks
>
>
> Zhang
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev

We will push back the full implementation. Stay tuned.

-Gerolf

> On Apr 23, 2019, at 11:13 AM, Ahmed Bougacha via llvm-dev <llvm-dev at
lists.llvm.org> wrote:
> 
> Hi Zhang,
> 
> On Tue, Apr 23, 2019 at 10:22 AM Zhang via llvm-dev
> <llvm-dev at lists.llvm.org> wrote:
>> 
>> Hey:
>> Apple's version of Clang has support for ``-arch arm64e``which
enables ARM PAC support. IIRC a few years ago someone from Apple/ARM says they
are planning to merge the support back to upstream and judging by my very
limited experience with backend it seems to be the case. However I just
couldn't get that part to work. Directly using ``-arch arm64e`` doesn't
seem to work and results in a ``invalid arch name '-arch arm64e'``.
>> 
>> I then tried multiple combinations like ``-target arm64-apple-ios5.0.0
-march=armv8.3-a`` but has no effect. The binary still doesn't have any
V8.3A instructions. Am I missing something here?
> 
> arm64e is only supported by Apple Clang at this time.
> Upstream LLVM/Clang has various bits and pieces, including: full
> assembler/disassembler for v8.3a, some basic codegen (for return
> address signing and v8.5a BTI), and minimal MachO object reading.
> 
> Let me know if you have any questions,
> -Ahmed
> 
>> 
>> Thanks
>> 
>> 
>> Zhang
>> _______________________________________________
>> LLVM Developers mailing list
>> llvm-dev at lists.llvm.org
>> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev