[llvm-dev] thumbv7 build errors "requires arm-mode"

[Tim Northover via llvm-dev]

Hi Steve,

On 19 November 2015 at 08:59, Steve King via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
> After a recent upstream pull, my builds for ARM thumbv7 suddenly fail
> with messages like:
>
> error: instruction requires: arm-mode
>  21         uxtah   r6, r0, r6
>
> I use llc with -mtriple=thumbv7-unknown-unknown and llvm-mc with
> -triple=thumbv7-unknown-unkown.
>
> What's the right way to generate thumbv7 binaries?

We recently refactored how the triple generated a default CPU, and it
seems support for uxtah was dropped from thumbv7. I suspect it's a
bug, but I'll check with Bradley if it was intentional.

Meanwhile, it should work again if you specify a CPU directly (e.g.
-mcpu=cortex-a15 ought to support all the nice v7 bits).

Cheers.

Tim.