[PATCH] ARM: fix thumb1 nop decoding

[Tim Northover]

On 21 Jun 2013, at 09:49, Renato Golin <renato.golin at linaro.org> wrote:

> On 21 June 2013 16:39, Amaury de la Vieuville <amaury.dlv at gmail.com> wrote:
> Hi rengolin, t.p.northover,
> 
> In thumb1, NOP is a pseudo-instruction equivalent to mov r8, r8.
> However the disassembler should not use this alias.
> 
> Why not? Looks more informative than "mov r8, r8". Will this break assemblers later?

Because it’s not the official NOP hint, and reassembling a disassembled instruction should produce the same bits.

Besides, you can’t just go around inventing assembly syntax like that even if another NOP didn’t exist — for a start why should “mov r8, r8” be NOP but not “mov r9, r9”?

I expect it’s used by the compiler because the official NOP is Thumb2.

The patch looks good to me.

Tim.