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Re: [GAS][ARM]Generate unpredictable warning for pc used in data processing instructions with register-shifted register operand
- From: Nick Clifton <nickc at redhat dot com>
- To: Renlin Li <renlin dot li at foss dot arm dot com>, "binutils at sourceware dot org" <binutils at sourceware dot org>
- Cc: Richard Earnshaw <Richard dot Earnshaw at arm dot com>, Ramana Radhakrishnan <Ramana dot Radhakrishnan at arm dot com>
- Date: Tue, 11 Oct 2016 14:06:38 +0100
- Subject: Re: [GAS][ARM]Generate unpredictable warning for pc used in data processing instructions with register-shifted register operand
- Authentication-results: sourceware.org; auth=none
- References: <57FB6409.3010105@foss.arm.com> <409c1bf7-aa48-4eb7-cd34-7c37a1494e39@redhat.com> <57FCDE48.1020107@foss.arm.com>
Hi Renlin,
> In ARMARM (ARMv7-A and ARMv7-R edition),
Ah - good we are using the same manual.
> if d == 15 || n == 15 || m == 15 || s == 15 then UNPREDICTABLE;
Right - thanks - I was looking at the wrong instruction - CMN (register)
rather than CMN (register-shifted register). Doh!
It seems a little strange that the PC cannot be read by these type
of instructions, but if that is what the ARMARM says, then so be it.
Cheers
Nick