[ARM] Allow MOV/MOV.W to accept all possible immediates

[Jan Beulich]

>>> On 05.01.17 at 14:59, <jiong.wang@foss.arm.com> wrote:
> On 05/01/17 10:49, Szabolcs Nagy wrote:
>> On 05/01/17 10:45, Szabolcs Nagy wrote:
>>> $ cat bug.s
>>> .syntax unified
>>> .text
>>> .arch armv7-a
>>> 	mov r3,#1
>>>
>>> .arch armv4t
>>> .eabi_attribute 6,2
>>> 	bx lr
>>>
>>> $ arm-none-linux-gnueabihf-as -mthumb bug.s
>>> bug.s: Assembler messages:
>>> bug.s:4: Error: invalid constant (1) after fixup
>>>
>>> previously this worked, but i'm not sure if the mix
>>> of .arch directives and .syntax unified is valid here.
> 
> It looks to me the failure is caused by the second ".arch armv4t" 
> overrides the
> first ".arch armv7-a", therefore the arch feature is lowerd to armv4t in
> assembler fixup stage.  While "mov r3, #1" under thumb mode is only allowed
> with ARMv6T2.
> 
> This patch tightend the check from
> 
>        if (fixP->fx_r_type == BFD_RELOC_ARM_T32_IMMEDIATE
>            || fixP->fx_r_type == BFD_RELOC_ARM_T32_ADD_IMM)
> 
> into:
> 
>        if ((fixP->fx_r_type == BFD_RELOC_ARM_T32_IMMEDIATE
>             && ARM_CPU_HAS_FEATURE (cpu_variant, arm_ext_v6t2))
>            || fixP->fx_r_type == BFD_RELOC_ARM_T32_ADD_IMM)
> 
> 
> thus the sequences in bug.s is not allowed.

Suggests pretty clearly that the fixup should record the arch in
use at the time it is being created.

Jan