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

On 01/11/16 12:21, Jiong Wang wrote:
> Hi,
>   AArch32 MOV Rd, #imm should accept all immediates which can be encoded into
> available encoding, A1/A2 for ARM, T1/T2/T3 for Thumb/Thumb2, and MOV is the
> preferred disassembly syntax.  See latest ARM Architecture Reference Manual for
> ARMv8-A, section F6.1.108 and for ARMv8-M, section C2.4.89.
>   The same for MOV.W under Thumb mode.  It should try all possible 32-bit Thumb
> encoding instead of T2 only.
>   This patch let MOV/MOV.W accept more immediate formats while their currently
> supported immediate formats are not affected, so there is no backward compatibility
> issue, also this patch haven't touched the disassembler.
>   I think this patch brings GAS closer to ARM Architecture Reference Manual.
>   OK for master?
> gas/
> 2016-11-01  Jiong Wang  <>
>                           * config/tc-arm.c (SBIT_SHIFT): New.
>         (T2_SBIT_SHIFT): Likewise.
>         (t32_insn_ok): Return TRUE for MOV in ARMv8-M Baseline.
>         (md_apply_fix): Try UINT16 encoding when ARM/Thumb modified immediate
>         encoding failed.
>         * testsuite/gas/arm/archv6t2-bad.s: New error case.
>         * testsuite/gas/arm/archv6t2-bad.l: New error match.
>         * testsuite/gas/arm/archv6t2.s: New testcase.
>         * testsuite/gas/arm/archv6t2.d: New expected result.
>         * testsuite/gas/arm/archv8m.s: New testcase
>         * testsuite/gas/arm/archv8m-base.d: New expected result.
>         * testsuite/gas/arm/archv8m-main.d: Likewise.
>         * testsuite/gas/arm/archv8m-main-dsp-1.d: Likewise.

this caused

$ cat bug.s
.syntax unified
.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.

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