[Bug gas/22773] New: [ARM] Invalid immediate constants produce incorrect instructions

[koops.j at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=22773

            Bug ID: 22773
           Summary: [ARM] Invalid immediate constants produce incorrect
                    instructions
           Product: binutils
           Version: 2.29
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: gas
          Assignee: unassigned at sourceware dot org
          Reporter: koops.j at gmail dot com
  Target Milestone: ---

I have the following bit of assembly:

    .syntax unified
    .cpu cortex-m4
    .thumb

    .section  .text

    orr r1, #12800
    orr r1, #12801

I invoke the GNU assembler as follows:

arm-none-eabi-gcc -g -Wall -c bla.s

The assembler issues no warnings, but the output, when inspected with objdump,
looks as follows:

    bla.o:     file format elf32-littlearm


    Disassembly of section .text:

    00000000 <.text>:
       0:   f441 5148   orr.w   r1, r1, #12800  ; 0x3200
       4:   f243 2101   movw    r1, #12801  ; 0x3201

The second orr instruction, which should've produced an error since the
constant #12801 cannot be encoded as an immediate, was silently changed into a
mov instruction instead.

The exact version of the assembler is:
GNU assembler version 2.29.51 (arm-none-eabi) using BFD version (GNU Tools for
Arm Embedded Processors 7-2017-q4-major) 2.29.51.20171128

I'm running OSX:
Darwin trumposaurus.local 15.6.0 Darwin Kernel Version 15.6.0: Sun Jun  4
21:43:07 PDT 2017; root:xnu-3248.70.3~1/RELEASE_X86_64 x86_64

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