objdump `-M no-aliases` doesn't work with `--macho`

[verhovsky]

Compile this trivial AArch64 program

.global _main
.align 2

_main:	MOV	W1, W2

like this

as main.s -o main.o
ld -o main -lSystem -syslibroot `xcrun -sdk macosx --show-sdk-path` main.o

then run objdump on it:

$ objdump -d main

main:	file format mach-o arm64

Disassembly of section __TEXT,__text:

0000000100003fb4 <_main>:
100003fb4: e1 03 02 2a 	mov	w1, w2
$ objdump -d --macho main
main:
(__TEXT,__text) section
_main:
100003fb4:	e1 03 02 2a	mov	w1, w2
$ objdump -d -M no-aliases main

main:	file format mach-o arm64

Disassembly of section __TEXT,__text:

0000000100003fb4 <_main>:
100003fb4: e1 03 02 2a 	orr	w1, wzr, w2
$ objdump -d --macho -M no-aliases main
main:
(__TEXT,__text) section
_main:
100003fb4:	e1 03 02 2a	mov	w1, w2

The last command (objdump -d --macho -M no-aliases main) outputs mov instead of orr.

I'm on an M1 Macbook Air, macOS 13.2.1, Xcode version 14.1 (14B47b)

$ as --version
Apple clang version 14.0.0 (clang-1400.0.29.202)
Target: arm64-apple-darwin22.3.0
Thread model: posix
InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin
$ objdump --version
Apple LLVM version 14.0.0 (clang-1400.0.29.202)
  Optimized build.
  Default target: arm64-apple-darwin22.3.0
  Host CPU: apple-a12
[...]

See below/HelloSilicon#43 for details.

[llvmbot]

@llvm/issue-subscribers-tools-llvm-objdump

[MaskRay]

myllvm-mc -filetype=obj -triple=arm64-apple-darwin a.s -o a.o && myllvm-objdump -d -M no-aliases a.o

works without --macho.