[Bug binutils/22464] New: x86 gas -n option does not work

[wilson at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=22464

            Bug ID: 22464
           Summary: x86 gas -n option does not work
           Product: binutils
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: binutils
          Assignee: unassigned at sourceware dot org
          Reporter: wilson at gcc dot gnu.org
  Target Milestone: ---

I noticed this by accident.  The x86 assembler has a -n option which says to
emit one byte nops instead of multi-byte nops.  But when I try it, it doesn't
work.

rohan:2162$ cat tmp.s
        .text
        movl    %edi, %eax
        .balign 8
        movl    $0, %edx
        .balign 8
        .section ".text.alt"
        movl    %edi, %eax
rohan:2163$ as tmp.s
rohan:2164$ objdump -d a.out

a.out:     file format elf64-x86-64


Disassembly of section .text:

0000000000000000 <.text>:
   0:   89 f8                   mov    %edi,%eax
   2:   66 0f 1f 44 00 00       nopw   0x0(%rax,%rax,1)
   8:   ba 00 00 00 00          mov    $0x0,%edx
   d:   0f 1f 00                nopl   (%rax)

Disassembly of section .text.alt:

0000000000000000 <.text.alt>:
   0:   89 f8                   mov    %edi,%eax
rohan:2165$ 

This option was introduced in binutils-2.15.  When I try building that, I see
that it doesn't work there either.  Which means it appears that the x86 gas -n
option has never worked in a release.

I'm willing to submit a patch to remove it, but if you want it to work, someone
else will have to fix it.

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