[llvm-dev] x86: How to Force 2-byte `jmp` instruction in lowering

Dean Michael Berris via llvm-dev llvm-dev at lists.llvm.org
Wed Jun 22 09:14:14 PDT 2016

On Wed, Jun 22, 2016 at 6:05 AM Nirav Davé <niravd at google.com> wrote:

> This appears to work:
> auto Target = OutContext.createLinkerPrivateTempSymbol();
> with
> auto Target = OutContext.createTempSymbol();
> -Nirav
Thanks Nirav -- I tried this but I'm still getting a "jmpq <address>" with
this incantation when I load and disassemble from gdb. I'm seeing a
5-instruction jump, followed by the nops.

If I disassemble with llvm-objdump though I see the following:

  400c10:       e9 09 00 00 00  jmp     9 <_Z3foov+0xE>
  400c15:       66 0f 1f 84 00 00 02 00 00      nopw    512(%rax,%rax)

I'm not sure whether the extra 0's after '0xe9 0x09' are alignment padding
(though I was expecing 0x90 to show up if this was an alignment issue).

Is there anything else I can try here?

Thanks in advance!
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