[Bug inline-asm/79880] New: Gcc refuses to encode vpgatherdd instruction (x86-64)

["kobalicek.petr at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79880

            Bug ID: 79880
           Summary: Gcc refuses to encode vpgatherdd instruction (x86-64)
           Product: gcc
           Version: 7.0.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: inline-asm
          Assignee: unassigned at gcc dot gnu.org
          Reporter: kobalicek.petr at gmail dot com
  Target Milestone: ---

I'm unable to encode `vpgatherdd xmm, mem, xmm` instruction in inline asm:

void test() {
  __asm(".intel_syntax\n"
      "vpgatherdd xmm4, [r13 + xmm3], xmm4\n"
      ".att_syntax\n");
}

It seems that ICC refuses this construct as well while clang is fine with that.
I'm not sure if it's bug or this form of the instruction is incorrect. But
according to X86 Architecture Reference Manual it's encodable.