[Bug breakpoints/31481] Certain instructions load the wrong RIP-relative memory after setting a breakpoint

["boudewijn83 at gmail dot com" <sourceware-bugzilla@sourceware.org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=31481

--- Comment #4 from Boudewijn <boudewijn83 at gmail dot com> ---
Created attachment 15409
  --> https://sourceware.org/bugzilla/attachment.cgi?id=15409&action=edit
Proposed patch, fixes #28999 and #31481

There's actually no need for an extra lookup table.

All (E)VEX prefixed instructions share the same two properties:

- the (explicit part of the) opcode is only 1 byte
- they all have a ModRM byte, except VZEROALL/VZEROUPPER

So when there's an (E)VEX prefix it suffices to test for VZEROALL/VZEROUPPER
(opcode 0x77):

  if (vex2 or vex3 or evex) {
    details->opcode_len = 1;
    need_modrm = (*insn != 0x77);
  } else {
    use the legacy has_modrm tables
  }

I've attached a patch that implements this.

PS: I've tested VEX2/VEX3, but don't have an AVX-512 capable CPU so I'm not
able to test the EVEX handling.

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