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[RFC PATCH, i386]: Deprecate -mmitigate-rop

From: Uros Bizjak <ubizjak at gmail dot com>
To: "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>
Cc: Jeff Law <law at redhat dot com>, Jakub Jelinek <jakub at redhat dot com>
Date: Fri, 10 Aug 2018 13:42:40 +0200
Subject: [RFC PATCH, i386]: Deprecate -mmitigate-rop

This option is fairly ineffective, and in the light of CET, nobody
seems interested to improve it. Deprecate the option, so it won't lure
developers to the land of false security.

2018-08-10  Uros Bizjak  <ubizjak@gmail.com>

    * config/i386/i386.opt (mmitigate-rop): Mark as deprecated.
    * doc/invoke.texi (mmitigate-rop): Remove.
    * config/i386/i386.c: Do not include "regrename.h".
    (ix86_rop_should_change_byte_p, reg_encoded_number)
    (ix86_get_modrm_for_rop, set_rop_modrm_reg_bits, ix86_mitigate_rop):
    Remove.
    (ix86_reorg): Remove call to ix86_mitigate_rop.
    * config/i386/i386.md (attr "modrm_class"): Remove.
    (cmp<mode>_ccno_1, mov<mode>_xor, movstrict<mode>_xor,
    x86_mov<mode>cc_0_m1. x86_mov<mode>cc_0_m1_se)
    (x86_mov<mode>cc_0_m1_neg): Remove modrm_class attribute override.

testsuite/Changelog:

2018-08-10  Uros Bizjak  <ubizjak@gmail.com>

    * gcc.target/i386/rop1.c: Remove.
    * gcc.target/i386/pr83554 (dg-options): Remove -mmitigate-rop.

Bootstrapped and regression tested on x86_64-linux-gnu {,-m32}.

Any opinion against the deprecation?

Uros.

Attachment: p.diff.txt
Description: Text document

Follow-Ups:
- Re: [RFC PATCH, i386]: Deprecate -mmitigate-rop
  - From: Jeff Law

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