[Bug target/66697] Feature request: -mstackrealign and force_align_arg_pointer for x86_64

["ubizjak at gmail dot com" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66697

--- Comment #19 from Uroš Bizjak <ubizjak at gmail dot com> ---
(In reply to Justas L from comment #18)
> Out of curiosity, what could it be that makes -mincoming-stack-boundary=3
> successfully deal with rogue code while -mstackrealign fails at that?
> Shouldn't -mstackrealign do the same job without being told what the outside
> stack alignment is, or am I misunderstanding it?

-mstackrealign conditionally generates realignment prologue, depending on
presence of insns that require 128bit alignment. It looks that heuristics is
not yet fully reliable on x86_64. Bugreports welcome!

-mincoming-stack-boundary=3 and force_align_arg_pointer will always
unconditionally generate realignment prologue
>From gcc-bugs-return-498928-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org Wed Oct 07 07:29:11 2015
Return-Path: <gcc-bugs-return-498928-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org>
Delivered-To: listarch-gcc-bugs@gcc.gnu.org
Received: (qmail 129774 invoked by alias); 7 Oct 2015 07:29:11 -0000
Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm
Precedence: bulk
List-Id: <gcc-bugs.gcc.gnu.org>
List-Archive: <http://gcc.gnu.org/ml/gcc-bugs/>
List-Post: <mailto:gcc-bugs@gcc.gnu.org>
List-Help: <mailto:gcc-bugs-help@gcc.gnu.org>
Sender: gcc-bugs-owner@gcc.gnu.org
Delivered-To: mailing list gcc-bugs@gcc.gnu.org
Received: (qmail 129717 invoked by uid 48); 7 Oct 2015 07:29:07 -0000
From: "chrbr at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/67880] New: [ARM] -fno-align-functions does not work for thumb
Date: Wed, 07 Oct 2015 07:29:00 -0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: new
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: target
X-Bugzilla-Version: unknown
X-Bugzilla-Keywords:
X-Bugzilla-Severity: normal
X-Bugzilla-Who: chrbr at gcc dot gnu.org
X-Bugzilla-Status: UNCONFIRMED
X-Bugzilla-Resolution:
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Flags:
X-Bugzilla-Changed-Fields: bug_id short_desc product version bug_status bug_severity priority component assigned_to reporter target_milestone
Message-ID: <bug-67880-4@http.gcc.gnu.org/bugzilla/>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: 7bit
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
MIME-Version: 1.0
X-SW-Source: 2015-10/txt/msg00483.txt.bz2
Content-length: 669

https://gcc.gnu.org/bugzilla/show_bug.cgi?idg880

            Bug ID: 67880
           Summary: [ARM] -fno-align-functions does not work for thumb
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: chrbr at gcc dot gnu.org
  Target Milestone: ---

void foo()
{
}

compiled with -O2 -mthumb -mno-align-functions

        .text
        .align  2
        .global foo
        .syntax unified
        .code   16
        .thumb_func

is aligned on 4 bytes instead of default required 2 bytes