From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugzilla@gcc.gnu.org>
Received: by sourceware.org (Postfix, from userid 48)
	id 073E4385843E; Tue, 10 Jan 2023 14:05:01 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 073E4385843E
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1673359502;
	bh=B9nPGlHNEgSdllo+WfouRKma4cH2FtSOP7iFYh2kAyY=;
	h=From:To:Subject:Date:From;
	b=L1DWjh4Tgdcdf56V8csnC/Hej1rLLoIOf3Q0HhEZtd+QlxI703XoiwyJW8hfbrz/m
	 100s11ORM233qniJl89Axy+7KLUL8Gvgqg6/FOVFByz6OKogtbA4q9st78o8HlsV7A
	 hwIk0qSmGkV38EcJNTHMNZfqZ25rPIrw+2rtNu0I=
From: "eric-bugs at omnifarious dot org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/108361] New: Assembly code that is never called emitted on
 x86_64
Date: Tue, 10 Jan 2023 14:05:01 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: new
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: c++
X-Bugzilla-Version: 12.2.1
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: eric-bugs at omnifarious dot 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
 attachments.created
Message-ID: <bug-108361-4@http.gcc.gnu.org/bugzilla/>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
MIME-Version: 1.0
List-Id: <gcc-bugs.sourceware.org>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D108361

            Bug ID: 108361
           Summary: Assembly code that is never called emitted on x86_64
           Product: gcc
           Version: 12.2.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: eric-bugs at omnifarious dot org
  Target Milestone: ---

Created attachment 54236
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=3D54236&action=3Dedit
Preprocessed C++ code that generates unneeded assembly

The nature of this bug makes a concise test case hard to whittle down to
something minimal...

The attached code generates a whole bunch of assembly that isn't needed. Th=
is
assembly references external symbols as well, which creates unnecessary lin=
ker
errors.

Clang handles it just fine. :-)

Attached is both the preprocessed C++ code, and the assembly it generates. =
The
only needed assembly is the code for main and the static data main needs.

_start is defined as a global in a separate file, which is also attached.

The compile command I'm using:

g++ -std=3Dc++20 -march=3Dznver2 -static -O3 -nostartfiles -nostdlib
-I/usr/include/c++/12 -I/home/hopper/src/posixpp/pubincludes -Wl,-e_start
preprocessed.s x86_64_start.s=