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 30EF23972039; Mon, 14 Jun 2021 21:22:53 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 30EF23972039
From: "i at maskray dot me" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug gcov-profile/80223] RFE: Exclude functions from profile
 instrumentation
Date: Mon, 14 Jun 2021 21:22:52 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: gcov-profile
X-Bugzilla-Version: 7.0
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: enhancement
X-Bugzilla-Who: i at maskray dot me
X-Bugzilla-Status: NEW
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: cc
Message-ID: <bug-80223-4-d5Lx4xhHzA@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-80223-4@http.gcc.gnu.org/bugzilla/>
References: <bug-80223-4@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
X-BeenThere: gcc-bugs@gcc.gnu.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Gcc-bugs mailing list <gcc-bugs.gcc.gnu.org>
List-Unsubscribe: <https://gcc.gnu.org/mailman/options/gcc-bugs>,
 <mailto:gcc-bugs-request@gcc.gnu.org?subject=unsubscribe>
List-Archive: <https://gcc.gnu.org/pipermail/gcc-bugs/>
List-Post: <mailto:gcc-bugs@gcc.gnu.org>
List-Help: <mailto:gcc-bugs-request@gcc.gnu.org?subject=help>
List-Subscribe: <https://gcc.gnu.org/mailman/listinfo/gcc-bugs>,
 <mailto:gcc-bugs-request@gcc.gnu.org?subject=subscribe>
X-List-Received-Date: Mon, 14 Jun 2021 21:22:53 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D80223

Fangrui Song <i at maskray dot me> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |i at maskray dot me

--- Comment #7 from Fangrui Song <i at maskray dot me> ---
Some notes.

{gcc,clang} -fsanitize-coverage=3D{trace-pc,trace-cmp} is another coverage
feature. It uses no_sanitize_coverage instead of no_instrument_function. The
GCC support for no_sanitize_coverage is very new (by Martin, in 2021-05-25).
(In Clang, the feature has more modes, e.g. you can control func/bb/edge.)

The Linux kernel use case (include/linux/compiler_types.h ) uses 'noinline'=
 so
inlining is not a concern.

/* Section for code which can't be instrumented at all */
#define noinstr                                                         \
        noinline notrace __attribute((__section__(".noinstr.text")))    \
        __no_kcsan __no_sanitize_address

Clang supports another filtering mechanism, -fprofile-list=3D
(https://reviews.llvm.org/D94820). But the kernel use case seems to prefer a
function attribute.=