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 75EC63858D39; Mon,  9 Oct 2023 02:38:40 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 75EC63858D39
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1696819120;
	bh=CcZPbtHfXCuQAgMCjznGmlsdeONKi3Kq2iYUg7Fbwe0=;
	h=From:To:Subject:Date:In-Reply-To:References:From;
	b=xZMtV4TN2cG9odSCx30p4HJQvMKngHNFxRmWwK6eTQp1BvI4VZpYmwqUYHWt/AOvK
	 e8hte90AAWFwSscm+KGgPl4c7oRNM60npQRemjnBIwBtlVViAx1D5h1juzpsdWryvY
	 QDcol7SrZLS/HBsxAt3hDjylZb2bSSJdvy6LKq8Y=
From: "xavier.cooney03 at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/111730] erroneous alloc-size-larger-than
 warning with -O1
Date: Mon, 09 Oct 2023 02:38:40 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: tree-optimization
X-Bugzilla-Version: 13.2.1
X-Bugzilla-Keywords: diagnostic
X-Bugzilla-Severity: normal
X-Bugzilla-Who: xavier.cooney03 at gmail dot com
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: 
Message-ID: <bug-111730-4-Lf4kd4O9pq@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-111730-4@http.gcc.gnu.org/bugzilla/>
References: <bug-111730-4@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=3D111730

--- Comment #4 from Xavier Cooney <xavier.cooney03 at gmail dot com> ---
I see, thanks for looking into this.

The unreduced test case (which was from a student confused about the error
message) was still passing a value to `malloc` which from the context which=
 gcc
could see wasn't /necessarily/ non-negative.

But the code
```
void foo2(int x) {
    char *a =3D malloc(x);
    (void) a;
}
```
doesn't trigger the warning, even though `x` could also be negative.

I'm not sure why the extra loops are necessary for the warning to be emitte=
d if
the compiler is trying to warn about any time a potentially negative value
might be passed to `malloc`.

Also the error message reads to me as saying that argument 1 must be in the
range [18446744071562067968, 18446744073709551615] (in which case it would =
be
incorrect), rather than saying the argument could be in the range (in which
case it would be correct).

Thanks again for look into this :)=