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 981A63858C52; Wed, 16 Aug 2023 09:42:03 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 981A63858C52
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1692178923;
	bh=tw/4otbqy6zhj67aR2Erw6O2rC/wfdRNuQij5dbHs+o=;
	h=From:To:Subject:Date:From;
	b=HeFygGTcCjy6kUJb2+4TPwX7pCMRm9i3FB6Z+z3gXxEGF+bFjwUCXBH9KiT9J9FFI
	 qDfY65/pb06Nhnd6PPhf6e6HsfgxVT0w2bk7gJ83J64l4yv8qktmf6q8RGHdGYUHUr
	 f4v+liKsW6/+WTCQ4CfVVZJ+sAmLHh91RpbIhEs0=
From: "bmei at broadcom dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/111036] New: Code generation error in
 handling __builtin_constant_p
Date: Wed, 16 Aug 2023 09:42:02 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: new
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: tree-optimization
X-Bugzilla-Version: 13.1.0
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: bmei at broadcom 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: bug_id short_desc product version bug_status
 bug_severity priority component assigned_to reporter target_milestone
Message-ID: <bug-111036-4@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=3D111036

            Bug ID: 111036
           Summary: Code generation error in handling __builtin_constant_p
           Product: gcc
           Version: 13.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: bmei at broadcom dot com
  Target Milestone: ---

Compile and run following code


#include <stdio.h>
#define __align(n) __attribute__((aligned(n)))

__attribute__((aligned(32))) static struct {

    unsigned long long available_cmd_ids_per_core[2];
} _rl2c_cmd_id_data;

static inline void __attribute__((always_inline))
foo (void *base, size_t length)
{
    unsigned long int p =3D (unsigned long int) base;
    if (__builtin_constant_p(p) && (p & 31) =3D=3D 0) { printf("constant p =
&&
aligned to 32\n"); }=20
    else if (__builtin_constant_p(length)) { printf("constant length\n");}=
=20
    else { printf("else\n"); }
}

int main(int argc, char **argv)
{
    foo(&_rl2c_cmd_id_data, sizeof(*(&_rl2c_cmd_id_data)));
    return 0;
}


With gcc 12.1.0 & gcc 13.1.0,  I got segmentation fault. With 11.1.0 and be=
low,
I got correct result. I examined the dumped tree IR. In einline pass, a
__builtin_unreachable is inserted for else if/else branches as the compiler
probably thinks __builtin_constant_p(p) & (p&31) is always true. But the la=
ter
passes think __builtin_constant_p(p) is always false. Therefore all code are
optimized away.=