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 A3797385842D; Tue, 21 Feb 2023 19:29:54 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org A3797385842D
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1677007794;
	bh=F4OqCtYl3MlDC+wH1RylMcWUgppg1l0wOSyLHKQKo1U=;
	h=From:To:Subject:Date:In-Reply-To:References:From;
	b=gPsKA7I9iib3PNibrrJgsX+soj+pCyM2TRQ5QuMryacQYt2hmu95AJFpzLgo37dDy
	 9IS2adzIwy5rt3Pjc8Vl3x6ykFEP1aGR1fQdh2wcLl+rVb8rjIuIikWOwjE1ky+Jgl
	 jB9Dzmp+ZeCe+J6dLCZbsRAR/TvCa7Iv3JWbqREQ=
From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug rtl-optimization/106041] [12/13 Regression] infinite loop in
 fast_dce at -O1 with aarch64
Date: Tue, 21 Feb 2023 19:29:54 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: rtl-optimization
X-Bugzilla-Version: 12.1.0
X-Bugzilla-Keywords: compile-time-hog, needs-bisection, needs-reduction
X-Bugzilla-Severity: normal
X-Bugzilla-Who: rguenth 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: 12.3
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: attachments.created
Message-ID: <bug-106041-4-XvaUaXVw3b@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-106041-4@http.gcc.gnu.org/bugzilla/>
References: <bug-106041-4@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=3D106041

--- Comment #11 from Richard Biener <rguenth at gcc dot gnu.org> ---
Created attachment 54503
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=3D54503&action=3Dedit
reduced testcase

Reduced testcase (on the GCC 12 branch).  Reduced with -O1 and

diff --git a/gcc/dce.cc b/gcc/dce.cc
index 6676cbcd429..8af54a96394 100644
--- a/gcc/dce.cc
+++ b/gcc/dce.cc
@@ -36,6 +36,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "tree-pass.h"
 #include "dbgcnt.h"
 #include "rtl-iter.h"
+#include "diagnostic-core.h"


 /* -----------------------------------------------------------------------=
--
@@ -1103,9 +1104,13 @@ fast_dce (bool word_level)

   dead_debug_global_init (&global_debug, NULL);

+  unsigned iters =3D 0;
   while (global_changed)
     {
       global_changed =3D false;
+      ++iters;
+      if (iters > 50)
+       internal_error ("too many iterations");

       for (i =3D 0; i < n_blocks; i++)
        {=