From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id 370F53846027; Tue, 6 Apr 2021 20:47:26 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 370F53846027 From: "msebor at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug middle-end/88897] [9/10/11 Regression] Bogus maybe-uninitialized warning on class field (missed CSE) Date: Tue, 06 Apr 2021 20:47:26 +0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: middle-end X-Bugzilla-Version: 8.2.1 X-Bugzilla-Keywords: diagnostic, missed-optimization X-Bugzilla-Severity: normal X-Bugzilla-Who: msebor at gcc dot gnu.org 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: short_desc Message-ID: In-Reply-To: References: 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 List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 06 Apr 2021 20:47:26 -0000 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D88897 Martin Sebor changed: What |Removed |Added ---------------------------------------------------------------------------- Summary|Bogus maybe-uninitialized |[9/10/11 Regression] Bogus |warning on class field |maybe-uninitialized warning |(missed CSE) |on class field (missed CSE) --- Comment #8 from Martin Sebor --- The warning first appeared in r245840 (GCC 7.0.1 20170302), ironically committed to fix PR tree-optimization/79345 (passing yet-uninitialized memb= er as argument to base class constructor should warn (-Wunitialized)). The IL emitted just before that revision doesn't look all that different: void foo() () { struct future_stateD.2397 _local_stateD.2411; struct future_stateD.2397 * _4; charD.10 * _6; voidD.45 * _7; boolD.2220 _8; ;; basic block 2, loop depth 0, count 0, freq 10000, maybe hot ;; prev block 0, next block 7, flags: (NEW, REACHABLE, VISITED) ;; pred: ENTRY [100.0%] (FALLTHRU,EXECUTABLE) # .MEM_3 =3D VDEF <.MEM_2(D)> # PT =3D nonlocal escaped null=20 # USE =3D nonlocal null { D.2411 } (escaped) # CLB =3D nonlocal null { D.2411 } (escaped) _4 =3D _Z3barvD.2407 (); # .MEM_5 =3D VDEF <.MEM_3> # USE =3D nonlocal null { D.2411 } (escaped) # CLB =3D nonlocal null { D.2411 } (escaped) _ZN12future_stateC1EvD.2402 (&_local_stateD.2411); # .MEM_10 =3D VDEF <.MEM_5> MEM[(struct &)&_local_stateD.2411] =3D{v} {CLOBBER}; # .MEM_11 =3D VDEF <.MEM_10> MEM[(struct optionalD.2323 *)&_local_stateD.2411]._M_engagedD.2340 =3D 0; # PT =3D nonlocal escaped null=20 _7 =3D &_4->valueD.2401; if (_7 !=3D 0B) goto ; [73.26%] else goto ; [26.74%] ;; succ: 4 [73.3%] (TRUE_VALUE,EXECUTABLE) ;; 7 [26.7%] (FALSE_VALUE,EXECUTABLE) ;; basic block 7, loop depth 0, count 0, freq 2674, maybe hot ;; prev block 2, next block 3, flags: (NEW) ;; pred: 2 [26.7%] (FALSE_VALUE,EXECUTABLE) ;; succ: 3 [100.0%] (FALLTHRU) ;; basic block 3, loop depth 0, count 0, freq 6044, maybe hot ;; prev block 7, next block 4, flags: (NEW, REACHABLE, VISITED) ;; pred: 7 [100.0%] (FALLTHRU) ;; 8 [100.0%] (FALLTHRU) # .MEM_17 =3D PHI <.MEM_11(7), .MEM_13(8)> goto ; [100.00%] ;; succ: 6 [100.0%] (FALLTHRU,EXECUTABLE) ;; basic block 4, loop depth 0, count 0, freq 7326, maybe hot ;; prev block 3, next block 8, flags: (NEW, REACHABLE, VISITED) ;; pred: 2 [73.3%] (TRUE_VALUE,EXECUTABLE) # .MEM_13 =3D VDEF <.MEM_11> MEM[(struct optionalD.2323 *)_4]._M_engagedD.2340 =3D 0; # VUSE <.MEM_13> _8 =3D MEM[(struct optionalD.2323 &)&_local_stateD.2411]._M_engagedD.2340; if (_8 !=3D 0) goto ; [54.00%] else goto ; [46.00%] ;; succ: 5 [54.0%] (TRUE_VALUE,EXECUTABLE) ;; 8 [46.0%] (FALSE_VALUE,EXECUTABLE) ;; basic block 8, loop depth 0, count 0, freq 3370, maybe hot ;; prev block 4, next block 5, flags: (NEW) ;; pred: 4 [46.0%] (FALSE_VALUE,EXECUTABLE) goto ; [100.00%] ;; succ: 3 [100.0%] (FALLTHRU) ;; basic block 5, loop depth 0, count 0, freq 3956, maybe hot ;; prev block 8, next block 6, flags: (NEW, REACHABLE, VISITED) ;; pred: 4 [54.0%] (TRUE_VALUE,EXECUTABLE) # VUSE <.MEM_13> # PT =3D nonlocal escaped null=20 _6 =3D MEM[(struct temporary_bufferD.2301 &)&_local_stateD.2411]._bufferD= .2303; # .MEM_15 =3D VDEF <.MEM_13> MEM[(struct temporary_bufferD.2301 *)_4]._bufferD.2303 =3D _6; # .MEM_16 =3D VDEF <.MEM_15> MEM[(struct optionalD.2323 *)_4]._M_engagedD.2340 =3D 1; ;; succ: 6 [100.0%] (FALLTHRU,EXECUTABLE) ;; basic block 6, loop depth 0, count 0, freq 10000, maybe hot ;; prev block 5, next block 1, flags: (NEW, REACHABLE, VISITED) ;; pred: 5 [100.0%] (FALLTHRU,EXECUTABLE) ;; 3 [100.0%] (FALLTHRU,EXECUTABLE) # .MEM_1 =3D PHI <.MEM_16(5), .MEM_17(3)> # .MEM_9 =3D VDEF <.MEM_1> _local_stateD.2411 =3D{v} {CLOBBER}; # VUSE <.MEM_9> return; ;; succ: EXIT [100.0%]=20 }=