https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88897
Martin Sebor <msebor at gcc dot gnu.org> 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 <msebor at gcc dot gnu.org> --- The warning first appeared in r245840 (GCC 7.0.1 20170302), ironically committed to fix PR tree-optimization/79345 (passing yet-uninitialized member 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 = VDEF <.MEM_2(D)> # PT = nonlocal escaped null # USE = nonlocal null { D.2411 } (escaped) # CLB = nonlocal null { D.2411 } (escaped) _4 = _Z3barvD.2407 (); # .MEM_5 = VDEF <.MEM_3> # USE = nonlocal null { D.2411 } (escaped) # CLB = nonlocal null { D.2411 } (escaped) _ZN12future_stateC1EvD.2402 (&_local_stateD.2411); # .MEM_10 = VDEF <.MEM_5> MEM[(struct &)&_local_stateD.2411] ={v} {CLOBBER}; # .MEM_11 = VDEF <.MEM_10> MEM[(struct optionalD.2323 *)&_local_stateD.2411]._M_engagedD.2340 = 0; # PT = nonlocal escaped null _7 = &_4->valueD.2401; if (_7 != 0B) goto <bb 4>; [73.26%] else goto <bb 7>; [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 = PHI <.MEM_11(7), .MEM_13(8)> goto <bb 6>; [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 = VDEF <.MEM_11> MEM[(struct optionalD.2323 *)_4]._M_engagedD.2340 = 0; # VUSE <.MEM_13> _8 = MEM[(struct optionalD.2323 &)&_local_stateD.2411]._M_engagedD.2340; if (_8 != 0) goto <bb 5>; [54.00%] else goto <bb 8>; [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 <bb 3>; [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 = nonlocal escaped null _6 = MEM[(struct temporary_bufferD.2301 &)&_local_stateD.2411]._bufferD.2303; # .MEM_15 = VDEF <.MEM_13> MEM[(struct temporary_bufferD.2301 *)_4]._bufferD.2303 = _6; # .MEM_16 = VDEF <.MEM_15> MEM[(struct optionalD.2323 *)_4]._M_engagedD.2340 = 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 = PHI <.MEM_16(5), .MEM_17(3)> # .MEM_9 = VDEF <.MEM_1> _local_stateD.2411 ={v} {CLOBBER}; # VUSE <.MEM_9> return; ;; succ: EXIT [100.0%] }