[Bug tree-optimization/100382] New: [12 Regression] go.test/test/fixedbugs/issue16095.go hang since r12-248

["jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100382

            Bug ID: 100382
           Summary: [12 Regression] go.test/test/fixedbugs/issue16095.go
                    hang since r12-248
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jakub at gcc dot gnu.org
  Target Milestone: ---

Since r12-248-gb58dc0b803057c0e6032e0d9bd92cd834f72c75c the
go.test/test/fixedbugs/issue16095.go
test hangs.
To reproduce e.g.:
../configure --enable-languages=c,c++,go --disable-bootstrap
make -j32
cd gcc
make -j32 check-go
The first difference (good to bad) is in the dse2 dump:
@@ -889,7 +889,6 @@ void main.main ()
   uint8[20] * _69;
   uint32 _72;
   uint64 GOTMP.131_73;
-  int _74;
   bool GOTMP.132_75;
   bool GOTMP.132_77;
   int GOTMP.16_155;
@@ -1190,7 +1189,6 @@ void main.main ()
   goto <bb 52>; [100.00%]

   <bb 54> [count: 0]:
-  _74 = MEM[(int *)0B];
   goto <bb 54>; [100.00%]

   <bb 55> [count: 0]:
@@ -1217,7 +1215,7 @@ void main.main ()
   goto <bb 68>; [100.00%]

   <bb 59> [count: 0]:
-  # x_76 = PHI <x_78(D)(36), _61(37), _61(41), _61(44), _61(45), _61(46),
_61(47), _61(48), _61(53), _61(54)>
+  # x_76 = PHI <x_78(D)(36), _61(37), _61(41), _61(44), _61(45), _61(46),
_61(47), _61(48), _61(53)>
 <L28>:
   # DEBUG x => x_76
   runtime.checkdefer (&GOTMP.15);