Actually, this appears on vanilla Python 3.3 with -DWITH_TSC:

Python/ceval.c: In function ‘PyEval_EvalFrameEx’:
Python/ceval.c:986:5: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]
     READ_TIMESTAMP(inst0);
     ^
Python/ceval.c:987:5: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]
     READ_TIMESTAMP(inst1);
     ^
Python/ceval.c:988:5: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]
     READ_TIMESTAMP(loop0);
     ^
Python/ceval.c:989:5: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]
     READ_TIMESTAMP(loop1);
     ^
Python/ceval.c:1225:13: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]
             READ_TIMESTAMP(inst1);
             ^
Python/ceval.c:1234:9: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]
         READ_TIMESTAMP(loop0);
         ^
Python/ceval.c:1348:9: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]
         READ_TIMESTAMP(inst0);
         ^
Python/ceval.c:2334:13: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]
             READ_TIMESTAMP(intr0);
             ^
Python/ceval.c:2338:13: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]
             READ_TIMESTAMP(intr1);
             ^
Python/ceval.c:2353:13: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]
             READ_TIMESTAMP(intr0);
             ^
Python/ceval.c:2355:13: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]
             READ_TIMESTAMP(intr1);
             ^
Python/ceval.c:2364:13: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]
             READ_TIMESTAMP(intr0);
             ^
Python/ceval.c:2366:13: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]
             READ_TIMESTAMP(intr1);
             ^
Python/ceval.c:2719:13: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]
             READ_TIMESTAMP(intr0);
             ^
Python/ceval.c:2721:13: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]
             READ_TIMESTAMP(intr1);
             ^
Python/ceval.c:2872:9: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]
         READ_TIMESTAMP(inst1);
         ^
Python/ceval.c:2885:21: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]
                     READ_TIMESTAMP(loop1);
                     ^
Python/ceval.c:3011:9: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]
         READ_TIMESTAMP(loop1);
         ^