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Created on 2013-05-21 08:32 by bkabrda, last changed 2022-04-11 14:57 by admin. This issue is now closed.
| Files | ||||
|---|---|---|---|---|
| File name | Uploaded | Description | Edit | |
| tsc_strict_aliasing.patch | christian.heimes, 2013-07-07 19:02 | review | ||
| Messages (10) | |||
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| msg189729 - (view) | Author: Bohuslav "Slavek" Kabrda (bkabrda) * | Date: 2013-05-21 08:32 | |
Hi, I'm getting these warnings with -fstrict-aliasing, compiling Python 3.3.2 (compiling with gcc 4.4.7): /builddir/build/BUILD/Python-3.Python/ceval.c: In function 'PyEval_EvalFrameEx': /builddir/build/BUILD/Python-3.Python/ceval.c:1006: warning: dereferencing type-punned pointer will break strict-aliasing rules /builddir/build/BUILD/Python-3.Python/ceval.c:1007: warning: dereferencing type-punned pointer will break strict-aliasing rules /builddir/build/BUILD/Python-3.Python/ceval.c:1008: warning: dereferencing type-punned pointer will break strict-aliasing rules /builddir/build/BUILD/Python-3.Python/ceval.c:1009: warning: dereferencing type-punned pointer will break strict-aliasing rules /builddir/build/BUILD/Python-3.Python/ceval.c:1249: warning: dereferencing type-punned pointer will break strict-aliasing rules /builddir/build/BUILD/Python-3.Python/ceval.c:1258: warning: dereferencing type-punned pointer will break strict-aliasing rules /builddir/build/BUILD/Python-3.Python/ceval.c:1372: warning: dereferencing type-punned pointer will break strict-aliasing rules /builddir/build/BUILD/Python-3.Python/ceval.c:2358: warning: dereferencing type-punned pointer will break strict-aliasing rules /builddir/build/BUILD/Python-3.Python/ceval.c:2362: warning: dereferencing type-punned pointer will break strict-aliasing rules /builddir/build/BUILD/Python-3.Python/ceval.c:2377: warning: dereferencing type-punned pointer will break strict-aliasing rules /builddir/build/BUILD/Python-3.Python/ceval.c:2379: warning: dereferencing type-punned pointer will break strict-aliasing rules /builddir/build/BUILD/Python-3.Python/ceval.c:2388: warning: dereferencing type-punned pointer will break strict-aliasing rules /builddir/build/BUILD/Python-3.Python/ceval.c:2390: warning: dereferencing type-punned pointer will break strict-aliasing rules /builddir/build/BUILD/Python-3.Python/ceval.c:2743: warning: dereferencing type-punned pointer will break strict-aliasing rules /builddir/build/BUILD/Python-3.Python/ceval.c:2745: warning: dereferencing type-punned pointer will break strict-aliasing rules /builddir/build/BUILD/Python-3.Python/ceval.c:2896: warning: dereferencing type-punned pointer will break strict-aliasing rules /builddir/build/BUILD/Python-3.Python/ceval.c:2909: warning: dereferencing type-punned pointer will break strict-aliasing rules /builddir/build/BUILD/Python-3.Python/ceval.c:3035: warning: dereferencing type-punned pointer will break strict-aliasing rules This seems to be quite serious, but I'm not a C expert, so I'd like to know whether this is a false positive or this is actually a dangerous bug. Thanks. |
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| msg189731 - (view) | Author: Arfrever Frehtes Taifersar Arahesis (Arfrever) *  |
Date: 2013-05-21 08:51 | |
Your Python/ceval.c has custom patches applied. Line 1006 is a comment in unmodified Python/ceval.c in Python 3.3.2. This bug might be caused by your patches. Alternatively it is a bug in GCC 4.4.7. I get 0 warnings for unmodified Python/ceval.c with GCC 4.7.3. |
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| msg189734 - (view) | Author: Bohuslav "Slavek" Kabrda (bkabrda) * | Date: 2013-05-21 09:07 | |
Hmm, you're probably right. The problem seems to be in downstream redefinition of READ_TIMESTAMP. Sorry for the fuzz, closing. |
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| msg189739 - (view) | Author: Bohuslav "Slavek" Kabrda (bkabrda) * | Date: 2013-05-21 09:59 | |
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); ^ |
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| msg192582 - (view) | Author: Christian Heimes (christian.heimes) *  |
Date: 2013-07-07 19:02 | |
The warning is caused by the X86_64 code for timestamps:
#define READ_TIMESTAMP(val) \
__asm__ __volatile__("rdtsc" : \
"=a" (((int*)&(val))[0]), "=d" (((int*)&(val))[1]));
The patch fixes the issue with two temp vars.
|
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| msg232473 - (view) | Author: Serhiy Storchaka (serhiy.storchaka) * |
Date: 2014-12-11 12:21 | |
LGTM. |
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| msg232491 - (view) | Author: Antoine Pitrou (pitrou) * |
Date: 2014-12-11 20:52 | |
Looks good to me as well. |
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| msg232515 - (view) | Author: Raymond Hettinger (rhettinger) * |
Date: 2014-12-12 07:52 | |
+1 |
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| msg232535 - (view) | Author: Roundup Robot (python-dev) |
Date: 2014-12-12 12:20 | |
New changeset 9565b56a4615 by Victor Stinner in branch '2.7': Issue #18028: Fix aliasing issue in READ_TIMESTAMP() of ceval.c on x86_64, https://hg.python.org/cpython/rev/9565b56a4615 New changeset adb445578995 by Victor Stinner in branch '3.4': Issue #18028: Fix aliasing issue in READ_TIMESTAMP() of ceval.c on x86_64, https://hg.python.org/cpython/rev/adb445578995 |
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| msg232536 - (view) | Author: STINNER Victor (vstinner) * |
Date: 2014-12-12 12:22 | |
3 core developers reviewed Christian's patch, so it also looks good to me :-) Since Christian looks to be busy, I commited his patch. Thanks Christian for your fix. We might enable -fstrict-aliasing later, at least to compile Python core (not to build extensions). |
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| History | |||
|---|---|---|---|
| Date | User | Action | Args |
| 2022-04-11 14:57:45 | admin | set | github: 62228 |
| 2014-12-12 12:22:32 | vstinner | set | status: open -> closed nosy: + vstinner messages: + msg232536 resolution: fixed |
| 2014-12-12 12:20:28 | python-dev | set | nosy:
+ python-dev messages: + msg232535 |
| 2014-12-12 07:52:39 | rhettinger | set | nosy:
+ rhettinger messages: + msg232515 |
| 2014-12-11 20:52:44 | pitrou | set | nosy:
+ pitrou messages: + msg232491 |
| 2014-12-11 12:21:41 | serhiy.storchaka | set | versions:
+ Python 3.5, - Python 3.3 nosy: + serhiy.storchaka messages: + msg232473 assignee: christian.heimes stage: patch review -> commit review |
| 2013-07-07 19:02:24 | christian.heimes | set | files:
+ tsc_strict_aliasing.patch priority: normal -> low type: compile error versions: + Python 3.4 keywords: + patch nosy: + christian.heimes messages: + msg192582 stage: patch review |
| 2013-05-21 09:59:36 | bkabrda | set | status: closed -> open messages: + msg189739 |
| 2013-05-21 09:07:55 | bkabrda | set | status: open -> closed messages: + msg189734 |
| 2013-05-21 08:51:25 | Arfrever | set | nosy:
+ Arfrever messages: + msg189731 |
| 2013-05-21 08:32:22 | bkabrda | create | |