Message 141701 - Python tracker

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Author	deadshort
Recipients	deadshort
Date	2011-08-06.02:46:57
SpamBayes Score	0.002032149
Marked as misclassified	No
Message-id	<1312598819.22.0.165585430892.issue12701@psf.upfronthosting.co.za>
In-reply-to

Content
Apple Radar ticket 9908625 has been filed. The clang 2.1 optimizer causes overflows in Object/intobject.c:int_pow() to be missed, so 2*63 turns into a negative integer. The attached test program narrows it down. llvm-gcc is fine, so this ticket is mostly an FYI. idiotbox:Python-2.7.2 cloomis$ ./seqpoint-OK 4000000000 4000000000 a=4000000000, b=4000000000, c(ab)=-2446744073709551616, c/b=-611686018 overflow detected: 1 to turn into: idiotbox:Python-2.7.2 cloomis$ ./seqpoint 4294967296 4200000000 a=4294967296, b=4200000000, c(a*b)=-407881430509551616, c/b=4294967296 overflow detected: 0

Apple Radar ticket 9908625 has been filed. The clang 2.1 optimizer causes overflows in Object/intobject.c:int_pow() to be missed, so 2**63 turns into a negative integer. The attached test program narrows it down. llvm-gcc is fine, so this ticket is mostly an FYI.

idiotbox:Python-2.7.2 cloomis$ ./seqpoint-OK 4000000000 4000000000
a=4000000000, b=4000000000, c(a*b)=-2446744073709551616, c/b=-611686018
overflow detected: 1

  to turn into:

idiotbox:Python-2.7.2 cloomis$ ./seqpoint 4294967296 4200000000
a=4294967296, b=4200000000, c(a*b)=-407881430509551616, c/b=4294967296
overflow detected: 0

History
Date	User	Action	Args
2011-08-06 02:46:59	deadshort	set	recipients: + deadshort
2011-08-06 02:46:59	deadshort	set	messageid: <1312598819.22.0.165585430892.issue12701@psf.upfronthosting.co.za>
2011-08-06 02:46:58	deadshort	link	issue12701 messages
2011-08-06 02:46:58	deadshort	create