Message 284639 - Python tracker

Message284639

Author	xiang.zhang
Recipients	benjamin.peterson, matejcik, xiang.zhang
Date	2017-01-04.14:31:02
SpamBayes Score	-1.0
Marked as misclassified	Yes
Message-id	<1483540262.63.0.590289499261.issue29145@psf.upfronthosting.co.za>
In-reply-to

Content
> It does, but "-fwrapv" is not automatically added when you specify custom OPT flags. Indeed I think this is why the changes in #27473 and #1621 make sense. > GCC 6 optimizes away broken overflow checks. I am sorry but I don't understand this. What do you mean by broken overflow checks? Is `if (size > PY_SSIZE_T_MAX - vo.len)` broken?

Content

> It does, but "-fwrapv" is not automatically added when you specify custom OPT flags.

Indeed I think this is why the changes in #27473 and #1621 make sense.

> GCC 6 optimizes away broken overflow checks.

I am sorry but I don't understand this. What do you mean by broken overflow checks? Is `if (size > PY_SSIZE_T_MAX - vo.len)` broken?

History
Date	User	Action	Args
2017-01-04 14:31:02	xiang.zhang	set	recipients: + xiang.zhang, matejcik, benjamin.peterson
2017-01-04 14:31:02	xiang.zhang	set	messageid: <1483540262.63.0.590289499261.issue29145@psf.upfronthosting.co.za>
2017-01-04 14:31:02	xiang.zhang	link	issue29145 messages
2017-01-04 14:31:02	xiang.zhang	create