Message 55579 - Python tracker

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Author	sanders_muc
Recipients	loewis, sanders_muc
Date	2007-09-02.09:31:39
SpamBayes Score	0.249093
Marked as misclassified	No
Message-id	<1188725500.46.0.384977575245.issue1084@psf.upfronthosting.co.za>
In-reply-to

Content
Martin, you are right: is is related to compiler optimization. I have boiled it down to a call of stringlib_find (defined in Python-2.5.1/Objects/stringlib/find.h) and this runs fine with 'icc -O2' but incorrectly for 'icc -O3'. (The test code is attached.) So, it seems that the lesson is simply once again: Do not use '-O3' with Intel's C compiler. (At least, for me, it is not the first time that this caused trouble.) On the other hand, Python's ./configure script is quite clear in its preference of GCC, anyway: It more or less ignores with option '--without-gcc' and uses the content of the CC environment variable only very occasionally.

Martin, you are right: is is related to compiler optimization. I have
boiled it down to a call of stringlib_find (defined in
Python-2.5.1/Objects/stringlib/find.h) and this runs fine with 'icc -O2'
but incorrectly for 'icc -O3'. (The test code is attached.)

So, it seems that the lesson is simply once again: Do not use '-O3' with
Intel's C compiler. (At least, for me, it is not the first time that
this caused trouble.)

On the other hand, Python's ./configure script is quite clear in its
preference of GCC, anyway: It more or less ignores with option
'--without-gcc' and uses the content of the CC environment variable only
very occasionally.

Files
File name	Uploaded
findtest.c	sanders_muc, 2007-09-02.09:31:39

History
Date	User	Action	Args
2007-09-02 09:31:40	sanders_muc	set	spambayes_score: 0.249093 -> 0.249093 recipients: + sanders_muc, loewis
2007-09-02 09:31:40	sanders_muc	set	spambayes_score: 0.249093 -> 0.249093 messageid: <1188725500.46.0.384977575245.issue1084@psf.upfronthosting.co.za>
2007-09-02 09:31:40	sanders_muc	link	issue1084 messages
2007-09-02 09:31:39	sanders_muc	create