Message 58480 - Python tracker

Message58480

Author	gvanrossum
Recipients	christian.heimes, gvanrossum, nascheme, noam, rhettinger, tim.peters
Date	2007-12-12.00:31:07
SpamBayes Score	0.017369375
Marked as misclassified	No
Message-id	<ca471dc20712111631r10ec54cyc34bb22c270485a5@mail.gmail.com>
In-reply-to	<ca471dc20712111606q46c1f464j2cd51dab4bb4acbc@mail.gmail.com>

Content
I've tracked my problem to the GCC optimizer. The default optimizer setting is -O3. When I edit the Makefile to change this to -O1 or -O0 and recompile (only) doubledigits.c, repr(1e5) starts returning '100000.0' again. -O2 behaves the same as -O3. Now, don't immediately start pointing fingers to the optimizer; it's quite possible that the code depends on behavior that the C standard doesn't actually guarantee. The code looks quote complicated. This is with GCC 4.0.3.

Content

I've tracked my problem to the GCC optimizer. The default optimizer
setting is -O3. When I edit the Makefile to change this to -O1 or -O0
and recompile (only) doubledigits.c, repr(1e5) starts returning
'100000.0' again. -O2 behaves the same as -O3.

Now, don't immediately start pointing fingers to the optimizer; it's
quite possible that the code depends on behavior that the C standard
doesn't actually guarantee. The code looks quote complicated.

This is with GCC 4.0.3.

History
Date	User	Action	Args
2007-12-12 00:31:08	gvanrossum	set	spambayes_score: 0.0173694 -> 0.017369375 recipients: + gvanrossum, tim.peters, nascheme, rhettinger, christian.heimes, noam
2007-12-12 00:31:07	gvanrossum	link	issue1580 messages
2007-12-12 00:31:07	gvanrossum	create