Bug 881489

Summary:	procps compiles with -ffast-math, breaking things
Product:	[Fedora] Fedora	Reporter:	Andy Lutomirski <luto>
Component:	procps	Assignee:	Jaromír Cápík <jcapik>
Status:	CLOSED CURRENTRELEASE	QA Contact:	Fedora Extras Quality Assurance <extras-qa>
Severity:	unspecified	Docs Contact:
Priority:	unspecified
Version:	17	CC:	davejohansen, fedora, jcapik, ovasik
Target Milestone:	---
Target Release:	---
Hardware:	x86_64
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2013-07-03 22:57:23 UTC	Type:	Bug
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description Andy Lutomirski 2012-11-29 00:43:37 UTC

libproc is built (and, in particular, linked) with -ffast-math.  That pulls in crtfastmath.o, which sets the flush-to-zero flag (on x86) for  which causes hilarity when you innocently link against libproc.

This is IMO so bad that I'm filing a GCC bug about it.  Fedora 18 should be unaffected because the package is completely gone.  In the mean time, please patch out the -ffast-math option.

Comment 1 Jaromír Cápík 2012-11-30 14:15:39 UTC

Hello Andy.

Could you please tell me more about those hilarities you've experienced?
Thank you.

Regards,
Jaromir.

Comment 2 Andy Lutomirski 2012-11-30 19:28:42 UTC

I have a financial program that (unsurprisingly) does math.  I added a feature that involved linking against libproc.  A while later, I noticed that floating-point math was behaving oddly.  After much cursing and modifying ld-linux to figure out what was going on, I figured out that libproc had an initializer that set the flush-to-zero and denormals-are-zero bits.  Oops.

There's nothing wrong with compiling with -ffast-math, but linking with -ffast-math is bad when you're a shared library.

Comment 3 Fedora End Of Life 2013-07-03 22:53:52 UTC

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Comment 4 Andy Lutomirski 2013-07-03 22:57:23 UTC

As noted, this is fixed in Fedora 18.