Bug 39115

Summary:	[4.3 Regression] Value of variable is not read again
Product:	gcc	Reporter:	Michael Tautschnig <mt>
Component:	target	Assignee:	Not yet assigned to anyone <unassigned>
Status:	RESOLVED FIXED
Severity:	normal	CC:	gcc-bugs
Priority:	P2
Version:	4.3.3
Target Milestone:	4.4.0
Host:	s390-unknown-linux-gnu	Target:	s390-unknown-linux-gnu
Build:	s390-unknown-linux-gnu	Known to work:	4.2.4, 4.4.0
Known to fail:	4.3.3	Last reconfirmed:
Attachments:	Not fully preprocessed source (includes <string>), compile with -DVOLATILE to see the correct behaviour Fully preprocessed source, compile with -O2 to see wrong behaviour

Description Michael Tautschnig 2009-02-05 22:56:36 UTC

[The bug has been reported to the Debian BTS before:
http://bugs.debian.org/491137]

On s390, when using -O2, the attached code fails to throw an exception, apparently because it does not re-evaluate the value of a variable. If the variable is marked volatile, the code works as expected.

Best,
Michael

Comment 1 Michael Tautschnig 2009-02-05 23:01:07 UTC

Created attachment 17255 [details]
Not fully preprocessed source (includes <string>), compile with -DVOLATILE to see the correct behaviour

Comment 2 Michael Tautschnig 2009-02-05 23:02:28 UTC

Created attachment 17256 [details]
Fully preprocessed source, compile with -O2 to see wrong behaviour

Comment 3 Michael Tautschnig 2009-02-05 23:04:37 UTC

I should have added that this worked fine on 4.2 and was broken as of 4.3.1 at least, earlier versions (> 4.2) untested.

Comment 4 Richard Biener 2009-03-13 22:58:11 UTC

Does it work with GCC 4.4?

Comment 5 Michael Tautschnig 2009-03-16 08:27:40 UTC

Indeed, seems to be fixed in 4.4.0 (tested using Debian's gcc-snapshot, g++ (Debian 20090224-1) 4.4.0 20090224 (experimental)). Sorry for not testing using a fresh build from 4.4 sources, but I hope that is helpful nevertheless.

Best,
Michael

Comment 6 Richard Biener 2009-08-04 12:29:56 UTC

GCC 4.3.4 is being released, adjusting target milestone.

Comment 7 Richard Biener 2010-05-22 18:13:23 UTC

GCC 4.3.5 is being released, adjusting target milestone.

Comment 8 Richard Biener 2011-06-27 11:47:54 UTC

Fixed for 4.4.0.