Bug 159274 - Optimizing produces incorrect code in some for loops
Summary: Optimizing produces incorrect code in some for loops
Status: CLOSED UPSTREAM
Alias: None
Product: Fedora
Classification: Fedora
Component: gcc   
(Show other bugs)
Version: 3
Hardware: i586 Linux
medium
medium
Target Milestone: ---
Assignee: Jakub Jelinek
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Blocks:
TreeView+ depends on / blocked
 
Reported: 2005-06-01 10:34 UTC by Kasper Dupont
Modified: 2007-11-30 22:11 UTC (History)
0 users

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
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Last Closed: 2005-06-01 13:13:48 UTC
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RHEL 7.3 requirements from Atomic Host:
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Attachments (Terms of Use)
Source that demonstrates the bug (1.25 KB, text/x-csrc)
2005-06-01 10:36 UTC, Kasper Dupont 		no flags Details
Add an attachment (proposed patch, testcase, etc.)


External Trackers
Tracker ID Priority Status Summary Last Updated
GNU Compiler Collection 21862 None None None Never

Description Kasper Dupont 2005-06-01 10:34:07 UTC 
From Bugzilla Helper:
User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.4.1) Gecko/20031114

Description of problem:
The attached program is supposed to execute a for loop 262144 times, but when compiled with -O2, -O3, or -Os, the loop is executed only once.

Version-Release number of selected component (if applicable):
gcc-3.4.3-22.fc3

How reproducible:
Always

Steps to Reproduce:
1. Download the attached file for-loop-optimizing-bug.c
2. gcc -Wall -W -O2 -s for-loop-optimizing-bug.c -o for-loop-optimizing-bug
3. ./for-loop-optimizing-bug | wc -c


Actual Results:  4096

Expected Results:  1073741824

Additional info:

This FC3 system is using kernel version 2.6.11-1.27_FC3. Notice that this bug is not limited to i586, I have reproduced it on an i686 systems running FC2 and an athlon system running FC1.
Comment 1 Kasper Dupont 2005-06-01 10:36:59 UTC 
Created attachment 115020 [details]
Source that demonstrates the bug
Comment 2 Jakub Jelinek 2005-06-01 13:13:48 UTC 
Tracking upstream.  gcc 3.2.3 fails the same way, gcc 4.0.0 is ok.
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