0000689: GCC7: Test failure on i686

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Category

Severity

Reproducibility

Date Submitted

Last Update

0000689

[ALGLIB] General

minor

always

2017-03-14 12:49

2017-10-24 13:19

Reporter

smani

View Status

public

Assigned To

SergeyB

Priority

normal

Resolution

open

Status

assigned

Product Version

3.10.0

Summary

0000689: GCC7: Test failure on i686

Description

The ReportCorrectnessTest of the linlsqr test fails on i686 when building with GCC7 (7.0.1 20170309) on Fedora rawhide. The failure occurs in the below section of test_c.cpp (some debug prints were added). The output of this snippet is:

ReportCorrectnessTest::Fail
1 0
TNorm=8107.5250330521303113;RNorm=8107.5250330521294018;S.R2=8107.525033052130;

-----------
/*
* check, that RNorm is't more than S.R2
* and difference between S.R2 and TNorm
* is't more than 'eps'(here S.R2=||rk||,
* calculated by the algorithm for LSQR, and
* TNorm=||A*S.x-b||, calculated by test function).
*/
if( ae_fp_greater(s.r2,rnorm)||ae_fp_greater(ae_fabs(s.r2-tnorm, _state),eps) )
{
    if( !silent )
    {
        printf("ReportCorrectnessTest::Fail\n");
        printf("%d %d\n", ae_fp_greater(s.r2,rnorm), ae_fp_greater(ae_fabs(s.r2-tnorm, _state),eps));
        printf("TNorm=%0.16f;RNorm=%0.16f;S.R2=%0.12f;\n",
            (double)(tnorm),
            (double)(rnorm),
            (double)(s.r2));
    }
    result = ae_true;
    ae_frame_leave(_state);
    return result;
}
-----------

By the way, the comment is also a bit confusing. If "is't" actually means "isn't", then the comment states that the test should verify:
rNorm < s.r2 <=> s.r2 > rNorm
|s.r2 - tNorm| < eps

but as far as I see the code fails if:
a) ae_fp_greater(s.r2,rnorm) <=> s.r2 > rNorm
b) ae_fp_greater(ae_fabs(s.r2-tnorm, _state),eps) <=> |s.r2 - tnorm| > eps

So a) matches the comment, but b) does not (and if "is't" means "is", then the opposite is true).

The build is using the following flags:
-O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m32 -march=i686 -fasynchronous-unwind-tables -fPIC

Build log is here:
https://koji.fedoraproject.org/koji/getfile?taskID=18371905&name=build.log

Other arches build correctly:
https://koji.fedoraproject.org/koji/taskinfo?taskID=18371900

Additional Information

Programming language

C++

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Issue History
Date Modified	Username	Field	Change
2017-03-14 12:49	smani	New Issue
2017-03-14 12:49	smani	Programming language	=> C++
2017-10-24 13:19	SergeyB	Status	new => assigned
2017-10-24 13:19	SergeyB	Assigned To	=> SergeyB

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