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* [Bug fortran/102011] New: Infinite loop in heron iteration when optimization is enabled with gfortran 10.3.0
@ 2021-08-22 10:27 Ralph-Trenkler@t-online.de
2021-08-22 16:58 ` [Bug fortran/102011] " kargl at gcc dot gnu.org
0 siblings, 1 reply; 2+ messages in thread
From: Ralph-Trenkler@t-online.de @ 2021-08-22 10:27 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102011
Bug ID: 102011
Summary: Infinite loop in heron iteration when optimization is
enabled with gfortran 10.3.0
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: fortran
Assignee: unassigned at gcc dot gnu.org
Reporter: Ralph-Trenkler@t-online.de
Target Milestone: ---
Created attachment 51346
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=51346&action=edit
The fortran program, which does the infinite loop with compiler version 10.3.0
I wrote a function in gfortran-10.3.0, which computes the square root with the
heron iteration method. Without optimization the program is okay, but if I turn
on optimization, then it does an infinite loop. I use Kubuntu 20.04.
^ permalink raw reply [flat|nested] 2+ messages in thread
* [Bug fortran/102011] Infinite loop in heron iteration when optimization is enabled with gfortran 10.3.0
2021-08-22 10:27 [Bug fortran/102011] New: Infinite loop in heron iteration when optimization is enabled with gfortran 10.3.0 Ralph-Trenkler@t-online.de
@ 2021-08-22 16:58 ` kargl at gcc dot gnu.org
0 siblings, 0 replies; 2+ messages in thread
From: kargl at gcc dot gnu.org @ 2021-08-22 16:58 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102011
kargl at gcc dot gnu.org changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |kargl at gcc dot gnu.org
Status|UNCONFIRMED |RESOLVED
Resolution|--- |INVALID
--- Comment #1 from kargl at gcc dot gnu.org ---
(In reply to Ralph Trenkler from comment #0)
> Created attachment 51346 [details]
> The fortran program, which does the infinite loop with compiler version
> 10.3.0
>
> I wrote a function in gfortran-10.3.0, which computes the square root with
> the heron iteration method. Without optimization the program is okay, but if
> I turn on optimization, then it does an infinite loop. I use Kubuntu 20.04.
If I compile your program with -Wall, I get
gfcx -o z -fcheck=all -Wall a.f90 && ./z
a.f90:11:13:
11 | if (abs((x2-x1)/(x1+x2)) < epsilon) exit
| ^
Warning: 'epsilon' may be used uninitialized [-Wmaybe-uninitialized]
Sure, enough.
real(8), parameter :: epilson = 1.0e-15
^^^^^^^
if (abs((x2-x1)/(x1+x2)) < epsilon) exit
^^^^^^^
One of these is wrong.
^ permalink raw reply [flat|nested] 2+ messages in thread
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2021-08-22 10:27 [Bug fortran/102011] New: Infinite loop in heron iteration when optimization is enabled with gfortran 10.3.0 Ralph-Trenkler@t-online.de
2021-08-22 16:58 ` [Bug fortran/102011] " kargl at gcc dot gnu.org
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