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* [Bug fortran/64530] New: [4.9 Regression] Incorrect calculation when assigning to array with -O3
@ 2015-01-07 21:39 jkaus at ucsd dot edu
2015-01-07 22:36 ` [Bug fortran/64530] " anlauf at gmx dot de
` (8 more replies)
0 siblings, 9 replies; 10+ messages in thread
From: jkaus at ucsd dot edu @ 2015-01-07 21:39 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64530
Bug ID: 64530
Summary: [4.9 Regression] Incorrect calculation when assigning
to array with -O3
Product: gcc
Version: 4.9.2
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: fortran
Assignee: unassigned at gcc dot gnu.org
Reporter: jkaus at ucsd dot edu
Created attachment 34398
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=34398&action=edit
Minimal example illustrating the issue.
With gfortran 4.9 using -O3, the assignment to an array
can occur before the rest of the calculation, giving
an incorrect result. I have attached a minimal example
which shows the bug along with modified code that
produces the correct results.
With O3 we get the wrong result (0.0):
gfortran -O3 a.F90
./a.out
> buggy 0.0000000000000000 0.0000000000000000 0.0000000000000000
> works 3.5000000000000000 3.5000000000000000 3.5000000000000000
With O2 we get the correct result (3.5):
gfortran -O2 a.F90
./a.out
> buggy 3.5000000000000000 3.5000000000000000 3.5000000000000000
> works 3.5000000000000000 3.5000000000000000 3.500000000000000
gfortran -v
Using built-in specs.
COLLECT_GCC=gfortran
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/4.9/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu
4.9.2-0ubuntu1~12.04' --with-bugurl=file:///usr/share/doc/gcc-4.9/README.Bugs
--enable-languages=c,c++,java,go,d,fortran,objc,obj-c++ --prefix=/usr
--program-suffix=-4.9 --enable-shared --enable-linker-build-id
--libexecdir=/usr/lib --without-included-gettext --enable-threads=posix
--with-gxx-include-dir=/usr/include/c++/4.9 --libdir=/usr/lib --enable-nls
--with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug
--enable-libstdcxx-time=yes --enable-gnu-unique-object --disable-vtable-verify
--enable-plugin --with-system-zlib --disable-browser-plugin
--enable-java-awt=gtk --enable-gtk-cairo
--with-java-home=/usr/lib/jvm/java-1.5.0-gcj-4.9-amd64/jre --enable-java-home
--with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-4.9-amd64
--with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-4.9-amd64
--with-arch-directory=amd64 --with-ecj-jar=/usr/share/java/eclipse-ecj.jar
--enable-objc-gc --enable-multiarch --disable-werror --with-arch-32=i686
--with-abi=m64 --with-multilib-list=m32,m64 --enable-multilib
--with-tune=generic --enable-checking=release --build=x86_64-linux-gnu
--host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 4.9.2 (Ubuntu 4.9.2-0ubuntu1~12.04)
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug fortran/64530] [4.9 Regression] Incorrect calculation when assigning to array with -O3
2015-01-07 21:39 [Bug fortran/64530] New: [4.9 Regression] Incorrect calculation when assigning to array with -O3 jkaus at ucsd dot edu
@ 2015-01-07 22:36 ` anlauf at gmx dot de
2015-01-07 22:51 ` dominiq at lps dot ens.fr
` (7 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: anlauf at gmx dot de @ 2015-01-07 22:36 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64530
Harald Anlauf <anlauf at gmx dot de> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |anlauf at gmx dot de
--- Comment #1 from Harald Anlauf <anlauf at gmx dot de> ---
(In reply to jkaus from comment #0)
> With O3 we get the wrong result (0.0):
> gfortran -O3 a.F90
> ./a.out
> > buggy 0.0000000000000000 0.0000000000000000 0.0000000000000000
> > works 3.5000000000000000 3.5000000000000000 3.5000000000000000
Interesting bug. I can confirm that it does not occur with 4.8,
but with 4.9 and 5.
Note that if one interchanges in subroutine "buggy" the lines
old(i) = ave(i)
tmp(i) = tmp(i) / scale_factor
to
tmp(i) = tmp(i) / scale_factor
old(i) = ave(i)
I also get the correct result.
With gfortran 4.9 and 5 I also get the correct result with -O3
when e.g. using UBSAN (-fsanitize=undefined); it probably also
reduces the optimization.
Since the dump tree looks the same for 4.8 and 4.9, could it be
a middle-end bug?
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug fortran/64530] [4.9 Regression] Incorrect calculation when assigning to array with -O3
2015-01-07 21:39 [Bug fortran/64530] New: [4.9 Regression] Incorrect calculation when assigning to array with -O3 jkaus at ucsd dot edu
2015-01-07 22:36 ` [Bug fortran/64530] " anlauf at gmx dot de
@ 2015-01-07 22:51 ` dominiq at lps dot ens.fr
2015-01-07 22:55 ` [Bug tree-optimization/64530] " dominiq at lps dot ens.fr
` (6 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: dominiq at lps dot ens.fr @ 2015-01-07 22:51 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64530
Dominique d'Humieres <dominiq at lps dot ens.fr> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2015-01-07
CC| |rguenth at gcc dot gnu.org
Ever confirmed|0 |1
--- Comment #2 from Dominique d'Humieres <dominiq at lps dot ens.fr> ---
(1) The problem goes away if the code is compiled with '-O3
-fno-tree-loop-vectorize'.
(2) The bug appeared between r204000 (OK, 2013-10-24) and r204945 (buggy,
2013-11-18).
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug tree-optimization/64530] [4.9 Regression] Incorrect calculation when assigning to array with -O3
2015-01-07 21:39 [Bug fortran/64530] New: [4.9 Regression] Incorrect calculation when assigning to array with -O3 jkaus at ucsd dot edu
2015-01-07 22:36 ` [Bug fortran/64530] " anlauf at gmx dot de
2015-01-07 22:51 ` dominiq at lps dot ens.fr
@ 2015-01-07 22:55 ` dominiq at lps dot ens.fr
2015-01-08 8:42 ` [Bug tree-optimization/64530] [4.9/5 " jakub at gcc dot gnu.org
` (5 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: dominiq at lps dot ens.fr @ 2015-01-07 22:55 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64530
Dominique d'Humieres <dominiq at lps dot ens.fr> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |wrong-code
Component|fortran |tree-optimization
Known to work| |4.8.5
Known to fail| |4.9.2, 5.0
--- Comment #3 from Dominique d'Humieres <dominiq at lps dot ens.fr> ---
> Since the dump tree looks the same for 4.8 and 4.9, could it be
> a middle-end bug?
Indeed! reassigned to tree optimization.
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug tree-optimization/64530] [4.9/5 Regression] Incorrect calculation when assigning to array with -O3
2015-01-07 21:39 [Bug fortran/64530] New: [4.9 Regression] Incorrect calculation when assigning to array with -O3 jkaus at ucsd dot edu
` (2 preceding siblings ...)
2015-01-07 22:55 ` [Bug tree-optimization/64530] " dominiq at lps dot ens.fr
@ 2015-01-08 8:42 ` jakub at gcc dot gnu.org
2015-01-08 9:07 ` rguenth at gcc dot gnu.org
` (4 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: jakub at gcc dot gnu.org @ 2015-01-08 8:42 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64530
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |jakub at gcc dot gnu.org
Target Milestone|--- |4.9.3
--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Started with r204062.
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug tree-optimization/64530] [4.9/5 Regression] Incorrect calculation when assigning to array with -O3
2015-01-07 21:39 [Bug fortran/64530] New: [4.9 Regression] Incorrect calculation when assigning to array with -O3 jkaus at ucsd dot edu
` (3 preceding siblings ...)
2015-01-08 8:42 ` [Bug tree-optimization/64530] [4.9/5 " jakub at gcc dot gnu.org
@ 2015-01-08 9:07 ` rguenth at gcc dot gnu.org
2015-01-12 15:37 ` rguenth at gcc dot gnu.org
` (3 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: rguenth at gcc dot gnu.org @ 2015-01-08 9:07 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64530
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |ASSIGNED
Assignee|unassigned at gcc dot gnu.org |rguenth at gcc dot gnu.org
--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
Mine.
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug tree-optimization/64530] [4.9/5 Regression] Incorrect calculation when assigning to array with -O3
2015-01-07 21:39 [Bug fortran/64530] New: [4.9 Regression] Incorrect calculation when assigning to array with -O3 jkaus at ucsd dot edu
` (4 preceding siblings ...)
2015-01-08 9:07 ` rguenth at gcc dot gnu.org
@ 2015-01-12 15:37 ` rguenth at gcc dot gnu.org
2015-01-12 15:39 ` [Bug tree-optimization/64530] [4.9 " rguenth at gcc dot gnu.org
` (2 subsequent siblings)
8 siblings, 0 replies; 10+ messages in thread
From: rguenth at gcc dot gnu.org @ 2015-01-12 15:37 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64530
--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> ---
Author: rguenth
Date: Mon Jan 12 15:37:07 2015
New Revision: 219474
URL: https://gcc.gnu.org/viewcvs?rev=219474&root=gcc&view=rev
Log:
2015-01-12 Richard Biener <rguenther@suse.de>
PR tree-optimization/64530
* tree-loop-distribution.c (pg_add_dependence_edges): Shuffle
back dr1.
* gfortran.dg/pr64530.f90: New testcase.
Added:
trunk/gcc/testsuite/gfortran.dg/pr64530.f90
Modified:
trunk/gcc/ChangeLog
trunk/gcc/testsuite/ChangeLog
trunk/gcc/tree-loop-distribution.c
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug tree-optimization/64530] [4.9 Regression] Incorrect calculation when assigning to array with -O3
2015-01-07 21:39 [Bug fortran/64530] New: [4.9 Regression] Incorrect calculation when assigning to array with -O3 jkaus at ucsd dot edu
` (5 preceding siblings ...)
2015-01-12 15:37 ` rguenth at gcc dot gnu.org
@ 2015-01-12 15:39 ` rguenth at gcc dot gnu.org
2015-02-20 7:32 ` rguenth at gcc dot gnu.org
2015-02-20 7:34 ` rguenth at gcc dot gnu.org
8 siblings, 0 replies; 10+ messages in thread
From: rguenth at gcc dot gnu.org @ 2015-01-12 15:39 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64530
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Known to work| |5.0
Summary|[4.9/5 Regression] |[4.9 Regression] Incorrect
|Incorrect calculation when |calculation when assigning
|assigning to array with -O3 |to array with -O3
Known to fail|5.0 |
--- Comment #7 from Richard Biener <rguenth at gcc dot gnu.org> ---
Fixed on trunk sofar.
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug tree-optimization/64530] [4.9 Regression] Incorrect calculation when assigning to array with -O3
2015-01-07 21:39 [Bug fortran/64530] New: [4.9 Regression] Incorrect calculation when assigning to array with -O3 jkaus at ucsd dot edu
` (6 preceding siblings ...)
2015-01-12 15:39 ` [Bug tree-optimization/64530] [4.9 " rguenth at gcc dot gnu.org
@ 2015-02-20 7:32 ` rguenth at gcc dot gnu.org
2015-02-20 7:34 ` rguenth at gcc dot gnu.org
8 siblings, 0 replies; 10+ messages in thread
From: rguenth at gcc dot gnu.org @ 2015-02-20 7:32 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64530
--- Comment #8 from Richard Biener <rguenth at gcc dot gnu.org> ---
Author: rguenth
Date: Fri Feb 20 07:32:08 2015
New Revision: 220835
URL: https://gcc.gnu.org/viewcvs?rev=220835&root=gcc&view=rev
Log:
2015-02-20 Richard Biener <rguenther@suse.de>
Backport from mainline
2015-01-12 Richard Biener <rguenther@suse.de>
PR tree-optimization/64530
* tree-loop-distribution.c (pg_add_dependence_edges): Shuffle
back dr1.
* gfortran.dg/pr64530.f90: New testcase.
2015-02-13 Richard Biener <rguenther@suse.de>
PR lto/64373
* lto-streamer-out.c (tree_is_indexable): Guard for NULL
DECL_CONTEXT.
* gcc.dg/lto/pr64373_0.c: New testcase.
2015-02-16 Richard Biener <rguenther@suse.de>
PR tree-optimization/63593
* tree-predcom.c (execute_pred_commoning_chain): Delay removing
stmts and releasing SSA names until...
(execute_pred_commoning): ... after processing all chains.
* gcc.dg/pr63593.c: New testcase.
2015-02-18 Richard Biener <rguenther@suse.de>
PR tree-optimization/65063
* tree-predcom.c (determine_unroll_factor): Return 1 if we
have replaced looparound PHIs.
* gcc.dg/pr65063.c: New testcase.
Added:
branches/gcc-4_9-branch/gcc/testsuite/gcc.dg/lto/pr64373_0.c
branches/gcc-4_9-branch/gcc/testsuite/gcc.dg/pr63593.c
branches/gcc-4_9-branch/gcc/testsuite/gcc.dg/pr65063.c
branches/gcc-4_9-branch/gcc/testsuite/gfortran.dg/pr64530.f90
Modified:
branches/gcc-4_9-branch/gcc/ChangeLog
branches/gcc-4_9-branch/gcc/lto-streamer-out.c
branches/gcc-4_9-branch/gcc/testsuite/ChangeLog
branches/gcc-4_9-branch/gcc/tree-loop-distribution.c
branches/gcc-4_9-branch/gcc/tree-predcom.c
^ permalink raw reply [flat|nested] 10+ messages in thread
* [Bug tree-optimization/64530] [4.9 Regression] Incorrect calculation when assigning to array with -O3
2015-01-07 21:39 [Bug fortran/64530] New: [4.9 Regression] Incorrect calculation when assigning to array with -O3 jkaus at ucsd dot edu
` (7 preceding siblings ...)
2015-02-20 7:32 ` rguenth at gcc dot gnu.org
@ 2015-02-20 7:34 ` rguenth at gcc dot gnu.org
8 siblings, 0 replies; 10+ messages in thread
From: rguenth at gcc dot gnu.org @ 2015-02-20 7:34 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64530
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|ASSIGNED |RESOLVED
Known to work| |4.9.3
Resolution|--- |FIXED
--- Comment #9 from Richard Biener <rguenth at gcc dot gnu.org> ---
Fixed.
^ permalink raw reply [flat|nested] 10+ messages in thread
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2015-01-07 21:39 [Bug fortran/64530] New: [4.9 Regression] Incorrect calculation when assigning to array with -O3 jkaus at ucsd dot edu
2015-01-07 22:36 ` [Bug fortran/64530] " anlauf at gmx dot de
2015-01-07 22:51 ` dominiq at lps dot ens.fr
2015-01-07 22:55 ` [Bug tree-optimization/64530] " dominiq at lps dot ens.fr
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