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* [Bug tree-optimization/57380] New: GCC 4.9.0 will not vectorize std::max and similar functions
@ 2013-05-22 21:42 jewillco at osl dot iu.edu
2013-05-22 21:47 ` [Bug tree-optimization/57380] " jewillco at osl dot iu.edu
` (7 more replies)
0 siblings, 8 replies; 9+ messages in thread
From: jewillco at osl dot iu.edu @ 2013-05-22 21:42 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57380
Bug ID: 57380
Summary: GCC 4.9.0 will not vectorize std::max and similar
functions
Product: gcc
Version: 4.9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: jewillco at osl dot iu.edu
It appears that having a function that returns a const reference to one of its
arguments causes vectorization of calls to that function to fail. Here is a
simple test program:
struct my_array {
int data[4] __attribute__((aligned(16)));
};
const int& my_max(const int& a, const int& b) {
return a < b ? b : a;
}
int f(my_array a, my_array b) {
int res = 0;
for (int i = 0; i < 4; ++i) {
res += my_max(a.data[i], b.data[i]);
}
return res;
}
The signature of my_max is a specialization of the one of std::max; std::max
itself has similar problems. The loop will vectorize without trouble if my_max
returns "int". The main errors from the vectorization report seem to be:
vec_min_max.cpp:11: note: not vectorized: not suitable for gather load _6 =
*iftmp.0_12;
vec_min_max.cpp:11: note: bad data references.
Other variants of the code get "control flow in loop" instead. The flags I am
using are:
-ftree-vectorizer-verbose=4 -Ofast -march=nocona
but the code should be able to vectorize under SSE2. The GCC version I am
using is "g++ (GCC) 4.9.0 20130519 (experimental)" on x86-64. GCC 4.7.2 has a
similar error, while "4.4.7 20120313 (Red Hat 4.4.7-3)" can vectorize it
without problems.
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug tree-optimization/57380] GCC 4.9.0 will not vectorize std::max and similar functions
2013-05-22 21:42 [Bug tree-optimization/57380] New: GCC 4.9.0 will not vectorize std::max and similar functions jewillco at osl dot iu.edu
@ 2013-05-22 21:47 ` jewillco at osl dot iu.edu
2013-05-23 8:35 ` [Bug tree-optimization/57380] [4.7/4.8/4.9 Regression] " rguenth at gcc dot gnu.org
` (6 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: jewillco at osl dot iu.edu @ 2013-05-22 21:47 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57380
--- Comment #1 from Jeremiah Willcock <jewillco at osl dot iu.edu> ---
I tested version "(Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3" and that fails as well
(with "note: not vectorized: data ref analysis failed D.2097_9 = *D.2115_16;"
in the vectorization report).
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug tree-optimization/57380] [4.7/4.8/4.9 Regression] GCC 4.9.0 will not vectorize std::max and similar functions
2013-05-22 21:42 [Bug tree-optimization/57380] New: GCC 4.9.0 will not vectorize std::max and similar functions jewillco at osl dot iu.edu
2013-05-22 21:47 ` [Bug tree-optimization/57380] " jewillco at osl dot iu.edu
@ 2013-05-23 8:35 ` rguenth at gcc dot gnu.org
2013-05-23 9:20 ` rguenth at gcc dot gnu.org
` (5 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: rguenth at gcc dot gnu.org @ 2013-05-23 8:35 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57380
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |ASSIGNED
Last reconfirmed| |2013-05-23
Known to work| |4.5.4
Assignee|unassigned at gcc dot gnu.org |rguenth at gcc dot gnu.org
Target Milestone|--- |4.7.4
Summary|GCC 4.9.0 will not |[4.7/4.8/4.9 Regression]
|vectorize std::max and |GCC 4.9.0 will not
|similar functions |vectorize std::max and
| |similar functions
Ever confirmed|0 |1
--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
For some reason phiprop doesn't work here. I'll investigate, but I guess
it is because the addresses are not constant but depend on the loop IV:
<bb 3>:
_3 = &b.data[i_2];
_4 = &a.data[i_2];
_10 = MEM[(const int &)&a].data[i_2];
_11 = MEM[(const int &)&b].data[i_2];
if (_10 < _11)
goto <bb 5>;
else
goto <bb 4>;
<bb 4>:
<bb 5>:
# iftmp.0_12 = PHI <_3(3), _4(4)>
<bb 6>:
_6 = *iftmp.0_12;
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug tree-optimization/57380] [4.7/4.8/4.9 Regression] GCC 4.9.0 will not vectorize std::max and similar functions
2013-05-22 21:42 [Bug tree-optimization/57380] New: GCC 4.9.0 will not vectorize std::max and similar functions jewillco at osl dot iu.edu
2013-05-22 21:47 ` [Bug tree-optimization/57380] " jewillco at osl dot iu.edu
2013-05-23 8:35 ` [Bug tree-optimization/57380] [4.7/4.8/4.9 Regression] " rguenth at gcc dot gnu.org
@ 2013-05-23 9:20 ` rguenth at gcc dot gnu.org
2013-05-23 12:24 ` [Bug tree-optimization/57380] [4.7/4.8 " rguenth at gcc dot gnu.org
` (4 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: rguenth at gcc dot gnu.org @ 2013-05-23 9:20 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57380
--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
There was a deliberate change to require at least one invariant address or
a re-use of a previous load.
2010-07-08 Richard Guenther <rguenther@suse.de>
+ PR tree-optimization/44831
+ * tree-ssa-phiprop.c (phiprop_insert_phi): Properly build
+ a MEM_REF preserving TBAA info of the original dereference.
+ Dereference the original pointer if the address is not
+ invariant.
+ (propagate_with_phi): Fixup type checks wrt MEM_REFs. Require
+ at least one invariant address that we are going to dereference.
I have a fix.
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug tree-optimization/57380] [4.7/4.8 Regression] GCC 4.9.0 will not vectorize std::max and similar functions
2013-05-22 21:42 [Bug tree-optimization/57380] New: GCC 4.9.0 will not vectorize std::max and similar functions jewillco at osl dot iu.edu
` (2 preceding siblings ...)
2013-05-23 9:20 ` rguenth at gcc dot gnu.org
@ 2013-05-23 12:24 ` rguenth at gcc dot gnu.org
2013-10-30 12:23 ` rguenth at gcc dot gnu.org
` (3 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: rguenth at gcc dot gnu.org @ 2013-05-23 12:24 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57380
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Known to work| |4.9.0
Summary|[4.7/4.8/4.9 Regression] |[4.7/4.8 Regression] GCC
|GCC 4.9.0 will not |4.9.0 will not vectorize
|vectorize std::max and |std::max and similar
|similar functions |functions
Known to fail|4.9.0 |4.8.1
--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
Author: rguenth
Date: Thu May 23 12:23:59 2013
New Revision: 199246
URL: http://gcc.gnu.org/viewcvs?rev=199246&root=gcc&view=rev
Log:
2013-05-23 Richard Biener <rguenther@suse.de>
PR tree-optimization/57380
* tree-ssa-phiprop.c (propagate_with_phi): Do not require at
least one invariant or re-used load.
* passes.c (init_optimization_passes): Move pass_phiprop before
pass_forwprop.
* g++.dg/tree-ssa/pr57380.C: New testcase.
Added:
trunk/gcc/testsuite/g++.dg/tree-ssa/pr57380.C
Modified:
trunk/gcc/ChangeLog
trunk/gcc/passes.c
trunk/gcc/testsuite/ChangeLog
trunk/gcc/tree-ssa-phiprop.c
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug tree-optimization/57380] [4.7/4.8 Regression] GCC 4.9.0 will not vectorize std::max and similar functions
2013-05-22 21:42 [Bug tree-optimization/57380] New: GCC 4.9.0 will not vectorize std::max and similar functions jewillco at osl dot iu.edu
` (3 preceding siblings ...)
2013-05-23 12:24 ` [Bug tree-optimization/57380] [4.7/4.8 " rguenth at gcc dot gnu.org
@ 2013-10-30 12:23 ` rguenth at gcc dot gnu.org
2014-01-16 21:04 ` law at redhat dot com
` (2 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: rguenth at gcc dot gnu.org @ 2013-10-30 12:23 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57380
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Priority|P3 |P2
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug tree-optimization/57380] [4.7/4.8 Regression] GCC 4.9.0 will not vectorize std::max and similar functions
2013-05-22 21:42 [Bug tree-optimization/57380] New: GCC 4.9.0 will not vectorize std::max and similar functions jewillco at osl dot iu.edu
` (4 preceding siblings ...)
2013-10-30 12:23 ` rguenth at gcc dot gnu.org
@ 2014-01-16 21:04 ` law at redhat dot com
2014-01-16 21:04 ` law at redhat dot com
2014-06-30 2:01 ` pinskia at gcc dot gnu.org
7 siblings, 0 replies; 9+ messages in thread
From: law at redhat dot com @ 2014-01-16 21:04 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57380
Jeffrey A. Law <law at redhat dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|ASSIGNED |RESOLVED
Resolution|--- |FIXED
--- Comment #6 from Jeffrey A. Law <law at redhat dot com> ---
fixed on trunk
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug tree-optimization/57380] [4.7/4.8 Regression] GCC 4.9.0 will not vectorize std::max and similar functions
2013-05-22 21:42 [Bug tree-optimization/57380] New: GCC 4.9.0 will not vectorize std::max and similar functions jewillco at osl dot iu.edu
` (5 preceding siblings ...)
2014-01-16 21:04 ` law at redhat dot com
@ 2014-01-16 21:04 ` law at redhat dot com
2014-06-30 2:01 ` pinskia at gcc dot gnu.org
7 siblings, 0 replies; 9+ messages in thread
From: law at redhat dot com @ 2014-01-16 21:04 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57380
Jeffrey A. Law <law at redhat dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |law at redhat dot com
--- Comment #5 from Jeffrey A. Law <law at redhat dot com> ---
Richi fixed on the trunk many months ago.
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug tree-optimization/57380] [4.7/4.8 Regression] GCC 4.9.0 will not vectorize std::max and similar functions
2013-05-22 21:42 [Bug tree-optimization/57380] New: GCC 4.9.0 will not vectorize std::max and similar functions jewillco at osl dot iu.edu
` (6 preceding siblings ...)
2014-01-16 21:04 ` law at redhat dot com
@ 2014-06-30 2:01 ` pinskia at gcc dot gnu.org
7 siblings, 0 replies; 9+ messages in thread
From: pinskia at gcc dot gnu.org @ 2014-06-30 2:01 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=57380
--- Comment #7 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
This testcase fails with -fPIC.
^ permalink raw reply [flat|nested] 9+ messages in thread
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2013-05-22 21:47 ` [Bug tree-optimization/57380] " jewillco at osl dot iu.edu
2013-05-23 8:35 ` [Bug tree-optimization/57380] [4.7/4.8/4.9 Regression] " rguenth at gcc dot gnu.org
2013-05-23 9:20 ` rguenth at gcc dot gnu.org
2013-05-23 12:24 ` [Bug tree-optimization/57380] [4.7/4.8 " rguenth at gcc dot gnu.org
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