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* [Bug c++/14703] New: Inadequate optimization of inline templated functions
@ 2004-03-24 2:25 eric-gcc at omnifarious dot org
2004-03-24 2:27 ` [Bug c++/14703] " eric-gcc at omnifarious dot org
` (5 more replies)
0 siblings, 6 replies; 7+ messages in thread
From: eric-gcc at omnifarious dot org @ 2004-03-24 2:25 UTC (permalink / raw)
To: gcc-bugs
This code:
=====================
#include <iostream>
namespace {
template <unsigned long long L> class fib {
public:
static const unsigned long long value = fib<L - 1>::value + fib<L - 2>::value;
};
template <> class fib<0> {
public:
static const unsigned long long value = 1;
};
template <> class fib<1> {
public:
static const unsigned long long value = 1;
};
template<unsigned long long L> inline unsigned long long fibconst()
{
return fibconst<L - 1>() + fibconst<L - 2>();
}
template <> inline unsigned long long fibconst<0>()
{
return 1ull;
}
template <> inline unsigned long long fibconst<1>()
{
return 1ull;
}
template <> inline unsigned long long fibconst<2>()
{
return 2ull;
}
}
int main()
{
::std::cerr << "fib<90>::value == " << fib<90>::value << "\n";
::std::cerr << "fibconst<90>() == " << fibconst<90>() << "\n";
}
=====================
does not result in the call to fibconst being optimized out of existence. In
fact, only calls to fibconst<11>() and lower are optimized out at -O3. The
compiler should have plenty enough information to realize that they can all be
optimized out. After all, in order to expand the template at all, it has to get
down to fibconst<0> or fibconst<1> or fibconst<2> and build things back up again.
This is against gcc 3.4 pre-release. I certainly don't expect anything to be
done to gcc 3.4 about it, but I think it should still be taken care of someday.
--
Summary: Inadequate optimization of inline templated functions
Product: gcc
Version: 3.4.0
Status: UNCONFIRMED
Severity: enhancement
Priority: P2
Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: eric-gcc at omnifarious dot org
CC: gcc-bugs at gcc dot gnu dot org
GCC build triplet: pentium4-redhat-linux
GCC host triplet: pentium4-redhat-linux
GCC target triplet: pentium4-redhat-linux
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14703
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c++/14703] Inadequate optimization of inline templated functions
2004-03-24 2:25 [Bug c++/14703] New: Inadequate optimization of inline templated functions eric-gcc at omnifarious dot org
@ 2004-03-24 2:27 ` eric-gcc at omnifarious dot org
2004-03-24 2:30 ` eric-gcc at omnifarious dot org
` (4 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: eric-gcc at omnifarious dot org @ 2004-03-24 2:27 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From eric-gcc at omnifarious dot org 2004-03-24 02:27 -------
Created an attachment (id=5985)
--> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=5985&action=view)
Source code for a test case
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14703
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c++/14703] Inadequate optimization of inline templated functions
2004-03-24 2:25 [Bug c++/14703] New: Inadequate optimization of inline templated functions eric-gcc at omnifarious dot org
2004-03-24 2:27 ` [Bug c++/14703] " eric-gcc at omnifarious dot org
@ 2004-03-24 2:30 ` eric-gcc at omnifarious dot org
2004-03-24 3:44 ` pinskia at gcc dot gnu dot org
` (3 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: eric-gcc at omnifarious dot org @ 2004-03-24 2:30 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From eric-gcc at omnifarious dot org 2004-03-24 02:30 -------
Created an attachment (id=5986)
--> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=5986&action=view)
Assembly code resulting from attachment 5985
g++-4 -v -pipe -march=pentium4 -O3 -Wall -S torturefib.cxx
Reading specs from
/workplace/hopdist-garnome-0.29.1/usr/bin/../lib/gcc/pentium4-redhat-linux/3.4.0/specs
Configured with: ../gcc/configure --program-suffix=-4 --prefix=/hopdist/usr
--enable-languages=c,c++ --enable-shared pentium4-redhat-linux
Thread model: posix
gcc version 3.4.0 20040323 (prerelease)
/workplace/hopdist-garnome-0.29.1/usr/bin/../libexec/gcc/pentium4-redhat-linux/3.4.0/cc1plus
-quiet -v -iprefix
/workplace/hopdist-garnome-0.29.1/usr/bin/../lib/gcc/pentium4-redhat-linux/3.4.0/
-D_GNU_SOURCE torturefib.cxx -quiet -dumpbase torturefib.cxx -march=pentium4
-auxbase torturefib -O3 -Wall -version -o torturefib.s
ignoring nonexistent directory
"/workplace/hopdist-garnome-0.29.1/usr/bin/../lib/gcc/pentium4-redhat-linux/3.4.0/../../../../pentium4-redhat-linux/include"
ignoring duplicate directory
"/hopdist/usr/lib/gcc/pentium4-redhat-linux/3.4.0/../../../../include/c++/3.4.0"
ignoring duplicate directory
"/hopdist/usr/lib/gcc/pentium4-redhat-linux/3.4.0/../../../../include/c++/3.4.0/pentium4-redhat-linux"
ignoring duplicate directory
"/hopdist/usr/lib/gcc/pentium4-redhat-linux/3.4.0/../../../../include/c++/3.4.0/backward"
ignoring duplicate directory
"/hopdist/usr/lib/gcc/pentium4-redhat-linux/3.4.0/include"
ignoring nonexistent directory
"/hopdist/usr/lib/gcc/pentium4-redhat-linux/3.4.0/../../../../pentium4-redhat-linux/include"
#include "..." search starts here:
#include <...> search starts here:
/workplace/hopdist-garnome-0.29.1/usr/bin/../lib/gcc/pentium4-redhat-linux/3.4.0/../../../../include/c++/3.4.0
/workplace/hopdist-garnome-0.29.1/usr/bin/../lib/gcc/pentium4-redhat-linux/3.4.0/../../../../include/c++/3.4.0/pentium4-redhat-linux
/workplace/hopdist-garnome-0.29.1/usr/bin/../lib/gcc/pentium4-redhat-linux/3.4.0/../../../../include/c++/3.4.0/backward
/workplace/hopdist-garnome-0.29.1/usr/bin/../lib/gcc/pentium4-redhat-linux/3.4.0/include
/usr/local/include
/hopdist/usr/include
/usr/include
End of search list.
GNU C++ version 3.4.0 20040323 (prerelease) (pentium4-redhat-linux)
compiled by GNU C version 3.4.0 20040323 (prerelease).
GGC heuristics: --param ggc-min-expand=98 --param ggc-min-heapsize=128170
Compilation finished at Tue Mar 23 18:28:03
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14703
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c++/14703] Inadequate optimization of inline templated functions
2004-03-24 2:25 [Bug c++/14703] New: Inadequate optimization of inline templated functions eric-gcc at omnifarious dot org
2004-03-24 2:27 ` [Bug c++/14703] " eric-gcc at omnifarious dot org
2004-03-24 2:30 ` eric-gcc at omnifarious dot org
@ 2004-03-24 3:44 ` pinskia at gcc dot gnu dot org
2004-03-24 4:25 ` pinskia at gcc dot gnu dot org
` (2 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2004-03-24 3:44 UTC (permalink / raw)
To: gcc-bugs
--
What |Removed |Added
----------------------------------------------------------------------------
Attachment #5985|application/octet-stream |text/plain
mime type| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14703
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c++/14703] Inadequate optimization of inline templated functions
2004-03-24 2:25 [Bug c++/14703] New: Inadequate optimization of inline templated functions eric-gcc at omnifarious dot org
` (2 preceding siblings ...)
2004-03-24 3:44 ` pinskia at gcc dot gnu dot org
@ 2004-03-24 4:25 ` pinskia at gcc dot gnu dot org
2005-02-25 23:49 ` [Bug tree-optimization/14703] " rguenth at gcc dot gnu dot org
2005-05-27 0:18 ` pinskia at gcc dot gnu dot org
5 siblings, 0 replies; 7+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2004-03-24 4:25 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From pinskia at gcc dot gnu dot org 2004-03-24 04:25 -------
Confirmed, it is much worse on the tree-ssa, most likely what needs to happen is that inline happens
after some optimizations and then do more inlining and more optimizations, repeat until the function
size does not raise.
--
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Ever Confirmed| |1
Keywords| |pessimizes-code
Last reconfirmed|0000-00-00 00:00:00 |2004-03-24 04:25:08
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14703
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug tree-optimization/14703] Inadequate optimization of inline templated functions
2004-03-24 2:25 [Bug c++/14703] New: Inadequate optimization of inline templated functions eric-gcc at omnifarious dot org
` (3 preceding siblings ...)
2004-03-24 4:25 ` pinskia at gcc dot gnu dot org
@ 2005-02-25 23:49 ` rguenth at gcc dot gnu dot org
2005-05-27 0:18 ` pinskia at gcc dot gnu dot org
5 siblings, 0 replies; 7+ messages in thread
From: rguenth at gcc dot gnu dot org @ 2005-02-25 23:49 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From rguenth at gcc dot gnu dot org 2005-02-25 16:53 -------
http://gcc.gnu.org/ml/gcc-patches/2005-02/msg01571.html
improves this to the extent that the inliner now estimates the size of
fibconst to
n size
0,1,2 0
3 1
4 2
5 4
6 7
etc., i.e. to the number of additions required.
Inlining all of fibconst<90> now only requires the appropriate limits, or,
of course folding during inlining.
--
What |Removed |Added
----------------------------------------------------------------------------
CC| |rguenth at tat dot physik
| |dot uni-tuebingen dot de
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14703
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug tree-optimization/14703] Inadequate optimization of inline templated functions
2004-03-24 2:25 [Bug c++/14703] New: Inadequate optimization of inline templated functions eric-gcc at omnifarious dot org
` (4 preceding siblings ...)
2005-02-25 23:49 ` [Bug tree-optimization/14703] " rguenth at gcc dot gnu dot org
@ 2005-05-27 0:18 ` pinskia at gcc dot gnu dot org
5 siblings, 0 replies; 7+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2005-05-27 0:18 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From pinskia at gcc dot gnu dot org 2005-05-27 00:15 -------
What we need for this testcase is the following:
inline, optimize, inline, ...
--
What |Removed |Added
----------------------------------------------------------------------------
Last reconfirmed|2004-12-25 01:27:52 |2005-05-27 00:15:50
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14703
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2005-05-27 0:16 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2004-03-24 2:25 [Bug c++/14703] New: Inadequate optimization of inline templated functions eric-gcc at omnifarious dot org
2004-03-24 2:27 ` [Bug c++/14703] " eric-gcc at omnifarious dot org
2004-03-24 2:30 ` eric-gcc at omnifarious dot org
2004-03-24 3:44 ` pinskia at gcc dot gnu dot org
2004-03-24 4:25 ` pinskia at gcc dot gnu dot org
2005-02-25 23:49 ` [Bug tree-optimization/14703] " rguenth at gcc dot gnu dot org
2005-05-27 0:18 ` pinskia at gcc dot gnu dot org
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