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* [Bug tree-optimization/50417] New: regression: memcpy with known alignment
@ 2011-09-15 8:57 wouter.vermaelen at scarlet dot be
2011-09-25 10:13 ` [Bug tree-optimization/50417] " rguenth at gcc dot gnu.org
` (11 more replies)
0 siblings, 12 replies; 13+ messages in thread
From: wouter.vermaelen at scarlet dot be @ 2011-09-15 8:57 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50417
Bug #: 50417
Summary: regression: memcpy with known alignment
Classification: Unclassified
Product: gcc
Version: 4.7.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
AssignedTo: unassigned@gcc.gnu.org
ReportedBy: wouter.vermaelen@scarlet.be
Consider these functions:
void copy1(char* d, const char* s) {
memcpy(d, s, 256);
}
void copy2(short* d, const short* s) {
memcpy(d, s, 256);
}
void copy3(int* d, const int* s) {
memcpy(d, s, 256);
}
void copy4(long* d, const long* s) {
memcpy(d, s, 256);
}
g++-4.5.2 is able to generate better code for the later functions. But when I
test with a recent snapshot (SVN revision 178875 on linux x86_64) it generates
the same code for all versions (same as copy1()).
^ permalink raw reply [flat|nested] 13+ messages in thread
* [Bug tree-optimization/50417] regression: memcpy with known alignment
2011-09-15 8:57 [Bug tree-optimization/50417] New: regression: memcpy with known alignment wouter.vermaelen at scarlet dot be
@ 2011-09-25 10:13 ` rguenth at gcc dot gnu.org
2012-06-06 11:01 ` rguenth at gcc dot gnu.org
` (10 subsequent siblings)
11 siblings, 0 replies; 13+ messages in thread
From: rguenth at gcc dot gnu.org @ 2011-09-25 10:13 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50417
Richard Guenther <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |rguenth at gcc dot gnu.org
--- Comment #1 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-09-25 09:58:43 UTC ---
The middle-end does not know anything about the parameters alignment.
^ permalink raw reply [flat|nested] 13+ messages in thread
* [Bug tree-optimization/50417] regression: memcpy with known alignment
2011-09-15 8:57 [Bug tree-optimization/50417] New: regression: memcpy with known alignment wouter.vermaelen at scarlet dot be
2011-09-25 10:13 ` [Bug tree-optimization/50417] " rguenth at gcc dot gnu.org
@ 2012-06-06 11:01 ` rguenth at gcc dot gnu.org
2013-07-14 10:31 ` olegendo at gcc dot gnu.org
` (9 subsequent siblings)
11 siblings, 0 replies; 13+ messages in thread
From: rguenth at gcc dot gnu.org @ 2012-06-06 11:01 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50417
Richard Guenther <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |jay.foad at gmail dot com
--- Comment #2 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-06-06 11:00:31 UTC ---
*** Bug 52415 has been marked as a duplicate of this bug. ***
^ permalink raw reply [flat|nested] 13+ messages in thread
* [Bug tree-optimization/50417] regression: memcpy with known alignment
2011-09-15 8:57 [Bug tree-optimization/50417] New: regression: memcpy with known alignment wouter.vermaelen at scarlet dot be
2011-09-25 10:13 ` [Bug tree-optimization/50417] " rguenth at gcc dot gnu.org
2012-06-06 11:01 ` rguenth at gcc dot gnu.org
@ 2013-07-14 10:31 ` olegendo at gcc dot gnu.org
2013-10-09 9:25 ` gjl at gcc dot gnu.org
` (8 subsequent siblings)
11 siblings, 0 replies; 13+ messages in thread
From: olegendo at gcc dot gnu.org @ 2013-07-14 10:31 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50417
Oleg Endo <olegendo at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target| |sh*-*-* arm*-*-* avr*-*-*
Status|UNCONFIRMED |NEW
Last reconfirmed| |2013-07-14
CC| |olegendo at gcc dot gnu.org
Ever confirmed|0 |1
--- Comment #3 from Oleg Endo <olegendo at gcc dot gnu.org> ---
I ran into this issue when trying out something on SH, too.
(4.9 trunk rev 200571)
Example:
void test (const int* a, int* b)
{
std::memcpy (b, a, 4);
}
Here I'd have expected this to result in a int load + int store, like...
mov.l @r4,r1
rts
mov.l r1,@r5
However, this does not happen. The SH's movmemsi pattern gets a 'common
alignment' of '1'. SH is a strict alignment target and thus the expander will
fall back to memcpy library call.
If I remember correctly, on strict alignment targets a pointer to some type is
by default assumed to satisfy the minimum alignment of that type.
For example
int test (const int* a)
{
return a[0];
}
resuls in (as expected):
rts
mov.l @r4,r0
In the memcpy case it should be safe to assume that the alignment of int* is 32
bit aligned.
As it has been mentioned in PR 52415, I've also tried out
__builtin_assume_aligned and the problem disappears. In this case the memcpy
is eliminated early on and the movmemsi pattern is not used at all.
^ permalink raw reply [flat|nested] 13+ messages in thread
* [Bug tree-optimization/50417] regression: memcpy with known alignment
2011-09-15 8:57 [Bug tree-optimization/50417] New: regression: memcpy with known alignment wouter.vermaelen at scarlet dot be
` (2 preceding siblings ...)
2013-07-14 10:31 ` olegendo at gcc dot gnu.org
@ 2013-10-09 9:25 ` gjl at gcc dot gnu.org
2014-04-02 8:39 ` rguenth at gcc dot gnu.org
` (7 subsequent siblings)
11 siblings, 0 replies; 13+ messages in thread
From: gjl at gcc dot gnu.org @ 2013-10-09 9:25 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50417
Georg-Johann Lay <gjl at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |missed-optimization
Target|sh*-*-* arm*-*-* avr*-*-* |sh*-*-* arm*-*-*
CC| |gjl at gcc dot gnu.org
--- Comment #4 from Georg-Johann Lay <gjl at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #1)
> The middle-end does not know anything about the parameters alignment.
But the following code will use SImode load / store, even on strict-alignment
backends
void test (const int* a, int* b)
{
*b = *a;
}
If SImode operations are in order here, why not in memcpy et al. provided it is
feeded with int*?
In the case where an unaligned pointer is used in *b = *a and this causes, e.g.
a trap, this is in order. Similar should apply for memcpy on strict-alignment
machines if it gets an unaligned int* for example and the size is a multiple of
the alignment requirement.
BTW: AVR is an 8-bit machine that copies in chunks of 1 byte, this applies also
for 4.5 and older. avr-gcc is /not/ a strict alignment backend. Thul removed
from the targets.
^ permalink raw reply [flat|nested] 13+ messages in thread
* [Bug tree-optimization/50417] regression: memcpy with known alignment
2011-09-15 8:57 [Bug tree-optimization/50417] New: regression: memcpy with known alignment wouter.vermaelen at scarlet dot be
` (3 preceding siblings ...)
2013-10-09 9:25 ` gjl at gcc dot gnu.org
@ 2014-04-02 8:39 ` rguenth at gcc dot gnu.org
2015-09-22 8:04 ` rguenth at gcc dot gnu.org
` (6 subsequent siblings)
11 siblings, 0 replies; 13+ messages in thread
From: rguenth at gcc dot gnu.org @ 2014-04-02 8:39 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50417
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |anton at samba dot org
--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
*** Bug 60737 has been marked as a duplicate of this bug. ***
^ permalink raw reply [flat|nested] 13+ messages in thread
* [Bug tree-optimization/50417] regression: memcpy with known alignment
2011-09-15 8:57 [Bug tree-optimization/50417] New: regression: memcpy with known alignment wouter.vermaelen at scarlet dot be
` (4 preceding siblings ...)
2014-04-02 8:39 ` rguenth at gcc dot gnu.org
@ 2015-09-22 8:04 ` rguenth at gcc dot gnu.org
2021-05-14 9:46 ` [Bug tree-optimization/50417] [9/10/11/12 regression]: " jakub at gcc dot gnu.org
` (5 subsequent siblings)
11 siblings, 0 replies; 13+ messages in thread
From: rguenth at gcc dot gnu.org @ 2015-09-22 8:04 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=50417
--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> ---
*** Bug 67676 has been marked as a duplicate of this bug. ***
^ permalink raw reply [flat|nested] 13+ messages in thread
* [Bug tree-optimization/50417] [9/10/11/12 regression]: memcpy with known alignment
2011-09-15 8:57 [Bug tree-optimization/50417] New: regression: memcpy with known alignment wouter.vermaelen at scarlet dot be
` (5 preceding siblings ...)
2015-09-22 8:04 ` rguenth at gcc dot gnu.org
@ 2021-05-14 9:46 ` jakub at gcc dot gnu.org
2021-06-01 8:05 ` rguenth at gcc dot gnu.org
` (4 subsequent siblings)
11 siblings, 0 replies; 13+ messages in thread
From: jakub at gcc dot gnu.org @ 2021-05-14 9:46 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=50417
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|8.5 |9.4
--- Comment #32 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
GCC 8 branch is being closed.
^ permalink raw reply [flat|nested] 13+ messages in thread
* [Bug tree-optimization/50417] [9/10/11/12 regression]: memcpy with known alignment
2011-09-15 8:57 [Bug tree-optimization/50417] New: regression: memcpy with known alignment wouter.vermaelen at scarlet dot be
` (6 preceding siblings ...)
2021-05-14 9:46 ` [Bug tree-optimization/50417] [9/10/11/12 regression]: " jakub at gcc dot gnu.org
@ 2021-06-01 8:05 ` rguenth at gcc dot gnu.org
2021-08-15 9:13 ` pinskia at gcc dot gnu.org
` (3 subsequent siblings)
11 siblings, 0 replies; 13+ messages in thread
From: rguenth at gcc dot gnu.org @ 2021-06-01 8:05 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=50417
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|9.4 |9.5
--- Comment #33 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC 9.4 is being released, retargeting bugs to GCC 9.5.
^ permalink raw reply [flat|nested] 13+ messages in thread
* [Bug tree-optimization/50417] [9/10/11/12 regression]: memcpy with known alignment
2011-09-15 8:57 [Bug tree-optimization/50417] New: regression: memcpy with known alignment wouter.vermaelen at scarlet dot be
` (7 preceding siblings ...)
2021-06-01 8:05 ` rguenth at gcc dot gnu.org
@ 2021-08-15 9:13 ` pinskia at gcc dot gnu.org
2022-05-27 9:34 ` [Bug tree-optimization/50417] [10/11/12/13 " rguenth at gcc dot gnu.org
` (2 subsequent siblings)
11 siblings, 0 replies; 13+ messages in thread
From: pinskia at gcc dot gnu.org @ 2021-08-15 9:13 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=50417
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |dragan.mladjenovic at syrmia dot c
| |om
--- Comment #34 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
*** Bug 101920 has been marked as a duplicate of this bug. ***
^ permalink raw reply [flat|nested] 13+ messages in thread
* [Bug tree-optimization/50417] [10/11/12/13 regression]: memcpy with known alignment
2011-09-15 8:57 [Bug tree-optimization/50417] New: regression: memcpy with known alignment wouter.vermaelen at scarlet dot be
` (8 preceding siblings ...)
2021-08-15 9:13 ` pinskia at gcc dot gnu.org
@ 2022-05-27 9:34 ` rguenth at gcc dot gnu.org
2022-06-28 10:30 ` jakub at gcc dot gnu.org
2023-07-07 10:29 ` [Bug tree-optimization/50417] [11/12/13/14 " rguenth at gcc dot gnu.org
11 siblings, 0 replies; 13+ messages in thread
From: rguenth at gcc dot gnu.org @ 2022-05-27 9:34 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=50417
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|9.5 |10.4
--- Comment #35 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC 9 branch is being closed
^ permalink raw reply [flat|nested] 13+ messages in thread
* [Bug tree-optimization/50417] [10/11/12/13 regression]: memcpy with known alignment
2011-09-15 8:57 [Bug tree-optimization/50417] New: regression: memcpy with known alignment wouter.vermaelen at scarlet dot be
` (9 preceding siblings ...)
2022-05-27 9:34 ` [Bug tree-optimization/50417] [10/11/12/13 " rguenth at gcc dot gnu.org
@ 2022-06-28 10:30 ` jakub at gcc dot gnu.org
2023-07-07 10:29 ` [Bug tree-optimization/50417] [11/12/13/14 " rguenth at gcc dot gnu.org
11 siblings, 0 replies; 13+ messages in thread
From: jakub at gcc dot gnu.org @ 2022-06-28 10:30 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=50417
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|10.4 |10.5
--- Comment #36 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
GCC 10.4 is being released, retargeting bugs to GCC 10.5.
^ permalink raw reply [flat|nested] 13+ messages in thread
* [Bug tree-optimization/50417] [11/12/13/14 regression]: memcpy with known alignment
2011-09-15 8:57 [Bug tree-optimization/50417] New: regression: memcpy with known alignment wouter.vermaelen at scarlet dot be
` (10 preceding siblings ...)
2022-06-28 10:30 ` jakub at gcc dot gnu.org
@ 2023-07-07 10:29 ` rguenth at gcc dot gnu.org
11 siblings, 0 replies; 13+ messages in thread
From: rguenth at gcc dot gnu.org @ 2023-07-07 10:29 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=50417
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|10.5 |11.5
--- Comment #37 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC 10 branch is being closed.
^ permalink raw reply [flat|nested] 13+ messages in thread
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2011-09-15 8:57 [Bug tree-optimization/50417] New: regression: memcpy with known alignment wouter.vermaelen at scarlet dot be
2011-09-25 10:13 ` [Bug tree-optimization/50417] " rguenth at gcc dot gnu.org
2012-06-06 11:01 ` rguenth at gcc dot gnu.org
2013-07-14 10:31 ` olegendo at gcc dot gnu.org
2013-10-09 9:25 ` gjl at gcc dot gnu.org
2014-04-02 8:39 ` rguenth at gcc dot gnu.org
2015-09-22 8:04 ` rguenth at gcc dot gnu.org
2021-05-14 9:46 ` [Bug tree-optimization/50417] [9/10/11/12 regression]: " jakub at gcc dot gnu.org
2021-06-01 8:05 ` rguenth at gcc dot gnu.org
2021-08-15 9:13 ` pinskia at gcc dot gnu.org
2022-05-27 9:34 ` [Bug tree-optimization/50417] [10/11/12/13 " rguenth at gcc dot gnu.org
2022-06-28 10:30 ` jakub at gcc dot gnu.org
2023-07-07 10:29 ` [Bug tree-optimization/50417] [11/12/13/14 " rguenth at gcc dot gnu.org
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