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* [Bug tree-optimization/21998] (cond ? result1 : result2) is vectorized, where equivalent if-syntax isn't (store)
[not found] <bug-21998-4@http.gcc.gnu.org/bugzilla/>
@ 2012-07-13 8:54 ` rguenth at gcc dot gnu.org
2012-07-13 11:04 ` steven at gcc dot gnu.org
` (3 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: rguenth at gcc dot gnu.org @ 2012-07-13 8:54 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21998
Richard Guenther <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Blocks| |53947
--- Comment #3 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-07-13 08:54:14 UTC ---
Link to vectorizer missed-optimization meta-bug.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug tree-optimization/21998] (cond ? result1 : result2) is vectorized, where equivalent if-syntax isn't (store)
[not found] <bug-21998-4@http.gcc.gnu.org/bugzilla/>
2012-07-13 8:54 ` [Bug tree-optimization/21998] (cond ? result1 : result2) is vectorized, where equivalent if-syntax isn't (store) rguenth at gcc dot gnu.org
@ 2012-07-13 11:04 ` steven at gcc dot gnu.org
2012-07-13 11:29 ` rguenth at gcc dot gnu.org
` (2 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: steven at gcc dot gnu.org @ 2012-07-13 11:04 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21998
Steven Bosscher <steven at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |steven at gcc dot gnu.org
--- Comment #4 from Steven Bosscher <steven at gcc dot gnu.org> 2012-07-13 11:04:13 UTC ---
(In reply to comment #1)
> They are not equivalent to GCC, the first always stores, the second has a
> conditional store.
Just to clarify, 7 years later: To GCC the two procedures are not equivalent.
In the first procedure,
a1[i] = (a1[i] == v1 ? v2 : a1[i]);
expands as:
if (a1[i] == v1)
a1[i] = v2;
else
a1[i] = a1[i];
while the second procedure expands just as-is:
if (a1[i] == v1)
a1[i] = v2;
In the first case, there will always be a store to a1[i], in the second example
this is not the case. Introducing new stores is not allowed, to avoid
introducing data races, see http://gcc.gnu.org/wiki/Atomic/GCCMM/DataRaces.
I'm not sure how GCC should transform the second procedure to allow the loop to
be vectorized.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug tree-optimization/21998] (cond ? result1 : result2) is vectorized, where equivalent if-syntax isn't (store)
[not found] <bug-21998-4@http.gcc.gnu.org/bugzilla/>
2012-07-13 8:54 ` [Bug tree-optimization/21998] (cond ? result1 : result2) is vectorized, where equivalent if-syntax isn't (store) rguenth at gcc dot gnu.org
2012-07-13 11:04 ` steven at gcc dot gnu.org
@ 2012-07-13 11:29 ` rguenth at gcc dot gnu.org
2013-03-27 11:32 ` rguenth at gcc dot gnu.org
2023-08-04 20:36 ` pinskia at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: rguenth at gcc dot gnu.org @ 2012-07-13 11:29 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21998
--- Comment #5 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-07-13 11:28:45 UTC ---
We have two related flags here, -ftree-loop-if-convert-stores, and
--param allow-store-data-races. We can adjust the former to honor the
latter if specified and then eventually vectorize this, too.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug tree-optimization/21998] (cond ? result1 : result2) is vectorized, where equivalent if-syntax isn't (store)
[not found] <bug-21998-4@http.gcc.gnu.org/bugzilla/>
` (2 preceding siblings ...)
2012-07-13 11:29 ` rguenth at gcc dot gnu.org
@ 2013-03-27 11:32 ` rguenth at gcc dot gnu.org
2023-08-04 20:36 ` pinskia at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: rguenth at gcc dot gnu.org @ 2013-03-27 11:32 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21998
--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> 2013-03-27 11:32:19 UTC ---
Note that the concern is also that a1 may be mapped to a read-only segment,
so introducing a store data-race may trap. That's probably out of the C99
language standards scope, but the middle-end has to care about this
possibility.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug tree-optimization/21998] (cond ? result1 : result2) is vectorized, where equivalent if-syntax isn't (store)
[not found] <bug-21998-4@http.gcc.gnu.org/bugzilla/>
` (3 preceding siblings ...)
2013-03-27 11:32 ` rguenth at gcc dot gnu.org
@ 2023-08-04 20:36 ` pinskia at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: pinskia at gcc dot gnu.org @ 2023-08-04 20:36 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=21998
--- Comment #7 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
We can vectorize test2 using mask stores ....
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug tree-optimization/21998] (cond ? result1 : result2) is vectorized, where equivalent if-syntax isn't (store)
2005-06-10 13:22 [Bug tree-optimization/21998] New: (cond ? result1 : result2) is vectorized, where equivalent if-syntax isn't stefaan dot deroeck at gmail dot com
@ 2005-06-19 14:24 ` pinskia at gcc dot gnu dot org
0 siblings, 0 replies; 6+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2005-06-19 14:24 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From pinskia at gcc dot gnu dot org 2005-06-19 14:24 -------
Confirmed.
--
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Ever Confirmed| |1
Last reconfirmed|0000-00-00 00:00:00 |2005-06-19 14:24:25
date| |
Summary|(cond ? result1 : result2) |(cond ? result1 : result2)
|is vectorized, where |is vectorized, where
|equivalent if-syntax isn't |equivalent if-syntax isn't
| |(store)
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21998
^ permalink raw reply [flat|nested] 6+ messages in thread
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[not found] <bug-21998-4@http.gcc.gnu.org/bugzilla/>
2012-07-13 8:54 ` [Bug tree-optimization/21998] (cond ? result1 : result2) is vectorized, where equivalent if-syntax isn't (store) rguenth at gcc dot gnu.org
2012-07-13 11:04 ` steven at gcc dot gnu.org
2012-07-13 11:29 ` rguenth at gcc dot gnu.org
2013-03-27 11:32 ` rguenth at gcc dot gnu.org
2023-08-04 20:36 ` pinskia at gcc dot gnu.org
2005-06-10 13:22 [Bug tree-optimization/21998] New: (cond ? result1 : result2) is vectorized, where equivalent if-syntax isn't stefaan dot deroeck at gmail dot com
2005-06-19 14:24 ` [Bug tree-optimization/21998] (cond ? result1 : result2) is vectorized, where equivalent if-syntax isn't (store) pinskia at gcc dot gnu dot org
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