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* [Bug rtl-optimization/60749] New: combine is overly cautious when operating on volatile memory references
@ 2014-04-03 15:41 amylaar at gcc dot gnu.org
2022-02-04 20:55 ` [Bug rtl-optimization/60749] " pinskia at gcc dot gnu.org
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: amylaar at gcc dot gnu.org @ 2014-04-03 15:41 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60749
Bug ID: 60749
Summary: combine is overly cautious when operating on volatile
memory references
Product: gcc
Version: 4.9.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: normal
Priority: P3
Component: rtl-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: amylaar at gcc dot gnu.org
Blocks: 53938
Curtesy of volatile_ok / init_recog_no_volatile, combine will
reject any combination that involves a volatile memref in the combined
pattern.
In particular, if any narrow memory location is read on a
WORD_REGISTER_OPERATIONS target, the zero/sign extension can't be combined
with a memory read, even if a suitably extending memory load instruction is
available - unless that pattern gets specifically written to accept
volatile memrefs, shunning the standard memory_operand and
general_operand predicates.
combine already needs to do special checks to make sure it doesn't
slip up when handling such patterns (E.g. see PR51374), so what good
does init_recog_non_volatile do combine these days?
At the very least, I think we should allow combinations involving a single
memref with unchanged mode before and after combination - that woud cover
the zero and sign extending loads.
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug rtl-optimization/60749] combine is overly cautious when operating on volatile memory references
2014-04-03 15:41 [Bug rtl-optimization/60749] New: combine is overly cautious when operating on volatile memory references amylaar at gcc dot gnu.org
@ 2022-02-04 20:55 ` pinskia at gcc dot gnu.org
2023-05-26 13:56 ` lis8215 at gmail dot com
2023-09-25 7:09 ` cptarse-luke at yahoo dot com
2 siblings, 0 replies; 4+ messages in thread
From: pinskia at gcc dot gnu.org @ 2022-02-04 20:55 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60749
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Ever confirmed|0 |1
Last reconfirmed| |2022-02-04
Status|UNCONFIRMED |NEW
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed.
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug rtl-optimization/60749] combine is overly cautious when operating on volatile memory references
2014-04-03 15:41 [Bug rtl-optimization/60749] New: combine is overly cautious when operating on volatile memory references amylaar at gcc dot gnu.org
2022-02-04 20:55 ` [Bug rtl-optimization/60749] " pinskia at gcc dot gnu.org
@ 2023-05-26 13:56 ` lis8215 at gmail dot com
2023-09-25 7:09 ` cptarse-luke at yahoo dot com
2 siblings, 0 replies; 4+ messages in thread
From: lis8215 at gmail dot com @ 2023-05-26 13:56 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60749
Siarhei Volkau <lis8215 at gmail dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |lis8215 at gmail dot com
--- Comment #2 from Siarhei Volkau <lis8215 at gmail dot com> ---
Created attachment 55167
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=55167&action=edit
allow combine ld/st of volatile mem with any_extend op
Is anyone bothering on that? I'm, as embedded engineer, sadly looking on that
long standing issue.
I can propose a quick patch which enables combining volatile mem ld/st with
any_extend for most cases. And it seems, like platform specific test results
remain the same with it (arm/aarch64/mips were tested).
Post it in hope it can help for anyone who needs it.
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug rtl-optimization/60749] combine is overly cautious when operating on volatile memory references
2014-04-03 15:41 [Bug rtl-optimization/60749] New: combine is overly cautious when operating on volatile memory references amylaar at gcc dot gnu.org
2022-02-04 20:55 ` [Bug rtl-optimization/60749] " pinskia at gcc dot gnu.org
2023-05-26 13:56 ` lis8215 at gmail dot com
@ 2023-09-25 7:09 ` cptarse-luke at yahoo dot com
2 siblings, 0 replies; 4+ messages in thread
From: cptarse-luke at yahoo dot com @ 2023-09-25 7:09 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60749
Luke <cptarse-luke at yahoo dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |cptarse-luke at yahoo dot com
--- Comment #3 from Luke <cptarse-luke at yahoo dot com> ---
*** Bug 111581 has been marked as a duplicate of this bug. ***
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2023-09-25 7:09 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2014-04-03 15:41 [Bug rtl-optimization/60749] New: combine is overly cautious when operating on volatile memory references amylaar at gcc dot gnu.org
2022-02-04 20:55 ` [Bug rtl-optimization/60749] " pinskia at gcc dot gnu.org
2023-05-26 13:56 ` lis8215 at gmail dot com
2023-09-25 7:09 ` cptarse-luke at yahoo dot com
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