* [Bug target/82666] [9/10/11/12 regression]: sum += (x>128/9/10/11/12 ? x : 0) puts the cmov on the critical path (at -O2)
[not found] <bug-82666-4@http.gcc.gnu.org/bugzilla/>
@ 2021-05-14 9:49 ` jakub at gcc dot gnu.org
2021-06-01 8:09 ` rguenth at gcc dot gnu.org
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From: jakub at gcc dot gnu.org @ 2021-05-14 9:49 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82666
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|8.5 |9.4
--- Comment #8 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
GCC 8 branch is being closed.
^ permalink raw reply [flat|nested] 7+ messages in thread* [Bug target/82666] [9/10/11/12 regression]: sum += (x>128/9/10/11/12 ? x : 0) puts the cmov on the critical path (at -O2)
[not found] <bug-82666-4@http.gcc.gnu.org/bugzilla/>
2021-05-14 9:49 ` [Bug target/82666] [9/10/11/12 regression]: sum += (x>128/9/10/11/12 ? x : 0) puts the cmov on the critical path (at -O2) jakub at gcc dot gnu.org
@ 2021-06-01 8:09 ` rguenth at gcc dot gnu.org
2022-05-27 9:37 ` [Bug target/82666] [10/11/12/13 regression]: sum += (x>128 " rguenth at gcc dot gnu.org
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From: rguenth at gcc dot gnu.org @ 2021-06-01 8:09 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82666
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|9.4 |9.5
--- Comment #9 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] 7+ messages in thread* [Bug target/82666] [10/11/12/13 regression]: sum += (x>128 ? x : 0) puts the cmov on the critical path (at -O2)
[not found] <bug-82666-4@http.gcc.gnu.org/bugzilla/>
2021-05-14 9:49 ` [Bug target/82666] [9/10/11/12 regression]: sum += (x>128/9/10/11/12 ? x : 0) puts the cmov on the critical path (at -O2) jakub at gcc dot gnu.org
2021-06-01 8:09 ` rguenth at gcc dot gnu.org
@ 2022-05-27 9:37 ` rguenth at gcc dot gnu.org
2022-06-28 10:33 ` jakub at gcc dot gnu.org
` (3 subsequent siblings)
6 siblings, 0 replies; 7+ messages in thread
From: rguenth at gcc dot gnu.org @ 2022-05-27 9:37 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82666
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|9.5 |10.4
--- Comment #10 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC 9 branch is being closed
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[not found] <bug-82666-4@http.gcc.gnu.org/bugzilla/>
` (2 preceding siblings ...)
2022-05-27 9:37 ` [Bug target/82666] [10/11/12/13 regression]: sum += (x>128 " rguenth at gcc dot gnu.org
@ 2022-06-28 10:33 ` jakub at gcc dot gnu.org
2023-07-07 10:32 ` [Bug target/82666] [11/12/13/14 " rguenth at gcc dot gnu.org
` (2 subsequent siblings)
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From: jakub at gcc dot gnu.org @ 2022-06-28 10:33 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82666
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|10.4 |10.5
--- Comment #11 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] 7+ messages in thread* [Bug target/82666] [11/12/13/14 regression]: sum += (x>128 ? x : 0) puts the cmov on the critical path (at -O2)
[not found] <bug-82666-4@http.gcc.gnu.org/bugzilla/>
` (3 preceding siblings ...)
2022-06-28 10:33 ` jakub at gcc dot gnu.org
@ 2023-07-07 10:32 ` rguenth at gcc dot gnu.org
2023-08-04 0:40 ` pinskia at gcc dot gnu.org
2023-08-04 4:18 ` law at gcc dot gnu.org
6 siblings, 0 replies; 7+ messages in thread
From: rguenth at gcc dot gnu.org @ 2023-07-07 10:32 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82666
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|10.5 |11.5
--- Comment #12 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC 10 branch is being closed.
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[not found] <bug-82666-4@http.gcc.gnu.org/bugzilla/>
` (4 preceding siblings ...)
2023-07-07 10:32 ` [Bug target/82666] [11/12/13/14 " rguenth at gcc dot gnu.org
@ 2023-08-04 0:40 ` pinskia at gcc dot gnu.org
2023-08-04 4:18 ` law at gcc dot gnu.org
6 siblings, 0 replies; 7+ messages in thread
From: pinskia at gcc dot gnu.org @ 2023-08-04 0:40 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82666
--- Comment #13 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
I don't know if this could help here but combine does produce:
Trying 37, 34 -> 38:
37: flags:CCGC=cmp(r82:SI,0x7f)
REG_DEAD r82:SI
34: {r92:DI=r87:DI+r89:DI;clobber flags:CC;}
REG_DEAD r89:DI
REG_UNUSED flags:CC
38: r87:DI={(flags:CCGC>0)?r92:DI:r87:DI}
REG_DEAD r92:DI
REG_DEAD flags:CCGC
Failed to match this instruction:
(set (reg/v:DI 87 [ <retval> ])
(plus:DI (mult:DI (gt:DI (reg:SI 82 [ _4 ])
(const_int 127 [0x7f]))
(reg:DI 89 [ _4 ]))
(reg/v:DI 87 [ <retval> ])))
I don't know if we could catch this in the backend and split this into 3
instructions if that would do the right thing ...
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[not found] <bug-82666-4@http.gcc.gnu.org/bugzilla/>
` (5 preceding siblings ...)
2023-08-04 0:40 ` pinskia at gcc dot gnu.org
@ 2023-08-04 4:18 ` law at gcc dot gnu.org
6 siblings, 0 replies; 7+ messages in thread
From: law at gcc dot gnu.org @ 2023-08-04 4:18 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82666
Jeffrey A. Law <law at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |law at gcc dot gnu.org
--- Comment #14 from Jeffrey A. Law <law at gcc dot gnu.org> ---
A better approach might be to to try and create COND_EXPRs for the conditional
move in the gimple code. The biggest problem I see with that is the
gimple->rtl converters aren't great at creating efficient code on targets
without conditional moves.
Meaning that we could well end up improving x86, but making several other
targets worse.
I know this because I was recently poking at a similar problem. We expressed a
conditional move of 0, C as a multiply of a boolean by C in gimple. It really
should just have been a COND_EXPR, but when we generate that form targets
without good conditional move expanders will end up recreating branchy code :(
^ permalink raw reply [flat|nested] 7+ messages in thread