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* [Bug rtl-optimization/82356] auto-vectorizing pack of 16->8 has a redundant AND after a shift
[not found] <bug-82356-4@http.gcc.gnu.org/bugzilla/>
@ 2021-08-14 21:14 ` pinskia at gcc dot gnu.org
2021-08-25 3:21 ` pinskia at gcc dot gnu.org
1 sibling, 0 replies; 2+ messages in thread
From: pinskia at gcc dot gnu.org @ 2021-08-14 21:14 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82356
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Component|tree-optimization |rtl-optimization
Severity|normal |enhancement
Last reconfirmed|2017-09-29 00:00:00 |2021-8-14
^ permalink raw reply [flat|nested] 2+ messages in thread
* [Bug rtl-optimization/82356] auto-vectorizing pack of 16->8 has a redundant AND after a shift
[not found] <bug-82356-4@http.gcc.gnu.org/bugzilla/>
2021-08-14 21:14 ` [Bug rtl-optimization/82356] auto-vectorizing pack of 16->8 has a redundant AND after a shift pinskia at gcc dot gnu.org
@ 2021-08-25 3:21 ` pinskia at gcc dot gnu.org
1 sibling, 0 replies; 2+ messages in thread
From: pinskia at gcc dot gnu.org @ 2021-08-25 3:21 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82356
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Last reconfirmed|2021-08-14 00:00:00 |2021-8-24
--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
With -O3 -fno-move-loop-invariants -fno-gcse
We get
Trying 38, 34 -> 39:
38: r160:V8HI=[`*.LC0']
REG_EQUAL const_vector
34: r154:V8HI=r153:V8HI 0>>0x8
REG_DEAD r153:V8HI
39: r158:V8HI=r160:V8HI&r154:V8HI
REG_DEAD r154:V8HI
Failed to match this instruction:
(parallel [
(set (reg:V8HI 158)
(and:V8HI (lshiftrt:V8HI (reg:V8HI 153 [ vect__1.12 ])
(const_int 8 [0x8]))
(const_vector:V8HI [
(const_int 255 [0xff]) repeated x8
])))
(set (reg:V8HI 160)
(mem/u/c:V8HI (symbol_ref/u:DI ("*.LC0") [flags 0x2]) [0 S16
A128]))
])
Failed to match this instruction:
(parallel [
(set (reg:V8HI 158)
(and:V8HI (lshiftrt:V8HI (reg:V8HI 153 [ vect__1.12 ])
(const_int 8 [0x8]))
(const_vector:V8HI [
(const_int 255 [0xff]) repeated x8
])))
(set (reg:V8HI 160)
(mem/u/c:V8HI (symbol_ref/u:DI ("*.LC0") [flags 0x2]) [0 S16
A128]))
])
Successfully matched this instruction:
(set (reg:V8HI 160)
(mem/u/c:V8HI (symbol_ref/u:DI ("*.LC0") [flags 0x2]) [0 S16 A128]))
Failed to match this instruction:
(set (reg:V8HI 158)
(and:V8HI (lshiftrt:V8HI (reg:V8HI 153 [ vect__1.12 ])
(const_int 8 [0x8]))
(const_vector:V8HI [
(const_int 255 [0xff]) repeated x8
])))
Which we don't recongize the and part is not needed.
Also since we don't emit REG_EQUAL when using vector_csts, we needed to use
"-fno-move-loop-invariants -fno-gcse ".
^ permalink raw reply [flat|nested] 2+ messages in thread
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[not found] <bug-82356-4@http.gcc.gnu.org/bugzilla/>
2021-08-14 21:14 ` [Bug rtl-optimization/82356] auto-vectorizing pack of 16->8 has a redundant AND after a shift pinskia at gcc dot gnu.org
2021-08-25 3:21 ` pinskia at gcc dot gnu.org
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