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* [Bug middle-end/111384] New: missed optimization: GCC adds extra any extend when storing subreg#0 multiple times
@ 2023-09-12 9:25 lis8215 at gmail dot com
2023-09-12 12:38 ` [Bug rtl-optimization/111384] " rguenth at gcc dot gnu.org
` (5 more replies)
0 siblings, 6 replies; 7+ messages in thread
From: lis8215 at gmail dot com @ 2023-09-12 9:25 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111384
Bug ID: 111384
Summary: missed optimization: GCC adds extra any extend when
storing subreg#0 multiple times
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: lis8215 at gmail dot com
Target Milestone: ---
Simple example:
void store_hi_twice(uint32_t src, uint16_t *dst1, uint16_t *dst2)
{
*dst1 = src;
*dst2 = src;
}
shows that GCC can't opt out unnecessary zero extend of the src's low half
aimed to store two or more times. Many targets are affected, although x86-64
don't.
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug rtl-optimization/111384] missed optimization: GCC adds extra any extend when storing subreg#0 multiple times
2023-09-12 9:25 [Bug middle-end/111384] New: missed optimization: GCC adds extra any extend when storing subreg#0 multiple times lis8215 at gmail dot com
@ 2023-09-12 12:38 ` rguenth at gcc dot gnu.org
2023-09-12 13:10 ` lis8215 at gmail dot com
` (4 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: rguenth at gcc dot gnu.org @ 2023-09-12 12:38 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111384
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Version|unknown |14.0
Component|middle-end |rtl-optimization
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
can you name one of many?
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug rtl-optimization/111384] missed optimization: GCC adds extra any extend when storing subreg#0 multiple times
2023-09-12 9:25 [Bug middle-end/111384] New: missed optimization: GCC adds extra any extend when storing subreg#0 multiple times lis8215 at gmail dot com
2023-09-12 12:38 ` [Bug rtl-optimization/111384] " rguenth at gcc dot gnu.org
@ 2023-09-12 13:10 ` lis8215 at gmail dot com
2023-09-12 15:27 ` pinskia at gcc dot gnu.org
` (3 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: lis8215 at gmail dot com @ 2023-09-12 13:10 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111384
--- Comment #2 from Siarhei Volkau <lis8215 at gmail dot com> ---
Well what the godbolt says with -O2 -fomit-frame-pointer.
ARM:
uxth r0, r0 @ << zero extend
strh r0, [r1]
strh r0, [r2]
bx lr
ARM64:
and w0, w0, 65535 @ << zero extend
strh w0, [x1]
strh w0, [x2]
ret
MIPS64:
andi $4,$4,0xffff @ << zero extend
sh $4,0($5)
jr $31
sh $4,0($6)
MRISC32:
shuf r1, r1, #2888 @ << zero extend
sth r1, [r2]
sth r1, [r3]
ret
RISC-V:
slli a0,a0,16 @ << zero extend
srli a0,a0,16 @ << zero extend
sh a0,0(a1)
sh a0,0(a2)
ret
RISC-V (64-bit):
slli a0,a0,48 @ << zero extend
srli a0,a0,48 @ << zero extend
sh a0,0(a1)
sh a0,0(a2)
ret
Xtensa ESP32:
entry sp, 32
extui a2, a2, 0, 16 @ << zero extend
s16i a2, a3, 0
s16i a2, a4, 0
retw.n
Loongarch64:
bstrpick.w $r4,$r4,15,0 @ << zero extend
st.h $r4,$r5,0
st.h $r4,$r6,0
jr $r1
MIPS:
andi $4,$4,0xffff @ << zero extend
sh $4,0($5)
jr $31
sh $4,0($6)
SH:
extu.w r4,r4 @ << zero extend
mov.w r4,@r5
rts
mov.w r4,@r6
Other available at godbolt (x86-64/Power/Power64/s390) unaffected.
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug rtl-optimization/111384] missed optimization: GCC adds extra any extend when storing subreg#0 multiple times
2023-09-12 9:25 [Bug middle-end/111384] New: missed optimization: GCC adds extra any extend when storing subreg#0 multiple times lis8215 at gmail dot com
2023-09-12 12:38 ` [Bug rtl-optimization/111384] " rguenth at gcc dot gnu.org
2023-09-12 13:10 ` lis8215 at gmail dot com
@ 2023-09-12 15:27 ` pinskia at gcc dot gnu.org
2023-09-12 15:35 ` pinskia at gcc dot gnu.org
` (2 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: pinskia at gcc dot gnu.org @ 2023-09-12 15:27 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111384
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Severity|normal |enhancement
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug rtl-optimization/111384] missed optimization: GCC adds extra any extend when storing subreg#0 multiple times
2023-09-12 9:25 [Bug middle-end/111384] New: missed optimization: GCC adds extra any extend when storing subreg#0 multiple times lis8215 at gmail dot com
` (2 preceding siblings ...)
2023-09-12 15:27 ` pinskia at gcc dot gnu.org
@ 2023-09-12 15:35 ` pinskia at gcc dot gnu.org
2023-10-07 20:54 ` law at gcc dot gnu.org
2023-11-01 6:30 ` lis8215 at gmail dot com
5 siblings, 0 replies; 7+ messages in thread
From: pinskia at gcc dot gnu.org @ 2023-09-12 15:35 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111384
--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
I thought I saw/reported a similar bug but I can't find it right now.
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug rtl-optimization/111384] missed optimization: GCC adds extra any extend when storing subreg#0 multiple times
2023-09-12 9:25 [Bug middle-end/111384] New: missed optimization: GCC adds extra any extend when storing subreg#0 multiple times lis8215 at gmail dot com
` (3 preceding siblings ...)
2023-09-12 15:35 ` pinskia at gcc dot gnu.org
@ 2023-10-07 20:54 ` law at gcc dot gnu.org
2023-11-01 6:30 ` lis8215 at gmail dot com
5 siblings, 0 replies; 7+ messages in thread
From: law at gcc dot gnu.org @ 2023-10-07 20:54 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111384
Jeffrey A. Law <law at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Last reconfirmed| |2023-10-07
Ever confirmed|0 |1
Status|UNCONFIRMED |NEW
--- Comment #4 from Jeffrey A. Law <law at gcc dot gnu.org> ---
So this is something we've been pondering over in rv64 land. Joern has an
extension to DCE which tracks subobjects in an attempt to determine if bits set
by sign/zero extensions are never read. If they aren't read, then the
extension can be eliminated.
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug rtl-optimization/111384] missed optimization: GCC adds extra any extend when storing subreg#0 multiple times
2023-09-12 9:25 [Bug middle-end/111384] New: missed optimization: GCC adds extra any extend when storing subreg#0 multiple times lis8215 at gmail dot com
` (4 preceding siblings ...)
2023-10-07 20:54 ` law at gcc dot gnu.org
@ 2023-11-01 6:30 ` lis8215 at gmail dot com
5 siblings, 0 replies; 7+ messages in thread
From: lis8215 at gmail dot com @ 2023-11-01 6:30 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111384
Siarhei Volkau <lis8215 at gmail dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |DUPLICATE
Status|NEW |RESOLVED
--- Comment #5 from Siarhei Volkau <lis8215 at gmail dot com> ---
Dup of bug 104387.
*** This bug has been marked as a duplicate of bug 104387 ***
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2023-11-01 6:30 UTC | newest]
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2023-09-12 9:25 [Bug middle-end/111384] New: missed optimization: GCC adds extra any extend when storing subreg#0 multiple times lis8215 at gmail dot com
2023-09-12 12:38 ` [Bug rtl-optimization/111384] " rguenth at gcc dot gnu.org
2023-09-12 13:10 ` lis8215 at gmail dot com
2023-09-12 15:27 ` pinskia at gcc dot gnu.org
2023-09-12 15:35 ` pinskia at gcc dot gnu.org
2023-10-07 20:54 ` law at gcc dot gnu.org
2023-11-01 6:30 ` lis8215 at gmail dot com
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