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* [Bug middle-end/111782] New: [11/12/13/14 Regression] Extra move in complex double multiplication
@ 2023-10-12 9:43 ktkachov at gcc dot gnu.org
2023-10-12 10:46 ` [Bug middle-end/111782] " rguenth at gcc dot gnu.org
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: ktkachov at gcc dot gnu.org @ 2023-10-12 9:43 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111782
Bug ID: 111782
Summary: [11/12/13/14 Regression] Extra move in complex double
multiplication
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: normal
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: ktkachov at gcc dot gnu.org
Target Milestone: ---
Target: aarch64
The testcase:
__complex double
foo (__complex double a, __complex double b)
{
return a * b;
}
With GCC trunk at -Ofast I see on aarch64:
foo(double _Complex, double _Complex):
fmov d31, d1
fmul d1, d1, d2
fmadd d1, d0, d3, d1
fmul d31, d31, d3
fnmsub d0, d0, d2, d31
ret
with GCC 10 the codegen used to be tighter:
foo(double _Complex, double _Complex):
fmul d4, d1, d3
fmul d5, d1, d2
fmadd d1, d0, d3, d5
fnmsub d0, d0, d2, d4
ret
There's an extra fmov emitted on trunk.
I noticed this regressed with the GCC 11 series
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug middle-end/111782] [11/12/13/14 Regression] Extra move in complex double multiplication
2023-10-12 9:43 [Bug middle-end/111782] New: [11/12/13/14 Regression] Extra move in complex double multiplication ktkachov at gcc dot gnu.org
@ 2023-10-12 10:46 ` rguenth at gcc dot gnu.org
2023-10-12 21:42 ` [Bug rtl-optimization/111782] " pinskia at gcc dot gnu.org
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: rguenth at gcc dot gnu.org @ 2023-10-12 10:46 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111782
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|--- |11.5
Keywords| |needs-bisection
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug rtl-optimization/111782] [11/12/13/14 Regression] Extra move in complex double multiplication
2023-10-12 9:43 [Bug middle-end/111782] New: [11/12/13/14 Regression] Extra move in complex double multiplication ktkachov at gcc dot gnu.org
2023-10-12 10:46 ` [Bug middle-end/111782] " rguenth at gcc dot gnu.org
@ 2023-10-12 21:42 ` pinskia at gcc dot gnu.org
2023-10-12 21:55 ` [Bug rtl-optimization/111782] [11/12/13/14 Regression] Extra move in double argument and multiplication and return pinskia at gcc dot gnu.org
2024-03-07 21:05 ` [Bug rtl-optimization/111782] [11/12/13/14 Regression] Extra move with arguments and returns and still using the argument for the last statement law at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: pinskia at gcc dot gnu.org @ 2023-10-12 21:42 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111782
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |ra
Last reconfirmed| |2023-10-12
Ever confirmed|0 |1
Status|UNCONFIRMED |NEW
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed, the first difference in the IR between the 10 and 11 is reload
(LRA).
I suspect this is only an argument register allocation issue.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug rtl-optimization/111782] [11/12/13/14 Regression] Extra move in double argument and multiplication and return
2023-10-12 9:43 [Bug middle-end/111782] New: [11/12/13/14 Regression] Extra move in complex double multiplication ktkachov at gcc dot gnu.org
2023-10-12 10:46 ` [Bug middle-end/111782] " rguenth at gcc dot gnu.org
2023-10-12 21:42 ` [Bug rtl-optimization/111782] " pinskia at gcc dot gnu.org
@ 2023-10-12 21:55 ` pinskia at gcc dot gnu.org
2024-03-07 21:05 ` [Bug rtl-optimization/111782] [11/12/13/14 Regression] Extra move with arguments and returns and still using the argument for the last statement law at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: pinskia at gcc dot gnu.org @ 2023-10-12 21:55 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111782
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Summary|[11/12/13/14 Regression] |[11/12/13/14 Regression]
|Extra move in complex |Extra move in double
|double argument and |argument and multiplication
|multiplication |and return
--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Here is another testcase without complex (or even needing -ffast-math) being
involved:
```
struct cmplx
{
double r;
double i;
};
struct cmplx
f(double ar, double ai, double br, double bi, __complex double *r)
{
double t = ai * bi;
double t1 = ai * br;
double t2 = ar * bi + t1;
double t3 = ar * br - t;
return (struct cmplx){t3,t2};
}
```
This only shows up wih both arguments and returns and using the same registers.
I am 99% sure this does not show up that much really either.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug rtl-optimization/111782] [11/12/13/14 Regression] Extra move with arguments and returns and still using the argument for the last statement
2023-10-12 9:43 [Bug middle-end/111782] New: [11/12/13/14 Regression] Extra move in complex double multiplication ktkachov at gcc dot gnu.org
` (2 preceding siblings ...)
2023-10-12 21:55 ` [Bug rtl-optimization/111782] [11/12/13/14 Regression] Extra move in double argument and multiplication and return pinskia at gcc dot gnu.org
@ 2024-03-07 21:05 ` law at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: law at gcc dot gnu.org @ 2024-03-07 21:05 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111782
Jeffrey A. Law <law at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Priority|P3 |P2
CC| |law at gcc dot gnu.org
^ permalink raw reply [flat|nested] 5+ messages in thread
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2023-10-12 9:43 [Bug middle-end/111782] New: [11/12/13/14 Regression] Extra move in complex double multiplication ktkachov at gcc dot gnu.org
2023-10-12 10:46 ` [Bug middle-end/111782] " rguenth at gcc dot gnu.org
2023-10-12 21:42 ` [Bug rtl-optimization/111782] " pinskia at gcc dot gnu.org
2023-10-12 21:55 ` [Bug rtl-optimization/111782] [11/12/13/14 Regression] Extra move in double argument and multiplication and return pinskia at gcc dot gnu.org
2024-03-07 21:05 ` [Bug rtl-optimization/111782] [11/12/13/14 Regression] Extra move with arguments and returns and still using the argument for the last statement law at gcc dot gnu.org
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