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* [Bug c++/107190] New: [aarch64] regression with optimization -fexpensive-optimizations
@ 2022-10-09 10:33 zhongyunde at huawei dot com
2022-10-10 16:54 ` [Bug rtl-optimization/107190] " pinskia at gcc dot gnu.org
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: zhongyunde at huawei dot com @ 2022-10-09 10:33 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107190
Bug ID: 107190
Summary: [aarch64] regression with optimization
-fexpensive-optimizations
Product: gcc
Version: 13.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: zhongyunde at huawei dot com
Target Milestone: ---
This case is simplify from https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107090,
and we can see that the codegen of function `test_m` has some regression with
optimization -fexpensive-optimizations, https://gcc.godbolt.org/z/zbKrEox4j
This is because the pass 208t.widening_mul is controlled by
-fexpensive-optimizations (default on at -O3), it conversion
```
m_12 = m_9 + m1_10;
if (m1_10 > m_12)
```
into
```
_17 = .ADD_OVERFLOW (m_9, m1_10);
m_12 = REALPART_EXPR <_17>;
_18 = IMAGPART_EXPR <_17>;
if (_18 != 0)``
```
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug rtl-optimization/107190] [aarch64] regression with optimization -fexpensive-optimizations
2022-10-09 10:33 [Bug c++/107190] New: [aarch64] regression with optimization -fexpensive-optimizations zhongyunde at huawei dot com
@ 2022-10-10 16:54 ` pinskia at gcc dot gnu.org
2022-10-10 17:31 ` [Bug middle-end/107190] " pinskia at gcc dot gnu.org
2023-05-19 1:22 ` pinskia at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: pinskia at gcc dot gnu.org @ 2022-10-10 16:54 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107190
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Component|c++ |rtl-optimization
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to vfdff from comment #0)
> This case is simplify from
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107090, and we can see that the
> codegen of function `test_m` has some regression with optimization
> -fexpensive-optimizations, https://gcc.godbolt.org/z/zbKrEox4j
>
> This is because the pass 208t.widening_mul is controlled by
> -fexpensive-optimizations (default on at -O3), it conversion
>
> ```
> m_12 = m_9 + m1_10;
> if (m1_10 > m_12)
> ```
> into
>
> ```
> _17 = .ADD_OVERFLOW (m_9, m1_10);
> m_12 = REALPART_EXPR <_17>;
> _18 = IMAGPART_EXPR <_17>;
> if (_18 != 0)``
This should always be better. If ifcvt.cc does not handle this case, then it
should be improved.
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug middle-end/107190] [aarch64] regression with optimization -fexpensive-optimizations
2022-10-09 10:33 [Bug c++/107190] New: [aarch64] regression with optimization -fexpensive-optimizations zhongyunde at huawei dot com
2022-10-10 16:54 ` [Bug rtl-optimization/107190] " pinskia at gcc dot gnu.org
@ 2022-10-10 17:31 ` pinskia at gcc dot gnu.org
2023-05-19 1:22 ` pinskia at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: pinskia at gcc dot gnu.org @ 2022-10-10 17:31 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107190
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Component|rtl-optimization |middle-end
--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
I think it is the expansion of the add with overflow causing things to be
worse.
(insn 16 15 17 (set (reg:DI 102 [ _17+8 ])
(const_int 0 [0])) -1
(nil))
(insn 17 16 18 (parallel [
(set (reg:CC_C 66 cc)
(compare:CC_C (plus:DI (reg:DI 109 [ m ])
(reg:DI 111 [ m1 ]))
(reg:DI 109 [ m ])))
(set (reg:DI 112)
(plus:DI (reg:DI 109 [ m ])
(reg:DI 111 [ m1 ])))
]) -1
(nil))
(jump_insn 18 17 19 (set (pc)
(if_then_else (ltu (reg:CC_C 66 cc)
(const_int 0 [0]))
(label_ref 21)
(pc))) -1
(int_list:REG_BR_PROB 536868 (nil)))
(jump_insn 19 18 20 (set (pc)
(label_ref 23)) -1
(nil))
(barrier 20 19 21)
(code_label 21 20 22 3 (nil) [0 uses])
(insn 22 21 23 (set (reg:DI 102 [ _17+8 ])
(const_int 1 [0x1])) -1
(nil))
(code_label 23 22 24 2 (nil) [0 uses])
I don't see why we need to expand to a jump here rather than a cset?
I think there is another bug about this already too.
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug middle-end/107190] [aarch64] regression with optimization -fexpensive-optimizations
2022-10-09 10:33 [Bug c++/107190] New: [aarch64] regression with optimization -fexpensive-optimizations zhongyunde at huawei dot com
2022-10-10 16:54 ` [Bug rtl-optimization/107190] " pinskia at gcc dot gnu.org
2022-10-10 17:31 ` [Bug middle-end/107190] " pinskia at gcc dot gnu.org
@ 2023-05-19 1:22 ` pinskia at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: pinskia at gcc dot gnu.org @ 2023-05-19 1:22 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107190
--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Created attachment 55113
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=55113&action=edit
testcase
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2023-05-19 1:22 UTC | newest]
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2022-10-09 10:33 [Bug c++/107190] New: [aarch64] regression with optimization -fexpensive-optimizations zhongyunde at huawei dot com
2022-10-10 16:54 ` [Bug rtl-optimization/107190] " pinskia at gcc dot gnu.org
2022-10-10 17:31 ` [Bug middle-end/107190] " pinskia at gcc dot gnu.org
2023-05-19 1:22 ` pinskia at gcc dot gnu.org
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