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* [Bug rtl-optimization/103386] New: stage1 with PGO produces bad offsets in rtl-reload on aarch64
@ 2021-11-23 15:06 mittorn at sibmail dot com
2021-11-23 18:30 ` [Bug middle-end/103386] " pinskia at gcc dot gnu.org
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: mittorn at sibmail dot com @ 2021-11-23 15:06 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103386
Bug ID: 103386
Summary: stage1 with PGO produces bad offsets in rtl-reload on
aarch64
Product: gcc
Version: 11.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: rtl-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: mittorn at sibmail dot com
Target Milestone: ---
Created attachment 51862
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=51862&action=edit
pgo build logs and system environment
This result in failed conftest binary returning nonzero status when trying to
build libgomp.
Simple program to reproduce conftest behaviour:
int main()
{
return 0;
}
stage1 makes bad assembly on it:
.cfi_startproc
stp x0, x1, [sp, -32]!
.cfi_def_cfa_offset 32
.cfi_offset 0, -32
.cfi_offset 1, -24
stp x2, x3, [sp, 16]
.cfi_offset 2, -16
.cfi_offset 3, -8
mov w0, 0
ldp x2, x3, [sp, 16]
ldp x0, x1, [sp], 32
.cfi_restore 1
.cfi_restore 0
.cfi_restore 2
.cfi_restore 3
.cfi_def_cfa_offset 0
ret
.cfi_endproc
instead of this one:
.cfi_startproc
mov w0, 0
ret
.cfi_endproc
after dumping RTL stages, i found this (source files are identical, second is
stage1):
~ # diff 1.c.292r.reload 2.c.292r.reload
7a8,12
> New elimination table:
> Can eliminate 65 to 31 (offset=32, prev_offset=0)
> Can eliminate 65 to 29 (offset=32, prev_offset=0)
> Can eliminate 64 to 31 (offset=32, prev_offset=0)
> Can eliminate 64 to 29 (offset=32, prev_offset=0)
51,54c56,59
< Can eliminate 65 to 31 (offset=0, prev_offset=0)
< Can eliminate 65 to 29 (offset=0, prev_offset=0)
< Can eliminate 64 to 31 (offset=0, prev_offset=0)
< Can eliminate 64 to 29 (offset=0, prev_offset=0)
---
> Can eliminate 65 to 31 (offset=32, prev_offset=32)
> Can eliminate 65 to 29 (offset=32, prev_offset=0)
> Can eliminate 64 to 31 (offset=32, prev_offset=32)
> Can eliminate 64 to 29 (offset=32, prev_offset=0)
81c86
< (const_int 0 [0])) "1.c":3:8 52 {*movsi_aarch64}
---
> (const_int 0 [0])) "2.c":3:8 52 {*movsi_aarch64}
83c88
< (insn 13 5 15 2 (use (reg/i:SI 0 x0)) "1.c":4:1 -1
---
> (insn 13 5 15 2 (use (reg/i:SI 0 x0)) "2.c":4:1 -1
Full build tree temporary placed here:
http://mittorn.mentality.rip/
needed log and environment info in attachment
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug middle-end/103386] stage1 with PGO produces bad offsets in rtl-reload on aarch64
2021-11-23 15:06 [Bug rtl-optimization/103386] New: stage1 with PGO produces bad offsets in rtl-reload on aarch64 mittorn at sibmail dot com
@ 2021-11-23 18:30 ` pinskia at gcc dot gnu.org
2021-11-24 16:57 ` mittorn at sibmail dot com
2021-11-25 1:02 ` [Bug middle-end/103386] -floop-nest-optimize -floop-interchange -fgraphite-identity miscompiles gcc pinskia at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: pinskia at gcc dot gnu.org @ 2021-11-23 18:30 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103386
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |WAITING
Ever confirmed|0 |1
Last reconfirmed| |2021-11-23
Component|rtl-optimization |middle-end
Keywords| |wrong-code
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
What GCC are you starting with?
Because you are building stage 1 compiler with "-O3 -ftree-vectorize
-fomit-frame-pointer -mcpu=neoverse-n1 -mtune=neoverse-n1 -fno-plt -fipa-pta
-funsafe-math-optimizations -funsafe-loop-optimizations
-fdevirtualize-at-ltrans -floop-nest-optimize -fgraphite-identity
-floop-interchange"
I think both "-fipa-pta" and "-fgraphite-identity" have known issues which
could be causing issues here. Plus GCC is not normally compiled with
"-funsafe-math-optimizations" or "-funsafe-loop-optimizations".
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug middle-end/103386] stage1 with PGO produces bad offsets in rtl-reload on aarch64
2021-11-23 15:06 [Bug rtl-optimization/103386] New: stage1 with PGO produces bad offsets in rtl-reload on aarch64 mittorn at sibmail dot com
2021-11-23 18:30 ` [Bug middle-end/103386] " pinskia at gcc dot gnu.org
@ 2021-11-24 16:57 ` mittorn at sibmail dot com
2021-11-25 1:02 ` [Bug middle-end/103386] -floop-nest-optimize -floop-interchange -fgraphite-identity miscompiles gcc pinskia at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: mittorn at sibmail dot com @ 2021-11-24 16:57 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103386
--- Comment #2 from mittorn at sibmail dot com ---
Removing -floop-nest-optimize -floop-interchange -fgraphite-identity fixes
build, but removing only -fgraphite-identity not
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug middle-end/103386] -floop-nest-optimize -floop-interchange -fgraphite-identity miscompiles gcc
2021-11-23 15:06 [Bug rtl-optimization/103386] New: stage1 with PGO produces bad offsets in rtl-reload on aarch64 mittorn at sibmail dot com
2021-11-23 18:30 ` [Bug middle-end/103386] " pinskia at gcc dot gnu.org
2021-11-24 16:57 ` mittorn at sibmail dot com
@ 2021-11-25 1:02 ` pinskia at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: pinskia at gcc dot gnu.org @ 2021-11-25 1:02 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103386
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Ever confirmed|1 |0
Summary|stage1 with PGO produces |-floop-nest-optimize
|bad offsets in rtl-reload |-floop-interchange
|on aarch64 |-fgraphite-identity
| |miscompiles gcc
Status|WAITING |UNCONFIRMED
^ permalink raw reply [flat|nested] 4+ messages in thread
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2021-11-23 15:06 [Bug rtl-optimization/103386] New: stage1 with PGO produces bad offsets in rtl-reload on aarch64 mittorn at sibmail dot com
2021-11-23 18:30 ` [Bug middle-end/103386] " pinskia at gcc dot gnu.org
2021-11-24 16:57 ` mittorn at sibmail dot com
2021-11-25 1:02 ` [Bug middle-end/103386] -floop-nest-optimize -floop-interchange -fgraphite-identity miscompiles gcc pinskia at gcc dot gnu.org
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