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* [Bug tree-optimization/102608] New: [12 regression] Recent change to VN causes bogus Wuninitialized warnings & kernel build failures
@ 2021-10-05 14:51 law at gcc dot gnu.org
2021-10-05 15:37 ` [Bug tree-optimization/102608] " pinskia at gcc dot gnu.org
` (4 more replies)
0 siblings, 5 replies; 6+ messages in thread
From: law at gcc dot gnu.org @ 2021-10-05 14:51 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102608
Bug ID: 102608
Summary: [12 regression] Recent change to VN causes bogus
Wuninitialized warnings & kernel build failures
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: law at gcc dot gnu.org
Target Milestone: ---
Created attachment 51555
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=51555&action=edit
Testcase
This change:
55a3be2f5255d69e740d61b2c5aaba1ccbc643b8 is the first bad commit
commit 55a3be2f5255d69e740d61b2c5aaba1ccbc643b8
Author: Richard Biener <rguenther@suse.de>
Date: Mon Oct 4 10:57:45 2021 +0200
tree-optimization/102570 - teach VN about internal functions
We're now using internal functions for a lot of stuff but there's
still missing VN support out of laziness. The following instantiates
support and adds testcases for FRE and PRE (hoisting).
Is causing mips64-linux-gnu and mips64el-linux-gnu kernel build failures due to
a bogus uninitialized warning with the attached file when compiled with -O2
-ftrivial-auto-var-init=zero:
../arch/mips/kernel/cmpxchg.c: In function '__xchg_small':
../arch/mips/kernel/cmpxchg.c:44:36: warning: 'old32' is used uninitialized
[-Wuninitialized]
../arch/mips/kernel/cmpxchg.c:12:6: note: 'old32' was declared here
__cmpxchg_small
../arch/mips/kernel/cmpxchg.c: In function '__cmpxchg_small':
../arch/mips/kernel/cmpxchg.c:100:36: warning: 'mask' may be used uninitialized
[-Wmaybe-uninitialized]
../arch/mips/kernel/cmpxchg.c:53:6: note: 'mask' was declared here
I haven't tracked this down any further.
^ permalink raw reply [flat|nested] 6+ messages in thread* [Bug tree-optimization/102608] [12 regression] Recent change to VN causes bogus Wuninitialized warnings & kernel build failures
2021-10-05 14:51 [Bug tree-optimization/102608] New: [12 regression] Recent change to VN causes bogus Wuninitialized warnings & kernel build failures law at gcc dot gnu.org
@ 2021-10-05 15:37 ` pinskia at gcc dot gnu.org
2021-10-05 15:38 ` pinskia at gcc dot gnu.org
` (3 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: pinskia at gcc dot gnu.org @ 2021-10-05 15:37 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102608
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
old32_34 = .DEFERRED_INIT (4, 2, 0);
...
- _24 = .DEFERRED_INIT (4, 2, 0);
- __res ={v} _24;
+ __res ={v} old32_34;
# 68 "../arch/mips/include/asm/cmpxchg.h"
This is due to __typeof(*((volatile u32 *)ptr)) __ret
The warning is kinda of correct but wrong as it uses the wrong decl :).
Fre maybe should be disabled for DEFERRED_INIT ....
^ permalink raw reply [flat|nested] 6+ messages in thread* [Bug tree-optimization/102608] [12 regression] Recent change to VN causes bogus Wuninitialized warnings & kernel build failures
2021-10-05 14:51 [Bug tree-optimization/102608] New: [12 regression] Recent change to VN causes bogus Wuninitialized warnings & kernel build failures law at gcc dot gnu.org
2021-10-05 15:37 ` [Bug tree-optimization/102608] " pinskia at gcc dot gnu.org
@ 2021-10-05 15:38 ` pinskia at gcc dot gnu.org
2021-10-06 8:39 ` rguenth at gcc dot gnu.org
` (2 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: pinskia at gcc dot gnu.org @ 2021-10-05 15:38 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102608
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|--- |12.0
^ permalink raw reply [flat|nested] 6+ messages in thread* [Bug tree-optimization/102608] [12 regression] Recent change to VN causes bogus Wuninitialized warnings & kernel build failures
2021-10-05 14:51 [Bug tree-optimization/102608] New: [12 regression] Recent change to VN causes bogus Wuninitialized warnings & kernel build failures law at gcc dot gnu.org
2021-10-05 15:37 ` [Bug tree-optimization/102608] " pinskia at gcc dot gnu.org
2021-10-05 15:38 ` pinskia at gcc dot gnu.org
@ 2021-10-06 8:39 ` rguenth at gcc dot gnu.org
2021-10-07 12:28 ` cvs-commit at gcc dot gnu.org
2021-10-07 12:29 ` rguenth at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: rguenth at gcc dot gnu.org @ 2021-10-06 8:39 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102608
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Version|11.0 |12.0
Last reconfirmed| |2021-10-06
Assignee|unassigned at gcc dot gnu.org |rguenth at gcc dot gnu.org
Status|UNCONFIRMED |ASSIGNED
Ever confirmed|0 |1
--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #1)
> old32_34 = .DEFERRED_INIT (4, 2, 0);
>
> ...
>
> - _24 = .DEFERRED_INIT (4, 2, 0);
> - __res ={v} _24;
> + __res ={v} old32_34;
>
>
> # 68 "../arch/mips/include/asm/cmpxchg.h"
> This is due to __typeof(*((volatile u32 *)ptr)) __ret
>
>
>
> The warning is kinda of correct but wrong as it uses the wrong decl :).
>
> Fre maybe should be disabled for DEFERRED_INIT ....
Hmm, I did consider that but then I thought it wouldn't matter (there were no
testsuite FAILs).
But sure, I can easily make .DEFERRED_INIT always produce a VARYING value.
^ permalink raw reply [flat|nested] 6+ messages in thread* [Bug tree-optimization/102608] [12 regression] Recent change to VN causes bogus Wuninitialized warnings & kernel build failures
2021-10-05 14:51 [Bug tree-optimization/102608] New: [12 regression] Recent change to VN causes bogus Wuninitialized warnings & kernel build failures law at gcc dot gnu.org
` (2 preceding siblings ...)
2021-10-06 8:39 ` rguenth at gcc dot gnu.org
@ 2021-10-07 12:28 ` cvs-commit at gcc dot gnu.org
2021-10-07 12:29 ` rguenth at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: cvs-commit at gcc dot gnu.org @ 2021-10-07 12:28 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102608
--- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Richard Biener <rguenth@gcc.gnu.org>:
https://gcc.gnu.org/g:1ebf2c14c60f5f37c00bea66aba46c25d4bcf473
commit r12-4225-g1ebf2c14c60f5f37c00bea66aba46c25d4bcf473
Author: Richard Biener <rguenther@suse.de>
Date: Thu Oct 7 14:24:03 2021 +0200
tree-optimization/102608 - avoid CSEing .DEFERRED_INIT
This makes VN not CSE .DEFERRED_INIT which confuses uninit
analysis which reports the wrong decl when facing copies
of not initialized data.
2021-10-07 Richard Biener <rguenther@suse.de>
PR tree-optimization/102608
* tree-ssa-sccvn.c (visit_stmt): Drop .DEFERRED_INIT to
varying.
^ permalink raw reply [flat|nested] 6+ messages in thread* [Bug tree-optimization/102608] [12 regression] Recent change to VN causes bogus Wuninitialized warnings & kernel build failures
2021-10-05 14:51 [Bug tree-optimization/102608] New: [12 regression] Recent change to VN causes bogus Wuninitialized warnings & kernel build failures law at gcc dot gnu.org
` (3 preceding siblings ...)
2021-10-07 12:28 ` cvs-commit at gcc dot gnu.org
@ 2021-10-07 12:29 ` rguenth at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: rguenth at gcc dot gnu.org @ 2021-10-07 12:29 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102608
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |FIXED
Status|ASSIGNED |RESOLVED
--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
fixed
^ permalink raw reply [flat|nested] 6+ messages in thread
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2021-10-05 14:51 [Bug tree-optimization/102608] New: [12 regression] Recent change to VN causes bogus Wuninitialized warnings & kernel build failures law at gcc dot gnu.org
2021-10-05 15:37 ` [Bug tree-optimization/102608] " pinskia at gcc dot gnu.org
2021-10-05 15:38 ` pinskia at gcc dot gnu.org
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