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 <rguent...@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.
