https://bugs.kde.org/show_bug.cgi?id=413642
Bug ID: 413642
Summary: gcc 9 with -O2 results in false positive:
Uninitialised value was created by a stack allocation
Product: valgrind
Version: 3.15 SVN
Platform: Debian unstable
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: memcheck
Assignee: jsew...@acm.org
Reporter: tim.rueh...@gmx.de
Target Milestone: ---
SUMMARY
Valgrind falsely detects "Uninitialised value was created by a stack
allocation" when the code is compiled with gcc 9 and -O2 (with -O0 all is
fine).
It looks like it's about how gcc optimizes strcmp().
STEPS TO REPRODUCE
All is pretty well described (incl. dgb assembler dumps) at
https://gitlab.com/gnutls/libtasn1/issues/9
OBSERVED RESULT
==15173== Conditional jump or move depends on uninitialised value(s)
==15173== at 0x1092C0: main (Test_choice.c:122)
==15173== Uninitialised value was created by a stack allocation
==15173== at 0x1090F0: main (Test_choice.c:28)
EXPECTED RESULT
No report at all - the variable is being initialized in a called function.
SOFTWARE/OS VERSIONS
Debian unstable, but also reported on Fedora. Key seems to be gcc 9.
ADDITIONAL INFORMATION
https://gitlab.com/gnutls/libtasn1/issues/9
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