https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108498
--- Comment #6 from Adam Stylinski <kungfujesus06 at gmail dot com> --- (In reply to Richard Biener from comment #5) > maybe a stack sharing issue? Can you try -fstack-reuse=none? So that does fix it, at least when the struct is backed by the stack. And also valgrind is no longer finding uninitialized memory being used: adam@g5box ~ $ gcc -O2 -fstack-reuse=none bug_rep2.c -o test.out adam@g5box ~ $ ./test.out sat? = 0 adam@g5box ~ $ valgrind ./test.out ==26982== Memcheck, a memory error detector ==26982== Copyright (C) 2002-2022, and GNU GPL'd, by Julian Seward et al. ==26982== Using Valgrind-3.20.0 and LibVEX; rerun with -h for copyright info ==26982== Command: ./test.out ==26982== sat? = 0 ==26982== ==26982== HEAP SUMMARY: ==26982== in use at exit: 0 bytes in 0 blocks ==26982== total heap usage: 1 allocs, 1 frees, 1,024 bytes allocated ==26982== ==26982== All heap blocks were freed -- no leaks are possible ==26982== ==26982== For lists of detected and suppressed errors, rerun with: -s ==26982== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0) Not sure what it might do if backed by the heap, but the code is written in a way that it initializes the struct on the stack, anyway.
