https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69117
Bug ID: 69117 Summary: wrong code at -Os and above on x86_64-linux-gnu Product: gcc Version: 6.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: rtl-optimization Assignee: unassigned at gcc dot gnu.org Reporter: su at cs dot ucdavis.edu Target Milestone: --- The current gcc trunk mis-compiles the following code on x86_64-linux-gnu at -Os and above in both 32-bit and 64-bit modes. This is a regression from 5.3.x. $ gcc-trunk -v Using built-in specs. COLLECT_GCC=gcc-trunk COLLECT_LTO_WRAPPER=/usr/local/gcc-trunk/libexec/gcc/x86_64-pc-linux-gnu/6.0.0/lto-wrapper Target: x86_64-pc-linux-gnu Configured with: ../gcc-trunk/configure --prefix=/usr/local/gcc-trunk --enable-languages=c,c++ --disable-werror --enable-multilib Thread model: posix gcc version 6.0.0 20160101 (experimental) [trunk revision 232023] (GCC) $ $ gcc-trunk -O1 small.c; ./a.out $ gcc-5.3 -Os small.c; ./a.out $ $ gcc-trunk -Os small.c $ ./a.out Aborted (core dumped) $ ---------------------------------------- int a, c, *d = &c, **e = &d, *g = &a; static int ***b, **f = &d; int main () { **f = 0; int ****h = 0; if (c) { *h = &e; ***b = 0; } *e = g; if (d != &a) __builtin_abort (); return 0; }