https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69326
Bug ID: 69326 Summary: wrong code at -O2 and -O3 on x86_64-linux-gnu Product: gcc Version: 6.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: su at cs dot ucdavis.edu Target Milestone: --- The current gcc trunk miscompiles the following code on x86_64-linux-gnu at -O2 and -O3 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 20160116 (experimental) [trunk revision 232466] (GCC) $ $ gcc-trunk -Os small.c; ./a.out 0 $ gcc-5.3 -O2 small.c; ./a.out 0 $ $ gcc-trunk -O2 small.c $ ./a.out 0 Floating point exception (core dumped) $ $ -------------------------------------- int printf (const char *, ...); int a, *c, d, e, g, f; short b; int fn1 () { int h = d != 10; if (h > g) printf ("%d\n", d); if (h == 10) { int *i = 0; a = 0; for (; a < 7; a++) for (; *i;) ; } else { b = e / h; return f; } c = &h; return 0; } int main () { fn1 (); return 0; }