https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79188
Bug ID: 79188 Summary: wrong code at -O3 on x86_64-linux-gnu Product: gcc Version: unknown 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: --- It appears to be a recent regression. $ 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/7.0.1/lto-wrapper Target: x86_64-pc-linux-gnu Configured with: ../gcc-source-trunk/configure --enable-languages=c,c++,lto --prefix=/usr/local/gcc-trunk --disable-bootstrap Thread model: posix gcc version 7.0.1 20170122 (experimental) [trunk revision 244756] (GCC) $ $ gcc-trunk -O2 small.c $ ./a.out $ $ gcc-trunk -O3 small.c $ ./a.out Aborted (core dumped) $ ------------------------------------------------ int a, b, c, d, e, f, h, j, k; static void fn1 () { int g = 1, i; if (!f) { for (; d < 1; d++) for (i = 0, j = 1; i < 1; i = j) a = 2; for (; e < 1; e++) { for (; k; k++) L: ; for (c = 0; c < 2; c++) { for (i = 0; i < 4; i++) { for (; h; h++) g = 0; b = 0; } if (b) goto L; } a = 0; } if (g < 0) goto L; } } int main () { fn1 (); if (a != 0) __builtin_abort (); return 0; }