https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66372
Bug ID: 66372 Summary: ICE on valid code at -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 following code causes an ICE when compiled with the current gcc trunk at -O3 on x86_64-linux-gnu in both 32-bit and 64-bit modes. It is a regression from 5.1.x. $ gcc-trunk -v Using built-in specs. COLLECT_GCC=gcc-trunk COLLECT_LTO_WRAPPER=/usr/local/gcc-trunk/libexec/gcc/x86_64-unknown-linux-gnu/6.0.0/lto-wrapper Target: x86_64-unknown-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 20150601 (experimental) [trunk revision 223995] (GCC) $ $ gcc-trunk -O2 small.c; ./a.out $ gcc-5.1 -O3 small.c; ./a.out $ $ gcc-trunk -O3 small.c small.c: In function ‘main’: small.c:29:1: internal compiler error: Segmentation fault main () ^ 0xb1212f crash_signal ../../gcc-trunk/gcc/toplev.c:380 0xcf4811 thread_through_all_blocks(bool) ../../gcc-trunk/gcc/tree-ssa-threadupdate.c:2693 0xc3310b execute ../../gcc-trunk/gcc/tree-ssa-dom.c:1244 Please submit a full bug report, with preprocessed source if appropriate. Please include the complete backtrace with any bug report. See <http://gcc.gnu.org/bugs.html> for instructions. $ ------------------------------------ int a, c, d, e, f; int fn1 () { for (;;) { if (a) break; unsigned int g = 1; lbl: c = g; for (g = 0; g < 1; g++) { if (c) continue; int h[1]; f = h[0]; for (; d; d = 0) if (e) goto lbl; } return 0; } return 0; } int main () { fn1 (); return 0; }