https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71595
Bug ID: 71595 Summary: ICE on valid code at -O2 and -O3 on x86_64-linux-gnu: in check_loop_closed_ssa_use, at tree-ssa-loop-manip.c:704 Product: gcc Version: 7.0 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 -O2 and -O3 on x86_64-linux-gnu in both 32-bit and 64-bit modes. It is a regression from 6.1.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/7.0.0/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 7.0.0 20160620 (experimental) [trunk revision 237587] (GCC) $ $ gcc-trunk -Os -c small.c $ gcc-6.1 -O2 -c small.c $ $ gcc-trunk -O2 -c small.c small.c: In function ‘fn1’: small.c:6:1: internal compiler error: in check_loop_closed_ssa_use, at tree-ssa-loop-manip.c:704 fn1 () ^~~ 0xd2e54c check_loop_closed_ssa_use ../../gcc-source-trunk/gcc/tree-ssa-loop-manip.c:703 0xd31306 check_loop_closed_ssa_stmt ../../gcc-source-trunk/gcc/tree-ssa-loop-manip.c:719 0xd31306 verify_loop_closed_ssa(bool) ../../gcc-source-trunk/gcc/tree-ssa-loop-manip.c:753 0xd1537e tree_unroll_loops_completely(bool, bool) ../../gcc-source-trunk/gcc/tree-ssa-loop-ivcanon.c:1431 0xd1540a execute ../../gcc-source-trunk/gcc/tree-ssa-loop-ivcanon.c:1537 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. $ ------------------------------------- volatile int a, e; int c, d[1][5]; long b; void fn1 () { for (; c;) { int f = c = 0; for (; c < 3; c++) { c && a; if (e) f = 1; b++; d[b][b + 1] = 1; if (f) break; } } }