https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64495
Bug ID: 64495 Summary: ICE at -O3 for trunk and wrong code for 4.8/4.9 on x86_64-linux-gnu Product: gcc Version: 5.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: su at cs dot ucdavis.edu This is an almost identical test as the one for PR 64493: (1) Like PR 64493, the 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; and (2) it is also miscompiled at -O3 by 4.8.x and 4.9.x (thus a regression from 4.7.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/5.0.0/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 5.0.0 20150104 (experimental) [trunk revision 219172] (GCC) $ $ gcc-trunk -O3 small.c small.c: In function ‘main’: small.c:7:1: error: definition in block 33 does not dominate use in block 31 main () ^ for SSA_NAME: vect_d.30_19 in statement: vect__32.36_66 = vect_d.30_19 | vect__32.36_39; small.c:7:1: internal compiler error: verify_ssa failed 0xc8c6b1 verify_ssa(bool, bool) ../../gcc-trunk/gcc/tree-ssa.c:1062 0x9daae5 execute_function_todo ../../gcc-trunk/gcc/passes.c:1947 0x9db523 execute_todo ../../gcc-trunk/gcc/passes.c:1997 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. $ $ gcc-4.7 -O3 small.c; a.out $ gcc-4.8 -O2 small.c; a.out $ gcc-4.9 -O2 small.c; a.out $ $ gcc-4.8 -O3 small.c; a.out Aborted (core dumped) $ gcc-4.9 -O3 small.c; a.out Aborted (core dumped) $ -------------------------------- #include <assert.h> int a, b, c, d, e, f, g, i, j; static int *h = &e; int main () { for (; a;) for (; g; g++) for (; f; f++) if (j) { assert(b); assert(0); } for (i = 24; i; i--) { for (c = 0; c < 6; c++) d |= 1; *h |= d; } if (e != 1) __builtin_abort (); return 0; }