https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63595
--- Comment #6 from Martin Liška <mliska at suse dot cz> --- > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63595 > > --- Comment #5 from Pat Haugen <pthaugen at gcc dot gnu.org> --- > Created attachment 33796 > --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=33796&action=edit > preprocessed source from 254.gap > > CPU2000 benchmark 254.gap started miscomparing with r216305 also. Attaching > preprocessed source as another example that gets miscompiled. Compile options > used 'gcc -m64 -O2 -mcpu=power7'. In this example, function 'FunOnRight' gets > redirected to 'FunOnLeft' (after initial test where the two functions have > differing error strings). But the last stmt in the functions which compute the > return value are not equivalent and therefor shouldn't be commoned. > > From list.i: > > FunOnRight() > ... > hdRes = ((*TabProd[(((long)(hdPnt) & 1) ? 1 : > ((hdPnt)->type))][(((long)(hdElm) & 1) ? 1 : > ((hdElm)->type))])((hdPnt),(hdElm))); > > > FunOnLeft() > ... > hdRes = ((*TabProd[(((long)(hdElm) & 1) ? 1 : > ((hdElm)->type))][(((long)(hdPnt) & 1) ? 1 : > ((hdPnt)->type))])((hdElm),(hdPnt))); > > > Note the swapping of 'hdPnt' and 'hdElm' references. > There's patch I've been testing: diff --git a/gcc/ipa-icf.c b/gcc/ipa-icf.c index d1238a4..7456fec 100644 --- a/gcc/ipa-icf.c +++ b/gcc/ipa-icf.c @@ -869,6 +869,12 @@ sem_function::compare_phi_node (basic_block bb1, basic_block bb2) phi1 = gsi_stmt (si1); phi2 = gsi_stmt (si2); + tree phi_result1 = gimple_phi_result (phi1); + tree phi_result2 = gimple_phi_result (phi2); + + if (!m_checker->compare_operand (phi_result1, phi_result2)) + return return_false_with_msg ("PHI results are different"); + size1 = gimple_phi_num_args (phi1); size2 = gimple_phi_num_args (phi2); Martin