From 937591d236e61d25b5677c29621f70e750a95709 Mon Sep 17 00:00:00 2001 From: Jan Hubicka Date: Thu, 10 Aug 2023 19:01:43 +0200 Subject: [PATCH] Fix profile update in duplicat_loop_body_to_header_edge for loops with 0 count_in this patch makes duplicate_loop_body_to_header_edge to not drop profile counts to uninitialized when count_in is 0. This happens because profile_probability in 0 count is undefined. gcc/ChangeLog: * cfgloopmanip.cc (duplicate_loop_body_to_header_edge): Special case loops with 0 iteration count. --- gcc/cfgloopmanip.cc | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/gcc/cfgloopmanip.cc b/gcc/cfgloopmanip.cc index b237ad4e8ac2..a2ed54a23bbc 100644 --- a/gcc/cfgloopmanip.cc +++ b/gcc/cfgloopmanip.cc @@ -1296,6 +1296,16 @@ duplicate_loop_body_to_header_edge (class loop *loop, edge e, } profile_probability prob_pass_wont_exit = new_count_le.probability_in (count_in); + /* If profile count is 0, the probability will be uninitialized. + We can set probability to any initialized value to avoid + precision loss. If profile is sane, all counts will be 0 anyway. */ + if (!count_in.nonzero_p ()) + { + prob_pass_thru + = profile_probability::always ().apply_scale (1, 2); + prob_pass_wont_exit + = profile_probability::always ().apply_scale (1, 2); + } scale_step = XNEWVEC (profile_probability, ndupl); @@ -1306,7 +1316,9 @@ duplicate_loop_body_to_header_edge (class loop *loop, edge e, /* Complete peeling is special as the probability of exit in last copy becomes 1. */ - if (flags & DLTHE_FLAG_COMPLETTE_PEEL) + if (!count_in.nonzero_p ()) + ; + else if (flags & DLTHE_FLAG_COMPLETTE_PEEL) { profile_count wanted_count = e->count (); -- 2.47.2