https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63851
--- Comment #11 from Martin Liška <marxin at gcc dot gnu.org> --- Hello. The problem is caused by missing static-chain in newly created GIMPLE_CALL in expand_thunk: fpi (struct array7_integer(kind=4) & xx1, struct array7_t & yy1) { <bb 2>: fpa (xx1_2(D), yy1_3(D)); [tail call] return; } where: main (integer(kind=4) argc, character(kind=1) * * argv) { ... fpa (&desc.2, &desc.3); [static-chain: &FRAME.7] fpi (&desc.4, &desc.5); [static-chain: &FRAME.7] ... } I've been testing following patch that stops ICF for such kind of situations: diff --git a/gcc/ipa-icf.c b/gcc/ipa-icf.c index b193200..7faaf56 100644 --- a/gcc/ipa-icf.c +++ b/gcc/ipa-icf.c @@ -685,6 +685,14 @@ sem_function::merge (sem_item *alias_item) return 0; } + if (DECL_STATIC_CHAIN (alias->decl)) + { + if (dump_file) + fprintf (dump_file, "Thunk creation is risky for static-chain functions.\n\n"); + + return 0; + } + alias->icf_merged = true; ipa_merge_profiles (local_original, alias); alias->create_wrapper (local_original); Thanks, Martin