Hi, This is another attempt to prevent head_count of 0 with AFDO profile. This is causing ICE with LTO:
during IPA pass: modref lto1: internal compiler error: in apply_scale, at profile-count.h:1192 0x2292433 internal_error(char const*, ...) /var/jenkins/workspace/GCC_oss-main/gcc/diagnostic-global-context.cc:787 0x8a2ba7 fancy_abort(char const*, int, char const*) /var/jenkins/workspace/GCC_oss-main/gcc/diagnostics/context.cc:1813 0x98efcf profile_count::apply_scale(profile_count, profile_count) const /var/jenkins/workspace/GCC_oss-main/gcc/profile-count.h:1192 0xd2536f ipa_merge_profiles(cgraph_node*, cgraph_node*, bool) /var/jenkins/workspace/GCC_oss-main/gcc/ipa-utils.cc:637 0x8fc01b lto_symtab_merge_symbols_1 /var/jenkins/workspace/GCC_oss-main/gcc/lto/lto-symtab.cc:934 0x8fc01b lto_symtab_merge_symbols() /var/jenkins/workspace/GCC_oss-main/gcc/lto/lto-symtab.cc:996 0x90b7f7 read_cgraph_and_symbols(unsigned int, char const**) /var/jenkins/workspace/GCC_oss-main/gcc/lto/lto-common.cc:3003 0x8e8abf lto_main() /var/jenkins/workspace/GCC_oss-main/gcc/lto/lto.cc:663 <http://lto.cc:663/> When afdo_adjust_guessed_profile runs scale_bbs, the entry block can be scaled to 0 (auto FDO) while inner basic blocks keep nonzero AFDO counts. Example from profile annotation (stats.ii, _M_get_insert_unique_pos): ... total:264 head:-1 bb 0 count updated 118111600 (estimated locally) -> 0 (auto FDO) Example ICE at LTO (WPA merge of comdat clones): Merging profiles of _M_get_insert_unique_pos/10 count:64711123189 (auto FDO) to _M_get_insert_unique_pos/1 count:0 (auto FDO) during IPA pass: modref lto1: internal compiler error: in apply_scale, at profile-count.h:1192 ipa_merge_profiles (dstnum, dstden) Fix by calling afdo_fixup_entry_after_scale immediately after each scale_bbs in afdo_adjust_guessed_profile when max_count_in_fn is nonzero but the entry block count is still zero. gcc/ChangeLog: * auto-profile.cc (afdo_fixup_entry_after_scale): New. (afdo_adjust_guessed_profile): Call it after scale_bbs. Regression tested on aarch64-linux-gnu with no new regressions. Is this OK for trunk? Thanks, Kugan
0001-AutoFDO-Do-not-leave-entry-block-at-zero-after-guess.patch
Description: 0001-AutoFDO-Do-not-leave-entry-block-at-zero-after-guess.patch
