Ping? Thanks Kugan
> On 19 May 2026, at 10:30 am, Kugan Vivekanandarajah <[email protected]> > wrote: > > External email: Use caution opening links or attachments > 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>
