https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94281
--- Comment #5 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jakub Jelinek <ja...@gcc.gnu.org>: https://gcc.gnu.org/g:10ea09ee846eaa345161a3a3f519b3780d6101fa commit r10-7395-g10ea09ee846eaa345161a3a3f519b3780d6101fa Author: Jakub Jelinek <ja...@redhat.com> Date: Thu Mar 26 10:10:21 2020 +0100 gimplify: Fix -fcompare-debug differences caused by gimplify_body [PR94281] The following testcase FAILs, because gimplify_body adds a GIMPLE_NOP only when there are no statements in the function and with -g there is a DEBUG_BEGIN_STMT, so it doesn't add it and due to -fno-tree-dce that never gets removed afterwards. Similarly, if the body seq after gimplification contains some DEBUG_BEGIN_STMTs plus a single gbind, then we could behave differently between -g0 and -g, by using that gbind as the body in the -g0 case and not in the -g case. This patch fixes that by ignoring DEBUG_BEGIN_STMTs (other debug stmts can't appear at this point yet thankfully) during decisions and if we pick the single gbind and there are DEBUG_BEGIN_STMTs next to it, it moves them into the gbind. While debugging this, I found also a bug in the gimple_seq_last_nondebug_stmt function, for a seq that has a single non-DEBUG_BEGIN_STMT statement followed by one or more DEBUG_BEGIN_STMTs it would return NULL rather than the first statement. 2020-03-26 Jakub Jelinek <ja...@redhat.com> PR debug/94281 * gimple.h (gimple_seq_first_nondebug_stmt): New function. (gimple_seq_last_nondebug_stmt): Don't return NULL if seq contains a single non-debug stmt followed by one or more debug stmts. * gimplify.c (gimplify_body): Use gimple_seq_first_nondebug_stmt instead of gimple_seq_first_stmt, use gimple_seq_first_nondebug_stmt and gimple_seq_last_nondebug_stmt instead of gimple_seq_first and gimple_seq_last to check if outer_stmt gbind could be reused and if yes and it is surrounded by any debug stmts, move them into the gbind body. * g++.dg/debug/pr94281.C: New test.
