From 10ea09ee846eaa345161a3a3f519b3780d6101fa Mon Sep 17 00:00:00 2001 From: Jakub Jelinek Date: Thu, 26 Mar 2020 10:10:21 +0100 Subject: [PATCH] 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 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. --- gcc/ChangeLog | 11 +++++++++ gcc/gimple.h | 14 ++++++++++- gcc/gimplify.c | 35 +++++++++++++++++++++++++--- gcc/testsuite/ChangeLog | 3 +++ gcc/testsuite/g++.dg/debug/pr94281.C | 11 +++++++++ 5 files changed, 70 insertions(+), 4 deletions(-) create mode 100644 gcc/testsuite/g++.dg/debug/pr94281.C diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 180c92f76f7..8005e1a91f7 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,5 +1,16 @@ 2020-03-26 Jakub Jelinek + 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. + PR rtl-optimization/92264 * var-tracking.c (add_stores): Call cselib_set_value_sp_based even for sp based values in !frame_pointer_needed diff --git a/gcc/gimple.h b/gcc/gimple.h index 0420d6d2251..305d98f5438 100644 --- a/gcc/gimple.h +++ b/gcc/gimple.h @@ -4728,6 +4728,18 @@ is_gimple_debug (const gimple *gs) } +/* Return the first nondebug statement in GIMPLE sequence S. */ + +static inline gimple * +gimple_seq_first_nondebug_stmt (gimple_seq s) +{ + gimple_seq_node n = gimple_seq_first (s); + while (n && is_gimple_debug (n)) + n = n->next; + return n; +} + + /* Return the last nondebug statement in GIMPLE sequence S. */ static inline gimple * @@ -4737,7 +4749,7 @@ gimple_seq_last_nondebug_stmt (gimple_seq s) for (n = gimple_seq_last (s); n && is_gimple_debug (n); n = n->prev) - if (n->prev == s) + if (n == s) return NULL; return n; } diff --git a/gcc/gimplify.c b/gcc/gimplify.c index ef531f3fd7b..787435c38cd 100644 --- a/gcc/gimplify.c +++ b/gcc/gimplify.c @@ -14849,7 +14849,7 @@ gimplify_body (tree fndecl, bool do_parms) /* Gimplify the function's body. */ seq = NULL; gimplify_stmt (&DECL_SAVED_TREE (fndecl), &seq); - outer_stmt = gimple_seq_first_stmt (seq); + outer_stmt = gimple_seq_first_nondebug_stmt (seq); if (!outer_stmt) { outer_stmt = gimple_build_nop (); @@ -14859,8 +14859,37 @@ gimplify_body (tree fndecl, bool do_parms) /* The body must contain exactly one statement, a GIMPLE_BIND. If this is not the case, wrap everything in a GIMPLE_BIND to make it so. */ if (gimple_code (outer_stmt) == GIMPLE_BIND - && gimple_seq_first (seq) == gimple_seq_last (seq)) - outer_bind = as_a (outer_stmt); + && (gimple_seq_first_nondebug_stmt (seq) + == gimple_seq_last_nondebug_stmt (seq))) + { + outer_bind = as_a (outer_stmt); + if (gimple_seq_first_stmt (seq) != outer_stmt + || gimple_seq_last_stmt (seq) != outer_stmt) + { + /* If there are debug stmts before or after outer_stmt, move them + inside of outer_bind body. */ + gimple_stmt_iterator gsi = gsi_for_stmt (outer_stmt, &seq); + gimple_seq second_seq = NULL; + if (gimple_seq_first_stmt (seq) != outer_stmt + && gimple_seq_last_stmt (seq) != outer_stmt) + { + second_seq = gsi_split_seq_after (gsi); + gsi_remove (&gsi, false); + } + else if (gimple_seq_first_stmt (seq) != outer_stmt) + gsi_remove (&gsi, false); + else + { + gsi_remove (&gsi, false); + second_seq = seq; + seq = NULL; + } + gimple_seq_add_seq_without_update (&seq, + gimple_bind_body (outer_bind)); + gimple_seq_add_seq_without_update (&seq, second_seq); + gimple_bind_set_body (outer_bind, seq); + } + } else outer_bind = gimple_build_bind (NULL_TREE, seq, NULL); diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index 6091bcc1f05..ea31955bbe2 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,5 +1,8 @@ 2020-03-26 Jakub Jelinek + PR debug/94281 + * g++.dg/debug/pr94281.C: New test. + PR c++/81349 * g++.dg/cpp1z/pr81349.C: New test. diff --git a/gcc/testsuite/g++.dg/debug/pr94281.C b/gcc/testsuite/g++.dg/debug/pr94281.C new file mode 100644 index 00000000000..06386917423 --- /dev/null +++ b/gcc/testsuite/g++.dg/debug/pr94281.C @@ -0,0 +1,11 @@ +// PR debug/94281 +// { dg-do compile } +// { dg-options "-O1 -fno-tree-dce -fipa-icf -fno-tree-forwprop -fcompare-debug" } + +void fn1() +{ +} +void fn2() +{ + ; +} -- 2.30.2