[gcc(refs/vendors/redhat/heads/gcc-10-branch)] gimplify: Fix -fcompare-debug differences caused by gimplify_body [PR94281]
Jakub Jelinek
jakub@gcc.gnu.org
Sat Mar 28 09:40:57 GMT 2020
https://gcc.gnu.org/g:10ea09ee846eaa345161a3a3f519b3780d6101fa
commit 10ea09ee846eaa345161a3a3f519b3780d6101fa
Author: Jakub Jelinek <jakub@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 <jakub@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.
Diff:
---
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(-)
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 <jakub@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.
+
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 <gbind *> (outer_stmt);
+ && (gimple_seq_first_nondebug_stmt (seq)
+ == gimple_seq_last_nondebug_stmt (seq)))
+ {
+ outer_bind = as_a <gbind *> (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 <jakub@redhat.com>
+ 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()
+{
+ ;
+}
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