From: Jakub Jelinek <jakub@redhat.com>
Date: Thu, 26 Mar 2020 09:35:52 +0000 (+0100)
Subject: tree: Fix -fcompare-debug issues due to protected_set_expr_location [PR94323]
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=da920d0c46c38fe25ee0b597a8698d3a4d098f3c;p=gcc.git

tree: Fix -fcompare-debug issues due to protected_set_expr_location [PR94323]

The following testcase FAILs since recently when the C++ FE started calling
protected_set_expr_location more often.
With -g, it is called on a STATEMENT_LIST that contains a DEBUG_BEGIN_STMT
and CLEANUP_POINT_EXPR, and as STATEMENT_LISTs have !CAN_HAVE_LOCATION_P,
nothing is set.  Without -g, it is called instead on the CLEANUP_POINT_EXPR
directly and changes its location.

The following patch recurses on the single non-DEBUG_BEGIN_STMT statement
of a STATEMENT_LIST if any to make the two behave the same.

2020-03-26  Jakub Jelinek  <jakub@redhat.com>

	PR debug/94323
	* tree.c (protected_set_expr_location): Recurse on STATEMENT_LIST
	that contains exactly one non-DEBUG_BEGIN_STMT statement.

	* g++.dg/debug/pr94323.C: New test.
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 8005e1a91f7..cc7f4d4ab37 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,9 @@
 2020-03-26  Jakub Jelinek  <jakub@redhat.com>
 
+	PR debug/94323
+	* tree.c (protected_set_expr_location): Recurse on STATEMENT_LIST
+	that contains exactly one non-DEBUG_BEGIN_STMT statement.
+
 	PR debug/94281
 	* gimple.h (gimple_seq_first_nondebug_stmt): New function.
 	(gimple_seq_last_nondebug_stmt): Don't return NULL if seq contains
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 65f32a3eb1d..4d73d481a64 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2020-03-26  Jakub Jelinek  <jakub@redhat.com>
+
+	PR debug/94323
+	* g++.dg/debug/pr94323.C: New test.
+
 2020-03-26  Martin Liska  <mliska@suse.cz>
 
 	PR testsuite/94334
diff --git a/gcc/testsuite/g++.dg/debug/pr94323.C b/gcc/testsuite/g++.dg/debug/pr94323.C
new file mode 100644
index 00000000000..eac81a3867e
--- /dev/null
+++ b/gcc/testsuite/g++.dg/debug/pr94323.C
@@ -0,0 +1,13 @@
+// PR debug/94323
+// { dg-do compile }
+// { dg-options "-O2 -fcompare-debug" }
+
+volatile int a;
+
+void
+foo ()
+{
+  ({
+     a;
+   });
+}
diff --git a/gcc/tree.c b/gcc/tree.c
index f38dfffc16e..63dc6730b2b 100644
--- a/gcc/tree.c
+++ b/gcc/tree.c
@@ -5146,6 +5146,33 @@ protected_set_expr_location (tree t, location_t loc)
 {
   if (CAN_HAVE_LOCATION_P (t))
     SET_EXPR_LOCATION (t, loc);
+  else if (t && TREE_CODE (t) == STATEMENT_LIST)
+    {
+      /* With -gstatement-frontiers we could have a STATEMENT_LIST with
+	 DEBUG_BEGIN_STMT(s) and only a single other stmt, which with
+	 -g wouldn't be present and we'd have that single other stmt
+	 directly instead.  */
+      struct tree_statement_list_node *n = STATEMENT_LIST_HEAD (t);
+      if (!n)
+	return;
+      while (TREE_CODE (n->stmt) == DEBUG_BEGIN_STMT)
+	{
+	  n = n->next;
+	  if (!n)
+	    return;
+	}
+      tree t2 = n->stmt;
+      do
+	{
+	  n = n->next;
+	  if (!n)
+	    {
+	      protected_set_expr_location (t2, loc);
+	      return;
+	    }
+	}
+      while (TREE_CODE (n->stmt) == DEBUG_BEGIN_STMT);
+    }
 }
 
 /* Data used when collecting DECLs and TYPEs for language data removal.  */