re PR c/85094 (-g with any optimization suppresses -Wduplicated-branches)

	PR c/85094
	* fold-const.c (operand_equal_p): Handle DEBUG_BEGIN_STMT.
	For STATEMENT_LIST, pass down OEP_LEXICOGRAPHIC and maybe
	OEP_NO_HASH_CHECK for recursive call, to avoid exponential
	checking.

	* c-c++-common/Wduplicated-branches-14.c: New test.

From-SVN: r258950

gcc/ChangeLog

+2018-03-29  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c/85094
+	* fold-const.c (operand_equal_p): Handle DEBUG_BEGIN_STMT.
+	For STATEMENT_LIST, pass down OEP_LEXICOGRAPHIC and maybe
+	OEP_NO_HASH_CHECK for recursive call, to avoid exponential
+	checking.
+
 2018-03-28  Peter Bergner  <bergner@vnet.ibm.com>
 
 	PR target/84912

gcc/fold-const.c

@@ -3479,7 +3479,8 @@ operand_equal_p (const_tree arg0, const_tree arg1, unsigned int flags)
 	      if (tsi_end_p (tsi1) && tsi_end_p (tsi2))
 		return 1;
 	      if (!operand_equal_p (tsi_stmt (tsi1), tsi_stmt (tsi2),
-				    OEP_LEXICOGRAPHIC))
+				    flags & (OEP_LEXICOGRAPHIC
+					     | OEP_NO_HASH_CHECK)))
 		return 0;
 	    }
 	}
@@ -3492,6 +3493,10 @@ operand_equal_p (const_tree arg0, const_tree arg1, unsigned int flags)
 	  if (flags & OEP_LEXICOGRAPHIC)
 	    return OP_SAME_WITH_NULL (0);
 	  return 0;
+	case DEBUG_BEGIN_STMT:
+	  if (flags & OEP_LEXICOGRAPHIC)
+	    return 1;
+	  return 0;
 	default:
 	  return 0;
 	 }

gcc/testsuite/ChangeLog

+2018-03-29  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c/85094
+	* c-c++-common/Wduplicated-branches-14.c: New test.
+
 2018-03-29  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	PR c++/84606

gcc/testsuite/c-c++-common/Wduplicated-branches-14.c

+/* PR c/85094 */
+/* { dg-do compile } */
+/* { dg-options "-O1 -Wduplicated-branches -g" } */
+
+extern int g;
+
+void
+foo (int r)
+{
+  if (r < 64)
+    g -= 48;
+  else if (r < 80)	/* { dg-warning "this condition has identical branches" } */
+    g -= 64 - 45;
+  else
+    g -= 80 - 61;
+}