From 4482e03418271a0dba2286c3a192915ef1fcb8db Mon Sep 17 00:00:00 2001
From: David Malcolm <dmalcolm@redhat.com>
Date: Tue, 26 May 2020 17:54:02 -0400
Subject: [PATCH 183/315] FIXME: fold associative ops; add refcounting test

---
 gcc/analyzer/region-model2.cc                 | 43 +++++++++++++------
 gcc/testsuite/gcc.dg/analyzer/refcounting-1.c | 31 +++++++++++++
 2 files changed, 60 insertions(+), 14 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/analyzer/refcounting-1.c

diff --git a/gcc/analyzer/region-model2.cc b/gcc/analyzer/region-model2.cc
index 70faab6366f..323b040b125 100644
--- a/gcc/analyzer/region-model2.cc
+++ b/gcc/analyzer/region-model2.cc
@@ -3008,6 +3008,23 @@ region_model2_manager::maybe_fold_binop (tree type, enum tree_code op,
 	}
       break;
     }
+
+  /* For associative ops, fold "(X op CST_A) op CST_B)" to
+     "X op (CST_A op CST_B)".  */
+  if (cst1 && associative_tree_code (op))
+    if (const binop_svalue2 *binop = arg0->dyn_cast_binop_svalue2 ())
+      if (binop->get_op () == op
+	  && binop->get_arg1 ()->maybe_get_constant ()
+	  && type == binop->get_type ()
+	  && type == binop->get_arg0 ()->get_type ()
+	  && type == binop->get_arg1 ()->get_type ())
+	return get_or_create_binop
+	  (type, op, binop->get_arg0 (),
+	   get_or_create_binop (type, op,
+				binop->get_arg1 (), arg1));
+
+  // TODO
+
   return NULL;
 }
 
@@ -8279,20 +8296,6 @@ test_binop_svalue2_folding ()
   // etc
   // TODO: do we want to use the match-and-simplify DSL for this?
 
-  /* TODO: Verify that ((x + 1) + 1) == (x + 2).  */
-  const svalue2 *x_init_plus_one
-    = mgr.get_or_create_binop (integer_type_node, PLUS_EXPR,
-			       x_init, cst_sval[1]);
-  const svalue2 *x_init_plus_two
-    = mgr.get_or_create_binop (integer_type_node, PLUS_EXPR,
-			       x_init, cst_sval[2]);
-  const svalue2 *x_init_plus_one_plus_one
-    = mgr.get_or_create_binop (integer_type_node, PLUS_EXPR,
-			       x_init_plus_one, cst_sval[1]);
-#if 0
-  ASSERT_EQ (x_init_plus_one_plus_one, x_init_plus_two);
-#endif
-
   /* Verify that binops put any constants on the RHS.  */
   const svalue2 *four_times_x_init
     = mgr.get_or_create_binop (integer_type_node, MULT_EXPR,
@@ -8305,6 +8308,18 @@ test_binop_svalue2_folding ()
   ASSERT_EQ (binop->get_op (), MULT_EXPR);
   ASSERT_EQ (binop->get_arg0 (), x_init);
   ASSERT_EQ (binop->get_arg1 (), cst_sval[4]);
+
+  /* Verify that ((x + 1) + 1) == (x + 2).  */
+  const svalue2 *x_init_plus_one
+    = mgr.get_or_create_binop (integer_type_node, PLUS_EXPR,
+			       x_init, cst_sval[1]);
+  const svalue2 *x_init_plus_two
+    = mgr.get_or_create_binop (integer_type_node, PLUS_EXPR,
+			       x_init, cst_sval[2]);
+  const svalue2 *x_init_plus_one_plus_one
+    = mgr.get_or_create_binop (integer_type_node, PLUS_EXPR,
+			       x_init_plus_one, cst_sval[1]);
+  ASSERT_EQ (x_init_plus_one_plus_one, x_init_plus_two);
 }
 
 /* Verify that sub_svalue2s are folded as expected.  */
diff --git a/gcc/testsuite/gcc.dg/analyzer/refcounting-1.c b/gcc/testsuite/gcc.dg/analyzer/refcounting-1.c
new file mode 100644
index 00000000000..4eb3a3e6ff2
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/analyzer/refcounting-1.c
@@ -0,0 +1,31 @@
+#include "analyzer-decls.h"
+
+typedef struct obj {
+  int ob_refcnt;
+} PyObject;
+
+extern void Py_Dealloc (PyObject *op);
+
+#define Py_INCREF(op)			\
+  do {					\
+    ((PyObject*)(op))->ob_refcnt++;	\
+  } while (0)
+
+#define Py_DECREF(op)                                   \
+    do {                                                \
+      if (--((PyObject*)(op))->ob_refcnt == 0)		\
+	{						\
+	  /*Py_Dealloc((PyObject *)(op));*/		\
+	}						\
+    } while (0)
+
+void test_1 (PyObject *obj)
+{
+  int orig_refcnt = obj->ob_refcnt;
+  Py_INCREF (obj);
+  Py_INCREF (obj);
+  Py_DECREF (obj);
+  Py_INCREF (obj);
+  __analyzer_eval (obj->ob_refcnt == orig_refcnt + 2); /* { dg-warning "TRUE" } */
+}
+/* TODO: uncomment the Py_Dealloc, which leads to two paths.  */
-- 
2.26.2