tree-dfa.c (get_ref_base_and_extent): Set *pmax_size to -1 if *poffset +…

tree-dfa.c (get_ref_base_and_extent): Set *pmax_size to -1 if *poffset + *pmax_size overflows in HOST_WIDE_INT.

	* tree-dfa.c (get_ref_base_and_extent): Set *pmax_size to -1
	if *poffset + *pmax_size overflows in HOST_WIDE_INT.
	Set *poffset to 0 and *psize and *pmax_size to -1 if
	*poffset + *psize overflows in HOST_WIDE_INT.

	* gcc.dg/pr82389.c: New test.

From-SVN: r253357

gcc/ChangeLog

 2017-10-02  Jakub Jelinek  <jakub@redhat.com>
 
+	* tree-dfa.c (get_ref_base_and_extent): Set *pmax_size to -1
+	if *poffset + *pmax_size overflows in HOST_WIDE_INT.
+	Set *poffset to 0 and *psize and *pmax_size to -1 if
+	*poffset + *psize overflows in HOST_WIDE_INT.
+
 	PR tree-optimization/82387
 	PR tree-optimization/82388
 	PR tree-optimization/82389

gcc/testsuite/ChangeLog

 2017-10-02  Jakub Jelinek  <jakub@redhat.com>
 
+	* gcc.dg/pr82389.c: New test.
+
 	PR tree-optimization/82387
 	PR tree-optimization/82388
 	PR tree-optimization/82389

gcc/testsuite/gcc.dg/pr82389.c

+/* PR tree-optimization/82389 */
+/* { dg-do compile { target lp64 } } */
+/* { dg-options "-w -O3" } */
+
+struct S { char s[0x40000000]; } s;
+
+void
+foo (struct S *p)
+{
+  char b[0x0ffffffff0000000L];
+  *(struct S *)&b[0x0fffffffef000000L] = s;
+  *p = *(struct S *)&b[0x0fffffffefffffffL];
+}

gcc/tree-dfa.c

@@ -654,7 +654,22 @@ get_ref_base_and_extent (tree exp, HOST_WIDE_INT *poffset,
   if (!wi::fits_shwi_p (maxsize) || wi::neg_p (maxsize))
     *pmax_size = -1;
   else
-    *pmax_size = maxsize.to_shwi ();
+    {
+      *pmax_size = maxsize.to_shwi ();
+      if (*poffset > HOST_WIDE_INT_MAX - *pmax_size)
+	*pmax_size = -1;
+    }
+
+  /* Punt if *POFFSET + *PSIZE overflows in HOST_WIDE_INT, the callers don't
+     check for such overflows individually and assume it works.  */
+  if (*psize != -1 && *poffset > HOST_WIDE_INT_MAX - *psize)
+    {
+      *poffset = 0;
+      *psize = -1;
+      *pmax_size = -1;
+
+      return exp;
+    }
 
   return exp;
 }