Fix PR middle-end/71654 (missed shortening of a compare)

gcc/ChangeLog:

	PR middle-end/71654
	* match.pd ((T)A CMP (T)B -> A CMP B): Allow (T)A to be a
	sign-changing cast from a shorter unsigned type to a wider
	signed type.

gcc/testsuite/ChangeLog:

	PR middle-end/71654
	* gcc.dg/c-c++-common/pr71654.c: New test.
	* gcc.dg/tree-ssa/vrp23: Add -fno-tree-forwprop to
	dg-options.
	* gcc.dg/tree-ssa/vrp24: Likewise.

From-SVN: r239421

gcc/ChangeLog

+2016-08-12  Patrick Palka  <ppalka@gcc.gnu.org>
+
+	PR middle-end/71654
+	* match.pd ((T)A CMP (T)B -> A CMP B): Allow (T)A to be a
+	sign-changing cast from a shorter unsigned type to a wider
+	signed type.
+
 2016-08-12  Jakub Jelinek  <jakub@redhat.com>
 
 	* config/i386/sse.md (avx512dq_vextract<shuffletype>64x2_1_maskm,

gcc/match.pd

@@ -2350,7 +2350,9 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
     (if (TYPE_PRECISION (TREE_TYPE (@0)) > TYPE_PRECISION (TREE_TYPE (@00)))
      /* If possible, express the comparison in the shorter mode.  */
      (if ((cmp == EQ_EXPR || cmp == NE_EXPR
-	   || TYPE_UNSIGNED (TREE_TYPE (@0)) == TYPE_UNSIGNED (TREE_TYPE (@00)))
+	   || TYPE_UNSIGNED (TREE_TYPE (@0)) == TYPE_UNSIGNED (TREE_TYPE (@00))
+	   || (!TYPE_UNSIGNED (TREE_TYPE (@0))
+	       && TYPE_UNSIGNED (TREE_TYPE (@00))))
 	  && (types_match (TREE_TYPE (@10), TREE_TYPE (@00))
 	      || ((TYPE_PRECISION (TREE_TYPE (@00))
 		   >= TYPE_PRECISION (TREE_TYPE (@10)))

gcc/testsuite/ChangeLog

+2016-08-12  Patrick Palka  <ppalka@gcc.gnu.org>
+
+	PR middle-end/71654
+	* gcc.dg/c-c++-common/pr71654.c: New test.
+	* gcc.dg/tree-ssa/vrp23: Add -fno-tree-forwprop to
+	dg-options.
+	* gcc.dg/tree-ssa/vrp24: Likewise.
+
 2016-08-12  Jakub Jelinek  <jakub@redhat.com>
 
 	PR c/67410

gcc/testsuite/c-c++-common/pr71654.c

+/* PR middle-end/71654  */
+/* { dg-do link }  */
+/* { dg-options "-O2" }  */
+
+unsigned char i0, i1;
+
+void foo (void);
+
+int
+main (void)
+{
+  int j = i0;
+  if (j < 4)
+    {
+      if (i0 & 4)
+        foo ();
+    }
+
+  unsigned int k = i1;
+  if (k < 8)
+    {
+      if (i1 & 8)
+        foo ();
+    }
+
+  return 0;
+}
+

gcc/testsuite/gcc.dg/tree-ssa/vrp23.c

 /* { dg-do compile } */
-/* { dg-options "-O2 -fdump-tree-vrp1-details" } */
+/* { dg-options "-O2 -fno-tree-forwprop -fdump-tree-vrp1-details" } */
 
 void aa (void);
 void aos (void);

gcc/testsuite/gcc.dg/tree-ssa/vrp24.c

 /* { dg-do compile } */
-/* { dg-options "-O2 -fdump-tree-vrp1-details" } */
+/* { dg-options "-O2 -fno-tree-forwprop -fdump-tree-vrp1-details" } */
 
 
 struct rtx_def;