2012-01-18  Michael Hope  <michael.hope@linaro.org>

	Backport from mainline r183126:

	2012-01-12  Ira Rosen  <irar@il.ibm.com>

	gcc/
	PR tree-optimization/51799
	* tree-vect-patterns.c (vect_recog_over_widening_pattern): Check
	that the last operation is a type demotion.

	gcc/testsuite/
	* gcc.dg/vect/pr51799.c: New test.
	* gcc.dg/vect/vect-widen-shift-u8.c: Expect two widening shift
	patterns.

=== added file 'gcc/testsuite/gcc.dg/vect/pr51799.c'
--- old/gcc/testsuite/gcc.dg/vect/pr51799.c	1970-01-01 00:00:00 +0000
+++ new/gcc/testsuite/gcc.dg/vect/pr51799.c	2012-01-18 01:53:19 +0000
@@ -0,0 +1,18 @@
+/* { dg-do compile } */
+
+typedef signed char int8_t;
+typedef unsigned char uint8_t;
+typedef signed short int16_t;
+typedef unsigned long uint32_t;
+void
+f0a (uint32_t * __restrict__ result, int8_t * __restrict__ arg1,
+     uint32_t * __restrict__ arg4, int8_t temp_6)
+{
+  int idx;
+  for (idx = 0; idx < 416; idx += 1)
+    {
+      result[idx] = (uint8_t)(((arg1[idx] << 7) + arg4[idx]) * temp_6);
+    }
+}
+
+/* { dg-final { cleanup-tree-dump "vect" } } */

=== modified file 'gcc/testsuite/gcc.dg/vect/vect-widen-shift-u8.c'
--- old/gcc/testsuite/gcc.dg/vect/vect-widen-shift-u8.c	2011-10-23 13:33:07 +0000
+++ new/gcc/testsuite/gcc.dg/vect/vect-widen-shift-u8.c	2012-01-18 01:53:19 +0000
@@ -59,7 +59,6 @@
   return 0;
 }
 
-/* { dg-final { scan-tree-dump-times "vect_recog_widen_shift_pattern: detected" 1 "vect" { target vect_widen_shift } } } */
+/* { dg-final { scan-tree-dump-times "vect_recog_widen_shift_pattern: detected" 2 "vect" { target vect_widen_shift } } } */
 /* { dg-final { scan-tree-dump-times "vectorized 1 loops" 1 "vect" } } */
 /* { dg-final { cleanup-tree-dump "vect" } } */
-

=== modified file 'gcc/tree-vect-patterns.c'
--- old/gcc/tree-vect-patterns.c	2011-12-20 07:47:44 +0000
+++ new/gcc/tree-vect-patterns.c	2012-01-18 01:53:19 +0000
@@ -1224,13 +1224,15 @@
     {
       use_lhs = gimple_assign_lhs (use_stmt);
       use_type = TREE_TYPE (use_lhs);
-      /* Support only type promotion or signedess change.  Check that USE_TYPE
-        is not bigger than the original type.  */
+      /* Support only type demotion or signedess change.  */
       if (!INTEGRAL_TYPE_P (use_type)
-          || TYPE_PRECISION (new_type) > TYPE_PRECISION (use_type)
-         || TYPE_PRECISION (type) < TYPE_PRECISION (use_type))
+	  || TYPE_PRECISION (type) <= TYPE_PRECISION (use_type))
         return NULL;
 
+      /* Check that NEW_TYPE is not bigger than the conversion result.  */
+      if (TYPE_PRECISION (new_type) > TYPE_PRECISION (use_type))
+	return NULL;
+
       if (TYPE_UNSIGNED (new_type) != TYPE_UNSIGNED (use_type)
           || TYPE_PRECISION (new_type) != TYPE_PRECISION (use_type))
         {