tree-optimization/99856 - fix overwideing pattern creation

This fixes an omission of promoting a bit-precision required precision
to a vector element precision.

2021-04-01  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/99856
	* tree-vect-patterns.c (vect_recog_over_widening_pattern): Promote
	precision to vector element precision.

	* gcc.dg/vect/pr99856.c: New testcase.

(cherry picked from commit 1cfe48d35e31e905632e37ae6a9cb37d35f9a228)

diff --git a/gcc/testsuite/gcc.dg/vect/pr99856.c b/gcc/testsuite/gcc.dg/vect/pr99856.c
new file mode 100644 (file)
index 0000000..e5d2a45
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/pr99856.c
@@ -0,0 +1,33 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target vect_int } */
+/* { dg-require-effective-target vect_unpack } */
+/* { dg-require-effective-target vect_pack_trunc } */
+
+#define SHIFTFORDIV255(a)\
+    ((((a) >> 8) + a) >> 8)
+
+#define DIV255(a)\
+    SHIFTFORDIV255(a + 0x80)
+
+typedef unsigned char uint8_t;
+
+void
+opSourceOver_premul(uint8_t* restrict Rrgba,
+                    const uint8_t* restrict Srgba,
+                    const uint8_t* restrict Drgba, int len)
+{
+  Rrgba = __builtin_assume_aligned (Rrgba, __BIGGEST_ALIGNMENT__);
+  Srgba = __builtin_assume_aligned (Rrgba, __BIGGEST_ALIGNMENT__);
+  Drgba = __builtin_assume_aligned (Rrgba, __BIGGEST_ALIGNMENT__);
+  int i = 0;
+  for (; i < len*4; i += 4)
+    {
+      uint8_t Sa = Srgba[i + 3];
+      Rrgba[i + 0] = DIV255(Srgba[i + 0] * 255 + Drgba[i + 0] * (255 - Sa));
+      Rrgba[i + 1] = DIV255(Srgba[i + 1] * 255 + Drgba[i + 1] * (255 - Sa));
+      Rrgba[i + 2] = DIV255(Srgba[i + 2] * 255 + Drgba[i + 2] * (255 - Sa));
+      Rrgba[i + 3] = DIV255(Srgba[i + 3] * 255 + Drgba[i + 3] * (255 - Sa));
+    }
+}
+
+/* { dg-final { scan-tree-dump "vectorized 1 loops in function" "vect" } } */

diff --git a/gcc/tree-vect-patterns.c b/gcc/tree-vect-patterns.c
index 4a6ef5377f26bcfbe9019e9426a501745339167b..167e1150e70286ead246b05ab182b76e3c098460 100644 (file)
--- a/gcc/tree-vect-patterns.c
+++ b/gcc/tree-vect-patterns.c
@@ -1657,6 +1657,7 @@ vect_recog_over_widening_pattern (stmt_vec_info last_stmt_info, tree *type_out)
   /* Apply the minimum efficient precision we just calculated.  */
   if (new_precision < min_precision)
     new_precision = min_precision;
+  new_precision = vect_element_precision (new_precision);
   if (new_precision >= TYPE_PRECISION (type))
     return NULL;