Convert A8 D32 mask blitters to Sk4px

Improves the newly added bench by ~25% (hsw):

-- before --

    micros   	bench
   2298.34  	shadermaskfilter_picture_80	8888
   2339.60  	shadermaskfilter_picture_ff	8888
   2287.11  	shadermaskfilter_bitmap_80	8888
   2223.14  	shadermaskfilter_bitmap_ff	8888

-- after --

   1693.36  	shadermaskfilter_picture_80	8888
   1637.45  	shadermaskfilter_picture_ff	8888
   1691.65  	shadermaskfilter_bitmap_80	8888
   1637.70  	shadermaskfilter_bitmap_ff	8888

But: skia:7810
Change-Id: I7274b10f517551ee2c0646842f72e0372d55e509
Reviewed-on: https://skia-review.googlesource.com/121642
Commit-Queue: Florin Malita <fmalita@chromium.org>
Reviewed-by: Mike Klein <mtklein@google.com>

1 files changed, 44 insertions, 0 deletions

diff --git a/tests/BlitMaskTest.cpp b/tests/BlitMaskTest.cpp
new file mode 100644
index 0000000000..04bec66189
--- /dev/null
+++ b/tests/BlitMaskTest.cpp
@@ -0,0 +1,44 @@
+/*
+ * Copyright 2018 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkBlitMask.h"
+#include "SkColorPriv.h"
+#include "SkMask.h"
+#include "Test.h"
+
+static void test_opaque_dest(skiatest::Reporter* reporter, SkMask::Format format) {
+    const auto& row_proc = SkBlitMask::RowFactory(SkColorType::kN32_SkColorType, format,
+                                                  static_cast<SkBlitMask::RowFlags>(0));
+
+    SkPMColor src[256],
+              dst[256];
+    uint8_t    aa[256];
+
+    // Coverage -> [0..255]
+    for (size_t i = 0; i < 256; ++i) {
+        aa[i] = static_cast<uint8_t>(i);
+    }
+
+    // src -> [0..255]
+    for (size_t src_a = 0; src_a < 256; ++src_a) {
+        memset(src, src_a, sizeof(src));
+
+        // dst -> 0xff (always opaque)
+        memset(dst, 0xff, sizeof(dst));
+
+        row_proc(dst, aa, src, 256);
+
+        for (size_t i = 0; i < 256; ++i) {
+            REPORTER_ASSERT(reporter, SkGetPackedA32(dst[i]) == 0xff);
+        }
+    }
+}
+
+// Verifies that D32 dest remains opaque for any (src_alpha, coverage) combination.
+DEF_TEST(BlitMask_OpaqueD32, reporter) {
+    test_opaque_dest(reporter, SkMask::Format::kA8_Format);
+}