Add specialized sRGB blitter for SkOpts

tests/SkBlend_optsTest.cpp

Index: tests/SkBlend_optsTest.cpp
diff --git a/tests/SkBlend_optsTest.cpp b/tests/SkBlend_optsTest.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..4f561fd86a7401bafa554ed49c1cffdd61cdfa79
--- /dev/null
+++ b/tests/SkBlend_optsTest.cpp
@@ -0,0 +1,114 @@
+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include <string>
+#include <tuple>
+#include <vector>
+#include "Resources.h"
+#include "SkCpu.h"
+#include "SkImage.h"
+#include "SkImage_Base.h"
+#include "SkOpts.h"
+#include "Test.h"
+
+typedef void (*Blender)(uint32_t* dst, const uint32_t* const srcStart, int ndst, const int nsrc);
+
+namespace sk_default {
+extern void brute_force_srcover_srgb_srgb(
+    uint32_t* dst, const uint32_t* const srcStart, int ndst, const int nsrc);
+}
+
+namespace sk_default {
+extern void trivial_srcover_srgb_srgb(
+    uint32_t* dst, const uint32_t* const srcStart, int ndst, const int nsrc);
+}
+
+namespace sk_default {
+extern void best_non_simd_srcover_srgb_srgb(
+    uint32_t* dst, const uint32_t* const srcStart, int ndst, const int nsrc);
+}
+
+namespace sk_default {

[f(malita), 2016/05/06 17:43:56]

Nit: combine sk_default namespaces?

[herb_g, 2016/05/06 20:57:46]

Done.

+extern void srcover_srgb_srgb(
+    uint32_t* dst, const uint32_t* const srcStart, int ndst, const int nsrc);
+}
+
+#if defined(SK_CPU_X86) && !defined(SK_BUILD_FOR_IOS)
+namespace sk_sse41 {
+extern void srcover_srgb_srgb(
+    uint32_t* dst, const uint32_t* const srcStart, int ndst, const int nsrc);
+}
+#endif
+
+static SkString missmatch_message(std::string resourceName, std::string name, int x, int y,
+                                  uint32_t src, uint32_t good, uint32_t bad) {
+    return SkStringPrintf(
+        "%s - %s missmatch at %d, %d src: %08x good: %08x bad: %08x",
+        resourceName.c_str(), name.c_str(), x, y, src, good, bad);
+}
+
+static void test_blender(
+    std::tuple<Blender, std::string> spec,
+    std::string resourceName,
+    skiatest::Reporter* reporter)
+{
+    Blender blender;
+    std::string name;
+    std::tie(blender, name) = spec;
+
+    std::string fileName = resourceName + ".png";
+    sk_sp<SkImage> image = GetResourceAsImage(fileName.c_str());

[f(malita), 2016/05/06 17:43:56]

Do we need to worry about GetResourceAsImage() failing (e.g. one of the
resources gets deleted)?

Maybe REPORTER_ASSERT(image) + bail when null.

[herb_g, 2016/05/06 20:57:46]

Done.

+    SkBitmap bm;
+    if (!as_IB(image)->getROPixels(&bm)) {
+        SkFAIL("Could not read resource");
+    }
+
+    SkPixmap pixmap;
+    bm.peekPixels(&pixmap);
+    SkASSERT(pixmap.colorType() == kRGBA_8888_SkColorType);
+    SkASSERT(pixmap.alphaType() == kPremul_SkAlphaType);
+    const int width = pixmap.rowBytesAsPixels();
+    const uint32_t* src = pixmap.addr32();
+    SkAutoTArray<uint32_t> correctDst(width);
+    SkAutoTArray<uint32_t> testDst(width);
+
+    for (int y = 0; y < pixmap.height(); y++) {
+        memset(correctDst.get(), 0, width * sizeof(uint32_t));
+        memset(testDst.get(), 0, width * sizeof(uint32_t));
+        sk_default::brute_force_srcover_srgb_srgb(correctDst.get(), src, width, width);
+        blender(testDst.get(), src, width, width);
+        for (int x = 0; x < width; x++) {
+            REPORTER_ASSERT_MESSAGE(
+                reporter, correctDst[x] == testDst[x],
+                missmatch_message(resourceName, name, x, y, src[x], correctDst[x], testDst[x]));

[f(malita), 2016/05/06 17:43:56]

I'm a bit concerned that this will flood the logs if something goes wrong. 
Maybe break after the first mismatch?

[herb_g, 2016/05/06 20:57:46]

Done.

+        }
+        src += width;
+    }
+}
+
+DEF_TEST(SkBlend_optsCheck, reporter) {
+    std::vector<std::tuple<Blender, std::string>> specs = {
+        {sk_default::trivial_srcover_srgb_srgb,       "trivial"},
+        {sk_default::best_non_simd_srcover_srgb_srgb, "best_non_simd"},
+        {sk_default::srcover_srgb_srgb,               "default"},
+    };
+    #if defined(SK_CPU_X86) && !defined(SK_BUILD_FOR_IOS)
+    if (SkCpu::Supports(SkCpu::SSE41)) {
+        specs.push_back({sk_sse41::srcover_srgb_srgb, "sse41", });
+    }
+    #endif
+
+    std::vector<std::string> testResources = {
+        "yellow_rose", "baby_tux", "plane", "mandrill_512", "iconstrip"
+    };
+
+    for (auto& spec : specs) {
+        for (auto& resourceName : testResources) {
+            test_blender(spec, resourceName, reporter);
+        }
+    }
+}