Reland "Convert GrDitherEffect to a runtime FP"

This reverts commit 3dd52c758b6cbcf1bf6eca1d0a594195e770d2ef.

Change-Id: Ie873ad570ffc57b3edd6ffe8612cbc2c73d40450
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/424259
Reviewed-by: Brian Osman <brianosman@google.com>
diff --git a/gn/gpu.gni b/gn/gpu.gni
index 37f31e1..4ba87a4 100644
--- a/gn/gpu.gni
+++ b/gn/gpu.gni
@@ -311,8 +311,6 @@
   "$_src/gpu/effects/GrYUVtoRGBEffect.h",
   "$_src/gpu/effects/generated/GrConfigConversionEffect.cpp",
   "$_src/gpu/effects/generated/GrConfigConversionEffect.h",
-  "$_src/gpu/effects/generated/GrDitherEffect.cpp",
-  "$_src/gpu/effects/generated/GrDitherEffect.h",
   "$_src/gpu/geometry/GrPathUtils.cpp",
   "$_src/gpu/geometry/GrPathUtils.h",
   "$_src/gpu/geometry/GrQuad.cpp",
diff --git a/gn/sksl.gni b/gn/sksl.gni
index 7ab85fd..3c04169 100644
--- a/gn/sksl.gni
+++ b/gn/sksl.gni
@@ -209,6 +209,5 @@
 
 skia_gpu_processor_sources = [
   "$_src/gpu/effects/GrConfigConversionEffect.fp",
-  "$_src/gpu/effects/GrDitherEffect.fp",
   "$_src/gpu/gradients/GrUnrolledBinaryGradientColorizer.fp",
 ]
diff --git a/include/effects/SkRuntimeEffect.h b/include/effects/SkRuntimeEffect.h
index 65cc884..88880f4 100644
--- a/include/effects/SkRuntimeEffect.h
+++ b/include/effects/SkRuntimeEffect.h
@@ -87,14 +87,20 @@
         int      index;
     };
 
-    struct Options {
+    class Options {
+    public:
         // For testing purposes, completely disable the inliner. (Normally, Runtime Effects don't
         // run the inliner directly, but they still get an inlining pass once they are painted.)
         bool forceNoInline = false;
-        // For testing purposes only; only honored when GR_TEST_UTILS is enabled. This flag lifts
-        // the ES2 restrictions on Runtime Effects that are gated by the `strictES2Mode` check.
-        // Be aware that the software renderer and pipeline-stage effect are still largely
-        // ES3-unaware and can still fail or crash if post-ES2 features are used.
+
+    private:
+        friend class SkRuntimeEffect;
+        friend class SkRuntimeEffectPriv;
+
+        // This flag lifts the ES2 restrictions on Runtime Effects that are gated by the
+        // `strictES2Mode` check. Be aware that the software renderer and pipeline-stage effect are
+        // still largely ES3-unaware and can still fail or crash if post-ES2 features are used.
+        // This is only intended for use by tests and certain internally created effects.
         bool enforceES2Restrictions = true;
     };
 
diff --git a/src/core/SkRuntimeEffect.cpp b/src/core/SkRuntimeEffect.cpp
index 314f82e..7d62bc7 100644
--- a/src/core/SkRuntimeEffect.cpp
+++ b/src/core/SkRuntimeEffect.cpp
@@ -149,9 +149,7 @@
         SkSL::Program::Settings settings;
         settings.fInlineThreshold = 0;
         settings.fForceNoInline = options.forceNoInline;
-#if GR_TEST_UTILS
         settings.fEnforceES2Restrictions = options.enforceES2Restrictions;
-#endif
         settings.fAllowNarrowingConversions = true;
         program = compiler->convertProgram(kind, SkSL::String(sksl.c_str(), sksl.size()), settings);
 
@@ -174,10 +172,6 @@
                                               const Options& options,
                                               SkSL::ProgramKind kind) {
     SkSL::SharedCompiler compiler;
-    SkSL::Program::Settings settings;
-    settings.fInlineThreshold = 0;
-    settings.fForceNoInline = options.forceNoInline;
-    settings.fAllowNarrowingConversions = true;
 
     // Find 'main', then locate the sample coords parameter. (It might not be present.)
     const SkSL::FunctionDefinition* main = SkSL::Program_GetFunction(*program, "main");
diff --git a/src/core/SkRuntimeEffectPriv.h b/src/core/SkRuntimeEffectPriv.h
index ec358a8..610410b 100644
--- a/src/core/SkRuntimeEffectPriv.h
+++ b/src/core/SkRuntimeEffectPriv.h
@@ -32,9 +32,11 @@
 
 // Internal API that assumes (and asserts) that the shader code is valid, but does no internal
 // caching. Used when the caller will cache the result in a static variable.
-inline sk_sp<SkRuntimeEffect> SkMakeRuntimeEffect(SkRuntimeEffect::Result (*make)(SkString sksl),
-                                                  const char* sksl) {
-    auto result = make(SkString{sksl});
+inline sk_sp<SkRuntimeEffect> SkMakeRuntimeEffect(
+        SkRuntimeEffect::Result (*make)(SkString, const SkRuntimeEffect::Options&),
+        const char* sksl,
+        SkRuntimeEffect::Options options = SkRuntimeEffect::Options{}) {
+    auto result = make(SkString{sksl}, options);
     SkASSERTF(result.effect, "%s", result.errorText.c_str());
     return result.effect;
 }
@@ -126,6 +128,12 @@
     static bool SupportsConstantOutputForConstantInput(sk_sp<SkRuntimeEffect> effect) {
         return effect->getFilterColorProgram();
     }
+
+    static SkRuntimeEffect::Options ES3Options() {
+        SkRuntimeEffect::Options options;
+        options.enforceES2Restrictions = false;
+        return options;
+    }
 };
 
 #endif
diff --git a/src/gpu/GrProcessor.h b/src/gpu/GrProcessor.h
index edb2c8a..ba8e8a4 100644
--- a/src/gpu/GrProcessor.h
+++ b/src/gpu/GrProcessor.h
@@ -64,7 +64,6 @@
         kGrDistanceFieldA8TextGeoProc_ClassID,
         kGrDistanceFieldLCDTextGeoProc_ClassID,
         kGrDistanceFieldPathGeoProc_ClassID,
-        kGrDitherEffect_ClassID,
         kGrDSLFPTest_DoStatement_ClassID,
         kGrDSLFPTest_ForStatement_ClassID,
         kGrDSLFPTest_IfStatement_ClassID,
diff --git a/src/gpu/GrProcessorUnitTest.cpp b/src/gpu/GrProcessorUnitTest.cpp
index 3a6f0d1..b4c673f 100644
--- a/src/gpu/GrProcessorUnitTest.cpp
+++ b/src/gpu/GrProcessorUnitTest.cpp
@@ -146,7 +146,7 @@
  * we verify the count is as expected.  If a new factory is added, then these numbers must be
  * manually adjusted.
  */
-static constexpr int kFPFactoryCount = 18;
+static constexpr int kFPFactoryCount = 17;
 static constexpr int kGPFactoryCount = 14;
 static constexpr int kXPFactoryCount = 4;
 
diff --git a/src/gpu/SkGr.cpp b/src/gpu/SkGr.cpp
index 5917100..059a8d2 100644
--- a/src/gpu/SkGr.cpp
+++ b/src/gpu/SkGr.cpp
@@ -28,6 +28,7 @@
 #include "src/core/SkMipmap.h"
 #include "src/core/SkPaintPriv.h"
 #include "src/core/SkResourceCache.h"
+#include "src/core/SkRuntimeEffectPriv.h"
 #include "src/core/SkTraceEvent.h"
 #include "src/gpu/GrCaps.h"
 #include "src/gpu/GrColorInfo.h"
@@ -42,7 +43,7 @@
 #include "src/gpu/effects/GrBicubicEffect.h"
 #include "src/gpu/effects/GrBlendFragmentProcessor.h"
 #include "src/gpu/effects/GrPorterDuffXferProcessor.h"
-#include "src/gpu/effects/generated/GrDitherEffect.h"
+#include "src/gpu/effects/GrSkSLFP.h"
 #include "src/image/SkImage_Base.h"
 #include "src/shaders/SkShaderBase.h"
 
@@ -322,6 +323,67 @@
     }
     SkUNREACHABLE;
 }
+
+static std::unique_ptr<GrFragmentProcessor> make_dither_effect(
+        std::unique_ptr<GrFragmentProcessor> inputFP, float range, const GrShaderCaps* caps) {
+    if (range == 0 || inputFP == nullptr) {
+        return inputFP;
+    }
+
+    if (caps->integerSupport()) {
+        // This ordered-dither code is lifted from the cpu backend.
+        static auto effect = SkMakeRuntimeEffect(SkRuntimeEffect::MakeForShader, R"(
+            uniform half range;
+            half4 main(float2 xy, half4 color) {
+                uint x = uint(sk_FragCoord.x);
+                uint y = uint(sk_FragCoord.y) ^ x;
+                uint m = (y & 1) << 5 | (x & 1) << 4 |
+                         (y & 2) << 2 | (x & 2) << 1 |
+                         (y & 4) >> 1 | (x & 4) >> 2;
+                half value = half(m) * 1.0 / 64.0 - 63.0 / 128.0;
+
+                // For each color channel, add the random offset to the channel value and then clamp
+                // between 0 and alpha to keep the color premultiplied.
+                return half4(clamp(color.rgb + value * range, 0.0, color.a), color.a);
+            }
+        )", SkRuntimeEffectPriv::ES3Options());
+        return GrSkSLFP::Make(effect, "Dither", std::move(inputFP),
+                              GrSkSLFP::OptFlags::kPreservesOpaqueInput,
+                              "range", range);
+    } else {
+        // Simulate the integer effect used above using step/mod/abs. For speed, simulates a 4x4
+        // dither pattern rather than an 8x8 one. Since it's 4x4, this is effectively computing:
+        // uint m = (y & 1) << 3 | (x & 1) << 2 |
+        //          (y & 2) << 0 | (x & 2) >> 1;
+        // where 'y' has already been XOR'ed with 'x' as in the integer-supported case.
+        static auto effect = SkMakeRuntimeEffect(SkRuntimeEffect::MakeForShader, R"(
+            uniform half range;
+            half4 main(float2 xy, half4 color) {
+                // To get the low bit of p.xy, we compute mod 2.0; for the high bit, we mod 4.0
+                half4 bits = mod(half4(sk_FragCoord.yxyx), half4(2.0, 2.0, 4.0, 4.0));
+                // Use step to convert the 0-3 value in bits.zw into a 0|1 value. bits.xy is
+                // already 0|1.
+                bits.zw = step(2.0, bits.zw);
+                // bits was constructed such that the p.x bits were already in the right place for
+                // interleaving (in bits.yw). We just need to update the other bits from p.y to
+                // (p.x ^ p.y). These are in bits.xz. Since the values are 0|1, we can simulate ^ as
+                // abs(y - x).
+                bits.xz = abs(bits.xz - bits.yw);
+
+                // Manual binary sum, divide by N^2, and offset
+                half value = dot(bits, half4(8.0 / 16.0, 4.0 / 16.0, 2.0 / 16.0, 1.0 / 16.0))
+                           - 15.0 / 32.0;
+
+                // For each color channel, add the random offset to the channel value and then clamp
+                // between 0 and alpha to keep the color premultiplied.
+                return half4(clamp(color.rgb + value * range, 0.0, color.a), color.a);
+            }
+        )");
+        return GrSkSLFP::Make(effect, "Dither", std::move(inputFP),
+                              GrSkSLFP::OptFlags::kPreservesOpaqueInput,
+                              "range", range);
+    }
+}
 #endif
 
 static inline bool skpaint_to_grpaint_impl(GrRecordingContext* context,
@@ -435,7 +497,8 @@
     GrColorType ct = dstColorInfo.colorType();
     if (SkPaintPriv::ShouldDither(skPaint, GrColorTypeToSkColorType(ct)) && paintFP != nullptr) {
         float ditherRange = dither_range_for_config(ct);
-        paintFP = GrDitherEffect::Make(std::move(paintFP), ditherRange);
+        paintFP = make_dither_effect(
+                std::move(paintFP), ditherRange, context->priv().caps()->shaderCaps());
     }
 #endif
 
diff --git a/src/gpu/effects/GrDitherEffect.fp b/src/gpu/effects/GrDitherEffect.fp
deleted file mode 100644
index e2eac5e..0000000
--- a/src/gpu/effects/GrDitherEffect.fp
+++ /dev/null
@@ -1,66 +0,0 @@
-/*
- * Copyright 2020 Google Inc.
- *
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
-
-in fragmentProcessor inputFP;
-
-// Larger values increase the strength of the dithering effect.
-in uniform half range;
-
-half4 main() {
-    half4 color = sample(inputFP);
-    half value;
-    @if (sk_Caps.integerSupport)
-    {
-        // This ordered-dither code is lifted from the cpu backend.
-        uint x = uint(sk_FragCoord.x);
-        uint y = uint(sk_FragCoord.y) ^ x;
-        uint m = (y & 1) << 5 | (x & 1) << 4 |
-                 (y & 2) << 2 | (x & 2) << 1 |
-                 (y & 4) >> 1 | (x & 4) >> 2;
-        value = half(m) * 1.0 / 64.0 - 63.0 / 128.0;
-    } else {
-        // Simulate the integer effect used above using step/mod/abs. For speed, simulates a 4x4
-        // dither pattern rather than an 8x8 one. Since it's 4x4, this is effectively computing:
-        // uint m = (y & 1) << 3 | (x & 1) << 2 |
-        //          (y & 2) << 0 | (x & 2) >> 1;
-        // where 'y' has already been XOR'ed with 'x' as in the integer-supported case.
-
-        // To get the low bit of p.x and p.y, we compute mod 2.0; for the high bit, we mod 4.0
-        half4 bits = mod(half4(sk_FragCoord.yxyx), half4(2.0, 2.0, 4.0, 4.0));
-        // Use step to convert the 0-3 value in bits.zw into a 0|1 value. bits.xy is already 0|1.
-        bits.zw = step(2.0, bits.zw);
-        // bits was constructed such that the p.x bits were already in the right place for
-        // interleaving (in bits.yw). We just need to update the other bits from p.y to (p.x ^ p.y).
-        // These are in bits.xz. Since the values are 0|1, we can simulate ^ as abs(y - x).
-        bits.xz = abs(bits.xz - bits.yw);
-
-        // Manual binary sum, divide by N^2, and offset
-        value = dot(bits, half4(8.0 / 16.0, 4.0 / 16.0, 2.0 / 16.0, 1.0 / 16.0)) - 15.0 / 32.0;
-    }
-    // For each color channel, add the random offset to the channel value and then clamp
-    // between 0 and alpha to keep the color premultiplied.
-    return half4(clamp(color.rgb + value * range, 0.0, color.a), color.a);
-}
-
-@optimizationFlags {
-    ProcessorOptimizationFlags(inputFP.get()) & kPreservesOpaqueInput_OptimizationFlag
-}
-
-@test(d) {
-    float range = 1.0f - d->fRandom->nextRangeF(0.0f, 1.0f);
-    return GrDitherEffect::Make(GrProcessorUnitTest::MakeChildFP(d), range);
-}
-
-@make {
-    static std::unique_ptr<GrFragmentProcessor> Make(std::unique_ptr<GrFragmentProcessor> inputFP,
-                                                     float range) {
-        if (range == 0.0 || inputFP == nullptr) {
-            return inputFP;
-        }
-        return std::unique_ptr<GrFragmentProcessor>(new GrDitherEffect(std::move(inputFP), range));
-    }
-}
diff --git a/src/gpu/effects/generated/GrDitherEffect.cpp b/src/gpu/effects/generated/GrDitherEffect.cpp
deleted file mode 100644
index db73639..0000000
--- a/src/gpu/effects/generated/GrDitherEffect.cpp
+++ /dev/null
@@ -1,87 +0,0 @@
-/*
- * Copyright 2020 Google Inc.
- *
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
-
-/**************************************************************************************************
- *** This file was autogenerated from GrDitherEffect.fp; do not modify.
- **************************************************************************************************/
-#include "GrDitherEffect.h"
-
-#include "src/core/SkUtils.h"
-#include "src/gpu/GrTexture.h"
-#include "src/gpu/glsl/GrGLSLFragmentProcessor.h"
-#include "src/gpu/glsl/GrGLSLFragmentShaderBuilder.h"
-#include "src/gpu/glsl/GrGLSLProgramBuilder.h"
-#include "src/sksl/SkSLCPP.h"
-#include "src/sksl/SkSLUtil.h"
-class GrGLSLDitherEffect : public GrGLSLFragmentProcessor {
-public:
-    GrGLSLDitherEffect() {}
-    void emitCode(EmitArgs& args) override {
-        GrGLSLFPFragmentBuilder* fragBuilder = args.fFragBuilder;
-        const GrDitherEffect& _outer = args.fFp.cast<GrDitherEffect>();
-        (void)_outer;
-        auto range = _outer.range;
-        (void)range;
-        rangeVar = args.fUniformHandler->addUniform(
-                &_outer, kFragment_GrShaderFlag, kHalf_GrSLType, "range");
-        SkString _sample0 = this->invokeChild(0, args);
-        fragBuilder->codeAppendf(
-                R"SkSL(half4 color = %s;
-half value;
-@if (sk_Caps.integerSupport) {
-    uint x = uint(sk_FragCoord.x);
-    uint y = uint(sk_FragCoord.y) ^ x;
-    uint m = (((((y & 1) << 5 | (x & 1) << 4) | (y & 2) << 2) | (x & 2) << 1) | (y & 4) >> 1) | (x & 4) >> 2;
-    value = half(m) / 64.0 - 0.4921875;
-} else {
-    half4 bits = mod(half4(sk_FragCoord.yxyx), half4(2.0, 2.0, 4.0, 4.0));
-    bits.zw = step(2.0, bits.zw);
-    bits.xz = abs(bits.xz - bits.yw);
-    value = dot(bits, half4(0.5, 0.25, 0.125, 0.0625)) - 0.46875;
-}
-return half4(clamp(color.xyz + value * %s, 0.0, color.w), color.w);
-)SkSL",
-                _sample0.c_str(),
-                args.fUniformHandler->getUniformCStr(rangeVar));
-    }
-
-private:
-    void onSetData(const GrGLSLProgramDataManager& pdman,
-                   const GrFragmentProcessor& _proc) override {
-        const GrDitherEffect& _outer = _proc.cast<GrDitherEffect>();
-        { pdman.set1f(rangeVar, _outer.range); }
-    }
-    UniformHandle rangeVar;
-};
-std::unique_ptr<GrGLSLFragmentProcessor> GrDitherEffect::onMakeProgramImpl() const {
-    return std::make_unique<GrGLSLDitherEffect>();
-}
-void GrDitherEffect::onGetGLSLProcessorKey(const GrShaderCaps& caps,
-                                           GrProcessorKeyBuilder* b) const {}
-bool GrDitherEffect::onIsEqual(const GrFragmentProcessor& other) const {
-    const GrDitherEffect& that = other.cast<GrDitherEffect>();
-    (void)that;
-    if (range != that.range) return false;
-    return true;
-}
-GrDitherEffect::GrDitherEffect(const GrDitherEffect& src)
-        : INHERITED(kGrDitherEffect_ClassID, src.optimizationFlags()), range(src.range) {
-    this->cloneAndRegisterAllChildProcessors(src);
-}
-std::unique_ptr<GrFragmentProcessor> GrDitherEffect::clone() const {
-    return std::make_unique<GrDitherEffect>(*this);
-}
-#if GR_TEST_UTILS
-SkString GrDitherEffect::onDumpInfo() const { return SkStringPrintf("(range=%f)", range); }
-#endif
-GR_DEFINE_FRAGMENT_PROCESSOR_TEST(GrDitherEffect);
-#if GR_TEST_UTILS
-std::unique_ptr<GrFragmentProcessor> GrDitherEffect::TestCreate(GrProcessorTestData* d) {
-    float range = 1.0f - d->fRandom->nextRangeF(0.0f, 1.0f);
-    return GrDitherEffect::Make(GrProcessorUnitTest::MakeChildFP(d), range);
-}
-#endif
diff --git a/src/gpu/effects/generated/GrDitherEffect.h b/src/gpu/effects/generated/GrDitherEffect.h
deleted file mode 100644
index 2abfdf2..0000000
--- a/src/gpu/effects/generated/GrDitherEffect.h
+++ /dev/null
@@ -1,50 +0,0 @@
-/*
- * Copyright 2020 Google Inc.
- *
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
-
-/**************************************************************************************************
- *** This file was autogenerated from GrDitherEffect.fp; do not modify.
- **************************************************************************************************/
-#ifndef GrDitherEffect_DEFINED
-#define GrDitherEffect_DEFINED
-
-#include "include/core/SkM44.h"
-#include "include/core/SkTypes.h"
-
-#include "src/gpu/GrFragmentProcessor.h"
-
-class GrDitherEffect : public GrFragmentProcessor {
-public:
-    static std::unique_ptr<GrFragmentProcessor> Make(std::unique_ptr<GrFragmentProcessor> inputFP,
-                                                     float range) {
-        if (range == 0.0 || inputFP == nullptr) {
-            return inputFP;
-        }
-        return std::unique_ptr<GrFragmentProcessor>(new GrDitherEffect(std::move(inputFP), range));
-    }
-    GrDitherEffect(const GrDitherEffect& src);
-    std::unique_ptr<GrFragmentProcessor> clone() const override;
-    const char* name() const override { return "DitherEffect"; }
-    float range;
-
-private:
-    GrDitherEffect(std::unique_ptr<GrFragmentProcessor> inputFP, float range)
-            : INHERITED(kGrDitherEffect_ClassID,
-                        (OptimizationFlags)ProcessorOptimizationFlags(inputFP.get()) &
-                                kPreservesOpaqueInput_OptimizationFlag)
-            , range(range) {
-        this->registerChild(std::move(inputFP), SkSL::SampleUsage::PassThrough());
-    }
-    std::unique_ptr<GrGLSLFragmentProcessor> onMakeProgramImpl() const override;
-    void onGetGLSLProcessorKey(const GrShaderCaps&, GrProcessorKeyBuilder*) const override;
-    bool onIsEqual(const GrFragmentProcessor&) const override;
-#if GR_TEST_UTILS
-    SkString onDumpInfo() const override;
-#endif
-    GR_DECLARE_FRAGMENT_PROCESSOR_TEST
-    using INHERITED = GrFragmentProcessor;
-};
-#endif
diff --git a/tests/SkRuntimeEffectTest.cpp b/tests/SkRuntimeEffectTest.cpp
index 9c29383..13fb550 100644
--- a/tests/SkRuntimeEffectTest.cpp
+++ b/tests/SkRuntimeEffectTest.cpp
@@ -79,8 +79,7 @@
 
 DEF_TEST(SkRuntimeEffectCanDisableES2Restrictions, r) {
     auto test_valid_es3 = [](skiatest::Reporter* r, const char* sksl) {
-        SkRuntimeEffect::Options opt;
-        opt.enforceES2Restrictions = false;
+        SkRuntimeEffect::Options opt = SkRuntimeEffectPriv::ES3Options();
         auto [effect, errorText] = SkRuntimeEffect::MakeForShader(SkString(sksl), opt);
         REPORTER_ASSERT(r, effect, "%s", errorText.c_str());
     };
diff --git a/tests/SkSLTest.cpp b/tests/SkSLTest.cpp
index 45812fc..c388a43 100644
--- a/tests/SkSLTest.cpp
+++ b/tests/SkSLTest.cpp
@@ -19,6 +19,7 @@
 #include "include/effects/SkRuntimeEffect.h"
 #include "include/private/SkSLDefines.h"  // for kDefaultInlineThreshold
 #include "include/utils/SkRandom.h"
+#include "src/core/SkRuntimeEffectPriv.h"
 #include "src/gpu/GrCaps.h"
 #include "src/gpu/GrDirectContextPriv.h"
 #include "tests/Test.h"
@@ -98,8 +99,8 @@
                               SkSurface* surface,
                               const char* testFile,
                               bool worksInES2) {
-    SkRuntimeEffect::Options options;
-    options.enforceES2Restrictions = worksInES2;
+    SkRuntimeEffect::Options options =
+            worksInES2 ? SkRuntimeEffect::Options{} : SkRuntimeEffectPriv::ES3Options();
     options.forceNoInline = false;
     test_one_permutation(r, surface, testFile, "", options);