[Impeller] Implement framebuffer-fetch via subpasses in Vulkan without extensions.

ci/licenses_golden/licenses_flutter

@@ -5478,6 +5478,8 @@ ORIGIN: ../../../flutter/impeller/renderer/backend/vulkan/pipeline_vk.cc + ../..
 ORIGIN: ../../../flutter/impeller/renderer/backend/vulkan/pipeline_vk.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/impeller/renderer/backend/vulkan/queue_vk.cc + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/impeller/renderer/backend/vulkan/queue_vk.h + ../../../flutter/LICENSE
+ORIGIN: ../../../flutter/impeller/renderer/backend/vulkan/render_pass_builder_vk.cc + ../../../flutter/LICENSE
+ORIGIN: ../../../flutter/impeller/renderer/backend/vulkan/render_pass_builder_vk.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/impeller/renderer/backend/vulkan/render_pass_vk.cc + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/impeller/renderer/backend/vulkan/render_pass_vk.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/impeller/renderer/backend/vulkan/resource_manager_vk.cc + ../../../flutter/LICENSE
@@ -8335,6 +8337,8 @@ FILE: ../../../flutter/impeller/renderer/backend/vulkan/pipeline_vk.cc
 FILE: ../../../flutter/impeller/renderer/backend/vulkan/pipeline_vk.h
 FILE: ../../../flutter/impeller/renderer/backend/vulkan/queue_vk.cc
 FILE: ../../../flutter/impeller/renderer/backend/vulkan/queue_vk.h
+FILE: ../../../flutter/impeller/renderer/backend/vulkan/render_pass_builder_vk.cc
+FILE: ../../../flutter/impeller/renderer/backend/vulkan/render_pass_builder_vk.h
 FILE: ../../../flutter/impeller/renderer/backend/vulkan/render_pass_vk.cc
 FILE: ../../../flutter/impeller/renderer/backend/vulkan/render_pass_vk.h
 FILE: ../../../flutter/impeller/renderer/backend/vulkan/resource_manager_vk.cc

impeller/entity/contents/content_context.cc

@@ -240,64 +240,49 @@ ContentContext::ContentContext(
   if (context_->GetCapabilities()->SupportsFramebufferFetch()) {
     framebuffer_blend_color_pipelines_.CreateDefault(
         *context_, options_trianglestrip,
-        {static_cast<Scalar>(BlendSelectValues::kColor), supports_decal},
-        UseSubpassInput::kYes);
+        {static_cast<Scalar>(BlendSelectValues::kColor), supports_decal});
     framebuffer_blend_colorburn_pipelines_.CreateDefault(
         *context_, options_trianglestrip,
-        {static_cast<Scalar>(BlendSelectValues::kColorBurn), supports_decal},
-        UseSubpassInput::kYes);
+        {static_cast<Scalar>(BlendSelectValues::kColorBurn), supports_decal});
     framebuffer_blend_colordodge_pipelines_.CreateDefault(
         *context_, options_trianglestrip,
-        {static_cast<Scalar>(BlendSelectValues::kColorDodge), supports_decal},
-        UseSubpassInput::kYes);
+        {static_cast<Scalar>(BlendSelectValues::kColorDodge), supports_decal});
     framebuffer_blend_darken_pipelines_.CreateDefault(
         *context_, options_trianglestrip,
-        {static_cast<Scalar>(BlendSelectValues::kDarken), supports_decal},
-        UseSubpassInput::kYes);
+        {static_cast<Scalar>(BlendSelectValues::kDarken), supports_decal});
     framebuffer_blend_difference_pipelines_.CreateDefault(
         *context_, options_trianglestrip,
-        {static_cast<Scalar>(BlendSelectValues::kDifference), supports_decal},
-        UseSubpassInput::kYes);
+        {static_cast<Scalar>(BlendSelectValues::kDifference), supports_decal});
     framebuffer_blend_exclusion_pipelines_.CreateDefault(
         *context_, options_trianglestrip,
-        {static_cast<Scalar>(BlendSelectValues::kExclusion), supports_decal},
-        UseSubpassInput::kYes);
+        {static_cast<Scalar>(BlendSelectValues::kExclusion), supports_decal});
     framebuffer_blend_hardlight_pipelines_.CreateDefault(
         *context_, options_trianglestrip,
-        {static_cast<Scalar>(BlendSelectValues::kHardLight), supports_decal},
-        UseSubpassInput::kYes);
+        {static_cast<Scalar>(BlendSelectValues::kHardLight), supports_decal});
     framebuffer_blend_hue_pipelines_.CreateDefault(
         *context_, options_trianglestrip,
-        {static_cast<Scalar>(BlendSelectValues::kHue), supports_decal},
-        UseSubpassInput::kYes);
+        {static_cast<Scalar>(BlendSelectValues::kHue), supports_decal});
     framebuffer_blend_lighten_pipelines_.CreateDefault(
         *context_, options_trianglestrip,
-        {static_cast<Scalar>(BlendSelectValues::kLighten), supports_decal},
-        UseSubpassInput::kYes);
+        {static_cast<Scalar>(BlendSelectValues::kLighten), supports_decal});
     framebuffer_blend_luminosity_pipelines_.CreateDefault(
         *context_, options_trianglestrip,
-        {static_cast<Scalar>(BlendSelectValues::kLuminosity), supports_decal},
-        UseSubpassInput::kYes);
+        {static_cast<Scalar>(BlendSelectValues::kLuminosity), supports_decal});
     framebuffer_blend_multiply_pipelines_.CreateDefault(
         *context_, options_trianglestrip,
-        {static_cast<Scalar>(BlendSelectValues::kMultiply), supports_decal},
-        UseSubpassInput::kYes);
+        {static_cast<Scalar>(BlendSelectValues::kMultiply), supports_decal});
     framebuffer_blend_overlay_pipelines_.CreateDefault(
         *context_, options_trianglestrip,
-        {static_cast<Scalar>(BlendSelectValues::kOverlay), supports_decal},
-        UseSubpassInput::kYes);
+        {static_cast<Scalar>(BlendSelectValues::kOverlay), supports_decal});
     framebuffer_blend_saturation_pipelines_.CreateDefault(
         *context_, options_trianglestrip,
-        {static_cast<Scalar>(BlendSelectValues::kSaturation), supports_decal},
-        UseSubpassInput::kYes);
+        {static_cast<Scalar>(BlendSelectValues::kSaturation), supports_decal});
     framebuffer_blend_screen_pipelines_.CreateDefault(
         *context_, options_trianglestrip,
-        {static_cast<Scalar>(BlendSelectValues::kScreen), supports_decal},
-        UseSubpassInput::kYes);
+        {static_cast<Scalar>(BlendSelectValues::kScreen), supports_decal});
     framebuffer_blend_softlight_pipelines_.CreateDefault(
         *context_, options_trianglestrip,
-        {static_cast<Scalar>(BlendSelectValues::kSoftLight), supports_decal},
-        UseSubpassInput::kYes);
+        {static_cast<Scalar>(BlendSelectValues::kSoftLight), supports_decal});
   }
 
   blend_color_pipelines_.CreateDefault(

impeller/entity/contents/content_context.h

@@ -826,15 +826,13 @@ class ContentContext {
 
     void CreateDefault(const Context& context,
                        const ContentContextOptions& options,
-                       const std::initializer_list<Scalar>& constants = {},
-                       UseSubpassInput subpass_input = UseSubpassInput::kNo) {
+                       const std::initializer_list<Scalar>& constants = {}) {
       auto desc =
           PipelineT::Builder::MakeDefaultPipelineDescriptor(context, constants);
       if (!desc.has_value()) {
         VALIDATION_LOG << "Failed to create default pipeline.";
         return;
       }
-      desc->SetUseSubpassInput(subpass_input);
       options.ApplyToPipelineDescriptor(*desc);
       SetDefault(options, std::make_unique<PipelineT>(context, desc));
     }

impeller/entity/entity_unittests.cc

@@ -2689,39 +2689,6 @@ TEST_P(EntityTest, DecalSpecializationAppliedToMorphologyFilter) {
             expected_constants);
 }
 
-TEST_P(EntityTest, FramebufferFetchPipelinesDeclareUsage) {
-  auto content_context =
-      ContentContext(GetContext(), TypographerContextSkia::Make());
-  if (!content_context.GetDeviceCapabilities().SupportsFramebufferFetch()) {
-    GTEST_SKIP() << "Framebuffer fetch not supported.";
-  }
-
-  ContentContextOptions options;
-  options.color_attachment_pixel_format = PixelFormat::kR8G8B8A8UNormInt;
-  auto color_burn =
-      content_context.GetFramebufferBlendColorBurnPipeline(options);
-
-  EXPECT_TRUE(color_burn->GetDescriptor().UsesSubpassInput());
-}
-
-TEST_P(EntityTest, PipelineDescriptorEqAndHash) {
-  auto desc_1 = std::make_shared<PipelineDescriptor>();
-  auto desc_2 = std::make_shared<PipelineDescriptor>();
-
-  EXPECT_TRUE(desc_1->IsEqual(*desc_2));
-  EXPECT_EQ(desc_1->GetHash(), desc_2->GetHash());
-
-  desc_1->SetUseSubpassInput(UseSubpassInput::kYes);
-
-  EXPECT_FALSE(desc_1->IsEqual(*desc_2));
-  EXPECT_NE(desc_1->GetHash(), desc_2->GetHash());
-
-  desc_2->SetUseSubpassInput(UseSubpassInput::kYes);
-
-  EXPECT_TRUE(desc_1->IsEqual(*desc_2));
-  EXPECT_EQ(desc_1->GetHash(), desc_2->GetHash());
-}
-
 // This doesn't really tell you if the hashes will have frequent
 // collisions, but since this type is only used to hash a bounded
 // set of options, we can just compare benchmarks.

impeller/fixtures/BUILD.gn

@@ -8,6 +8,9 @@ import("//flutter/testing/testing.gni")
 impeller_shaders("shader_fixtures") {
   name = "fixtures"
 
+  # 2.3 adds support for framebuffer fetch in Metal.
+  metal_version = "2.3"
+
   # Not analyzing because they are not performance critical, and mipmap uses
   # textureLod, which uses an extension that malioc does not support.
   analyze = false
@@ -16,8 +19,9 @@ impeller_shaders("shader_fixtures") {
     "array.vert",
     "box_fade.frag",
     "box_fade.vert",
-    "colors.vert",
     "colors.frag",
+    "colors.vert",
+    "half.frag",
     "impeller.frag",
     "impeller.vert",
     "inactive_uniforms.frag",
@@ -27,12 +31,16 @@ impeller_shaders("shader_fixtures") {
     "mipmaps.frag",
     "mipmaps.vert",
     "sample.comp",
+    "sepia.frag",
+    "sepia.vert",
+    "simple.vert",
     "stage1.comp",
     "stage2.comp",
-    "simple.vert",
+    "swizzle.frag",
     "test_texture.frag",
     "test_texture.vert",
-    "half.frag",
+    "texture.frag",
+    "texture.vert",
   ]
 
   if (impeller_enable_opengles) {

impeller/fixtures/sepia.frag

@@ -0,0 +1,17 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+out vec4 frag_color;
+
+layout(input_attachment_index = 0) uniform subpassInputMS subpass_input;
+
+void main() {
+  // https://github.com/chinmaygarde/merle/blob/3eecb311ac8862c41f0c53a5d9b360be923142bb/src/texture.cc#L195
+  const mat4 sepia_matrix = mat4(0.3588, 0.2990, 0.2392, 0.0000,  //
+                                 0.7044, 0.5870, 0.4696, 0.0000,  //
+                                 0.1368, 0.1140, 0.0912, 0.0000,  //
+                                 0.0000, 0.0000, 0.0000, 1.0000   //
+  );
+  frag_color = sepia_matrix * subpassLoad(subpass_input, 0);
+}

impeller/fixtures/sepia.vert

@@ -0,0 +1,14 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+uniform UniformBuffer {
+  mat4 mvp;
+}
+uniform_buffer;
+
+in vec3 vertex_position;
+
+void main() {
+  gl_Position = uniform_buffer.mvp * vec4(vertex_position, 1.0);
+}

impeller/fixtures/swizzle.frag

@@ -0,0 +1,11 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+out vec4 frag_color;
+
+layout(input_attachment_index = 0) uniform subpassInputMS subpass_input;
+
+void main() {
+  frag_color = subpassLoad(subpass_input, 0).gbra;
+}

impeller/fixtures/texture.frag

@@ -0,0 +1,13 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+in vec2 interporlated_texture_coordinates;
+
+out vec4 frag_color;
+
+uniform sampler2D texture_contents;
+
+void main() {
+  frag_color = texture(texture_contents, interporlated_texture_coordinates);
+}

impeller/fixtures/texture.vert

@@ -0,0 +1,18 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+uniform UniformBuffer {
+  mat4 mvp;
+}
+uniform_buffer;
+
+in vec3 vertex_position;
+in vec2 texture_coordinates;
+
+out vec2 interpolated_texture_coordinates;
+
+void main() {
+  gl_Position = uniform_buffer.mvp * vec4(vertex_position, 1.0);
+  interpolated_texture_coordinates = texture_coordinates;
+}

impeller/renderer/backend/vulkan/BUILD.gn

@@ -75,6 +75,8 @@ impeller_component("vulkan") {
     "pipeline_vk.h",
     "queue_vk.cc",
     "queue_vk.h",
+    "render_pass_builder_vk.cc",
+    "render_pass_builder_vk.h",
     "render_pass_vk.cc",
     "render_pass_vk.h",
     "resource_manager_vk.cc",

impeller/renderer/backend/vulkan/allocator_vk.cc

@@ -147,7 +147,6 @@ AllocatorVK::AllocatorVK(std::weak_ptr<Context> context,
   allocator_.reset(allocator);
   supports_memoryless_textures_ =
       capabilities.SupportsDeviceTransientTextures();
-  supports_framebuffer_fetch_ = capabilities.SupportsFramebufferFetch();
   is_valid_ = true;
 }
 
@@ -167,8 +166,7 @@ static constexpr vk::ImageUsageFlags ToVKImageUsageFlags(
     PixelFormat format,
     TextureUsageMask usage,
     StorageMode mode,
-    bool supports_memoryless_textures,
-    bool supports_framebuffer_fetch) {
+    bool supports_memoryless_textures) {
   vk::ImageUsageFlags vk_usage;
 
   switch (mode) {
@@ -188,9 +186,7 @@ static constexpr vk::ImageUsageFlags ToVKImageUsageFlags(
     } else {
       vk_usage |= vk::ImageUsageFlagBits::eColorAttachment;
     }
-    if (supports_framebuffer_fetch) {
-      vk_usage |= vk::ImageUsageFlagBits::eInputAttachment;
-    }
+    vk_usage |= vk::ImageUsageFlagBits::eInputAttachment;
   }
 
   if (usage & static_cast<TextureUsageMask>(TextureUsage::kShaderRead)) {
@@ -267,8 +263,7 @@ class AllocatedTextureSourceVK final : public TextureSourceVK {
                            const TextureDescriptor& desc,
                            VmaAllocator allocator,
                            vk::Device device,
-                           bool supports_memoryless_textures,
-                           bool supports_framebuffer_fetch)
+                           bool supports_memoryless_textures)
       : TextureSourceVK(desc), resource_(std::move(resource_manager)) {
     FML_DCHECK(desc.format != PixelFormat::kUnknown);
     vk::ImageCreateInfo image_info;
@@ -285,9 +280,9 @@ class AllocatedTextureSourceVK final : public TextureSourceVK {
     image_info.arrayLayers = ToArrayLayerCount(desc.type);
     image_info.tiling = vk::ImageTiling::eOptimal;
     image_info.initialLayout = vk::ImageLayout::eUndefined;
-    image_info.usage = ToVKImageUsageFlags(
-        desc.format, desc.usage, desc.storage_mode,
-        supports_memoryless_textures, supports_framebuffer_fetch);
+    image_info.usage =
+        ToVKImageUsageFlags(desc.format, desc.usage, desc.storage_mode,
+                            supports_memoryless_textures);
     image_info.sharingMode = vk::SharingMode::eExclusive;
 
     VmaAllocationCreateInfo alloc_nfo = {};
@@ -433,8 +428,7 @@ std::shared_ptr<Texture> AllocatorVK::OnCreateTexture(
       desc,                                            //
       allocator_.get(),                                //
       device_holder->GetDevice(),                      //
-      supports_memoryless_textures_,                   //
-      supports_framebuffer_fetch_                      //
+      supports_memoryless_textures_                    //
   );
   if (!source->IsValid()) {
     return nullptr;

impeller/renderer/backend/vulkan/allocator_vk.h

@@ -34,7 +34,6 @@ class AllocatorVK final : public Allocator {
   ISize max_texture_size_;
   bool is_valid_ = false;
   bool supports_memoryless_textures_ = false;
-  bool supports_framebuffer_fetch_ = false;
   // TODO(jonahwilliams): figure out why CI can't create these buffer pools.
   bool created_buffer_pool_ = true;
 

impeller/renderer/backend/vulkan/barrier_vk.h

@@ -18,6 +18,13 @@ namespace impeller {
 ///             and the Vulkan spec. The docs for the various member of this
 ///             class are based on verbiage in the spec.
 ///
+///             A useful mnemonic for building a mental model of how to add
+///             these barriers is to build a sentence like so; "All commands
+///             before this barrier may continue till they encounter a <src
+///             access> in the <src pipeline stage>. And, all commands after
+///             this barrier may proceed till <dst access> in the <dst pipeline
+///             stage>."
+///
 struct BarrierVK {
   vk::CommandBuffer cmd_buffer = {};
   vk::ImageLayout new_layout = vk::ImageLayout::eUndefined;