[Impeller] Remove StC flag.

impeller/entity/contents/clip_contents.cc

@@ -250,11 +250,7 @@ bool ClipContents::Render(const ContentContext& renderer,
   if (!geometry_) {
     return true;
   }
-  if constexpr (ContentContext::kEnableStencilThenCover) {
-    return RenderDepthClip(renderer, entity, pass, clip_op_, *geometry_);
-  } else {
-    return RenderStencilClip(renderer, entity, pass, clip_op_, *geometry_);
-  }
+  return RenderDepthClip(renderer, entity, pass, clip_op_, *geometry_);
 }
 
 /*******************************************************************************

impeller/entity/contents/clip_contents_unittests.cc

@@ -22,11 +22,6 @@ namespace testing {
 using EntityTest = EntityPlayground;
 
 TEST_P(EntityTest, ClipContentsOptimizesFullScreenIntersectClips) {
-  if (!ContentContext::kEnableStencilThenCover) {
-    GTEST_SKIP();
-    return;
-  }
-
   // Set up mock environment.
 
   auto content_context = GetContentContext();

impeller/entity/contents/color_source_contents.h

@@ -203,11 +203,7 @@ class ColorSourceContents : public Contents {
       options.stencil_mode =
           ContentContextOptions::StencilMode::kLegacyClipIncrement;
     }
-    if constexpr (ContentContext::kEnableStencilThenCover) {
-      pass.SetStencilReference(0);
-    } else {
-      pass.SetStencilReference(entity.GetClipDepth());
-    }
+    pass.SetStencilReference(0);
 
     VertexShaderT::BindFrameInfo(
         pass, renderer.GetTransientsBuffer().EmplaceUniform(frame_info));
@@ -232,13 +228,9 @@ class ColorSourceContents : public Contents {
     if (geometry_result.mode == GeometryResult::Mode::kPreventOverdraw) {
       auto restore = ClipRestoreContents();
       restore.SetRestoreCoverage(GetCoverage(entity));
-      if constexpr (ContentContext::kEnableStencilThenCover) {
-        Entity restore_entity = entity.Clone();
-        restore_entity.SetClipDepth(0);
-        return restore.Render(renderer, restore_entity, pass);
-      } else {
-        return restore.Render(renderer, entity, pass);
-      }
+      Entity restore_entity = entity.Clone();
+      restore_entity.SetClipDepth(0);
+      return restore.Render(renderer, restore_entity, pass);
     }
     return true;
   }

impeller/entity/contents/content_context.h

@@ -397,16 +397,6 @@ class ContentContext {
 
   bool IsValid() const;
 
-  /// This setting does two things:
-  /// 1. Enables clipping with the depth buffer, freeing up the stencil buffer.
-  ///    See also: https://github.com/flutter/flutter/issues/138460
-  /// 2. Switches the generic tessellation fallback to use stencil-then-cover.
-  ///    See also: https://github.com/flutter/flutter/issues/123671
-  ///
-  // TODO(bdero): Remove this setting once StC is fully de-risked
-  //              https://github.com/flutter/flutter/issues/123671
-  static constexpr bool kEnableStencilThenCover = true;
-
 #if IMPELLER_ENABLE_3D
   std::shared_ptr<scene::SceneContext> GetSceneContext() const;
 #endif  // IMPELLER_ENABLE_3D

impeller/entity/contents/contents.cc

@@ -27,10 +27,8 @@ ContentContextOptions OptionsFromPass(const RenderPass& pass) {
   FML_DCHECK(pass.HasDepthAttachment() == pass.HasStencilAttachment());
 
   opts.has_depth_stencil_attachments = has_depth_stencil_attachments;
-  if constexpr (ContentContext::kEnableStencilThenCover) {
-    opts.depth_compare = CompareFunction::kGreater;
-    opts.stencil_mode = ContentContextOptions::StencilMode::kIgnore;
-  }
+  opts.depth_compare = CompareFunction::kGreater;
+  opts.stencil_mode = ContentContextOptions::StencilMode::kIgnore;
   return opts;
 }
 

impeller/entity/contents/filters/gaussian_blur_filter_contents.cc

@@ -232,9 +232,6 @@ Entity ApplyClippedBlurStyle(Entity::ClipOperation clip_operation,
         blur_entity.SetNewClipDepth(entity.GetNewClipDepth());
         blur_entity.SetTransform(entity.GetTransform() * blur_transform);
         result = blur_entity.Render(renderer, pass) && result;
-        if constexpr (!ContentContext::kEnableStencilThenCover) {
-          result = restore->Render(renderer, entity, pass) && result;
-        }
         return result;
       });
   auto coverage =

impeller/entity/entity_pass.cc

@@ -756,9 +756,6 @@ EntityPass::EntityResult EntityPass::GetEntityForElement(
 static void SetClipScissor(std::optional<Rect> clip_coverage,
                            RenderPass& pass,
                            Point global_pass_position) {
-  if constexpr (!ContentContext::kEnableStencilThenCover) {
-    return;
-  }
   // Set the scissor to the clip coverage area. We do this prior to rendering
   // the clip itself and all its contents.
   IRect scissor;

impeller/entity/entity_pass_clip_stack.cc

@@ -101,22 +101,11 @@ EntityPassClipStack::ClipStateResult EntityPassClipStack::ApplyClipState(
       subpass_state.clip_coverage.resize(restoration_index + 1);
       result.clip_did_change = true;
 
-      if constexpr (ContentContext::kEnableStencilThenCover) {
-        // Skip all clip restores when stencil-then-cover is enabled.
-        if (subpass_state.clip_coverage.back().coverage.has_value()) {
-          RecordEntity(entity, global_clip_coverage.type, Rect());
-        }
-        return result;
+      // Skip all clip restores when stencil-then-cover is enabled.
+      if (subpass_state.clip_coverage.back().coverage.has_value()) {
+        RecordEntity(entity, global_clip_coverage.type, Rect());
       }
-
-      if (!subpass_state.clip_coverage.back().coverage.has_value()) {
-        // Running this restore op won't make anything renderable, so skip it.
-        return result;
-      }
-
-      auto restore_contents =
-          static_cast<ClipRestoreContents*>(entity.GetContents().get());
-      restore_contents->SetRestoreCoverage(restore_coverage);
+      return result;
 
     } break;
   }

impeller/entity/entity_unittests.cc

@@ -2795,11 +2795,7 @@ TEST_P(EntityTest, FillPathGeometryGetPositionBufferReturnsExpectedMode) {
                     .Close()
                     .TakePath();
     GeometryResult result = get_result(path);
-    if constexpr (ContentContext::kEnableStencilThenCover) {
-      EXPECT_EQ(result.mode, GeometryResult::Mode::kNonZero);
-    } else {
-      EXPECT_EQ(result.mode, GeometryResult::Mode::kNormal);
-    }
+    EXPECT_EQ(result.mode, GeometryResult::Mode::kNonZero);
   }
 }
 

impeller/entity/geometry/fill_path_geometry.cc

@@ -37,37 +37,6 @@ GeometryResult FillPathGeometry::GetPositionBuffer(
   }
 
   VertexBuffer vertex_buffer;
-  if constexpr (!ContentContext::kEnableStencilThenCover) {
-    if (!path_.IsConvex()) {
-      auto tesselation_result = renderer.GetTessellator()->Tessellate(
-          path_, entity.GetTransform().GetMaxBasisLength(),
-          [&vertex_buffer, &host_buffer](
-              const float* vertices, size_t vertices_count,
-              const uint16_t* indices, size_t indices_count) {
-            vertex_buffer.vertex_buffer = host_buffer.Emplace(
-                vertices, vertices_count * sizeof(float) * 2, alignof(float));
-            if (indices != nullptr) {
-              vertex_buffer.index_buffer = host_buffer.Emplace(
-                  indices, indices_count * sizeof(uint16_t), alignof(uint16_t));
-              vertex_buffer.vertex_count = indices_count;
-              vertex_buffer.index_type = IndexType::k16bit;
-            } else {
-              vertex_buffer.index_buffer = {};
-              vertex_buffer.vertex_count = vertices_count;
-              vertex_buffer.index_type = IndexType::kNone;
-            }
-            return true;
-          });
-      if (tesselation_result != Tessellator::Result::kSuccess) {
-        return {};
-      }
-      return GeometryResult{
-          .type = PrimitiveType::kTriangle,
-          .vertex_buffer = vertex_buffer,
-          .transform = entity.GetShaderTransform(pass),
-      };
-    }
-  }
 
   auto points = renderer.GetTessellator()->TessellateConvex(
       path_, entity.GetTransform().GetMaxBasisLength());
@@ -111,41 +80,6 @@ GeometryResult FillPathGeometry::GetPositionUVBuffer(
   auto uv_transform =
       texture_coverage.GetNormalizingTransform() * effect_transform;
 
-  if constexpr (!ContentContext::kEnableStencilThenCover) {
-    if (!path_.IsConvex()) {
-      VertexBufferBuilder<VS::PerVertexData> vertex_builder;
-      auto tesselation_result = renderer.GetTessellator()->Tessellate(
-          path_, entity.GetTransform().GetMaxBasisLength(),
-          [&vertex_builder, &uv_transform](
-              const float* vertices, size_t vertices_count,
-              const uint16_t* indices, size_t indices_count) {
-            for (auto i = 0u; i < vertices_count * 2; i += 2) {
-              VS::PerVertexData data;
-              Point vtx = {vertices[i], vertices[i + 1]};
-              data.position = vtx;
-              data.texture_coords = uv_transform * vtx;
-              vertex_builder.AppendVertex(data);
-            }
-            FML_DCHECK(vertex_builder.GetVertexCount() == vertices_count);
-            if (indices != nullptr) {
-              for (auto i = 0u; i < indices_count; i++) {
-                vertex_builder.AppendIndex(indices[i]);
-              }
-            }
-            return true;
-          });
-      if (tesselation_result != Tessellator::Result::kSuccess) {
-        return {};
-      }
-      return GeometryResult{
-          .type = PrimitiveType::kTriangle,
-          .vertex_buffer =
-              vertex_builder.CreateVertexBuffer(renderer.GetTransientsBuffer()),
-          .transform = entity.GetShaderTransform(pass),
-      };
-    }
-  }
-
   auto points = renderer.GetTessellator()->TessellateConvex(
       path_, entity.GetTransform().GetMaxBasisLength());
 
@@ -169,7 +103,7 @@ GeometryResult FillPathGeometry::GetPositionUVBuffer(
 
 GeometryResult::Mode FillPathGeometry::GetResultMode() const {
   const auto& bounding_box = path_.GetBoundingBox();
-  if (!ContentContext::kEnableStencilThenCover || path_.IsConvex() ||
+  if (path_.IsConvex() ||
       (bounding_box.has_value() && bounding_box->IsEmpty())) {
     return GeometryResult::Mode::kNormal;
   }

impeller/entity/inline_pass_context.cc

@@ -151,19 +151,16 @@ InlinePassContext::RenderPassResult InlinePassContext::GetRenderPass(
   color0.store_action =
       is_msaa ? StoreAction::kMultisampleResolve : StoreAction::kStore;
 
-  if (ContentContext::kEnableStencilThenCover) {
-    auto depth = pass_target_.GetRenderTarget().GetDepthAttachment();
-    if (!depth.has_value()) {
-      VALIDATION_LOG << "Depth attachment unexpectedly missing from the "
-                        "EntityPass render target.";
-      return {};
-    }
-    depth->load_action = LoadAction::kClear;
-    depth->store_action = StoreAction::kDontCare;
-    pass_target_.target_.SetDepthAttachment(depth.value());
+  auto depth = pass_target_.GetRenderTarget().GetDepthAttachment();
+  if (!depth.has_value()) {
+    VALIDATION_LOG << "Depth attachment unexpectedly missing from the "
+                      "EntityPass render target.";
+    return {};
   }
+  depth->load_action = LoadAction::kClear;
+  depth->store_action = StoreAction::kDontCare;
+  pass_target_.target_.SetDepthAttachment(depth.value());
 
-  auto depth = pass_target_.GetRenderTarget().GetDepthAttachment();
   auto stencil = pass_target_.GetRenderTarget().GetStencilAttachment();
   if (!depth.has_value() || !stencil.has_value()) {
     VALIDATION_LOG << "Stencil/Depth attachment unexpectedly missing from the "