Revert "gpui: Take advantage of unified memory on Apple silicon (#44273)" (#45022)

This reverts commit 0bf857b66e.

Release Notes:

- N/A

crates/gpui/src/platform/mac/metal_atlas.rs

@@ -15,9 +15,6 @@ pub(crate) struct MetalAtlas(Mutex<MetalAtlasState>);
 impl MetalAtlas {
     pub(crate) fn new(device: Device) -> Self {
         MetalAtlas(Mutex::new(MetalAtlasState {
-            // Shared memory can be used only if CPU and GPU share the same memory space.
-            // https://developer.apple.com/documentation/metal/setting-resource-storage-modes
-            unified_memory: device.has_unified_memory(),
             device: AssertSend(device),
             monochrome_textures: Default::default(),
             polychrome_textures: Default::default(),
@@ -32,7 +29,6 @@ impl MetalAtlas {
 
 struct MetalAtlasState {
     device: AssertSend<Device>,
-    unified_memory: bool,
     monochrome_textures: AtlasTextureList<MetalAtlasTexture>,
     polychrome_textures: AtlasTextureList<MetalAtlasTexture>,
     tiles_by_key: FxHashMap<AtlasKey, AtlasTile>,
@@ -150,11 +146,6 @@ impl MetalAtlasState {
         }
         texture_descriptor.set_pixel_format(pixel_format);
         texture_descriptor.set_usage(usage);
-        texture_descriptor.set_storage_mode(if self.unified_memory {
-            metal::MTLStorageMode::Shared
-        } else {
-            metal::MTLStorageMode::Managed
-        });
         let metal_texture = self.device.new_texture(&texture_descriptor);
 
         let texture_list = match kind {

crates/gpui/src/platform/mac/metal_renderer.rs

@@ -76,22 +76,12 @@ impl InstanceBufferPool {
         self.buffers.clear();
     }
 
-    pub(crate) fn acquire(
-        &mut self,
-        device: &metal::Device,
-        unified_memory: bool,
-    ) -> InstanceBuffer {
+    pub(crate) fn acquire(&mut self, device: &metal::Device) -> InstanceBuffer {
         let buffer = self.buffers.pop().unwrap_or_else(|| {
-            let options = if unified_memory {
-                MTLResourceOptions::StorageModeShared
-                    // Buffers are write only which can benefit from the combined cache
-                    // https://developer.apple.com/documentation/metal/mtlresourceoptions/cpucachemodewritecombined
-                    | MTLResourceOptions::CPUCacheModeWriteCombined
-            } else {
-                MTLResourceOptions::StorageModeManaged
-            };
-
-            device.new_buffer(self.buffer_size as u64, options)
+            device.new_buffer(
+                self.buffer_size as u64,
+                MTLResourceOptions::StorageModeManaged,
+            )
         });
         InstanceBuffer {
             metal_buffer: buffer,
@@ -109,7 +99,6 @@ impl InstanceBufferPool {
 pub(crate) struct MetalRenderer {
     device: metal::Device,
     layer: metal::MetalLayer,
-    unified_memory: bool,
     presents_with_transaction: bool,
     command_queue: CommandQueue,
     paths_rasterization_pipeline_state: metal::RenderPipelineState,
@@ -190,10 +179,6 @@ impl MetalRenderer {
             output
         }
 
-        // Shared memory can be used only if CPU and GPU share the same memory space.
-        // https://developer.apple.com/documentation/metal/setting-resource-storage-modes
-        let unified_memory = device.has_unified_memory();
-
         let unit_vertices = [
             to_float2_bits(point(0., 0.)),
             to_float2_bits(point(1., 0.)),
@@ -205,12 +190,7 @@ impl MetalRenderer {
         let unit_vertices = device.new_buffer_with_data(
             unit_vertices.as_ptr() as *const c_void,
             mem::size_of_val(&unit_vertices) as u64,
-            if unified_memory {
-                MTLResourceOptions::StorageModeShared
-                    | MTLResourceOptions::CPUCacheModeWriteCombined
-            } else {
-                MTLResourceOptions::StorageModeManaged
-            },
+            MTLResourceOptions::StorageModeManaged,
         );
 
         let paths_rasterization_pipeline_state = build_path_rasterization_pipeline_state(
@@ -288,7 +268,6 @@ impl MetalRenderer {
             device,
             layer,
             presents_with_transaction: false,
-            unified_memory,
             command_queue,
             paths_rasterization_pipeline_state,
             path_sprites_pipeline_state,
@@ -358,23 +337,14 @@ impl MetalRenderer {
         texture_descriptor.set_width(size.width.0 as u64);
         texture_descriptor.set_height(size.height.0 as u64);
         texture_descriptor.set_pixel_format(metal::MTLPixelFormat::BGRA8Unorm);
-        texture_descriptor.set_storage_mode(metal::MTLStorageMode::Private);
         texture_descriptor
             .set_usage(metal::MTLTextureUsage::RenderTarget | metal::MTLTextureUsage::ShaderRead);
         self.path_intermediate_texture = Some(self.device.new_texture(&texture_descriptor));
 
         if self.path_sample_count > 1 {
-            // https://developer.apple.com/documentation/metal/choosing-a-resource-storage-mode-for-apple-gpus
-            // Rendering MSAA textures are done in a single pass, so we can use memory-less storage on Apple Silicon
-            let storage_mode = if self.unified_memory {
-                metal::MTLStorageMode::Memoryless
-            } else {
-                metal::MTLStorageMode::Private
-            };
-
             let mut msaa_descriptor = texture_descriptor;
             msaa_descriptor.set_texture_type(metal::MTLTextureType::D2Multisample);
-            msaa_descriptor.set_storage_mode(storage_mode);
+            msaa_descriptor.set_storage_mode(metal::MTLStorageMode::Private);
             msaa_descriptor.set_sample_count(self.path_sample_count as _);
             self.path_intermediate_msaa_texture = Some(self.device.new_texture(&msaa_descriptor));
         } else {
@@ -408,10 +378,7 @@ impl MetalRenderer {
         };
 
         loop {
-            let mut instance_buffer = self
-                .instance_buffer_pool
-                .lock()
-                .acquire(&self.device, self.unified_memory);
+            let mut instance_buffer = self.instance_buffer_pool.lock().acquire(&self.device);
 
             let command_buffer =
                 self.draw_primitives(scene, &mut instance_buffer, drawable, viewport_size);
@@ -583,14 +550,10 @@ impl MetalRenderer {
 
         command_encoder.end_encoding();
 
-        if !self.unified_memory {
-            // Sync the instance buffer to the GPU
-            instance_buffer.metal_buffer.did_modify_range(NSRange {
-                location: 0,
-                length: instance_offset as NSUInteger,
-            });
-        }
-
+        instance_buffer.metal_buffer.did_modify_range(NSRange {
+            location: 0,
+            length: instance_offset as NSUInteger,
+        });
         Ok(command_buffer.to_owned())
     }