metal: set max_buffer_size by the correct physical device restriction

wgpu-hal/src/metal/adapter.rs

@@ -1,5 +1,9 @@
 use mtl::{MTLFeatureSet, MTLGPUFamily, MTLLanguageVersion};
-use objc::{class, msg_send, sel, sel_impl};
+use objc::{
+    class, msg_send,
+    runtime::{BOOL, YES},
+    sel, sel_impl,
+};
 use parking_lot::Mutex;
 use wgt::{AstcBlock, AstcChannel};
 
@@ -819,10 +823,18 @@ impl super::PrivateCapabilities {
             max_textures_per_stage: if os_is_mac { 128 } else { 31 },
             max_samplers_per_stage: 16,
             buffer_alignment: if os_is_mac { 256 } else { 64 },
-            max_buffer_size: if device.supports_feature_set(MTLFeatureSet::macOS_GPUFamily1_v2) {
-                1 << 30 // 1GB on macOS 1.2 and up
-            } else {
-                1 << 28 // 256MB otherwise
+            max_buffer_size: unsafe {
+                let sel = sel!(maxBufferLength);
+                let can_use: BOOL = msg_send![device.as_ref(), respondsToSelector: sel];
+                if can_use == YES {
+                    // maxBufferLength available on macOS 10.14+ and iOS 12.0+
+                    let buffer_size: mtl::NSInteger = msg_send![device.as_ref(), maxBufferLength];
+                    buffer_size as _
+                } else if os_is_mac {
+                    1 << 30 // 1GB on macOS 10.11 and up
+                } else {
+                    1 << 28 // 256MB on iOS 8.0+
+                }
             },
             max_texture_size: if Self::supports_any(
                 device,

wgpu-hal/src/metal/surface.rs

@@ -134,30 +134,12 @@ impl super::Surface {
     }
 
     pub(super) fn dimensions(&self) -> wgt::Extent3d {
-        let (size, scale): (CGSize, CGFloat) = match self.view {
-            Some(view) if !cfg!(target_os = "macos") => unsafe {
-                let bounds: CGRect = msg_send![view.as_ptr(), bounds];
-                let window: Option<NonNull<Object>> = msg_send![view.as_ptr(), window];
-                let screen = window.and_then(|window| -> Option<NonNull<Object>> {
-                    msg_send![window.as_ptr(), screen]
-                });
-                match screen {
-                    Some(screen) => {
-                        let screen_space: *mut Object = msg_send![screen.as_ptr(), coordinateSpace];
-                        let rect: CGRect = msg_send![view.as_ptr(), convertRect:bounds toCoordinateSpace:screen_space];
-                        let scale_factor: CGFloat = msg_send![screen.as_ptr(), nativeScale];
-                        (rect.size, scale_factor)
-                    }
-                    None => (bounds.size, 1.0),
-                }
-            },
-            _ => unsafe {
-                let render_layer_borrow = self.render_layer.lock();
-                let render_layer = render_layer_borrow.as_ref();
-                let bounds: CGRect = msg_send![render_layer, bounds];
-                let contents_scale: CGFloat = msg_send![render_layer, contentsScale];
-                (bounds.size, contents_scale)
-            },
+        let (size, scale): (CGSize, CGFloat) = unsafe {
+            let render_layer_borrow = self.render_layer.lock();
+            let render_layer = render_layer_borrow.as_ref();
+            let bounds: CGRect = msg_send![render_layer, bounds];
+            let contents_scale: CGFloat = msg_send![render_layer, contentsScale];
+            (bounds.size, contents_scale)
         };
 
         wgt::Extent3d {