From 6917be2911518e572858ad15c6884a8e28279679 Mon Sep 17 00:00:00 2001
From: Robert Swain <robert.swain@gmail.com>
Date: Fri, 28 Jan 2022 17:46:14 +0100
Subject: [PATCH 1/2] Identify Apple M1 GPU as integrated

---
 wgpu-hal/src/gles/adapter.rs | 1 +
 wgpu-hal/src/metal/mod.rs    | 3 ++-
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/wgpu-hal/src/gles/adapter.rs b/wgpu-hal/src/gles/adapter.rs
index bcac8bf318..87307ac27f 100644
--- a/wgpu-hal/src/gles/adapter.rs
+++ b/wgpu-hal/src/gles/adapter.rs
@@ -118,6 +118,7 @@ impl super::Adapter {
             "mali",
             "intel",
             "v3d",
+            "apple m1",
         ];
         let strings_that_imply_cpu = ["mesa offscreen", "swiftshader", "llvmpipe"];
 
diff --git a/wgpu-hal/src/metal/mod.rs b/wgpu-hal/src/metal/mod.rs
index dd8fee1840..1fd0a7b522 100644
--- a/wgpu-hal/src/metal/mod.rs
+++ b/wgpu-hal/src/metal/mod.rs
@@ -108,13 +108,14 @@ impl crate::Instance<Api> for Instance {
             .into_iter()
             .map(|dev| {
                 let name = dev.name().into();
+                let has_unified_memory = dev.has_unified_memory();
                 let shared = AdapterShared::new(dev);
                 crate::ExposedAdapter {
                     info: wgt::AdapterInfo {
                         name,
                         vendor: 0,
                         device: 0,
-                        device_type: if shared.private_caps.low_power {
+                        device_type: if has_unified_memory {
                             wgt::DeviceType::IntegratedGpu
                         } else {
                             wgt::DeviceType::DiscreteGpu

From ea4ca325b4bbab2e1a5b64f5a4e7e83eb33679d4 Mon Sep 17 00:00:00 2001
From: Robert Swain <robert.swain@gmail.com>
Date: Fri, 28 Jan 2022 23:16:22 +0100
Subject: [PATCH 2/2] metal: Call has_unified_memory conditional on OS version

Fall back to current low_power implies integrated GPU for older OSes.
---
 wgpu-hal/src/metal/adapter.rs | 15 +++++++++++++++
 wgpu-hal/src/metal/mod.rs     |  8 ++------
 2 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/wgpu-hal/src/metal/adapter.rs b/wgpu-hal/src/metal/adapter.rs
index 1a05240ccd..9ce28eef19 100644
--- a/wgpu-hal/src/metal/adapter.rs
+++ b/wgpu-hal/src/metal/adapter.rs
@@ -988,6 +988,21 @@ impl super::PrivateCapabilities {
             } else {
                 Self::version_at_least(major, minor, 13, 0)
             },
+            has_unified_memory: if (os_is_mac && Self::version_at_least(major, minor, 10, 15))
+                || (!os_is_mac && Self::version_at_least(major, minor, 13, 0))
+            {
+                Some(device.has_unified_memory())
+            } else {
+                None
+            },
+        }
+    }
+
+    pub fn device_type(&self) -> wgt::DeviceType {
+        if self.has_unified_memory.unwrap_or(self.low_power) {
+            wgt::DeviceType::IntegratedGpu
+        } else {
+            wgt::DeviceType::DiscreteGpu
         }
     }
 
diff --git a/wgpu-hal/src/metal/mod.rs b/wgpu-hal/src/metal/mod.rs
index 1fd0a7b522..1dd3e252c2 100644
--- a/wgpu-hal/src/metal/mod.rs
+++ b/wgpu-hal/src/metal/mod.rs
@@ -108,18 +108,13 @@ impl crate::Instance<Api> for Instance {
             .into_iter()
             .map(|dev| {
                 let name = dev.name().into();
-                let has_unified_memory = dev.has_unified_memory();
                 let shared = AdapterShared::new(dev);
                 crate::ExposedAdapter {
                     info: wgt::AdapterInfo {
                         name,
                         vendor: 0,
                         device: 0,
-                        device_type: if has_unified_memory {
-                            wgt::DeviceType::IntegratedGpu
-                        } else {
-                            wgt::DeviceType::DiscreteGpu
-                        },
+                        device_type: shared.private_caps.device_type(),
                         backend: wgt::Backend::Metal,
                     },
                     features: shared.private_caps.features(),
@@ -231,6 +226,7 @@ struct PrivateCapabilities {
     supports_mutability: bool,
     supports_depth_clip_control: bool,
     supports_preserve_invariance: bool,
+    has_unified_memory: Option<bool>,
 }
 
 #[derive(Clone, Debug)]