commit 73f59080013d08c4b4997d61997c829b0ca96e2e
author Peter McNeeley <petermcneeley@google.com> Mon Dec 02 19:38:41 2024 +0000
committer Dawn LUCI CQ <dawn-scoped@luci-project-accounts.iam.gserviceaccount.com> Mon Dec 02 19:38:41 2024 +0000
tree e206f03c7b746fb3724382f0d3a422e222d34523
parent 28258a5769a4212fec19a467f1dd4afa886b8179

[dawn] Begin deprecation of SubgroupsF16 feature; step 1

This change drops Subgroups support for Vulkan devices that support
ShaderF16 but not SubgroupsF16. This is a very narrow set of devices
estimated to be 4%. [0]

No immediate changes are required for D3D or Metal as support for
extended types (f16) is consistent with subgroup operations.

[0]
https://github.com/gpuweb/gpuweb/blob/main/proposals/subgroups.md#enable-extension

Bug:380244620
Change-Id: I81c31fa8b3ce5d664e98f3b7a6c74c8d512c3ed6
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/217474
Reviewed-by: James Price <jrprice@google.com>
Commit-Queue: Peter McNeeley <petermcneeley@google.com>

src/dawn/native/d3d12/PhysicalDeviceD3D12.cpp

diff --git a/src/dawn/native/d3d12/PhysicalDeviceD3D12.cpp b/src/dawn/native/d3d12/PhysicalDeviceD3D12.cpp
index b8fc14d..d95fe66 100644
--- a/src/dawn/native/d3d12/PhysicalDeviceD3D12.cpp
+++ b/src/dawn/native/d3d12/PhysicalDeviceD3D12.cpp
@@ -167,6 +167,7 @@
     if (GetBackend()->IsDXCAvailable() && mDeviceInfo.supportsWaveOps) {
         EnableFeature(Feature::Subgroups);
         // D3D12 devices that support both native f16 and wave ops can support subgroups-f16.
+        // TODO(crbug.com/380244620): Remove when 'subgroups_f16' has been fully deprecated.
         if (shaderF16Enabled) {
             EnableFeature(Feature::SubgroupsF16);
         }

src/dawn/native/vulkan/DeviceVk.cpp

diff --git a/src/dawn/native/vulkan/DeviceVk.cpp b/src/dawn/native/vulkan/DeviceVk.cpp
index 0216c97..3d22b86 100644
--- a/src/dawn/native/vulkan/DeviceVk.cpp
+++ b/src/dawn/native/vulkan/DeviceVk.cpp
@@ -504,7 +504,8 @@
     }
 
     // Set device feature for subgroups with f16 types.
-    if (HasFeature(Feature::SubgroupsF16)) {
+    if (HasFeature(Feature::SubgroupsF16) ||
+        (HasFeature(Feature::ShaderF16) && HasFeature(Feature::Subgroups))) {
         DAWN_ASSERT(usedKnobs.HasExt(DeviceExt::ShaderSubgroupExtendedTypes) &&
                     mDeviceInfo.shaderSubgroupExtendedTypes.shaderSubgroupExtendedTypes ==
                         VK_TRUE &&

src/dawn/native/vulkan/PhysicalDeviceVk.cpp

diff --git a/src/dawn/native/vulkan/PhysicalDeviceVk.cpp b/src/dawn/native/vulkan/PhysicalDeviceVk.cpp
index f81e7fc..3306fb9 100644
--- a/src/dawn/native/vulkan/PhysicalDeviceVk.cpp
+++ b/src/dawn/native/vulkan/PhysicalDeviceVk.cpp
@@ -406,15 +406,24 @@
         (mDeviceInfo.HasExt(DeviceExt::SubgroupSizeControl)) &&
         (mDeviceInfo.subgroupSizeControlFeatures.subgroupSizeControl == VK_TRUE) &&
         (mDeviceInfo.subgroupSizeControlFeatures.computeFullSubgroups == VK_TRUE)) {
-        EnableFeature(Feature::Subgroups);
-        // Enable SubgroupsF16 feature if:
-        // 1. Subgroups feature is enabled, and
-        // 2. ShaderF16 feature is enabled, and
-        // 3. shaderSubgroupExtendedTypes is TRUE in
-        //    VkPhysicalDeviceShaderSubgroupExtendedTypesFeaturesKHR.
-        if (shaderF16Enabled &&
-            mDeviceInfo.shaderSubgroupExtendedTypes.shaderSubgroupExtendedTypes == VK_TRUE) {
-            EnableFeature(Feature::SubgroupsF16);
+        if (shaderF16Enabled) {
+            if (mDeviceInfo.shaderSubgroupExtendedTypes.shaderSubgroupExtendedTypes == VK_TRUE) {
+                // Enable SubgroupsF16 feature if:
+                // 1. Subgroups feature is enabled, and
+                // 2. ShaderF16 feature is enabled, and
+                // 3. shaderSubgroupExtendedTypes is TRUE in
+                //    VkPhysicalDeviceShaderSubgroupExtendedTypesFeaturesKHR.
+                // TODO(crbug.com/380244620): Remove when 'subgroups_f16' has been fully deprecated.
+                EnableFeature(Feature::SubgroupsF16);
+                // If shader f16 is enable we only enable subgroups if we extended subgroup support.
+                // This means there is a vary narrow number of devices (~4%) will not get subgroup
+                // support due to the fact that they support shader f16 but not actually f16
+                // operations in subgroups.
+                EnableFeature(Feature::Subgroups);
+            }
+        } else {
+            // Subgroups without extended type support (f16).
+            EnableFeature(Feature::Subgroups);
         }
     }