From c28466cc21b0a36b85b9c32d703b255238e56a5d Mon Sep 17 00:00:00 2001
From: Erich Gubler <erichdongubler@gmail.com>
Date: Fri, 26 Jan 2024 13:16:34 -0500
Subject: [PATCH] feat: make GPU-based validation opt-in with new
 `InstanceFlags::GPU_BASED_VALIDATION`

---
 CHANGELOG.md                  |  5 +++++
 wgpu-hal/src/dx12/instance.rs | 19 +++++++++++++++----
 wgpu-types/src/lib.rs         | 13 ++++++++++++-
 3 files changed, 32 insertions(+), 5 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 58a01f23e..839ae0572 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -89,6 +89,11 @@ Bottom level categories:
 - Eager release of GPU resources comes from device.trackers. By @bradwerth in [#5075](https://github.com/gfx-rs/wgpu/pull/5075)
 - `wgpu-types`'s `trace` and `replay` features have been replaced by the `serde` feature. By @KirmesBude in [#5149](https://github.com/gfx-rs/wgpu/pull/5149)
 - `wgpu-core`'s `serial-pass` feature has been removed. Use `serde` instead. By @KirmesBude in [#5149](https://github.com/gfx-rs/wgpu/pull/5149)
+- Added `InstanceFlags::GPU_BASED_VALIDATION`, which enables GPU-based validation for shaders. This is currently only supported on the DX12 back end; other platforms ignore this flag, for now.
+  - This has been added to the set of flags set by `InstanceFlags::debugging` and `InstanceFlags::from_build_config`. If you notice your graphics workloads running more slowly, this may be the culprit.
+  - As with other instance flags, this flag can be changed in calls to `InstanceFlags::with_env` with the new `WGPU_GPU_BASED_VALIDATION` environment variable.
+
+  By @ErichDonGubler in [#5046](https://github.com/gfx-rs/wgpu/pull/5046).
 
 
 ### Bug Fixes
diff --git a/wgpu-hal/src/dx12/instance.rs b/wgpu-hal/src/dx12/instance.rs
index d7ed76219..020809328 100644
--- a/wgpu-hal/src/dx12/instance.rs
+++ b/wgpu-hal/src/dx12/instance.rs
@@ -20,14 +20,25 @@ impl crate::Instance<super::Api> for super::Instance {
             crate::InstanceError::with_source(String::from("failed to load d3d12.dll"), e)
         })?;
 
-        if desc.flags.contains(wgt::InstanceFlags::VALIDATION) {
+        if desc
+            .flags
+            .intersects(wgt::InstanceFlags::VALIDATION | wgt::InstanceFlags::GPU_BASED_VALIDATION)
+        {
             // Enable debug layer
             match lib_main.get_debug_interface() {
                 Ok(pair) => match pair.into_result() {
                     Ok(debug_controller) => {
-                        debug_controller.enable_layer();
-                        if !debug_controller.enable_gpu_based_validation() {
-                            log::warn!("Failed to enable GPU-based validation");
+                        if desc.flags.intersects(wgt::InstanceFlags::VALIDATION) {
+                            debug_controller.enable_layer();
+                        }
+                        if desc
+                            .flags
+                            .intersects(wgt::InstanceFlags::GPU_BASED_VALIDATION)
+                        {
+                            #[allow(clippy::collapsible_if)]
+                            if !debug_controller.enable_gpu_based_validation() {
+                                log::warn!("Failed to enable GPU-based validation");
+                            }
                         }
                     }
                     Err(err) => {
diff --git a/wgpu-types/src/lib.rs b/wgpu-types/src/lib.rs
index 7c39c32e0..6cd8c54d0 100644
--- a/wgpu-types/src/lib.rs
+++ b/wgpu-types/src/lib.rs
@@ -895,6 +895,14 @@ bitflags::bitflags! {
         /// This mainly applies to a Vulkan driver's compliance version. If the major compliance version
         /// is `0`, then the driver is ignored. This flag allows that driver to be enabled for testing.
         const ALLOW_UNDERLYING_NONCOMPLIANT_ADAPTER = 1 << 3;
+        /// Enable GPU-based validation. Currently, this only changes behavior on DX12 and Vulkan
+        /// back ends.
+        ///
+        /// Supported platforms:
+        ///
+        /// - D3D12; called ["GPU-based validation", or
+        ///   "GBV"](https://web.archive.org/web/20230206120404/https://learn.microsoft.com/en-us/windows/win32/direct3d12/using-d3d12-debug-layer-gpu-based-validation)
+        const GPU_BASED_VALIDATION = 1 << 4;
     }
 }
 
@@ -907,7 +915,7 @@ impl Default for InstanceFlags {
 impl InstanceFlags {
     /// Enable debugging and validation flags.
     pub fn debugging() -> Self {
-        InstanceFlags::DEBUG | InstanceFlags::VALIDATION
+        InstanceFlags::DEBUG | InstanceFlags::VALIDATION | InstanceFlags::GPU_BASED_VALIDATION
     }
 
     /// Infer good defaults from the build type
@@ -950,6 +958,9 @@ impl InstanceFlags {
         if let Some(bit) = env("WGPU_ALLOW_UNDERLYING_NONCOMPLIANT_ADAPTER") {
             self.set(Self::ALLOW_UNDERLYING_NONCOMPLIANT_ADAPTER, bit);
         }
+        if let Some(bit) = env("WGPU_GPU_BASED_VALIDATION") {
+            self.set(Self::GPU_BASED_VALIDATION, bit);
+        }
 
         self
     }