Add toggle to warn the dst-alpha issue on Intel GPUs

Bug: dawn:1579
Change-Id: Ifdf09aefcdd62be82bd874a6e185b18ab96cb29a
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/114920
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Jiawei Shao <jiawei.shao@intel.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Austin Eng <enga@chromium.org>

src/dawn/native/Toggles.cpp

@@ -343,7 +343,12 @@ static constexpr ToggleEnumAndInfoList kToggleNameAndInfoList = {{
      {"no_workaround_indirect_base_vertex_not_applied",
       "MacOS Intel < Gen9 has a bug where indirect base vertex is not applied for "
       "drawIndexedIndirect. Draws are done as if it is always zero.",
-      "https://crbug.com/dawn/966"}}
+      "https://crbug.com/dawn/966"}},
+    {Toggle::NoWorkaroundDstAlphaBlendDoesNotWork,
+     {"no_workaround_dst_alpha_blend_does_not_work",
+      "Using D3D12_BLEND_DEST_ALPHA as blend factor doesn't work correctly on the D3D12 backend "
+      "using Intel Gen9 or Gen9.5 GPUs.",
+      "https://crbug.com/dawn/1579"}},
     // Comment to separate the }} so it is clearer what to copy-paste to add a toggle.
 }};
 }  // anonymous namespace

src/dawn/native/Toggles.h

@@ -87,6 +87,7 @@ enum class Toggle {
     // Unresolved issues.
     NoWorkaroundSampleMaskBecomesZeroForAllButLastColorTarget,
     NoWorkaroundIndirectBaseVertexNotApplied,
+    NoWorkaroundDstAlphaBlendDoesNotWork,
 
     EnumCount,
     InvalidEnum = EnumCount,

src/dawn/native/d3d12/DeviceD3D12.cpp

@@ -734,6 +734,12 @@ void Device::InitTogglesFromDriver() {
         gpu_info::IsIntelGen11(vendorId, deviceId)) {
         SetToggle(Toggle::D3D12Allocate2DTexturewithCopyDstAsCommittedResource, true);
     }
+
+    // Currently this toggle is only needed on Intel Gen9 and Gen9.5 GPUs.
+    // See http://crbug.com/dawn/1579 for more information.
+    if (gpu_info::IsIntelGen9(vendorId, deviceId)) {
+        SetToggle(Toggle::NoWorkaroundDstAlphaBlendDoesNotWork, true);
+    }
 }
 
 MaybeError Device::WaitForIdleForDestruction() {