Bug 1645223 - Disable WebRender if XRender is enabled. r=aosmond

Differential Revision: https://phabricator.services.mozilla.com/D83655

gfx/config/gfxConfigManager.cpp

@@ -66,6 +66,7 @@ void gfxConfigManager::Init() {
 
 #ifdef MOZ_WIDGET_GTK
   mDisableHwCompositingNoWr = true;
+  mXRenderEnabled = mozilla::Preferences::GetBool("gfx.xrender.enabled");
 #endif
 
 #ifdef NIGHTLY_BUILD
@@ -267,6 +268,13 @@ void gfxConfigManager::ConfigureWebRender() {
                              "FEATURE_FAILURE_SAFE_MODE"_ns);
   }
 
+  if (mXRenderEnabled) {
+    // XRender and WebRender don't play well together. XRender is disabled by
+    // default. If the user opts into it don't enable webrender.
+    mFeatureWr->ForceDisable(FeatureStatus::Blocked,"XRender is enabled",
+                             "FEATURE_FAILURE_XRENDER"_ns);
+  }
+
   mFeatureWrAngle->DisableByDefault(FeatureStatus::OptIn,
                                     "WebRender ANGLE is an opt-in feature",
                                     "FEATURE_FAILURE_DEFAULT_OFF"_ns);

gfx/config/gfxConfigManager.h

@@ -34,6 +34,7 @@ class gfxConfigManager {
         mWrPictureCaching(false),
         mWrPartialPresent(false),
         mGPUProcessAllowSoftware(false),
+        mXRenderEnabled(false),
         mWrEnvForceEnabled(false),
         mWrEnvForceDisabled(false),
         mHwStretchingSupport(false),
@@ -81,6 +82,7 @@ class gfxConfigManager {
   bool mWrPictureCaching;
   bool mWrPartialPresent;
   bool mGPUProcessAllowSoftware;
+  bool mXRenderEnabled;
 
   /**
    * Environment variables

gfx/tests/gtest/TestConfigManager.cpp

@@ -696,3 +696,19 @@ TEST_F(GfxConfigManager, WebRenderAtRefreshRateThreshold) {
   EXPECT_TRUE(mFeatures.mGPUProcess.IsEnabled());
   EXPECT_TRUE(mFeatures.mD3D11HwAngle.IsEnabled());
 }
+
+TEST_F(GfxConfigManager, WebRenderWhenXRenderEnabled) {
+  mXRenderEnabled = true;
+  ConfigureWebRender();
+
+  EXPECT_TRUE(mFeatures.mWrQualified.IsEnabled());
+  EXPECT_FALSE(mFeatures.mWr.IsEnabled());
+  EXPECT_FALSE(mFeatures.mWrCompositor.IsEnabled());
+  EXPECT_FALSE(mFeatures.mWrAngle.IsEnabled());
+  EXPECT_FALSE(mFeatures.mWrDComp.IsEnabled());
+  EXPECT_FALSE(mFeatures.mWrPartial.IsEnabled());
+  EXPECT_TRUE(mFeatures.mHwCompositing.IsEnabled());
+  EXPECT_TRUE(mFeatures.mGPUProcess.IsEnabled());
+  EXPECT_TRUE(mFeatures.mD3D11HwAngle.IsEnabled());
+}
+