[fence_manager, ui] antiflicker fix + toggle integration (#4004)

tldr: we (me and maran) found the missing piece to make delay_fence and should_flush coop and cover all remaining flicker issues tested so far.
the lil change is in src/video_core/fence_manager.h
the rest is toggle stuff.

END

(credits rolls up)

post credits scene for the toggle drama:

i've been forced to use custom builds for around 1 year now, coz gpu mode above fast was pulling performance down yet not covering flicker entirely in most games tested. and we know that it's a mess to rely on gpu mode as it brings along a bunch of undesired stuff.
i need this toggle. and i've seem far less relevant before, so hey, gimme this one so i can call it mine :3

Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/4004
Reviewed-by: MaranBr <maranbr@eden-emu.dev>
Reviewed-by: Lizzie <lizzie@eden-emu.dev>
Reviewed-by: CamilleLaVey <camillelavey99@gmail.com>

src/android/app/src/main/java/org/yuzu/yuzu_emu/features/settings/model/BooleanSetting.kt

@@ -16,6 +16,7 @@ enum class BooleanSetting(override val key: String) : AbstractBooleanSetting {
     RENDERER_USE_SPEED_LIMIT("use_speed_limit"),
     USE_CUSTOM_CPU_TICKS("use_custom_cpu_ticks"),
     SKIP_CPU_INNER_INVALIDATION("skip_cpu_inner_invalidation"),
+    ANTIFLICKER("antiflicker"),
     FIX_BLOOM_EFFECTS("fix_bloom_effects"),
     EMULATE_BGR565("emulate_bgr565"),
     RESCALE_HACK("rescale_hack"),

src/android/app/src/main/java/org/yuzu/yuzu_emu/features/settings/model/view/SettingsItem.kt

@@ -750,6 +750,13 @@ abstract class SettingsItem(
                     descriptionId = R.string.skip_cpu_inner_invalidation_description
                 )
             )
+            put(
+                SwitchSetting(
+                    BooleanSetting.ANTIFLICKER,
+                    titleId = R.string.antiflicker,
+                    descriptionId = R.string.antiflicker_description
+                )
+            )
             put(
                 SwitchSetting(
                     BooleanSetting.FIX_BLOOM_EFFECTS,

src/android/app/src/main/java/org/yuzu/yuzu_emu/features/settings/ui/SettingsFragmentPresenter.kt

@@ -291,6 +291,7 @@ class SettingsFragmentPresenter(
 
             add(IntSetting.FAST_GPU_TIME.key)
             add(BooleanSetting.SKIP_CPU_INNER_INVALIDATION.key)
+            add(BooleanSetting.ANTIFLICKER.key)
             add(BooleanSetting.FIX_BLOOM_EFFECTS.key)
             add(BooleanSetting.EMULATE_BGR565.key)
             add(BooleanSetting.RESCALE_HACK.key)

src/android/app/src/main/res/values/strings.xml

@@ -509,6 +509,8 @@
     <string name="fast_gpu_time_description">Forces most games to run at their highest native resolution. Use 256 for maximal performance and 512 for maximal graphics fidelity.</string>
     <string name="skip_cpu_inner_invalidation">Skip CPU Inner Invalidation</string>
     <string name="skip_cpu_inner_invalidation_description">Skips certain CPU-side cache invalidations during memory updates, reducing CPU usage and improving it\'s performance. This may cause glitches or crashes on some games.</string>
+    <string name="antiflicker">Anti-Flicker</string>
+    <string name="antiflicker_description">Forces GPU fence callbacks to wait for submitted GPU work. Use with Fast GPU mode, to avoid flicker with lower performance impact.</string>
     <string name="fix_bloom_effects">Fix Bloom Effects</string>
     <string name="fix_bloom_effects_description">Reduces bloom blur in LA/EOW (Adreno A6XX - A7XX/ Turnip), removes bloom in Burnout. Warning: may cause graphical artifacts in other games.</string>
     <string name="emulate_bgr565">Emulate BGR565</string>

src/common/settings.h

@@ -545,6 +545,13 @@ struct Values {
                                                         Specialization::Default,
                                                         true,
                                                         true};
+    SwitchableSetting<bool> antiflicker{linkage,
+                                        false,
+                                        "antiflicker",
+                                        Category::RendererHacks,
+                                        Specialization::Default,
+                                        true,
+                                        true};
     SwitchableSetting<bool> async_presentation{linkage,
 #ifdef ANDROID
                                                false,

src/qt_common/config/shared_translation.cpp

@@ -193,6 +193,9 @@ std::unique_ptr<TranslationMap> InitializeTranslations(QObject* parent) {
     INSERT(Settings, skip_cpu_inner_invalidation, tr("Skip CPU Inner Invalidation"),
            tr("Skips certain cache invalidations during memory updates, reducing CPU usage and "
               "improving latency. This may cause soft-crashes."));
+    INSERT(Settings, antiflicker, tr("Anti-Flicker"),
+           tr("Forces GPU fence callbacks to wait for submitted GPU work.\n"
+              "Use with Fast GPU mode, to avoid flicker with lower performance impact."));
     INSERT(Settings, vsync_mode, tr("VSync Mode:"),
            tr("FIFO (VSync) does not drop frames or exhibit tearing but is limited by the screen "
               "refresh rate.\nFIFO Relaxed allows tearing as it recovers from a slow down.\n"

src/video_core/fence_manager.h

@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
 // SPDX-License-Identifier: GPL-3.0-or-later
 
 // SPDX-FileCopyrightText: Copyright 2020 yuzu Emulator Project
@@ -76,9 +76,9 @@ public:
             TryReleasePendingFences<false>();
         }
         const bool should_flush = ShouldFlush();
-        const bool delay_fence = Settings::IsGPULevelHigh() || (Settings::IsGPULevelMedium() && should_flush);
+        const bool delay_fence = Settings::values.antiflicker.GetValue() || !Settings::IsGPULevelLow();
         CommitAsyncFlushes();
-        TFence new_fence = CreateFence(!should_flush);
+        TFence new_fence = CreateFence(!should_flush && !delay_fence);
         if constexpr (can_async_check) {
             guard.lock();
         }