From b1d379eeba2f97a7d258373fe27828d8195c6c2b Mon Sep 17 00:00:00 2001
From: Arkady Shlykov <arkady.shlykov@intel.com>
Date: Thu, 2 Apr 2026 13:30:34 +0000
Subject: [PATCH] anv: Add control over divergent atomics fusion opt via
 driconf

anv_enable_opt_divergent_atomics dricong option supported values:
   1 - fuse buffer divergent atomics
   2 - fuse image divergent atomics

Enabled for titles:
   Total War: WARHAMMER III
   The Elder Scrolls IV: Oblivion Remastered
   Call of Duty: Black Ops III

Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/40631>
---
 src/intel/vulkan/anv_instance.c       |  3 +++
 src/intel/vulkan/anv_private.h        |  1 +
 src/intel/vulkan/anv_shader_compile.c |  1 +
 src/util/00-mesa-defaults.conf        | 10 ++++++++++
 src/util/driconf.h                    |  4 ++++
 5 files changed, 19 insertions(+)

diff --git a/src/intel/vulkan/anv_instance.c b/src/intel/vulkan/anv_instance.c
index 0a3b43522ce..aa270a39efb 100644
--- a/src/intel/vulkan/anv_instance.c
+++ b/src/intel/vulkan/anv_instance.c
@@ -40,6 +40,7 @@ static const driOptionDescription anv_dri_options[] = {
       DRI_CONF_ANV_QUERY_COPY_WITH_SHADER_THRESHOLD(6)
       DRI_CONF_ANV_FORCE_INDIRECT_DESCRIPTORS(false)
       DRI_CONF_ANV_DISABLE_LINK_TIME_OPTIMIZATION(false)
+      DRI_CONF_ANV_ENABLE_OPT_DIVERGENT_ATOMICS(0)
       DRI_CONF_SHADER_SPILLING_RATE(11)
       DRI_CONFIG_INTEL_FORCE_COMPUTE_SURFACE_PREFETCH(true)
       DRI_CONFIG_INTEL_FORCE_SAMPLER_PREFETCH(false)
@@ -268,6 +269,8 @@ anv_init_dri_options(struct anv_instance *instance)
 
     instance->disable_lto =
         driQueryOptionb(&instance->dri_options, "anv_disable_link_time_optimization");
+    instance->enable_opt_divergent_atomics =
+        driQueryOptioni(&instance->dri_options, "anv_enable_opt_divergent_atomics");
 
     instance->stack_ids = driQueryOptioni(&instance->dri_options, "intel_stack_id");
     switch (instance->stack_ids) {
diff --git a/src/intel/vulkan/anv_private.h b/src/intel/vulkan/anv_private.h
index a01a0d2d5e4..e4b9ccfc5be 100644
--- a/src/intel/vulkan/anv_private.h
+++ b/src/intel/vulkan/anv_private.h
@@ -1848,6 +1848,7 @@ struct anv_instance {
      * Performance workarounds
      */
     bool                                        disable_lto;
+    enum brw_divergent_atomics_flags            enable_opt_divergent_atomics;
 
     /**
      * Ray tracing configuration.
diff --git a/src/intel/vulkan/anv_shader_compile.c b/src/intel/vulkan/anv_shader_compile.c
index 4bf599d70af..e5f67bcd3df 100644
--- a/src/intel/vulkan/anv_shader_compile.c
+++ b/src/intel/vulkan/anv_shader_compile.c
@@ -293,6 +293,7 @@ populate_base_prog_key(struct brw_base_prog_key *key,
     */
    if (rs != NULL)
       key->robust_flags = anv_get_robust_flags(rs);
+   key->divergent_atomics_flags = pdevice->instance->enable_opt_divergent_atomics;
    key->limit_trig_input_range = pdevice->instance->limit_trig_input_range;
 }
 
diff --git a/src/util/00-mesa-defaults.conf b/src/util/00-mesa-defaults.conf
index 45c656b63dc..800233970d1 100644
--- a/src/util/00-mesa-defaults.conf
+++ b/src/util/00-mesa-defaults.conf
@@ -1131,6 +1131,16 @@ TODO: document the other workarounds.
         </application>
         <application name="Total War: WARHAMMER III" executable="TotalWarhammer3">
             <option name="anv_fake_nonlocal_memory" value="true" />
+            <option name="anv_enable_opt_divergent_atomics" value="1" />
+        </application>
+        <application name="Total War: WARHAMMER III" executable="Warhammer3.exe">
+            <option name="anv_enable_opt_divergent_atomics" value="1" />
+        </application>
+        <application name="The Elder Scrolls IV: Oblivion Remastered" executable="OblivionRemastered-Win.exe">
+            <option name="anv_enable_opt_divergent_atomics" value="1" />
+        </application>
+        <application name="Call of Duty: Black Ops III" executable="BlackOps3.exe">
+            <option name="anv_enable_opt_divergent_atomics" value="1" />
         </application>
         <application name="Horizon Forbidden West" executable="HorizonForbiddenWest.exe">
             <!-- Missing barrier between clear/init shader & write
diff --git a/src/util/driconf.h b/src/util/driconf.h
index 5db3866d0c8..398f6829ec7 100644
--- a/src/util/driconf.h
+++ b/src/util/driconf.h
@@ -976,6 +976,10 @@
    DRI_CONF_OPT_B(anv_barrier_post_typed_clear_shader, def, \
                   "Insert pipeline barriers post clearing shader on typed data")
 
+#define DRI_CONF_ANV_ENABLE_OPT_DIVERGENT_ATOMICS(def) \
+   DRI_CONF_OPT_I(anv_enable_opt_divergent_atomics, def, 0, 3,\
+                  "Enable fusion of divergent atomics (see brw_divergent_atomics_flags)")
+
 /**
  * \brief HASVK specific configuration options
  */