[Fix, Test] (MG_Backend/DirectGLES, MG_Util, CI): keep an explicit LOD constant under a new avoid flag - folding the bias uniform into it kills the ANGLE llvmpipe JIT

.github/workflows/apk.yml

@@ -411,6 +411,9 @@ jobs:
           if [ "${{ matrix.backend.name }}" = "DirectGLES" ] && [ "${{ matrix.case.name }}" = "minecraft-1.21.4-fabric-iris-bliss-in-world" ]; then
             extra_retrace_args+=(--avoid-angle-llvmpipe-sampler-mipmap-min-filter)
           fi
+          if [ "${{ matrix.backend.name }}" = "DirectGLES" ] && [ "${{ matrix.case.avoid_angle_llvmpipe_explicit_lod_bias || false }}" = "true" ]; then
+            extra_retrace_args+=(--avoid-angle-llvmpipe-explicit-lod-bias)
+          fi
           if [ "${{ matrix.case.coherent_as_flush || false }}" = "true" ]; then
             extra_retrace_args+=(--coherent-as-flush)
           fi

MobileGL/Config.h

@@ -89,6 +89,13 @@ namespace MobileGL::MG_Config {
         // MOBILEGL_AVOID_SAMPLER_MIPMAP_MIN_FILTER: avoid mipmap min filters in samplers,
         // resolves certain rendering bugs on ANGLE + llvmpipe.
         Bool AvoidSamplerMipmapMinFilter = false;
+        // MOBILEGL_AVOID_EXPLICIT_LOD_BIAS: leave an already-explicit LOD argument alone when
+        // emulating GL_TEXTURE_LOD_BIAS, instead of adding the bias uniform to it. Injecting
+        // the uniform turns a compile-time-constant LOD into a runtime expression, which
+        // sends ANGLE + llvmpipe down a mip-selection path that dereferences a NULL
+        // descriptor and kills the process. Deviates from spec (Vulkan adds the bias to
+        // OpImageSampleExplicitLod), so it is an avoidance for that stack only.
+        Bool AvoidExplicitLodBias = false;
         // MOBILEGL_COHERENT_AS_FLUSH: app-compat for engines (e.g. Flywheel) that write
         // GPU-read data through persistent GL_MAP_FLUSH_EXPLICIT_BIT maps they never
         // flush. Persistent FLUSH_EXPLICIT map requests are rewritten to coherent

MobileGL/ConfigLoader.cpp

@@ -171,6 +171,7 @@ namespace MobileGL::MG_ConfigLoader {
         features.MagmaFramesInFlight = QueryEnvUint32("MOBILEGL_MAGMA_FRAMESINFLIGHT", 3, 1, 64);
         features.AvoidSamplerMipmapMinFilter =
             QueryEnvFlag("MOBILEGL_AVOID_SAMPLER_MIPMAP_MIN_FILTER");
+        features.AvoidExplicitLodBias = QueryEnvFlag("MOBILEGL_AVOID_EXPLICIT_LOD_BIAS");
         features.CoherentAsFlush = QueryEnvFlag("MOBILEGL_COHERENT_AS_FLUSH");
         features.TraceSkipAutodestroy = QueryEnvFlag("MOBILEGL_TRACE_SKIP_AUTODESTROY");
         features.DisableUboRing = QueryEnvFlag("MOBILEGL_DISABLE_UBO_RING");

MobileGL/MG_Backend/DirectGLES/Managers.cpp

@@ -55,6 +55,12 @@ namespace MobileGL::MG_Backend::DirectGLES {
         return g_GLESCapabilities.AvoidSamplerMipmapMinFilter;
     }
 
+    static Bool ShouldAvoidExplicitLodBiasOnAngleLlvmpipe() {
+        // IsAngleLlvmpipeRenderer combined with the MOBILEGL_AVOID_EXPLICIT_LOD_BIAS
+        // feature toggle, both resolved in FillInGLESCapabilities.
+        return g_GLESCapabilities.AvoidExplicitLodBias;
+    }
+
     static GLenum ResolveBackendMinFilter(const SamplerParameters& samplerParams,
                                           Bool avoidMipmapMinFilter) {
         GLenum filter = MG_Util::ConvertSamplerFilterModeToGLEnum(samplerParams.minFilter,
@@ -4466,7 +4472,7 @@ namespace MobileGL::MG_Backend::DirectGLES {
                 source = ProcessOutColorLocations(source);
                 source = ForceFlatIntegerVaryings(source, glShaderType);
                 source = BroadcastLegacyFragColor(std::move(source), glShaderType, m_fragColorBroadcastCount);
-                source = EmulateTextureLodBias(source);
+                source = EmulateTextureLodBias(source, ShouldAvoidExplicitLodBiasOnAngleLlvmpipe());
                 source = EmulateBaseInstanceInVertexShader(std::move(source), glShaderType);
                 source = PromoteDrawParameterGlobalsToUniforms(std::move(source), glShaderType);
                 source = ForceSupporterOutput(source);

MobileGL/MG_Backend/DirectGLES/Utils.cpp

@@ -957,7 +957,7 @@ namespace MobileGL::MG_Backend::DirectGLES {
             }
         } // namespace
 
-        String EmulateTextureLodBias(const String& glslCode) {
+        String EmulateTextureLodBias(const String& glslCode, Bool avoidExplicitLodBias) {
 #ifdef TRACY_ENABLE
             ZoneScopedC(TRACY_ZONECOLOR_BACKEND);
 #endif
@@ -1018,6 +1018,11 @@ namespace MobileGL::MG_Backend::DirectGLES {
                 if (samplerIt == samplerNames.end()) continue;
 
                 const String& biasName = samplerIt->second;
+                if (form->explicitLodArg >= 0 && avoidExplicitLodBias) {
+                    // The lookup already names its level; leaving it alone keeps a constant
+                    // LOD constant. Costs the bias on explicit-LOD lookups only.
+                    continue;
+                }
                 if (form->explicitLodArg >= 0) {
                     // Explicit LOD: the bias adds to it, as Vulkan does for
                     // OpImageSampleExplicitLod and as the CTS reference expects.

MobileGL/MG_Backend/DirectGLES/Utils.h

@@ -183,7 +183,12 @@ namespace MobileGL::MG_Backend::DirectGLES {
         // the bound texture's (or sampler object's) value into it; a shader whose samplers
         // all have a zero bias is therefore unaffected. Returns the source unchanged when
         // there is nothing to rewrite.
-        String EmulateTextureLodBias(const String& glslCode);
+        //
+        // avoidExplicitLodBias leaves lookups that already carry an explicit LOD untouched,
+        // so their constant level stays constant; only the implicit-LOD forms take the bias.
+        // Off by default and only ever set on ANGLE + llvmpipe, where injecting the uniform
+        // into a constant LOD crashes the driver (MOBILEGL_AVOID_EXPLICIT_LOD_BIAS).
+        String EmulateTextureLodBias(const String& glslCode, Bool avoidExplicitLodBias = false);
     } // namespace PrgramImpl
 
     namespace Utils {

MobileGL/MG_Util/BackendLoaders/OpenGL/Loader.cpp

@@ -1343,6 +1343,8 @@ namespace MobileGL::MG_Util::BackendLoader {
             caps.IsAngleRenderer && caps.GLESRendererString.find("llvmpipe") != String::npos;
         caps.AvoidSamplerMipmapMinFilter =
             caps.IsAngleLlvmpipeRenderer && MG_Config::Features.AvoidSamplerMipmapMinFilter;
+        caps.AvoidExplicitLodBias =
+            caps.IsAngleLlvmpipeRenderer && MG_Config::Features.AvoidExplicitLodBias;
         MGLOG_I("    GL_EXT_disjoint_timer_query supported: %s",
                 caps.SupportsDisjointTimerQuery ? "true" : "false");
         MGLOG_I("    GL_KHR_parallel_shader_compile supported: %s",
@@ -1351,6 +1353,7 @@ namespace MobileGL::MG_Util::BackendLoader {
         MGLOG_I("    ANGLE llvmpipe renderer: %s", caps.IsAngleLlvmpipeRenderer ? "true" : "false");
         MGLOG_I("    Avoid sampler mipmap min filter: %s",
                 caps.AvoidSamplerMipmapMinFilter ? "true" : "false");
+        MGLOG_I("    Avoid explicit LOD bias: %s", caps.AvoidExplicitLodBias ? "true" : "false");
 
         return true;
     }

MobileGL/MG_Util/BackendLoaders/OpenGL/Loader.h

@@ -1156,6 +1156,9 @@ namespace MobileGL {
             // MOBILEGL_AVOID_SAMPLER_MIPMAP_MIN_FILTER feature toggle:
             // sampler min filters should drop their mipmap component.
             Bool AvoidSamplerMipmapMinFilter = false;
+            // IsAngleLlvmpipeRenderer combined with the MOBILEGL_AVOID_EXPLICIT_LOD_BIAS
+            // feature toggle: LOD-bias emulation should not touch explicit-LOD lookups.
+            Bool AvoidExplicitLodBias = false;
             // True when indirect draws leak the command's baseInstance word ("reserved,
             // must be zero" in unextended ES) into gl_InstanceID. Conforming ES drivers
             // keep gl_InstanceID zero-based; ANGLE's Vulkan backend hands the command

android-plugin/app/src/trace/cpp/trace_replay_core.cpp

@@ -154,6 +154,11 @@ bool LoadMobileGL(const Request& request, std::string& error) {
     } else {
         unsetenv("MOBILEGL_AVOID_SAMPLER_MIPMAP_MIN_FILTER");
     }
+    if (request.avoidAngleLlvmpipeExplicitLodBias) {
+        setenv("MOBILEGL_AVOID_EXPLICIT_LOD_BIAS", "1", 1);
+    } else {
+        unsetenv("MOBILEGL_AVOID_EXPLICIT_LOD_BIAS");
+    }
     if (request.coherentAsFlush) {
         setenv("MOBILEGL_COHERENT_AS_FLUSH", "1", 1);
     } else {
@@ -792,6 +797,8 @@ bool WriteResultJson(const Request& request, const Result& result) {
     file << "  \"usePbuffer\": " << (request.usePbuffer ? "true" : "false") << ",\n";
     file << "  \"avoidAngleLlvmpipeSamplerMipmapMinFilter\": "
          << (request.avoidAngleLlvmpipeSamplerMipmapMinFilter ? "true" : "false") << ",\n";
+    file << "  \"avoidAngleLlvmpipeExplicitLodBias\": "
+         << (request.avoidAngleLlvmpipeExplicitLodBias ? "true" : "false") << ",\n";
     file << "  \"holdMs\": " << request.holdMs << ",\n";
     file << "  \"mismatchPixels\": " << result.mismatchPixels << "\n";
     file << "}\n";

android-plugin/app/src/trace/cpp/trace_replay_core.hpp

@@ -39,6 +39,7 @@ struct Request {
     bool useAngle = false;
     bool usePbuffer = true;
     bool avoidAngleLlvmpipeSamplerMipmapMinFilter = false;
+    bool avoidAngleLlvmpipeExplicitLodBias = false;
     bool coherentAsFlush = false;
     int holdMs = 0;
 };

android-plugin/app/src/trace/cpp/trace_replay_jni.cpp

@@ -102,6 +102,7 @@ Java_top_mobilegl_plugin_trace_TraceReplayActivity_nativeRunTraceReplay(JNIEnv*
                                                                         jboolean useAngle,
                                                                         jboolean usePbuffer,
                                                                         jboolean avoidAngleLlvmpipeSamplerMipmapMinFilter,
+                                                                        jboolean avoidAngleLlvmpipeExplicitLodBias,
                                                                         jboolean coherentAsFlush) {
     mobilegl_trace::Request request;
     request.tracePath = ToString(env, tracePath);
@@ -127,6 +128,7 @@ Java_top_mobilegl_plugin_trace_TraceReplayActivity_nativeRunTraceReplay(JNIEnv*
     request.usePbuffer = usePbuffer == JNI_TRUE;
     request.avoidAngleLlvmpipeSamplerMipmapMinFilter =
         avoidAngleLlvmpipeSamplerMipmapMinFilter == JNI_TRUE;
+    request.avoidAngleLlvmpipeExplicitLodBias = avoidAngleLlvmpipeExplicitLodBias == JNI_TRUE;
     request.coherentAsFlush = coherentAsFlush == JNI_TRUE;
 
     ScopedTraceReplayState replayState;

android-plugin/app/src/trace/java/top/mobilegl/plugin/trace/TraceReplayActivity.java

@@ -114,6 +114,7 @@ public final class TraceReplayActivity extends Activity {
                 request.useAngle,
                 request.usePbuffer,
                 request.avoidAngleLlvmpipeSamplerMipmapMinFilter,
+                request.avoidAngleLlvmpipeExplicitLodBias,
                 request.coherentAsFlush
         );
         Log.i(TAG, result.toString());
@@ -145,6 +146,7 @@ public final class TraceReplayActivity extends Activity {
             boolean useAngle,
             boolean usePbuffer,
             boolean avoidAngleLlvmpipeSamplerMipmapMinFilter,
+            boolean avoidAngleLlvmpipeExplicitLodBias,
             boolean coherentAsFlush
     );
 
@@ -168,6 +170,7 @@ public final class TraceReplayActivity extends Activity {
         final boolean useAngle;
         final boolean usePbuffer;
         final boolean avoidAngleLlvmpipeSamplerMipmapMinFilter;
+        final boolean avoidAngleLlvmpipeExplicitLodBias;
         final boolean coherentAsFlush;
 
         private TraceReplayRequest(
@@ -190,6 +193,7 @@ public final class TraceReplayActivity extends Activity {
                 boolean useAngle,
                 boolean usePbuffer,
                 boolean avoidAngleLlvmpipeSamplerMipmapMinFilter,
+                boolean avoidAngleLlvmpipeExplicitLodBias,
                 boolean coherentAsFlush
         ) {
             this.tracePath = tracePath;
@@ -211,6 +215,7 @@ public final class TraceReplayActivity extends Activity {
             this.useAngle = useAngle;
             this.usePbuffer = usePbuffer;
             this.avoidAngleLlvmpipeSamplerMipmapMinFilter = avoidAngleLlvmpipeSamplerMipmapMinFilter;
+            this.avoidAngleLlvmpipeExplicitLodBias = avoidAngleLlvmpipeExplicitLodBias;
             this.coherentAsFlush = coherentAsFlush;
         }
 
@@ -237,6 +242,7 @@ public final class TraceReplayActivity extends Activity {
                     intent.getBooleanExtra("use_angle", false),
                     intent.getBooleanExtra("use_pbuffer", false),
                     intent.getBooleanExtra("avoid_angle_llvmpipe_sampler_mipmap_min_filter", false),
+                    intent.getBooleanExtra("avoid_angle_llvmpipe_explicit_lod_bias", false),
                     intent.getBooleanExtra("coherent_as_flush", false)
             );
         }

android-plugin/trace-replay-ci.sh

@@ -29,6 +29,7 @@ Usage:
     --crop-height N \
     [--use-pbuffer] \
     [--avoid-angle-llvmpipe-sampler-mipmap-min-filter] \
+    [--avoid-angle-llvmpipe-explicit-lod-bias] \
     [--coherent-as-flush] \
     --timeout-seconds N
 
@@ -40,6 +41,9 @@ Set MOBILEGL_RETRACE_USE_PBUFFER=1 or pass --use-pbuffer to run DirectGLES
 against an offscreen EGL pbuffer instead of the Activity surface.
 Pass --avoid-angle-llvmpipe-sampler-mipmap-min-filter for DirectGLES traces that
 need ANGLE llvmpipe sampler mipmap filters downgraded to avoid driver stalls.
+Pass --avoid-angle-llvmpipe-explicit-lod-bias for DirectGLES traces whose shaders
+sample with an explicit LOD that ANGLE llvmpipe cannot take a LOD bias on
+(MOBILEGL_AVOID_EXPLICIT_LOD_BIAS=1).
 Pass --coherent-as-flush for traces whose engine writes persistent
 GL_MAP_FLUSH_EXPLICIT_BIT maps it never flushes (MOBILEGL_COHERENT_AS_FLUSH=1).
 EOF
@@ -98,6 +102,7 @@ crop_width=""
 crop_height=""
 use_pbuffer=0
 avoid_angle_llvmpipe_sampler_mipmap_min_filter=0
+avoid_angle_llvmpipe_explicit_lod_bias=0
 coherent_as_flush=0
 timeout_seconds=""
 
@@ -134,6 +139,10 @@ while [ "$#" -gt 0 ]; do
       avoid_angle_llvmpipe_sampler_mipmap_min_filter=1
       shift 1
       ;;
+    --avoid-angle-llvmpipe-explicit-lod-bias)
+      avoid_angle_llvmpipe_explicit_lod_bias=1
+      shift 1
+      ;;
     --coherent-as-flush) coherent_as_flush=1; shift 1 ;;
     --timeout-seconds) timeout_seconds="$(next_arg "$@")"; shift 2 ;;
     -h|--help) usage; exit 0 ;;
@@ -320,6 +329,9 @@ run_retrace() {
   if [ "${avoid_angle_llvmpipe_sampler_mipmap_min_filter}" -eq 1 ] && [ "${backend}" = "DirectGLES" ]; then
     set -- "$@" --ez avoid_angle_llvmpipe_sampler_mipmap_min_filter true
   fi
+  if [ "${avoid_angle_llvmpipe_explicit_lod_bias}" -eq 1 ] && [ "${backend}" = "DirectGLES" ]; then
+    set -- "$@" --ez avoid_angle_llvmpipe_explicit_lod_bias true
+  fi
   if [ "${coherent_as_flush}" -eq 1 ]; then
     set -- "$@" --ez coherent_as_flush true
   fi

tools/trace_replay/README.md

@@ -275,7 +275,10 @@ default; pass `--ez use_pbuffer true` to use the offscreen pbuffer path. Always
 process-local. For cases registered with `coherent_as_flush` (Flywheel-style
 unflushed persistent maps, e.g. the Create fixtures), pass
 `--ez coherent_as_flush true` so the replay runs with
-`MOBILEGL_COHERENT_AS_FLUSH=1`.
+`MOBILEGL_COHERENT_AS_FLUSH=1`. For cases registered with
+`avoid_angle_llvmpipe_explicit_lod_bias` (DirectGLES on ANGLE llvmpipe, e.g. the
+sundial-lite fixture), pass `--ez avoid_angle_llvmpipe_explicit_lod_bias true` so
+the replay runs with `MOBILEGL_AVOID_EXPLICIT_LOD_BIAS=1`.
 
 ## Reproducing the Android DirectGLES lane on Linux (ANGLE on lavapipe)
 

tools/trace_replay/run_android_retrace_local.py

@@ -184,6 +184,8 @@ def run_case(case, backend):
         command.append("--use-pbuffer")
     if backend_info["use_angle"] and case["name"] == BLISS_CASE:
         command.append("--avoid-angle-llvmpipe-sampler-mipmap-min-filter")
+    if backend_info["use_angle"] and case.get("avoid_angle_llvmpipe_explicit_lod_bias"):
+        command.append("--avoid-angle-llvmpipe-explicit-lod-bias")
     if case.get("coherent_as_flush"):
         command.append("--coherent-as-flush")
     env = dict(**__import__("os").environ)

tools/trace_replay/trace_cases.json

@@ -181,7 +181,8 @@
       "name": "minecraft-1.21.4-fabric-iris-sundial-lite-in-world",
       "trace_archive": "minecraft-1.21.4-fabric-iris-sundial-lite-in-world.tgz",
       "golden": "minecraft-1.21.4-fabric-iris-sundial-lite-in-world.0000150023.png",
-      "target_call": 150023
+      "target_call": 150023,
+      "avoid_angle_llvmpipe_explicit_lod_bias": true
     },
     {
       "name": "minecraft-1.21.4-fabric-iris-complementary-reimagined-in-world",