[Fix] (MG_State, MG_Backend/DirectGLES): join both link phases on the draw and drain paths, and refuse to bind a program whose SPIR-V never arrived

MobileGL/MG_Backend/DirectGLES/DirectGLES.cpp

@@ -2028,7 +2028,9 @@ namespace MobileGL::MG_Backend::DirectGLES {
             g_currentDrawFrontendProgram = nullptr;
             g_currentDrawBackendProgram = nullptr;
 
-            if (!currentProgram || !currentProgram->GetLinkStatus()) {
+            // ... || !GetSpirvStatus(): see BackendProgramObjectImpl::SyncToBackend - a
+            // program whose SPIR-V never arrived is linked but not drawable.
+            if (!currentProgram || !currentProgram->GetLinkStatus() || !currentProgram->GetSpirvStatus()) {
                 g_GLESFuncs.glUseProgram(0);
                 g_lastUsedBackendProgramId = 0;
                 return;
@@ -2589,7 +2591,7 @@ namespace MobileGL::MG_Backend::DirectGLES {
     static void BindCurrentProgramWithResources(
         const SharedPtr<MG_State::GLState::ProgramObject>& currentProgram,
         const TextureImpl::DrawTextureSyncKeys& keys) {
-        if (currentProgram && currentProgram->GetLinkStatus()) {
+        if (currentProgram && currentProgram->GetLinkStatus() && currentProgram->GetSpirvStatus()) {
 #ifdef TRACY_ENABLE
             ZoneScopedNC("BindCurrentProgram", TRACY_ZONECOLOR_BACKEND);
 #endif
@@ -2859,7 +2861,7 @@ namespace MobileGL::MG_Backend::DirectGLES {
     // is pinned for the duration. Prefers the per-draw stash those preparations wrote.
     static PrgramImpl::BackendProgramObjectImpl* GetCurrentBackendProgram() {
         const auto& currentProgram = MG_State::pGLContext->GetProgramForDraw();
-        if (!currentProgram || !currentProgram->GetLinkStatus()) {
+        if (!currentProgram || !currentProgram->GetLinkStatus() || !currentProgram->GetSpirvStatus()) {
             return nullptr;
         }
         if (PrgramImpl::g_currentDrawFrontendProgram == currentProgram.get()) {
@@ -3017,7 +3019,7 @@ namespace MobileGL::MG_Backend::DirectGLES {
         TextureImpl::SyncImageTextureBindings();
         PrgramImpl::SyncCurrentProgram(currentProgram);
 
-        if (!currentProgram || !currentProgram->GetLinkStatus()) {
+        if (!currentProgram || !currentProgram->GetLinkStatus() || !currentProgram->GetSpirvStatus()) {
             g_GLESFuncs.glUseProgram(0);
             PrgramImpl::g_lastUsedBackendProgramId = 0;
             return;

MobileGL/MG_Backend/DirectGLES/Managers.cpp

@@ -4156,8 +4156,14 @@ namespace MobileGL::MG_Backend::DirectGLES {
                 return;
             }
 
-            if (!stateProgramObject->GetLinkStatus()) {
-                MGLOG_E("Program object is not linked, skipping backend sync. State program ID: %u",
+            // GetSpirvStatus() as well as GetLinkStatus(): a program whose phase-B job was
+            // cancelled (teardown) or whose optimizer run failed is fully linked and fully
+            // queryable, but has no SPIR-V to build a driver program out of. GL cannot retract
+            // a LINK_STATUS it already reported true, so "linked but not drawable" is the
+            // answer, and this is where the ES backend expresses it.
+            if (!stateProgramObject->GetLinkStatus() || !stateProgramObject->GetSpirvStatus()) {
+                MGLOG_E("Program object is not linked or has no generated SPIR-V, skipping backend sync. State "
+                        "program ID: %u",
                         stateProgramObject->GetExternalIndex());
                 return;
             }

MobileGL/MG_State/GLState/Core.cpp

@@ -380,8 +380,14 @@ namespace MobileGL::MG_State {
                 // inside the same draw when it finally touched an artifact, and cache under a
                 // version the publish had already superseded. Settling here means every
                 // version a backend reads during a draw describes the program it is drawing.
-                // One null check in steady state.
-                currentProgram->JoinLink();
+                // Two null checks in steady state.
+                //
+                // BOTH phases, and that is not optional: the phase-B publish bumps those same
+                // versions, so joining only phase A here would leave exactly the hazard this
+                // site exists to close - a backend samples a version, then trips the phase-B
+                // gate through GetGeneratedSpirv() deeper inside the same draw, and memoizes
+                // under a version the publish has already superseded.
+                currentProgram->JoinLinkAndSpirv();
                 return currentProgram;
             }
             if (m_boundProgramPipeline == 0) return nullProgram;
@@ -398,7 +404,7 @@ namespace MobileGL::MG_State {
             // programs. In steady state this is a null check per stage.
             for (SizeT stage = 0; stage < static_cast<SizeT>(ShaderStage::ShaderStageCount); ++stage) {
                 const auto& stageProgram = pipeline->GetStageProgram(static_cast<ShaderStage>(stage));
-                if (stageProgram) stageProgram->JoinLink();
+                if (stageProgram) stageProgram->JoinLinkAndSpirv();
             }
 
             const auto signature = pipeline->ComputeDrawProgramSignature();
@@ -430,8 +436,9 @@ namespace MobileGL::MG_State {
             composite->Link(true);
             // P1 join site J2. The draw that asked for this program is the very next thing to
             // happen, so enqueueing the composite's link buys nothing and only moves the wait
-            // to whichever backend accessor happens to touch its artifacts first.
-            composite->JoinLink();
+            // to whichever backend accessor happens to touch its artifacts first. Both phases,
+            // for the same reason: the backend is about to read its SPIR-V.
+            composite->JoinLinkAndSpirv();
             pipeline->SetCachedDrawProgram(signature, Move(composite));
             return pipeline->GetCachedDrawProgram(signature);
         }

MobileGL/MG_State/GLState/ProgramState/ProgramState.cpp

@@ -111,9 +111,13 @@ namespace MobileGL::MG_State::GLState {
         // that can grow, and a reallocation underneath this loop would be a use-after-free
         // that only shows up on the one GL call that walks the whole table. The copy costs a
         // refcount bump on a path a mode switch takes at most once.
+        // BOTH phases per program. This is the glMaxShaderCompilerThreadsKHR(0) path, whose
+        // contract is that nothing is outstanding when it returns - a program left with its
+        // SPIR-V job in flight would make the very next GL_COMPLETION_STATUS_KHR read GL_FALSE
+        // in a mode the extension says cannot have anything pending.
         for (SizeT i = 0; i < m_programObjects.size(); ++i) {
             const SharedPtr<ProgramObject> program = m_programObjects[i];
-            if (program) program->JoinLink();
+            if (program) program->JoinLinkAndSpirv();
         }
         for (SizeT i = 0; i < m_shaderObjects.size(); ++i) {
             const SharedPtr<ShaderObject> shader = m_shaderObjects[i];
@@ -122,7 +126,7 @@ namespace MobileGL::MG_State::GLState {
         // The currently-used program is reachable through m_programObjects unless
         // glDeleteProgram already freed its slot while it stayed current. Nothing else holds
         // a GL-visible name for it, but a draw would still join it, so settle it here too.
-        if (m_currentProgram) m_currentProgram->JoinLink();
+        if (m_currentProgram) m_currentProgram->JoinLinkAndSpirv();
     }
 
     void ProgramState::MarkShaderObjectForDeletion(Uint shader) {