[Fix] (MG_State, MG_Util): a default-block uniform starts at its declared initializer instead of zero

MobileGL/MG_State/GLState/ProgramState/ProgramLinkTask.cpp

@@ -301,6 +301,29 @@ namespace MobileGL::MG_State::GLState {
         Vector<SharedPtr<glslang::TShader>> shaders;
         if (!ConsumeShaders(shaders)) return;
 
+        // Harvest the declared default-block uniform initializers before the TShaders are
+        // handed to the linker. They come from the parse itself (glslang folds the constant
+        // and hands it over instead of dropping it), not from a lexical scan, so an
+        // expression like vec3(10, 20, 30) or int[](1, 2, 3) is already evaluated.
+        //
+        // Stage order decides a tie. GLSL requires a uniform declared in several stages to be
+        // declared identically, initializer included, so a conflict is a malformed program;
+        // taking the first stage's value keeps a link that other implementations accept from
+        // failing here, and both stages agree in every well-formed one.
+        for (const auto& shader : shaders) {
+            const glslang::TIntermediate* intermediate = shader ? shader->getIntermediate() : nullptr;
+            if (intermediate == nullptr) continue;
+            for (const auto& initializer : intermediate->getUniformInitializers()) {
+                const auto known = std::find_if(artifacts.uniformInitialValues.begin(),
+                                                artifacts.uniformInitialValues.end(),
+                                                [&initializer](const auto& existing) {
+                                                    return existing.name == initializer.name;
+                                                });
+                if (known != artifacts.uniformInitialValues.end()) continue;
+                artifacts.uniformInitialValues.push_back(initializer);
+            }
+        }
+
         // Merge the shaders' lexically extracted explicit uniform locations. The same
         // uniform declared in several stages must agree on its location (config-A glslang
         // enforced this at mapIO; the relaxed parse no longer sees the qualifiers).

MobileGL/MG_State/GLState/ProgramState/ProgramObject.cpp

@@ -90,8 +90,11 @@ namespace MobileGL::MG_State::GLState {
         // A node that settled as Cancelled published nothing, so m_spirv stays empty with
         // spirvStatus false: linked, queryable, not drawable. Nothing to repair.
 
-        // Before the version bump, and before any caller can read the shadow: the writes the
+        // Order matters, and it is the GL order. The shadow arrives zero-filled; the shaders'
-        // application made while the layout did not exist yet.
+        // declared uniform initializers are what it should actually start from, and only then
+        // do the application's own writes - the ones it made while the layout did not exist
+        // yet - land on top. Seeding after the replay would clobber them.
+        ApplyUniformInitialValues();
         ReplayBufferedUniformWrites();
 
         // The THIRD version bump of this link (enqueue, phase-A publish, phase-B publish), and
@@ -126,6 +129,89 @@ namespace MobileGL::MG_State::GLState {
         return true;
     }
 
+    // "uniform vec3 v = vec3(10, 20, 30);" - legal desktop GLSL since 1.20, and the value is
+    // what the uniform reads until glUniform* replaces it (and again after every relink).
+    // MobileGL parses with Vulkan-relaxed rules, which sweep default-block uniforms into
+    // MGL_GLOBAL_UBO; a block member cannot carry an initializer in SPIR-V, so glslang hands
+    // the folded constants over as a side-channel (TIntermediate::getUniformInitializers) and
+    // this is where they are honoured. Without it every such uniform silently read zero -
+    // which is what half of KHR-GL43.shader_storage_buffer_object was actually failing on.
+    //
+    // Writes go straight into the shadow rather than through glUniform*: this runs INSIDE the
+    // phase-B publish, so re-entering the join gate is not available, and the location space
+    // reflection assigns (one location per array element) is all that is needed.
+    void ProgramObject::ApplyUniformInitialValues() const {
+        const auto& initializers = m_artifacts.uniformInitialValues;
+        if (initializers.empty()) return;
+        if (m_spirv.globalUboScratch.empty() || m_spirv.uniformOffsets.empty()) {
+            // Phase B published no shadow (cancelled, or superseded by a relink). The program
+            // is not drawable; there is nowhere for these to land.
+            return;
+        }
+
+        Uint8* const scratch = m_spirv.globalUboScratch.data();
+        const SizeT uboSize = m_spirv.globalUboScratch.size();
+
+        for (const auto& init : initializers) {
+            // Scalars per array ELEMENT. A matrix element carries cols * rows of them, laid
+            // out column by column - which is also the order glslang folded them in.
+            const Int columns = init.matrixCols;
+            const Int rows = init.matrixRows;
+            const Int componentsPerElement = columns > 0 ? columns * rows : init.vectorSize;
+            const Int elements = init.arraySize;
+            if (componentsPerElement <= 0 || elements <= 0) continue;
+
+            const Bool isFloat = init.basicType == glslang::EbtFloat || init.basicType == glslang::EbtFloat16;
+            const Bool isInt = init.basicType == glslang::EbtInt || init.basicType == glslang::EbtUint ||
+                               init.basicType == glslang::EbtBool;
+            // Anything else (fp64, 64-bit integers) has no 32-bit shadow encoding here, and a
+            // half-written uniform is worse than an untouched one.
+            if (!isFloat && !isInt) continue;
+            const SizeT provided = isFloat ? init.floatValues.size() : init.intValues.size();
+            if (provided < static_cast<SizeT>(componentsPerElement) * static_cast<SizeT>(elements)) continue;
+
+            const Int baseLocation = GetUniformLocation(init.name);
+            if (baseLocation < 0) continue; // optimized away, or not a default-block uniform
+
+            for (Int element = 0; element < elements; ++element) {
+                const Int location = baseLocation + element;
+                if (element > 0 && !UniformLocationsAliasSameUniform(baseLocation, location)) break;
+                if (!IsValidUniformLocation(location)) break;
+                const Uint offset = GetUniformOffset(static_cast<Uint>(location));
+                if (offset == kInvalidUniformOffset) continue;
+
+                // std140 pads every column of a float matrix out to a vec4, so the columns of
+                // a mat3 are 16 bytes apart even though each carries 12. The slot's own span
+                // states the stride the rest of the pipeline agreed on rather than guessing it.
+                const SizeT slotSpan = GetUniformStorageSpanInBytes(static_cast<Uint>(location));
+                const SizeT columnStride =
+                    columns > 0 ? slotSpan / static_cast<SizeT>(columns) : slotSpan;
+                const Int componentsPerColumn = columns > 0 ? rows : componentsPerElement;
+                const Int columnCount = columns > 0 ? columns : 1;
+
+                for (Int column = 0; column < columnCount; ++column) {
+                    const SizeT byteOffset = static_cast<SizeT>(offset) + static_cast<SizeT>(column) * columnStride;
+                    const SizeT writeSize = static_cast<SizeT>(componentsPerColumn) * sizeof(Uint32);
+                    if (byteOffset + writeSize > uboSize) break;
+                    const SizeT firstComponent = static_cast<SizeT>(element) * componentsPerElement +
+                                                 static_cast<SizeT>(column) * componentsPerColumn;
+                    for (Int component = 0; component < componentsPerColumn; ++component) {
+                        const SizeT source = firstComponent + static_cast<SizeT>(component);
+                        Uint8* const destination = scratch + byteOffset + component * sizeof(Uint32);
+                        if (isFloat) {
+                            const Float value = static_cast<Float>(init.floatValues[source]);
+                            std::memcpy(destination, &value, sizeof(value));
+                        } else {
+                            const Int32 value = static_cast<Int32>(init.intValues[source]);
+                            std::memcpy(destination, &value, sizeof(value));
+                        }
+                    }
+                }
+            }
+        }
+        MarkUBOContentDirty();
+    }
+
     void ProgramObject::ReplayBufferedUniformWrites() const {
         if (m_pendingUniformWrites.empty()) {
             m_pendingUniformBytes.clear();
@@ -234,6 +320,7 @@ namespace MobileGL::MG_State::GLState {
         artifacts.glBlockIndexToTProgram.clear();
         artifacts.tProgramBlockIndexToGl.clear();
         artifacts.linkedExplicitUniformLocations.clear();
+        artifacts.uniformInitialValues.clear();
         artifacts.uniformIndexInTProgram.clear();
         artifacts.uniformSamplerOrImageUnitIndex.clear();
         artifacts.explicitOpaqueUniformBindings.clear();

MobileGL/MG_State/GLState/ProgramState/ProgramObject.h

@@ -756,6 +756,13 @@ namespace MobileGL::MG_State::GLState {
             // layout(location = N) default-block uniform qualifiers (the relaxed parse drops
             // them from reflection; the DoReflection assigner restores them from here).
             UnorderedMap<String, Int> linkedExplicitUniformLocations;
+            // Per-link snapshot of the default-block uniform INITIALIZERS the attached shaders
+            // declared ("uniform int i = 1;"). Desktop GLSL says that value is what the uniform
+            // reads until the application overwrites it, and relinking restores it - but the
+            // relaxed parse turns those uniforms into members of MGL_GLOBAL_UBO, where SPIR-V
+            // cannot carry an initializer, so the value only survives as this side-channel.
+            // Applied into the uniform shadow at the phase-B publish (ApplyUniformInitialValues).
+            Vector<glslang::TIntermediate::TUniformInitializer> uniformInitialValues;
             UnorderedMap<String, Uint> uniformLocations;
             // Ordered by location,
             // aka. uniformIndexInTProgram[loc] == "uniform index of TProgram at location `loc`"
@@ -1010,6 +1017,10 @@ namespace MobileGL::MG_State::GLState {
         // detour exactly - and a record that really does change bytes moves the version, which
         // is what makes a backend re-upload the UBO it cached during the window.
         void ReplayBufferedUniformWrites() const;
+        // Seeds the freshly published uniform shadow with the declared initializers. Runs at
+        // the phase-B publish, BEFORE ReplayBufferedUniformWrites, so an application write
+        // made during the A->B window still wins - which is the GL ordering.
+        void ApplyUniformInitialValues() const;
         // Past this, BufferUniformWrite declines and the write joins instead. Sized so an
         // ordinary pack load never reaches it (a pending window is one program's worth of
         // uniforms) while a pathological writer cannot grow the heap without bound.

include/glslang/MachineIndependent/ParseHelper.h

@@ -367,6 +367,7 @@ public:
 
     TIntermTyped* vkRelaxedRemapFunctionCall(const TSourceLoc&, TFunction*, TIntermNode*);
     // returns true if the variable was remapped to something else
+    void recordUniformInitializer(const TString&, const TType&, const TConstUnionArray&);
     bool vkRelaxedRemapUniformVariable(const TSourceLoc&, TString&, const TPublicType&, TArraySizes*, TIntermTyped*, TType&);
     void vkRelaxedRemapUniformMembers(const TSourceLoc&, const TPublicType&, const TType&, const TString&);
     void vkRelaxedRemapFunctionParameter(TFunction*, TParameter&, std::vector<int>* newParams = nullptr);

include/glslang/MachineIndependent/localintermediate.h

@@ -611,6 +611,32 @@ public:
     void setGlobalUniformBinding(unsigned int binding) { globalUniformBlockBinding = binding; }
     unsigned int getGlobalUniformBinding() const { return globalUniformBlockBinding; }
 
+    // A default-block uniform's initializer, folded to constants at parse time.
+    //
+    // Desktop GLSL 1.20+ lets a default-block uniform carry an initializer, and that value is
+    // what the uniform reads until the application overwrites it with glUniform*. Vulkan-relaxed
+    // parsing sweeps such uniforms into a uniform BLOCK, and a block member cannot carry an
+    // initializer in SPIR-V - so the value has nowhere to live in the generated module and used
+    // to be dropped outright, leaving the uniform silently zero. The CLIENT is the only party
+    // that can still honor it, by writing the value into the block's backing storage once the
+    // program links, so the folded constants are handed out here instead of discarded.
+    //
+    // Scalars appear in the same flattened order glslang folds them in: array element by array
+    // element, and within a matrix, column by column. Exactly one of the two value vectors is
+    // populated, chosen by basicType.
+    struct TUniformInitializer {
+        std::string name;
+        TBasicType basicType = EbtVoid;
+        int vectorSize = 1;  // components per vector; 1 for a scalar
+        int matrixCols = 0;  // 0 when the type is not a matrix
+        int matrixRows = 0;
+        int arraySize = 1;   // outer array element count; 1 when not an array
+        std::vector<long long> intValues;
+        std::vector<double> floatValues;
+    };
+    void addUniformInitializer(TUniformInitializer&& init) { uniformInitializers.push_back(std::move(init)); }
+    const std::vector<TUniformInitializer>& getUniformInitializers() const { return uniformInitializers; }
+
     void setAtomicCounterBlockName(const char* name) { atomicCounterBlockName = std::string(name); }
     const char* getAtomicCounterBlockName() const { return atomicCounterBlockName.c_str(); }
     void setAtomicCounterBlockSet(unsigned int set) { atomicCounterBlockSet = set; }
@@ -1223,6 +1249,7 @@ protected:
 
     std::string globalUniformBlockName;
     std::string atomicCounterBlockName;
+    std::vector<TUniformInitializer> uniformInitializers;
     unsigned int globalUniformBlockSet;
     unsigned int globalUniformBlockBinding;
     unsigned int atomicCounterBlockSet;