Pure Texture to Sampled Texture Transform

Adds a transformation step to the post processing step.
Two modes are available:
1) keep
- Keeps samplers, textures and sampled textures as is
2) transform pure texture into sampled texture and remove pure samplers
- removes all pure samplers
- transforms all pure textures into its sampled counter part

Change-Id: If54972e8052961db66c23f4b7e719d363cf6edbd

glslang/MachineIndependent/Intermediate.cpp

@@ -1776,6 +1776,14 @@ bool TIntermediate::postProcess(TIntermNode* root, EShLanguage /*language*/)
     // Propagate 'noContraction' label in backward from 'precise' variables.
     glslang::PropagateNoContraction(*this);
 
+    switch (textureSamplerTransformMode) {
+    case EShTexSampTransKeep:
+        break;
+    case EShTexSampTransUpgradeTextureRemoveSampler:
+        performTextureUpgradeAndSamplerRemovalTransformation(root);
+        break;
+    }
+
     return true;
 }
 
@@ -2943,4 +2951,41 @@ bool TIntermediate::specConstantPropagates(const TIntermTyped& node1, const TInt
            (node2.getType().getQualifier().isSpecConstant() && node1.getType().getQualifier().isConstant());
 }
 
+struct TextureUpgradeAndSamplerRemovalTransform : public TIntermTraverser {
+    bool visitAggregate(TVisit, TIntermAggregate* ag) override {
+        using namespace std;
+        TIntermSequence& seq = ag->getSequence();
+        // remove pure sampler variables
+        TIntermSequence::iterator newEnd = remove_if(seq.begin(), seq.end(), [](TIntermNode* node) {
+            TIntermSymbol* symbol = node->getAsSymbolNode();
+            if (!symbol)
+                return false;
+
+            return (symbol->getBasicType() == EbtSampler && symbol->getType().getSampler().isPureSampler());
+        });
+        seq.erase(newEnd, seq.end());
+        // replace constructors with sampler/textures
+        // update textures into sampled textures
+        for_each(seq.begin(), seq.end(), [](TIntermNode*& node) {
+            TIntermSymbol* symbol = node->getAsSymbolNode();
+            if (!symbol) {
+                TIntermAggregate *constructor = node->getAsAggregate();
+                if (constructor && constructor->getOp() == EOpConstructTextureSampler) {
+                    if (!constructor->getSequence().empty())
+                        node = constructor->getSequence()[0];
+                }
+            } else if (symbol->getBasicType() == EbtSampler && symbol->getType().getSampler().isTexture()) {
+                symbol->getWritableType().getSampler().combined = true;
+            }
+        });
+        return true;
+    }
+};
+
+void TIntermediate::performTextureUpgradeAndSamplerRemovalTransformation(TIntermNode* root)
+{
+    TextureUpgradeAndSamplerRemovalTransform transform;
+    root->traverse(&transform);
+}
+
 } // end namespace glslang

glslang/MachineIndependent/ShaderLang.cpp

@@ -1578,6 +1578,7 @@ void TShader::setHlslIoMapping(bool hlslIoMap)          { intermediate->setHlslI
 void TShader::setFlattenUniformArrays(bool flatten)     { intermediate->setFlattenUniformArrays(flatten); }
 void TShader::setNoStorageFormat(bool useUnknownFormat) { intermediate->setNoStorageFormat(useUnknownFormat); }
 void TShader::setResourceSetBinding(const std::vector<std::string>& base)   { intermediate->setResourceSetBinding(base); }
+void TShader::setTextureSamplerTransformMode(EShTextureSamplerTransformMode mode) { intermediate->setTextureSamplerTransformMode(mode); }
 
 //
 // Turn the shader strings into a parse tree in the TIntermediate.

glslang/MachineIndependent/localintermediate.h

@@ -182,7 +182,8 @@ public:
         useUnknownFormat(false),
         hlslOffsets(false),
         useStorageBuffer(false),
-        hlslIoMapping(false)
+        hlslIoMapping(false),
+        textureSamplerTransformMode(EShTexSampTransKeep)
     {
         localSize[0] = 1;
         localSize[1] = 1;
@@ -233,6 +234,7 @@ public:
     bool usingStorageBuffer() const { return useStorageBuffer; }
     void setHlslIoMapping(bool b) { hlslIoMapping = b; }
     bool usingHlslIoMapping()     { return hlslIoMapping; }
+    void setTextureSamplerTransformMode(EShTextureSamplerTransformMode mode) { textureSamplerTransformMode = mode; }
 
     void setVersion(int v) { version = v; }
     int getVersion() const { return version; }
@@ -472,6 +474,7 @@ protected:
     void pushSelector(TIntermSequence&, const TVectorSelector&, const TSourceLoc&);
     void pushSelector(TIntermSequence&, const TMatrixSelector&, const TSourceLoc&);
     bool specConstantPropagates(const TIntermTyped&, const TIntermTyped&);
+    void performTextureUpgradeAndSamplerRemovalTransformation(TIntermNode* root);
 
     const EShLanguage language;  // stage, known at construction time
     EShSource source;            // source language, known a bit later
@@ -536,6 +539,8 @@ protected:
     std::unordered_set<int> usedConstantId; // specialization constant ids used
     std::set<TString> semanticNameSet;
 
+    EShTextureSamplerTransformMode textureSamplerTransformMode;
+
 private:
     void operator=(TIntermediate&); // prevent assignments
 };