HLSL: Non-functional: Move partial flattened access into symbol node.

Lays the groundwork for fixing issue #954.

Partial flattenings were previously tracked through a stack of active subsets
in the parse context, but full functionality needs AST nodes to represent
this across time, removing the need for parsecontext tracking.

glslang/Include/intermediate.h

@@ -945,7 +945,11 @@ public:
     // per process threadPoolAllocator, then it causes increased memory usage per compile
     // it is essential to use "symbol = sym" to assign to symbol
     TIntermSymbol(int i, const TString& n, const TType& t)
-        : TIntermTyped(t), id(i), constSubtree(nullptr)
+        : TIntermTyped(t), id(i),
+#ifdef ENABLE_HLSL
+        flattenSubset(-1),
+#endif
+        constSubtree(nullptr)
           { name = n; }
     virtual int getId() const { return id; }
     virtual const TString& getName() const { return name; }
@@ -956,9 +960,16 @@ public:
     const TConstUnionArray& getConstArray() const { return constArray; }
     void setConstSubtree(TIntermTyped* subtree) { constSubtree = subtree; }
     TIntermTyped* getConstSubtree() const { return constSubtree; }
+#ifdef ENABLE_HLSL
+    void setFlattenSubset(int subset) { flattenSubset = subset; }
+    int getFlattenSubset() const { return flattenSubset; } // -1 means full object
+#endif
 
 protected:
     int id;                      // the unique id of the symbol this node represents
+#ifdef ENABLE_HLSL
+    int flattenSubset;           // how deeply the flattened object rooted at id has been dereferenced
+#endif
     TString name;                // the name of the symbol this node represents
     TConstUnionArray constArray; // if the symbol is a front-end compile-time constant, this is its value
     TIntermTyped* constSubtree;

hlsl/hlslGrammar.cpp

@@ -2870,23 +2870,6 @@ bool HlslGrammar::acceptPostfixExpression(TIntermTyped*& node)
         return false;
     }
 
-    // This is to guarantee we do this no matter how we get out of the stack frame.
-    // This way there's no bug if an early return forgets to do it.
-    struct tFinalize {
-        tFinalize(HlslParseContext& p) : parseContext(p) { }
-        ~tFinalize() { parseContext.finalizeFlattening(); }
-        HlslParseContext& parseContext;
-    private:
-        const tFinalize& operator=(const tFinalize&) { return *this; }
-        tFinalize(const tFinalize& f) : parseContext(f.parseContext) { }
-    } finalize(parseContext);
-
-    // Initialize the flattening accumulation data, so we can track data across multiple bracket or
-    // dot operators.  This can also be nested, e.g, for [], so we have to track each nesting
-    // level: hence the init and finalize.  Even though in practice these must be
-    // constants, they are parsed no matter what.
-    parseContext.initFlattening();
-
     // Something was found, chain as many postfix operations as exist.
     do {
         TSourceLoc loc = token.loc;

hlsl/hlslParseHelper.cpp

@@ -1348,11 +1348,11 @@ TIntermTyped* HlslParseContext::flattenAccess(TIntermTyped* base, int member)
     const TType dereferencedType(base->getType(), member);  // dereferenced type
     const TIntermSymbol& symbolNode = *base->getAsSymbolNode();
 
-    TIntermTyped* flattened = flattenAccess(symbolNode.getId(), member, dereferencedType);
+    TIntermTyped* flattened = flattenAccess(symbolNode.getId(), member, dereferencedType, symbolNode.getFlattenSubset());
 
     return flattened ? flattened : base;
 }
-TIntermTyped* HlslParseContext::flattenAccess(int uniqueId, int member, const TType& dereferencedType)
+TIntermTyped* HlslParseContext::flattenAccess(int uniqueId, int member, const TType& dereferencedType, int subset)
 {
     const auto flattenData = flattenMap.find(uniqueId);
 
@@ -1360,18 +1360,24 @@ TIntermTyped* HlslParseContext::flattenAccess(int uniqueId, int member, const TT
         return nullptr;
 
     // Calculate new cumulative offset from the packed tree
-    flattenOffset.back() = flattenData->second.offsets[flattenOffset.back() + member];
+    int newSubset = flattenData->second.offsets[subset >= 0 ? subset + member : member];
 
+    TIntermSymbol* subsetSymbol;
     if (isFinalFlattening(dereferencedType)) {
         // Finished flattening: create symbol for variable
-        member = flattenData->second.offsets[flattenOffset.back()];
+        member = flattenData->second.offsets[newSubset];
         const TVariable* memberVariable = flattenData->second.members[member];
-        return intermediate.addSymbol(*memberVariable);
+        subsetSymbol = intermediate.addSymbol(*memberVariable);
+        subsetSymbol->setFlattenSubset(-1);
     } else {
+
         // If this is not the final flattening, accumulate the position and return
         // an object of the partially dereferenced type.
-        return new TIntermSymbol(uniqueId, "flattenShadow", dereferencedType);
+        subsetSymbol = new TIntermSymbol(uniqueId, "flattenShadow", dereferencedType);
+        subsetSymbol->setFlattenSubset(newSubset);
     }
+
+    return subsetSymbol;
 }
 
 // Find and return the split IO TVariable for id, or nullptr if none.
@@ -1753,11 +1759,9 @@ TIntermAggregate* HlslParseContext::handleFunctionDefinition(const TSourceLoc& l
                 flatten(loc, *variable);
                 const TTypeList* structure = variable->getType().getStruct();
                 for (int mem = 0; mem < (int)structure->size(); ++mem) {
-                    initFlattening();
                     paramNodes = intermediate.growAggregate(paramNodes,
                                                             flattenAccess(variable->getUniqueId(), mem, *(*structure)[mem].type),
                                                             loc);
-                    finalizeFlattening();
                 }
             } else {
                 // Add the parameter to the AST
@@ -4908,11 +4912,8 @@ void HlslParseContext::expandArguments(const TSourceLoc& loc, const TFunction& f
         if (wasFlattened(arg) && shouldFlatten(*function[param].type)) {
             // Need to pass the structure members instead of the structure.
             TVector<TIntermTyped*> memberArgs;
-            for (int memb = 0; memb < (int)arg->getType().getStruct()->size(); ++memb) {
+            for (int memb = 0; memb < (int)arg->getType().getStruct()->size(); ++memb)
-                initFlattening();
                 memberArgs.push_back(flattenAccess(arg, memb));
-                finalizeFlattening();
-            }
             setArgList(param + functionParamNumberOffset, memberArgs);
         }
     }

hlsl/hlslParseHelper.h

@@ -204,10 +204,6 @@ public:
     // Potentially rename shader entry point function
     void renameShaderFunction(const TString*& name) const;
 
-    // Reset data for incrementally built referencing of flattened composite structures
-    void initFlattening() { flattenLevel.push_back(0); flattenOffset.push_back(0); }
-    void finalizeFlattening() { flattenLevel.pop_back(); flattenOffset.pop_back(); }
-
     // Share struct buffer deep types
     void shareStructBufferType(TType&);
 
@@ -242,7 +238,7 @@ protected:
 
     // Array and struct flattening
     TIntermTyped* flattenAccess(TIntermTyped* base, int member);
-    TIntermTyped* flattenAccess(int uniqueId, int member, const TType&);
+    TIntermTyped* flattenAccess(int uniqueId, int member, const TType&, int subset = -1);
     bool shouldFlatten(const TType&) const;
     bool wasFlattened(const TIntermTyped* node) const;
     bool wasFlattened(int id) const { return flattenMap.find(id) != flattenMap.end(); }
@@ -368,7 +364,6 @@ protected:
 
     TMap<int, TFlattenData> flattenMap;
     TVector<int> flattenLevel;  // nested postfix operator level for flattening
-    TVector<int> flattenOffset; // cumulative offset for flattening
 
     // IO-type map. Maps a pure symbol-table form of a structure-member list into
     // each of the (up to) three kinds of IO, as each as different allowed decorations,