GL_EXT_vulkan_glsl_relaxed - retarget gl_VertexID to gl_VertexIndex

instead of allowing for multiple declarations of the variable in the
resulting SPIR-V, instead use a retargeted mechanism to cause references
to gl_VertexID and gl_InstanceID to use the gl_VertexIndex and
gl_InstanceIndex symbol.

glslang/MachineIndependent/Initialize.cpp

@@ -7701,6 +7701,11 @@ static void BuiltInVariable(const char* name, TBuiltInVariable builtIn, TSymbolT
     symQualifier.builtIn = builtIn;
 }
 
+static void RetargetVariable(const char* from, const char* to, TSymbolTable& symbolTable)
+{
+    symbolTable.retargetSymbol(from, to);
+}
+
 //
 // For built-in variables inside a named block.
 // SpecialQualifier() won't ever go inside a block; their member's qualifier come
@@ -7768,8 +7773,8 @@ void TBuiltIns::identifyBuiltIns(int version, EProfile profile, const SpvVersion
 
         if (spvVersion.vulkan > 0 && spvVersion.vulkanRelaxed) {
             // treat these built-ins as aliases of VertexIndex and InstanceIndex
-            BuiltInVariable("gl_VertexID", EbvVertexIndex, symbolTable);
-            BuiltInVariable("gl_InstanceID", EbvInstanceIndex, symbolTable);
+            RetargetVariable("gl_InstanceID", "gl_InstanceIndex", symbolTable);
+            RetargetVariable("gl_VertexID", "gl_VertexIndex", symbolTable);
         }
 
         if (profile != EEsProfile) {

glslang/MachineIndependent/SymbolTable.cpp

@@ -279,8 +279,14 @@ TFunction::~TFunction()
 //
 TSymbolTableLevel::~TSymbolTableLevel()
 {
-    for (tLevel::iterator it = level.begin(); it != level.end(); ++it)
-        delete (*it).second;
+    for (tLevel::iterator it = level.begin(); it != level.end(); ++it) {
+        const TString& name = it->first;
+        auto retargetIter = std::find_if(retargetedSymbols.begin(), retargetedSymbols.end(),
+                                      [&name](const std::pair<TString, TString>& i) { return i.first == name; });
+        if (retargetIter == retargetedSymbols.end())
+            delete (*it).second;
+    }
+
 
     delete [] defaultPrecision;
 }
@@ -418,6 +424,15 @@ TSymbolTableLevel* TSymbolTableLevel::clone() const
     TSymbolTableLevel *symTableLevel = new TSymbolTableLevel();
     symTableLevel->anonId = anonId;
     symTableLevel->thisLevel = thisLevel;
+    symTableLevel->retargetedSymbols.clear();
+    for (auto &s : retargetedSymbols) {
+        // Extra constructions to make sure they use the correct allocator pool
+        TString newFrom;
+        newFrom = s.first;
+        TString newTo;
+        newTo = s.second;
+        symTableLevel->retargetedSymbols.push_back({std::move(newFrom), std::move(newTo)});
+    }
     std::vector<bool> containerCopied(anonId, false);
     tLevel::const_iterator iter;
     for (iter = level.begin(); iter != level.end(); ++iter) {
@@ -433,8 +448,25 @@ TSymbolTableLevel* TSymbolTableLevel::clone() const
                 symTableLevel->insert(*container, false);
                 containerCopied[anon->getAnonId()] = true;
             }
-        } else
+        } else {
+            const TString& name = iter->first;
+            auto retargetIter = std::find_if(retargetedSymbols.begin(), retargetedSymbols.end(),
+                                          [&name](const std::pair<TString, TString>& i) { return i.first == name; });
+            if (retargetIter != retargetedSymbols.end())
+                continue;
             symTableLevel->insert(*iter->second->clone(), false);
+        }
+    }
+    // Now point retargeted symbols to the newly created versions of them
+    for (auto &s : retargetedSymbols) {
+        TSymbol* sym = symTableLevel->find(s.second);
+        if (!sym)
+            continue;
+
+        // Need to declare and assign so newS is using the correct pool allocator
+        TString newS;
+        newS = s.first;
+        symTableLevel->insert(newS, sym);
     }
 
     return symTableLevel;

glslang/MachineIndependent/SymbolTable.h

@@ -413,13 +413,20 @@ public:
     TSymbolTableLevel() : defaultPrecision(0), anonId(0), thisLevel(false) { }
     ~TSymbolTableLevel();
 
-    bool insert(TSymbol& symbol, bool separateNameSpaces)
+    bool insert(const TString& name, TSymbol* symbol) {
+        return level.insert(tLevelPair(name, symbol)).second;
+    }
+
+    bool insert(TSymbol& symbol, bool separateNameSpaces, const TString& forcedKeyName = TString())
     {
         //
         // returning true means symbol was added to the table with no semantic errors
         //
         const TString& name = symbol.getName();
-        if (name == "") {
+        if (forcedKeyName.length()) {
+            return level.insert(tLevelPair(forcedKeyName, &symbol)).second;
+        }
+        else if (name == "") {
             symbol.getAsVariable()->setAnonId(anonId++);
             // An empty name means an anonymous container, exposing its members to the external scope.
             // Give it a name and insert its members in the symbol table, pointing to the container.
@@ -471,6 +478,16 @@ public:
         return true;
     }
 
+    void retargetSymbol(const TString& from, const TString& to) {
+        tLevel::const_iterator fromIt = level.find(from);
+        tLevel::const_iterator toIt = level.find(to);
+        if (fromIt == level.end() || toIt == level.end())
+            return;
+        delete fromIt->second;
+        level[from] = toIt->second;
+        retargetedSymbols.push_back({from, to});
+    }
+
     TSymbol* find(const TString& name) const
     {
         tLevel::const_iterator it = level.find(name);
@@ -583,6 +600,8 @@ protected:
 
     tLevel level;  // named mappings
     TPrecisionQualifier *defaultPrecision;
+    // pair<FromName, ToName>
+    TVector<std::pair<TString, TString>> retargetedSymbols;
     int anonId;
     bool thisLevel;  // True if this level of the symbol table is a structure scope containing member function
                      // that are supposed to see anonymous access to member variables.
@@ -788,6 +807,12 @@ public:
         return symbol;
     }
 
+    void retargetSymbol(const TString& from, const TString& to) {
+        int level = currentLevel();
+        table[level]->retargetSymbol(from, to);
+    }
+
+
     // Find of a symbol that returns how many layers deep of nested
     // structures-with-member-functions ('this' scopes) deep the symbol was
     // found in.