also search global variables assignment for live variables

when traversing the AST to find live UBOs etc, also traverse
references to global module-level variables, incase they are
being filled in from UBOs etc.

glslang/MachineIndependent/LiveTraverser.h

@@ -74,14 +74,33 @@ public:
         for (unsigned int f = 0; f < globals.size(); ++f) {
             TIntermAggregate* candidate = globals[f]->getAsAggregate();
             if (candidate && candidate->getOp() == EOpFunction && candidate->getName() == name) {
-                functions.push_back(candidate);
+                destinations.push_back(candidate);
                 break;
             }
         }
     }
 
-    typedef std::list<TIntermAggregate*> TFunctionStack;
+    void pushGlobalReference(const TString& name)
-    TFunctionStack functions;
+    {
+        TIntermSequence& globals = intermediate.getTreeRoot()->getAsAggregate()->getSequence();
+        for (unsigned int f = 0; f < globals.size(); ++f) {
+            TIntermAggregate* candidate = globals[f]->getAsAggregate();
+            if (candidate && candidate->getOp() == EOpSequence &&
+                candidate->getSequence().size() == 1 &&
+                candidate->getSequence()[0]->getAsBinaryNode()) {
+                TIntermBinary* binary = candidate->getSequence()[0]->getAsBinaryNode();
+                TIntermSymbol* symbol = binary->getLeft()->getAsSymbolNode();
+                if (symbol && symbol->getQualifier().storage == EvqGlobal &&
+                    symbol->getName() == name) {
+                    destinations.push_back(candidate);
+                    break;
+                }
+            }
+        }
+    }
+
+    typedef std::list<TIntermAggregate*> TDestinationStack;
+    TDestinationStack destinations;
 
 protected:
     // To catch which function calls are not dead, and hence which functions must be visited.
@@ -117,16 +136,27 @@ protected:
     // and only visit each function once.
     void addFunctionCall(TIntermAggregate* call)
     {
-        // // just use the map to ensure we process each function at most once
+        // just use the map to ensure we process each function at most once
         if (liveFunctions.find(call->getName()) == liveFunctions.end()) {
             liveFunctions.insert(call->getName());
             pushFunction(call->getName());
         }
     }
 
+    void addGlobalReference(const TString& name)
+    {
+        // just use the map to ensure we process each global at most once
+        if (liveGlobals.find(name) == liveGlobals.end()) {
+            liveGlobals.insert(name);
+            pushGlobalReference(name);
+        }
+    }
+
     const TIntermediate& intermediate;
     typedef std::unordered_set<TString> TLiveFunctions;
     TLiveFunctions liveFunctions;
+    typedef std::unordered_set<TString> TLiveGlobals;
+    TLiveGlobals liveGlobals;
     bool traverseAll;
 
 private:

glslang/MachineIndependent/iomapper.cpp

@@ -79,6 +79,11 @@ public:
             target = &outputList;
         else if (base->getQualifier().isUniformOrBuffer() && !base->getQualifier().isPushConstant())
             target = &uniformList;
+        // If a global is being visited, then we should also traverse it incase it's evaluation
+        // ends up visiting inputs we want to tag as live
+        else if (base->getQualifier().storage == EvqGlobal)
+            addGlobalReference(base->getName());
+
         if (target) {
             TVarEntryInfo ent = {base->getId(), base, ! traverseAll};
             ent.stage = intermediate.getStage();
@@ -1105,11 +1110,12 @@ bool TIoMapper::addStage(EShLanguage stage, TIntermediate& intermediate, TInfoSi
     TVarGatherTraverser iter_binding_live(intermediate, false, inVarMap, outVarMap, uniformVarMap);
     root->traverse(&iter_binding_all);
     iter_binding_live.pushFunction(intermediate.getEntryPointMangledName().c_str());
-    while (! iter_binding_live.functions.empty()) {
+    while (! iter_binding_live.destinations.empty()) {
-        TIntermNode* function = iter_binding_live.functions.back();
+        TIntermNode* destination = iter_binding_live.destinations.back();
-        iter_binding_live.functions.pop_back();
+        iter_binding_live.destinations.pop_back();
-        function->traverse(&iter_binding_live);
+        destination->traverse(&iter_binding_live);
     }
+
     // sort entries by priority. see TVarEntryInfo::TOrderByPriority for info.
     std::for_each(inVarMap.begin(), inVarMap.end(),
                   [&inVector](TVarLivePair p) { inVector.push_back(p); });
@@ -1200,11 +1206,12 @@ bool TGlslIoMapper::addStage(EShLanguage stage, TIntermediate& intermediate, TIn
                                           *uniformVarMap[stage]);
     root->traverse(&iter_binding_all);
     iter_binding_live.pushFunction(intermediate.getEntryPointMangledName().c_str());
-    while (! iter_binding_live.functions.empty()) {
+    while (! iter_binding_live.destinations.empty()) {
-        TIntermNode* function = iter_binding_live.functions.back();
+        TIntermNode* destination = iter_binding_live.destinations.back();
-        iter_binding_live.functions.pop_back();
+        iter_binding_live.destinations.pop_back();
-        function->traverse(&iter_binding_live);
+        destination->traverse(&iter_binding_live);
     }
+
     TNotifyInOutAdaptor inOutNotify(stage, *resolver);
     TNotifyUniformAdaptor uniformNotify(stage, *resolver);
     // Resolve current stage input symbol location with previous stage output here,