Initialize uninitialized GLSL arrays in a for loop

src/compiler/translator/Compiler.cpp

@@ -595,7 +595,9 @@ bool TCompiler::checkAndSimplifyAST(TIntermBlock *root,
     // on ESSL >= 3.00, and the initializers that need to be deferred can only exist in ESSL < 3.00.
     bool initializeLocalsAndGlobals =
         (compileOptions & SH_INITIALIZE_UNINITIALIZED_LOCALS) && !IsOutputHLSL(getOutputType());
-    DeferGlobalInitializers(root, initializeLocalsAndGlobals, &symbolTable);
+    bool canUseLoopsToInitialize = !(compileOptions & SH_DONT_USE_LOOPS_TO_INITIALIZE_VARIABLES);
+    DeferGlobalInitializers(root, initializeLocalsAndGlobals, canUseLoopsToInitialize, &symbolTable);
+
 
     if (initializeLocalsAndGlobals)
     {
@@ -615,7 +617,8 @@ bool TCompiler::checkAndSimplifyAST(TIntermBlock *root,
                                    &getSymbolTable(), getShaderVersion());
         }
 
-        InitializeUninitializedLocals(root, getShaderVersion());
+        InitializeUninitializedLocals(root, getShaderVersion(), canUseLoopsToInitialize,
+                                      &getSymbolTable());
     }
 
     if (getShaderType() == GL_VERTEX_SHADER && (compileOptions & SH_CLAMP_POINT_SIZE))
@@ -1055,7 +1058,7 @@ void TCompiler::initializeGLPosition(TIntermBlock *root)
     sh::ShaderVariable var(GL_FLOAT_VEC4);
     var.name = "gl_Position";
     list.push_back(var);
-    InitializeVariables(root, list, symbolTable, shaderVersion, extensionBehavior);
+    InitializeVariables(root, list, &symbolTable, shaderVersion, extensionBehavior, false);
 }
 
 void TCompiler::useAllMembersInUnusedStandardAndSharedBlocks(TIntermBlock *root)
@@ -1097,7 +1100,7 @@ void TCompiler::initializeOutputVariables(TIntermBlock *root)
             list.push_back(var);
         }
     }
-    InitializeVariables(root, list, symbolTable, shaderVersion, extensionBehavior);
+    InitializeVariables(root, list, &symbolTable, shaderVersion, extensionBehavior, false);
 }
 
 const TExtensionBehavior &TCompiler::getExtensionBehavior() const

src/compiler/translator/DeferGlobalInitializers.cpp

@@ -29,7 +29,9 @@ namespace
 
 void GetDeferredInitializers(TIntermDeclaration *declaration,
                              bool initializeUninitializedGlobals,
-                             TIntermSequence *deferredInitializersOut)
+                             bool canUseLoopsToInitialize,
+                             TIntermSequence *deferredInitializersOut,
+                             TSymbolTable *symbolTable)
 {
     // SeparateDeclarations should have already been run.
     ASSERT(declaration->getSequence()->size() == 1);
@@ -81,7 +83,8 @@ void GetDeferredInitializers(TIntermDeclaration *declaration,
 
         if (symbolNode->getQualifier() == EvqGlobal && symbolNode->getSymbol() != "")
         {
-            TIntermSequence *initCode = CreateInitCode(symbolNode);
+            TIntermSequence *initCode =
+                CreateInitCode(symbolNode, canUseLoopsToInitialize, symbolTable);
             deferredInitializersOut->insert(deferredInitializersOut->end(), initCode->begin(),
                                             initCode->end());
         }
@@ -117,6 +120,7 @@ void InsertInitCallToMain(TIntermBlock *root,
 
 void DeferGlobalInitializers(TIntermBlock *root,
                              bool initializeUninitializedGlobals,
+                             bool canUseLoopsToInitialize,
                              TSymbolTable *symbolTable)
 {
     TIntermSequence *deferredInitializers = new TIntermSequence();
@@ -129,7 +133,7 @@ void DeferGlobalInitializers(TIntermBlock *root,
         if (declaration)
         {
             GetDeferredInitializers(declaration, initializeUninitializedGlobals,
-                                    deferredInitializers);
+                                    canUseLoopsToInitialize, deferredInitializers, symbolTable);
         }
     }
 

src/compiler/translator/DeferGlobalInitializers.h

@@ -24,6 +24,7 @@ class TSymbolTable;
 
 void DeferGlobalInitializers(TIntermBlock *root,
                              bool initializeUninitializedGlobals,
+                             bool canUseLoopsToInitialize,
                              TSymbolTable *symbolTable);
 
 }  // namespace sh

src/compiler/translator/InitializeVariables.h

@@ -18,12 +18,20 @@ class TSymbolTable;
 
 typedef std::vector<sh::ShaderVariable> InitVariableList;
 
+// For all of the functions below: If canUseLoopsToInitialize is set, for loops are used instead of
+// a large number of initializers where it can make sense, such as for initializing large arrays.
+
 // Return a sequence of assignment operations to initialize "initializedSymbol". initializedSymbol
 // may be an array, struct or any combination of these, as long as it contains only basic types.
-TIntermSequence *CreateInitCode(const TIntermTyped *initializedSymbol);
+TIntermSequence *CreateInitCode(const TIntermTyped *initializedSymbol,
+                                bool canUseLoopsToInitialize,
+                                TSymbolTable *symbolTable);
 
 // Initialize all uninitialized local variables, so that undefined behavior is avoided.
-void InitializeUninitializedLocals(TIntermBlock *root, int shaderVersion);
+void InitializeUninitializedLocals(TIntermBlock *root,
+                                   int shaderVersion,
+                                   bool canUseLoopsToInitialize,
+                                   TSymbolTable *symbolTable);
 
 // This function can initialize all the types that CreateInitCode is able to initialize. All
 // variables must be globals which can be found in the symbol table. For now it is used for the
@@ -35,9 +43,10 @@ void InitializeUninitializedLocals(TIntermBlock *root, int shaderVersion);
 // enabled extensions.
 void InitializeVariables(TIntermBlock *root,
                          const InitVariableList &vars,
-                         const TSymbolTable &symbolTable,
+                         TSymbolTable *symbolTable,
                          int shaderVersion,
-                         const TExtensionBehavior &extensionBehavior);
+                         const TExtensionBehavior &extensionBehavior,
+                         bool canUseLoopsToInitialize);
 
 }  // namespace sh