1 files changed, 194 insertions, 0 deletions
diff --git a/gfx/angle/src/compiler/translator/DeferGlobalInitializers.cpp b/gfx/angle/src/compiler/translator/DeferGlobalInitializers.cpp
new file mode 100755
index 000000000..1c58562fc
--- /dev/null
+++ b/gfx/angle/src/compiler/translator/DeferGlobalInitializers.cpp
@@ -0,0 +1,194 @@
+//
+// Copyright (c) 2016 The ANGLE Project Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+//
+// DeferGlobalInitializers is an AST traverser that moves global initializers into a function, and
+// adds a function call to that function in the beginning of main().
+// This enables initialization of globals with uniforms or non-constant globals, as allowed by
+// the WebGL spec. Some initializers referencing non-constants may need to be unfolded into if
+// statements in HLSL - this kind of steps should be done after DeferGlobalInitializers is run.
+//
+
+#include "compiler/translator/DeferGlobalInitializers.h"
+
+#include "compiler/translator/IntermNode.h"
+#include "compiler/translator/SymbolTable.h"
+
+namespace sh
+{
+
+namespace
+{
+
+void SetInternalFunctionName(TFunctionSymbolInfo *functionInfo, const char *name)
+{
+    TString nameStr(name);
+    nameStr = TFunction::mangleName(nameStr);
+    TName nameObj(nameStr);
+    nameObj.setInternal(true);
+    functionInfo->setNameObj(nameObj);
+}
+
+TIntermAggregate *CreateFunctionPrototypeNode(const char *name, const int functionId)
+{
+    TIntermAggregate *functionNode = new TIntermAggregate(EOpPrototype);
+
+    SetInternalFunctionName(functionNode->getFunctionSymbolInfo(), name);
+    TType returnType(EbtVoid);
+    functionNode->setType(returnType);
+    functionNode->getFunctionSymbolInfo()->setId(functionId);
+    return functionNode;
+}
+
+TIntermFunctionDefinition *CreateFunctionDefinitionNode(const char *name,
+                                                        TIntermBlock *functionBody,
+                                                        const int functionId)
+{
+    TType returnType(EbtVoid);
+    TIntermAggregate *paramsNode = new TIntermAggregate(EOpParameters);
+    TIntermFunctionDefinition *functionNode =
+        new TIntermFunctionDefinition(returnType, paramsNode, functionBody);
+
+    SetInternalFunctionName(functionNode->getFunctionSymbolInfo(), name);
+    functionNode->getFunctionSymbolInfo()->setId(functionId);
+    return functionNode;
+}
+
+TIntermAggregate *CreateFunctionCallNode(const char *name, const int functionId)
+{
+    TIntermAggregate *functionNode = new TIntermAggregate(EOpFunctionCall);
+
+    functionNode->setUserDefined();
+    SetInternalFunctionName(functionNode->getFunctionSymbolInfo(), name);
+    TType returnType(EbtVoid);
+    functionNode->setType(returnType);
+    functionNode->getFunctionSymbolInfo()->setId(functionId);
+    return functionNode;
+}
+
+class DeferGlobalInitializersTraverser : public TIntermTraverser
+{
+  public:
+    DeferGlobalInitializersTraverser();
+
+    bool visitBinary(Visit visit, TIntermBinary *node) override;
+
+    void insertInitFunction(TIntermBlock *root);
+
+  private:
+    TIntermSequence mDeferredInitializers;
+};
+
+DeferGlobalInitializersTraverser::DeferGlobalInitializersTraverser()
+    : TIntermTraverser(true, false, false)
+{
+}
+
+bool DeferGlobalInitializersTraverser::visitBinary(Visit visit, TIntermBinary *node)
+{
+    if (node->getOp() == EOpInitialize)
+    {
+        TIntermSymbol *symbolNode = node->getLeft()->getAsSymbolNode();
+        ASSERT(symbolNode);
+        TIntermTyped *expression = node->getRight();
+
+        if (mInGlobalScope && (expression->getQualifier() != EvqConst ||
+                               (expression->getAsConstantUnion() == nullptr &&
+                                !expression->isConstructorWithOnlyConstantUnionParameters())))
+        {
+            // For variables which are not constant, defer their real initialization until
+            // after we initialize uniforms.
+            // Deferral is done also in any cases where the variable has not been constant folded,
+            // since otherwise there's a chance that HLSL output will generate extra statements
+            // from the initializer expression.
+            TIntermBinary *deferredInit =
+                new TIntermBinary(EOpAssign, symbolNode->deepCopy(), node->getRight());
+            mDeferredInitializers.push_back(deferredInit);
+
+            // Change const global to a regular global if its initialization is deferred.
+            // This can happen if ANGLE has not been able to fold the constant expression used
+            // as an initializer.
+            ASSERT(symbolNode->getQualifier() == EvqConst ||
+                   symbolNode->getQualifier() == EvqGlobal);
+            if (symbolNode->getQualifier() == EvqConst)
+            {
+                // All of the siblings in the same declaration need to have consistent qualifiers.
+                auto *siblings = getParentNode()->getAsDeclarationNode()->getSequence();
+                for (TIntermNode *siblingNode : *siblings)
+                {
+                    TIntermBinary *siblingBinary = siblingNode->getAsBinaryNode();
+                    if (siblingBinary)
+                    {
+                        ASSERT(siblingBinary->getOp() == EOpInitialize);
+                        siblingBinary->getLeft()->getTypePointer()->setQualifier(EvqGlobal);
+                    }
+                    siblingNode->getAsTyped()->getTypePointer()->setQualifier(EvqGlobal);
+                }
+                // This node is one of the siblings.
+                ASSERT(symbolNode->getQualifier() == EvqGlobal);
+            }
+            // Remove the initializer from the global scope and just declare the global instead.
+            queueReplacement(node, symbolNode, OriginalNode::IS_DROPPED);
+        }
+    }
+    return false;
+}
+
+void DeferGlobalInitializersTraverser::insertInitFunction(TIntermBlock *root)
+{
+    if (mDeferredInitializers.empty())
+    {
+        return;
+    }
+    const int initFunctionId  = TSymbolTable::nextUniqueId();
+
+    const char *functionName = "initializeDeferredGlobals";
+
+    // Add function prototype to the beginning of the shader
+    TIntermAggregate *functionPrototypeNode =
+        CreateFunctionPrototypeNode(functionName, initFunctionId);
+    root->getSequence()->insert(root->getSequence()->begin(), functionPrototypeNode);
+
+    // Add function definition to the end of the shader
+    TIntermBlock *functionBodyNode = new TIntermBlock();
+    TIntermSequence *functionBody = functionBodyNode->getSequence();
+    for (const auto &deferredInit : mDeferredInitializers)
+    {
+        functionBody->push_back(deferredInit);
+    }
+    TIntermFunctionDefinition *functionDefinition =
+        CreateFunctionDefinitionNode(functionName, functionBodyNode, initFunctionId);
+    root->getSequence()->push_back(functionDefinition);
+
+    // Insert call into main function
+    for (TIntermNode *node : *root->getSequence())
+    {
+        TIntermFunctionDefinition *nodeFunction = node->getAsFunctionDefinition();
+        if (nodeFunction != nullptr && nodeFunction->getFunctionSymbolInfo()->isMain())
+        {
+            TIntermAggregate *functionCallNode =
+                CreateFunctionCallNode(functionName, initFunctionId);
+
+            TIntermBlock *mainBody = nodeFunction->getBody();
+            ASSERT(mainBody != nullptr);
+            mainBody->getSequence()->insert(mainBody->getSequence()->begin(), functionCallNode);
+        }
+    }
+}
+
+}  // namespace
+
+void DeferGlobalInitializers(TIntermBlock *root)
+{
+    DeferGlobalInitializersTraverser traverser;
+    root->traverse(&traverser);
+
+    // Replace the initializers of the global variables.
+    traverser.updateTree();
+
+    // Add the function with initialization and the call to that.
+    traverser.insertInitFunction(root);
+}
+
+}  // namespace sh