1 files changed, 196 insertions, 0 deletions
diff --git a/gfx/angle/checkout/src/compiler/translator/tree_ops/DeclareAndInitBuiltinsForInstancedMultiview.cpp b/gfx/angle/checkout/src/compiler/translator/tree_ops/DeclareAndInitBuiltinsForInstancedMultiview.cpp
new file mode 100644
index 0000000000..8c2925949d
--- /dev/null
+++ b/gfx/angle/checkout/src/compiler/translator/tree_ops/DeclareAndInitBuiltinsForInstancedMultiview.cpp
@@ -0,0 +1,196 @@
+//
+// Copyright 2017 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.
+//
+// Applies the necessary AST transformations to support multiview rendering through instancing.
+// Check the header file For more information.
+//
+
+#include "compiler/translator/tree_ops/DeclareAndInitBuiltinsForInstancedMultiview.h"
+
+#include "compiler/translator/Compiler.h"
+#include "compiler/translator/StaticType.h"
+#include "compiler/translator/SymbolTable.h"
+#include "compiler/translator/tree_ops/InitializeVariables.h"
+#include "compiler/translator/tree_util/BuiltIn.h"
+#include "compiler/translator/tree_util/FindMain.h"
+#include "compiler/translator/tree_util/IntermNode_util.h"
+#include "compiler/translator/tree_util/IntermTraverse.h"
+#include "compiler/translator/tree_util/ReplaceVariable.h"
+#include "compiler/translator/util.h"
+
+namespace sh
+{
+
+namespace
+{
+
+constexpr const ImmutableString kViewIDVariableName("ViewID_OVR");
+constexpr const ImmutableString kInstanceIDVariableName("InstanceID");
+constexpr const ImmutableString kMultiviewBaseViewLayerIndexVariableName(
+    "multiviewBaseViewLayerIndex");
+
+// Adds the InstanceID and ViewID_OVR initializers to the end of the initializers' sequence.
+void InitializeViewIDAndInstanceID(const TVariable *viewID,
+                                   const TVariable *instanceID,
+                                   unsigned numberOfViews,
+                                   const TSymbolTable &symbolTable,
+                                   TIntermSequence *initializers)
+{
+    // Create an unsigned numberOfViews node.
+    TConstantUnion *numberOfViewsUnsignedConstant = new TConstantUnion();
+    numberOfViewsUnsignedConstant->setUConst(numberOfViews);
+    TIntermConstantUnion *numberOfViewsUint =
+        new TIntermConstantUnion(numberOfViewsUnsignedConstant, TType(EbtUInt, EbpLow, EvqConst));
+
+    // Create a uint(gl_InstanceID) node.
+    TIntermSequence glInstanceIDSymbolCastArguments;
+    glInstanceIDSymbolCastArguments.push_back(new TIntermSymbol(BuiltInVariable::gl_InstanceID()));
+    TIntermAggregate *glInstanceIDAsUint = TIntermAggregate::CreateConstructor(
+        TType(EbtUInt, EbpHigh, EvqTemporary), &glInstanceIDSymbolCastArguments);
+
+    // Create a uint(gl_InstanceID) / numberOfViews node.
+    TIntermBinary *normalizedInstanceID =
+        new TIntermBinary(EOpDiv, glInstanceIDAsUint, numberOfViewsUint);
+
+    // Create an int(uint(gl_InstanceID) / numberOfViews) node.
+    TIntermSequence normalizedInstanceIDCastArguments;
+    normalizedInstanceIDCastArguments.push_back(normalizedInstanceID);
+    TIntermAggregate *normalizedInstanceIDAsInt = TIntermAggregate::CreateConstructor(
+        TType(EbtInt, EbpHigh, EvqTemporary), &normalizedInstanceIDCastArguments);
+
+    // Create an InstanceID = int(uint(gl_InstanceID) / numberOfViews) node.
+    TIntermBinary *instanceIDInitializer =
+        new TIntermBinary(EOpAssign, new TIntermSymbol(instanceID), normalizedInstanceIDAsInt);
+    initializers->push_back(instanceIDInitializer);
+
+    // Create a uint(gl_InstanceID) % numberOfViews node.
+    TIntermBinary *normalizedViewID =
+        new TIntermBinary(EOpIMod, glInstanceIDAsUint->deepCopy(), numberOfViewsUint->deepCopy());
+
+    // Create a ViewID_OVR = uint(gl_InstanceID) % numberOfViews node.
+    TIntermBinary *viewIDInitializer =
+        new TIntermBinary(EOpAssign, new TIntermSymbol(viewID), normalizedViewID);
+    initializers->push_back(viewIDInitializer);
+}
+
+// Adds a branch to write int(ViewID_OVR) to either gl_ViewportIndex or gl_Layer. The branch is
+// added to the end of the initializers' sequence.
+void SelectViewIndexInVertexShader(const TVariable *viewID,
+                                   const TVariable *multiviewBaseViewLayerIndex,
+                                   TIntermSequence *initializers,
+                                   const TSymbolTable &symbolTable)
+{
+    // Create an int(ViewID_OVR) node.
+    TIntermSequence viewIDSymbolCastArguments;
+    viewIDSymbolCastArguments.push_back(new TIntermSymbol(viewID));
+    TIntermAggregate *viewIDAsInt = TIntermAggregate::CreateConstructor(
+        TType(EbtInt, EbpHigh, EvqTemporary), &viewIDSymbolCastArguments);
+
+    // Create a gl_ViewportIndex node.
+    TIntermSymbol *viewportIndexSymbol = new TIntermSymbol(BuiltInVariable::gl_ViewportIndex());
+
+    // Create a { gl_ViewportIndex = int(ViewID_OVR) } node.
+    TIntermBlock *viewportIndexInitializerInBlock = new TIntermBlock();
+    viewportIndexInitializerInBlock->appendStatement(
+        new TIntermBinary(EOpAssign, viewportIndexSymbol, viewIDAsInt));
+
+    // Create a gl_Layer node.
+    TIntermSymbol *layerSymbol = new TIntermSymbol(BuiltInVariable::gl_LayerVS());
+
+    // Create an int(ViewID_OVR) + multiviewBaseViewLayerIndex node
+    TIntermBinary *sumOfViewIDAndBaseViewIndex = new TIntermBinary(
+        EOpAdd, viewIDAsInt->deepCopy(), new TIntermSymbol(multiviewBaseViewLayerIndex));
+
+    // Create a { gl_Layer = int(ViewID_OVR) + multiviewBaseViewLayerIndex } node.
+    TIntermBlock *layerInitializerInBlock = new TIntermBlock();
+    layerInitializerInBlock->appendStatement(
+        new TIntermBinary(EOpAssign, layerSymbol, sumOfViewIDAndBaseViewIndex));
+
+    // Create a node to compare whether the base view index uniform is less than zero.
+    TIntermBinary *multiviewBaseViewLayerIndexZeroComparison =
+        new TIntermBinary(EOpLessThan, new TIntermSymbol(multiviewBaseViewLayerIndex),
+                          CreateZeroNode(TType(EbtInt, EbpHigh, EvqConst)));
+
+    // Create an if-else statement to select the code path.
+    TIntermIfElse *multiviewBranch =
+        new TIntermIfElse(multiviewBaseViewLayerIndexZeroComparison,
+                          viewportIndexInitializerInBlock, layerInitializerInBlock);
+
+    initializers->push_back(multiviewBranch);
+}
+
+}  // namespace
+
+bool DeclareAndInitBuiltinsForInstancedMultiview(TCompiler *compiler,
+                                                 TIntermBlock *root,
+                                                 unsigned numberOfViews,
+                                                 GLenum shaderType,
+                                                 const ShCompileOptions &compileOptions,
+                                                 ShShaderOutput shaderOutput,
+                                                 TSymbolTable *symbolTable)
+{
+    ASSERT(shaderType == GL_VERTEX_SHADER || shaderType == GL_FRAGMENT_SHADER);
+
+    TQualifier viewIDQualifier = (shaderType == GL_VERTEX_SHADER) ? EvqFlatOut : EvqFlatIn;
+    const TVariable *viewID =
+        new TVariable(symbolTable, kViewIDVariableName,
+                      new TType(EbtUInt, EbpHigh, viewIDQualifier), SymbolType::AngleInternal);
+
+    DeclareGlobalVariable(root, viewID);
+    if (!ReplaceVariable(compiler, root, BuiltInVariable::gl_ViewID_OVR(), viewID))
+    {
+        return false;
+    }
+    if (shaderType == GL_VERTEX_SHADER)
+    {
+        // Replacing gl_InstanceID with InstanceID should happen before adding the initializers of
+        // InstanceID and ViewID.
+        const TType *instanceIDVariableType = StaticType::Get<EbtInt, EbpHigh, EvqGlobal, 1, 1>();
+        const TVariable *instanceID =
+            new TVariable(symbolTable, kInstanceIDVariableName, instanceIDVariableType,
+                          SymbolType::AngleInternal);
+        DeclareGlobalVariable(root, instanceID);
+        if (!ReplaceVariable(compiler, root, BuiltInVariable::gl_InstanceID(), instanceID))
+        {
+            return false;
+        }
+
+        TIntermSequence initializers;
+        InitializeViewIDAndInstanceID(viewID, instanceID, numberOfViews, *symbolTable,
+                                      &initializers);
+
+        // The AST transformation which adds the expression to select the viewport index should
+        // be done only for the GLSL and ESSL output.
+        const bool selectView = compileOptions.selectViewInNvGLSLVertexShader;
+        // Assert that if the view is selected in the vertex shader, then the output is
+        // either GLSL or ESSL.
+        ASSERT(!selectView || IsOutputGLSL(shaderOutput) || IsOutputESSL(shaderOutput));
+        if (selectView)
+        {
+            // Add a uniform to switch between side-by-side and layered rendering.
+            const TType *baseLayerIndexVariableType =
+                StaticType::Get<EbtInt, EbpHigh, EvqUniform, 1, 1>();
+            const TVariable *multiviewBaseViewLayerIndex =
+                new TVariable(symbolTable, kMultiviewBaseViewLayerIndexVariableName,
+                              baseLayerIndexVariableType, SymbolType::AngleInternal);
+            DeclareGlobalVariable(root, multiviewBaseViewLayerIndex);
+
+            // Setting a value to gl_ViewportIndex or gl_Layer should happen after ViewID_OVR's
+            // initialization.
+            SelectViewIndexInVertexShader(viewID, multiviewBaseViewLayerIndex, &initializers,
+                                          *symbolTable);
+        }
+
+        // Insert initializers at the beginning of main().
+        TIntermBlock *initializersBlock = new TIntermBlock();
+        initializersBlock->getSequence()->swap(initializers);
+        TIntermBlock *mainBody = FindMainBody(root);
+        mainBody->getSequence()->insert(mainBody->getSequence()->begin(), initializersBlock);
+    }
+
+    return compiler->validateAST(root);
+}
+
+}  // namespace sh