1 files changed, 123 insertions, 0 deletions
diff --git a/gfx/angle/checkout/src/compiler/translator/tree_ops/d3d/RewriteElseBlocks.cpp b/gfx/angle/checkout/src/compiler/translator/tree_ops/d3d/RewriteElseBlocks.cpp
new file mode 100644
index 0000000000..10647d1bf1
--- /dev/null
+++ b/gfx/angle/checkout/src/compiler/translator/tree_ops/d3d/RewriteElseBlocks.cpp
@@ -0,0 +1,123 @@
+//
+// Copyright 2014 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.
+//
+// RewriteElseBlocks.cpp: Implementation for tree transform to change
+//   all if-else blocks to if-if blocks.
+//
+
+#include "compiler/translator/tree_ops/d3d/RewriteElseBlocks.h"
+
+#include "compiler/translator/Compiler.h"
+#include "compiler/translator/IntermNode.h"
+#include "compiler/translator/SymbolTable.h"
+#include "compiler/translator/tree_util/IntermNode_util.h"
+#include "compiler/translator/tree_util/NodeSearch.h"
+
+namespace sh
+{
+
+namespace
+{
+
+class ElseBlockRewriter : public TIntermTraverser
+{
+  public:
+    ElseBlockRewriter(TSymbolTable *symbolTable);
+
+  protected:
+    bool visitFunctionDefinition(Visit visit, TIntermFunctionDefinition *aggregate) override;
+    bool visitBlock(Visit visit, TIntermBlock *block) override;
+
+  private:
+    TIntermNode *rewriteIfElse(TIntermIfElse *ifElse);
+
+    const TType *mFunctionType;
+};
+
+ElseBlockRewriter::ElseBlockRewriter(TSymbolTable *symbolTable)
+    : TIntermTraverser(true, false, true, symbolTable), mFunctionType(nullptr)
+{}
+
+bool ElseBlockRewriter::visitFunctionDefinition(Visit visit, TIntermFunctionDefinition *node)
+{
+    // Store the current function context (see comment below)
+    mFunctionType = ((visit == PreVisit) ? &node->getFunctionPrototype()->getType() : nullptr);
+    return true;
+}
+
+bool ElseBlockRewriter::visitBlock(Visit visit, TIntermBlock *node)
+{
+    if (visit == PostVisit)
+    {
+        for (size_t statementIndex = 0; statementIndex != node->getSequence()->size();
+             statementIndex++)
+        {
+            TIntermNode *statement = (*node->getSequence())[statementIndex];
+            TIntermIfElse *ifElse  = statement->getAsIfElseNode();
+            if (ifElse && ifElse->getFalseBlock() != nullptr)
+            {
+                (*node->getSequence())[statementIndex] = rewriteIfElse(ifElse);
+            }
+        }
+    }
+    return true;
+}
+
+TIntermNode *ElseBlockRewriter::rewriteIfElse(TIntermIfElse *ifElse)
+{
+    ASSERT(ifElse != nullptr);
+
+    TIntermDeclaration *storeCondition = nullptr;
+    TVariable *conditionVariable =
+        DeclareTempVariable(mSymbolTable, ifElse->getCondition(), EvqTemporary, &storeCondition);
+
+    TIntermBlock *falseBlock = nullptr;
+
+    TType boolType(EbtBool, EbpUndefined, EvqTemporary);
+
+    if (ifElse->getFalseBlock())
+    {
+        TIntermBlock *negatedElse = nullptr;
+        // crbug.com/346463
+        // D3D generates error messages claiming a function has no return value, when rewriting
+        // an if-else clause that returns something non-void in a function. By appending mock
+        // returns (that are unreachable) we can silence this compile error.
+        if (mFunctionType && mFunctionType->getBasicType() != EbtVoid)
+        {
+            TIntermNode *returnNode = new TIntermBranch(EOpReturn, CreateZeroNode(*mFunctionType));
+            negatedElse             = new TIntermBlock();
+            negatedElse->appendStatement(returnNode);
+        }
+
+        TIntermSymbol *conditionSymbolElse = CreateTempSymbolNode(conditionVariable);
+        TIntermUnary *negatedCondition =
+            new TIntermUnary(EOpLogicalNot, conditionSymbolElse, nullptr);
+        TIntermIfElse *falseIfElse =
+            new TIntermIfElse(negatedCondition, ifElse->getFalseBlock(), negatedElse);
+        falseBlock = EnsureBlock(falseIfElse);
+    }
+
+    TIntermSymbol *conditionSymbolSel = CreateTempSymbolNode(conditionVariable);
+    TIntermIfElse *newIfElse =
+        new TIntermIfElse(conditionSymbolSel, ifElse->getTrueBlock(), falseBlock);
+
+    TIntermBlock *block = new TIntermBlock();
+    block->getSequence()->push_back(storeCondition);
+    block->getSequence()->push_back(newIfElse);
+
+    return block;
+}
+
+}  // anonymous namespace
+
+bool RewriteElseBlocks(TCompiler *compiler, TIntermNode *node, TSymbolTable *symbolTable)
+{
+    ElseBlockRewriter rewriter(symbolTable);
+    node->traverse(&rewriter);
+
+    return compiler->validateAST(node);
+}
+
+}  // namespace sh