1 files changed, 368 insertions, 0 deletions
diff --git a/src/3rdparty/angle/src/compiler/translator/UnfoldShortCircuitToIf.cpp b/src/3rdparty/angle/src/compiler/translator/UnfoldShortCircuitToIf.cpp
new file mode 100644
index 0000000000..be23b524d7
--- /dev/null
+++ b/src/3rdparty/angle/src/compiler/translator/UnfoldShortCircuitToIf.cpp
@@ -0,0 +1,368 @@
+//
+// Copyright (c) 2002-2013 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.
+//
+// UnfoldShortCircuitToIf is an AST traverser to convert short-circuiting operators to if-else statements.
+// The results are assigned to s# temporaries, which are used by the main translator instead of
+// the original expression.
+//
+
+#include "compiler/translator/UnfoldShortCircuitToIf.h"
+
+#include "compiler/translator/IntermNode.h"
+
+namespace
+{
+
+// Traverser that unfolds one short-circuiting operation at a time.
+class UnfoldShortCircuitTraverser : public TIntermTraverser
+{
+  public:
+    UnfoldShortCircuitTraverser();
+
+    bool visitBinary(Visit visit, TIntermBinary *node) override;
+    bool visitAggregate(Visit visit, TIntermAggregate *node) override;
+    bool visitSelection(Visit visit, TIntermSelection *node) override;
+    bool visitLoop(Visit visit, TIntermLoop *node) override;
+
+    void nextIteration();
+    bool foundShortCircuit() const { return mFoundShortCircuit; }
+
+  protected:
+    // Check if the traversal is inside a loop condition or expression, in which case the unfolded
+    // expression needs to be copied inside the loop. Returns true if the copying is done, in which
+    // case no further unfolding should be done on the same traversal.
+    // The parameters are the node that will be unfolded to multiple statements and so can't remain
+    // inside a loop condition, and its parent.
+    bool copyLoopConditionOrExpression(TIntermNode *parent, TIntermTyped *node);
+
+    // Marked to true once an operation that needs to be unfolded has been found.
+    // After that, no more unfolding is performed on that traversal.
+    bool mFoundShortCircuit;
+
+    // Set to the loop node while a loop condition or expression is being traversed.
+    TIntermLoop *mParentLoop;
+    // Parent of the loop node while a loop condition or expression is being traversed.
+    TIntermNode *mLoopParent;
+
+    bool mInLoopCondition;
+    bool mInLoopExpression;
+};
+
+UnfoldShortCircuitTraverser::UnfoldShortCircuitTraverser()
+    : TIntermTraverser(true, false, true),
+      mFoundShortCircuit(false),
+      mParentLoop(nullptr),
+      mLoopParent(nullptr),
+      mInLoopCondition(false),
+      mInLoopExpression(false)
+{
+}
+
+bool UnfoldShortCircuitTraverser::visitBinary(Visit visit, TIntermBinary *node)
+{
+    if (mFoundShortCircuit)
+        return false;
+    // If our right node doesn't have side effects, we know we don't need to unfold this
+    // expression: there will be no short-circuiting side effects to avoid
+    // (note: unfolding doesn't depend on the left node -- it will always be evaluated)
+    if (!node->getRight()->hasSideEffects())
+    {
+        return true;
+    }
+
+    switch (node->getOp())
+    {
+      case EOpLogicalOr:
+        mFoundShortCircuit = true;
+        if (!copyLoopConditionOrExpression(getParentNode(), node))
+        {
+            // "x || y" is equivalent to "x ? true : y", which unfolds to "bool s; if(x) s = true;
+            // else s = y;",
+            // and then further simplifies down to "bool s = x; if(!s) s = y;".
+
+            TIntermSequence insertions;
+            TType boolType(EbtBool, EbpUndefined, EvqTemporary);
+
+            ASSERT(node->getLeft()->getType() == boolType);
+            insertions.push_back(createTempInitDeclaration(node->getLeft()));
+
+            TIntermAggregate *assignRightBlock = new TIntermAggregate(EOpSequence);
+            ASSERT(node->getRight()->getType() == boolType);
+            assignRightBlock->getSequence()->push_back(createTempAssignment(node->getRight()));
+
+            TIntermUnary *notTempSymbol = new TIntermUnary(EOpLogicalNot, boolType);
+            notTempSymbol->setOperand(createTempSymbol(boolType));
+            TIntermSelection *ifNode = new TIntermSelection(notTempSymbol, assignRightBlock, nullptr);
+            insertions.push_back(ifNode);
+
+            insertStatementsInParentBlock(insertions);
+
+            NodeUpdateEntry replaceVariable(getParentNode(), node, createTempSymbol(boolType), false);
+            mReplacements.push_back(replaceVariable);
+        }
+        return false;
+      case EOpLogicalAnd:
+        mFoundShortCircuit = true;
+        if (!copyLoopConditionOrExpression(getParentNode(), node))
+        {
+            // "x && y" is equivalent to "x ? y : false", which unfolds to "bool s; if(x) s = y;
+            // else s = false;",
+            // and then further simplifies down to "bool s = x; if(s) s = y;".
+            TIntermSequence insertions;
+            TType boolType(EbtBool, EbpUndefined, EvqTemporary);
+
+            ASSERT(node->getLeft()->getType() == boolType);
+            insertions.push_back(createTempInitDeclaration(node->getLeft()));
+
+            TIntermAggregate *assignRightBlock = new TIntermAggregate(EOpSequence);
+            ASSERT(node->getRight()->getType() == boolType);
+            assignRightBlock->getSequence()->push_back(createTempAssignment(node->getRight()));
+
+            TIntermSelection *ifNode = new TIntermSelection(createTempSymbol(boolType), assignRightBlock, nullptr);
+            insertions.push_back(ifNode);
+
+            insertStatementsInParentBlock(insertions);
+
+            NodeUpdateEntry replaceVariable(getParentNode(), node, createTempSymbol(boolType), false);
+            mReplacements.push_back(replaceVariable);
+        }
+        return false;
+      default:
+        return true;
+    }
+}
+
+bool UnfoldShortCircuitTraverser::visitSelection(Visit visit, TIntermSelection *node)
+{
+    if (mFoundShortCircuit)
+        return false;
+
+    // Unfold "b ? x : y" into "type s; if(b) s = x; else s = y;"
+    if (visit == PreVisit && node->usesTernaryOperator())
+    {
+        mFoundShortCircuit = true;
+        if (!copyLoopConditionOrExpression(getParentNode(), node))
+        {
+            TIntermSequence insertions;
+
+            TIntermSymbol *tempSymbol         = createTempSymbol(node->getType());
+            TIntermAggregate *tempDeclaration = new TIntermAggregate(EOpDeclaration);
+            tempDeclaration->getSequence()->push_back(tempSymbol);
+            insertions.push_back(tempDeclaration);
+
+            TIntermAggregate *trueBlock = new TIntermAggregate(EOpSequence);
+            TIntermBinary *trueAssignment =
+                createTempAssignment(node->getTrueBlock()->getAsTyped());
+            trueBlock->getSequence()->push_back(trueAssignment);
+
+            TIntermAggregate *falseBlock = new TIntermAggregate(EOpSequence);
+            TIntermBinary *falseAssignment =
+                createTempAssignment(node->getFalseBlock()->getAsTyped());
+            falseBlock->getSequence()->push_back(falseAssignment);
+
+            TIntermSelection *ifNode =
+                new TIntermSelection(node->getCondition()->getAsTyped(), trueBlock, falseBlock);
+            insertions.push_back(ifNode);
+
+            insertStatementsInParentBlock(insertions);
+
+            TIntermSymbol *ternaryResult = createTempSymbol(node->getType());
+            NodeUpdateEntry replaceVariable(getParentNode(), node, ternaryResult, false);
+            mReplacements.push_back(replaceVariable);
+        }
+        return false;
+    }
+
+    return true;
+}
+
+bool UnfoldShortCircuitTraverser::visitAggregate(Visit visit, TIntermAggregate *node)
+{
+    if (visit == PreVisit && mFoundShortCircuit)
+        return false; // No need to traverse further
+
+    if (node->getOp() == EOpComma)
+    {
+        ASSERT(visit != PreVisit || !mFoundShortCircuit);
+
+        if (visit == PostVisit && mFoundShortCircuit)
+        {
+            // We can be sure that we arrived here because there was a short-circuiting operator
+            // inside the sequence operator since we only start traversing the sequence operator in
+            // case a short-circuiting operator has not been found so far.
+            // We need to unfold the sequence (comma) operator, otherwise the evaluation order of
+            // statements would be messed up by unfolded operations inside.
+            // Don't do any other unfolding on this round of traversal.
+            mReplacements.clear();
+            mMultiReplacements.clear();
+            mInsertions.clear();
+
+            if (!copyLoopConditionOrExpression(getParentNode(), node))
+            {
+                TIntermSequence insertions;
+                TIntermSequence *seq = node->getSequence();
+
+                TIntermSequence::size_type i = 0;
+                ASSERT(!seq->empty());
+                while (i < seq->size() - 1)
+                {
+                    TIntermTyped *child = (*seq)[i]->getAsTyped();
+                    insertions.push_back(child);
+                    ++i;
+                }
+
+                insertStatementsInParentBlock(insertions);
+
+                NodeUpdateEntry replaceVariable(getParentNode(), node, (*seq)[i], false);
+                mReplacements.push_back(replaceVariable);
+            }
+        }
+    }
+    return true;
+}
+
+bool UnfoldShortCircuitTraverser::visitLoop(Visit visit, TIntermLoop *node)
+{
+    if (visit == PreVisit)
+    {
+        if (mFoundShortCircuit)
+            return false;  // No need to traverse further
+
+        mLoopParent = getParentNode();
+        mParentLoop = node;
+        incrementDepth(node);
+
+        if (node->getInit())
+        {
+            node->getInit()->traverse(this);
+            if (mFoundShortCircuit)
+            {
+                decrementDepth();
+                return false;
+            }
+        }
+
+        if (node->getCondition())
+        {
+            mInLoopCondition = true;
+            node->getCondition()->traverse(this);
+            mInLoopCondition = false;
+
+            if (mFoundShortCircuit)
+            {
+                decrementDepth();
+                return false;
+            }
+        }
+
+        if (node->getExpression())
+        {
+            mInLoopExpression = true;
+            node->getExpression()->traverse(this);
+            mInLoopExpression = false;
+
+            if (mFoundShortCircuit)
+            {
+                decrementDepth();
+                return false;
+            }
+        }
+
+        if (node->getBody())
+            node->getBody()->traverse(this);
+
+        decrementDepth();
+    }
+    return false;
+}
+
+bool UnfoldShortCircuitTraverser::copyLoopConditionOrExpression(TIntermNode *parent,
+                                                                TIntermTyped *node)
+{
+    if (mInLoopCondition)
+    {
+        mReplacements.push_back(
+            NodeUpdateEntry(parent, node, createTempSymbol(node->getType()), false));
+        TIntermAggregate *body = mParentLoop->getBody();
+        TIntermSequence empty;
+        if (mParentLoop->getType() == ELoopDoWhile)
+        {
+            // Declare the temporary variable before the loop.
+            TIntermSequence insertionsBeforeLoop;
+            insertionsBeforeLoop.push_back(createTempDeclaration(node->getType()));
+            insertStatementsInParentBlock(insertionsBeforeLoop);
+
+            // Move a part of do-while loop condition to inside the loop.
+            TIntermSequence insertionsInLoop;
+            insertionsInLoop.push_back(createTempAssignment(node));
+            mInsertions.push_back(NodeInsertMultipleEntry(body, body->getSequence()->size() - 1,
+                                                          empty, insertionsInLoop));
+        }
+        else
+        {
+            // The loop initializer expression and one copy of the part of the loop condition are
+            // executed before the loop. They need to be in a new scope.
+            TIntermAggregate *loopScope = new TIntermAggregate(EOpSequence);
+
+            TIntermNode *initializer = mParentLoop->getInit();
+            if (initializer != nullptr)
+            {
+                // Move the initializer to the newly created outer scope, so that condition can
+                // depend on it.
+                mReplacements.push_back(NodeUpdateEntry(mParentLoop, initializer, nullptr, false));
+                loopScope->getSequence()->push_back(initializer);
+            }
+
+            loopScope->getSequence()->push_back(createTempInitDeclaration(node));
+            loopScope->getSequence()->push_back(mParentLoop);
+            mReplacements.push_back(NodeUpdateEntry(mLoopParent, mParentLoop, loopScope, true));
+
+            // The second copy of the part of the loop condition is executed inside the loop.
+            TIntermSequence insertionsInLoop;
+            insertionsInLoop.push_back(createTempAssignment(node->deepCopy()));
+            mInsertions.push_back(NodeInsertMultipleEntry(body, body->getSequence()->size() - 1,
+                                                          empty, insertionsInLoop));
+        }
+        return true;
+    }
+
+    if (mInLoopExpression)
+    {
+        TIntermTyped *movedExpression = mParentLoop->getExpression();
+        mReplacements.push_back(NodeUpdateEntry(mParentLoop, movedExpression, nullptr, false));
+        TIntermAggregate *body = mParentLoop->getBody();
+        TIntermSequence empty;
+        TIntermSequence insertions;
+        insertions.push_back(movedExpression);
+        mInsertions.push_back(
+            NodeInsertMultipleEntry(body, body->getSequence()->size() - 1, empty, insertions));
+        return true;
+    }
+    return false;
+}
+
+void UnfoldShortCircuitTraverser::nextIteration()
+{
+    mFoundShortCircuit = false;
+    nextTemporaryIndex();
+}
+
+} // namespace
+
+void UnfoldShortCircuitToIf(TIntermNode *root, unsigned int *temporaryIndex)
+{
+    UnfoldShortCircuitTraverser traverser;
+    ASSERT(temporaryIndex != nullptr);
+    traverser.useTemporaryIndex(temporaryIndex);
+    // Unfold one operator at a time, and reset the traverser between iterations.
+    do
+    {
+        traverser.nextIteration();
+        root->traverse(&traverser);
+        if (traverser.foundShortCircuit())
+            traverser.updateTree();
+    }
+    while (traverser.foundShortCircuit());
+}