1 files changed, 173 insertions, 0 deletions
diff --git a/gfx/angle/checkout/src/compiler/translator/tree_ops/SplitSequenceOperator.cpp b/gfx/angle/checkout/src/compiler/translator/tree_ops/SplitSequenceOperator.cpp
new file mode 100644
index 0000000000..45985954b0
--- /dev/null
+++ b/gfx/angle/checkout/src/compiler/translator/tree_ops/SplitSequenceOperator.cpp
@@ -0,0 +1,173 @@
+//
+// Copyright 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.
+//
+// SplitSequenceOperator is an AST traverser that detects sequence operator expressions that
+// go through further AST transformations that generate statements, and splits them so that
+// possible side effects of earlier parts of the sequence operator expression are guaranteed to be
+// evaluated before the latter parts of the sequence operator expression are evaluated.
+//
+
+#include "compiler/translator/tree_ops/SplitSequenceOperator.h"
+
+#include "compiler/translator/tree_util/IntermNodePatternMatcher.h"
+#include "compiler/translator/tree_util/IntermTraverse.h"
+
+namespace sh
+{
+
+namespace
+{
+
+class SplitSequenceOperatorTraverser : public TLValueTrackingTraverser
+{
+  public:
+    SplitSequenceOperatorTraverser(unsigned int patternsToSplitMask, TSymbolTable *symbolTable);
+
+    bool visitUnary(Visit visit, TIntermUnary *node) override;
+    bool visitBinary(Visit visit, TIntermBinary *node) override;
+    bool visitAggregate(Visit visit, TIntermAggregate *node) override;
+    bool visitTernary(Visit visit, TIntermTernary *node) override;
+
+    void nextIteration();
+    bool foundExpressionToSplit() const { return mFoundExpressionToSplit; }
+
+  protected:
+    // Marked to true once an operation that needs to be hoisted out of the expression has been
+    // found. After that, no more AST updates are performed on that traversal.
+    bool mFoundExpressionToSplit;
+    int mInsideSequenceOperator;
+
+    IntermNodePatternMatcher mPatternToSplitMatcher;
+};
+
+SplitSequenceOperatorTraverser::SplitSequenceOperatorTraverser(unsigned int patternsToSplitMask,
+                                                               TSymbolTable *symbolTable)
+    : TLValueTrackingTraverser(true, false, true, symbolTable),
+      mFoundExpressionToSplit(false),
+      mInsideSequenceOperator(0),
+      mPatternToSplitMatcher(patternsToSplitMask)
+{}
+
+void SplitSequenceOperatorTraverser::nextIteration()
+{
+    mFoundExpressionToSplit = false;
+    mInsideSequenceOperator = 0;
+}
+
+bool SplitSequenceOperatorTraverser::visitAggregate(Visit visit, TIntermAggregate *node)
+{
+    if (mFoundExpressionToSplit)
+        return false;
+
+    if (mInsideSequenceOperator > 0 && visit == PreVisit)
+    {
+        // Detect expressions that need to be simplified
+        mFoundExpressionToSplit = mPatternToSplitMatcher.match(node, getParentNode());
+        return !mFoundExpressionToSplit;
+    }
+
+    return true;
+}
+
+bool SplitSequenceOperatorTraverser::visitUnary(Visit visit, TIntermUnary *node)
+{
+    if (mFoundExpressionToSplit)
+        return false;
+
+    if (mInsideSequenceOperator > 0 && visit == PreVisit)
+    {
+        // Detect expressions that need to be simplified
+        mFoundExpressionToSplit = mPatternToSplitMatcher.match(node);
+        return !mFoundExpressionToSplit;
+    }
+
+    return true;
+}
+
+bool SplitSequenceOperatorTraverser::visitBinary(Visit visit, TIntermBinary *node)
+{
+    if (node->getOp() == EOpComma)
+    {
+        if (visit == PreVisit)
+        {
+            if (mFoundExpressionToSplit)
+            {
+                return false;
+            }
+            mInsideSequenceOperator++;
+        }
+        else if (visit == PostVisit)
+        {
+            // Split sequence operators starting from the outermost one to preserve correct
+            // execution order.
+            if (mFoundExpressionToSplit && mInsideSequenceOperator == 1)
+            {
+                // Move the left side operand into a separate statement in the parent block.
+                TIntermSequence insertions;
+                insertions.push_back(node->getLeft());
+                insertStatementsInParentBlock(insertions);
+                // Replace the comma node with its right side operand.
+                queueReplacement(node->getRight(), OriginalNode::IS_DROPPED);
+            }
+            mInsideSequenceOperator--;
+        }
+        return true;
+    }
+
+    if (mFoundExpressionToSplit)
+        return false;
+
+    if (mInsideSequenceOperator > 0 && visit == PreVisit)
+    {
+        // Detect expressions that need to be simplified
+        mFoundExpressionToSplit =
+            mPatternToSplitMatcher.match(node, getParentNode(), isLValueRequiredHere());
+        return !mFoundExpressionToSplit;
+    }
+
+    return true;
+}
+
+bool SplitSequenceOperatorTraverser::visitTernary(Visit visit, TIntermTernary *node)
+{
+    if (mFoundExpressionToSplit)
+        return false;
+
+    if (mInsideSequenceOperator > 0 && visit == PreVisit)
+    {
+        // Detect expressions that need to be simplified
+        mFoundExpressionToSplit = mPatternToSplitMatcher.match(node);
+        return !mFoundExpressionToSplit;
+    }
+
+    return true;
+}
+
+}  // namespace
+
+bool SplitSequenceOperator(TCompiler *compiler,
+                           TIntermNode *root,
+                           int patternsToSplitMask,
+                           TSymbolTable *symbolTable)
+{
+    SplitSequenceOperatorTraverser traverser(patternsToSplitMask, symbolTable);
+    // Separate one expression at a time, and reset the traverser between iterations.
+    do
+    {
+        traverser.nextIteration();
+        root->traverse(&traverser);
+        if (traverser.foundExpressionToSplit())
+        {
+            if (!traverser.updateTree(compiler, root))
+            {
+                return false;
+            }
+        }
+    } while (traverser.foundExpressionToSplit());
+
+    return true;
+}
+
+}  // namespace sh