1 files changed, 120 insertions, 0 deletions
diff --git a/gfx/angle/checkout/src/compiler/translator/tree_ops/FoldExpressions.cpp b/gfx/angle/checkout/src/compiler/translator/tree_ops/FoldExpressions.cpp
new file mode 100644
index 0000000000..1ede8c1a46
--- /dev/null
+++ b/gfx/angle/checkout/src/compiler/translator/tree_ops/FoldExpressions.cpp
@@ -0,0 +1,120 @@
+//
+// Copyright 2018 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.
+//
+// FoldExpressions.cpp: Fold expressions. This may fold expressions so that the qualifier of the
+// folded node differs from the qualifier of the original expression, so it needs to be done after
+// parsing and validation of qualifiers is complete. Expressions that are folded:
+//  1. Ternary ops with a constant condition.
+//  2. Sequence aka comma ops where the left side has no side effects.
+//  3. Any expressions containing any of the above.
+
+#include "compiler/translator/tree_ops/FoldExpressions.h"
+
+#include "compiler/translator/Diagnostics.h"
+#include "compiler/translator/IntermNode.h"
+#include "compiler/translator/tree_util/IntermTraverse.h"
+
+namespace sh
+{
+
+namespace
+{
+
+class FoldExpressionsTraverser : public TIntermTraverser
+{
+  public:
+    FoldExpressionsTraverser(TDiagnostics *diagnostics)
+        : TIntermTraverser(true, false, false), mDiagnostics(diagnostics), mDidReplace(false)
+    {}
+
+    bool didReplace() { return mDidReplace; }
+
+    void nextIteration() { mDidReplace = false; }
+
+  protected:
+    bool visitTernary(Visit visit, TIntermTernary *node) override
+    {
+        TIntermTyped *folded = node->fold(mDiagnostics);
+        if (folded != node)
+        {
+            queueReplacement(folded, OriginalNode::IS_DROPPED);
+            mDidReplace = true;
+            return false;
+        }
+        return true;
+    }
+
+    bool visitAggregate(Visit visit, TIntermAggregate *node) override
+    {
+        TIntermTyped *folded = node->fold(mDiagnostics);
+        if (folded != node)
+        {
+            queueReplacement(folded, OriginalNode::IS_DROPPED);
+            mDidReplace = true;
+            return false;
+        }
+        return true;
+    }
+
+    bool visitBinary(Visit visit, TIntermBinary *node) override
+    {
+        TIntermTyped *folded = node->fold(mDiagnostics);
+        if (folded != node)
+        {
+            queueReplacement(folded, OriginalNode::IS_DROPPED);
+            mDidReplace = true;
+            return false;
+        }
+        return true;
+    }
+
+    bool visitUnary(Visit visit, TIntermUnary *node) override
+    {
+        TIntermTyped *folded = node->fold(mDiagnostics);
+        if (folded != node)
+        {
+            queueReplacement(folded, OriginalNode::IS_DROPPED);
+            mDidReplace = true;
+            return false;
+        }
+        return true;
+    }
+
+    bool visitSwizzle(Visit visit, TIntermSwizzle *node) override
+    {
+        TIntermTyped *folded = node->fold(mDiagnostics);
+        if (folded != node)
+        {
+            queueReplacement(folded, OriginalNode::IS_DROPPED);
+            mDidReplace = true;
+            return false;
+        }
+        return true;
+    }
+
+  private:
+    TDiagnostics *mDiagnostics;
+    bool mDidReplace;
+};
+
+}  // anonymous namespace
+
+bool FoldExpressions(TCompiler *compiler, TIntermBlock *root, TDiagnostics *diagnostics)
+{
+    FoldExpressionsTraverser traverser(diagnostics);
+    do
+    {
+        traverser.nextIteration();
+        root->traverse(&traverser);
+        if (!traverser.updateTree(compiler, root))
+        {
+            return false;
+        }
+    } while (traverser.didReplace());
+
+    return true;
+}
+
+}  // namespace sh