1 files changed, 99 insertions, 0 deletions
diff --git a/gfx/angle/src/compiler/translator/RemovePow.cpp b/gfx/angle/src/compiler/translator/RemovePow.cpp
new file mode 100755
index 000000000..192084c36
--- /dev/null
+++ b/gfx/angle/src/compiler/translator/RemovePow.cpp
@@ -0,0 +1,99 @@
+//
+// Copyright (c) 2002-2015 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.
+//
+// RemovePow is an AST traverser to convert pow(x, y) built-in calls where y is a
+// constant to exp2(y * log2(x)). This works around an issue in NVIDIA 311 series
+// OpenGL drivers.
+//
+
+#include "compiler/translator/RemovePow.h"
+
+#include "compiler/translator/InfoSink.h"
+#include "compiler/translator/IntermNode.h"
+
+namespace sh
+{
+
+namespace
+{
+
+bool IsProblematicPow(TIntermTyped *node)
+{
+    TIntermAggregate *agg = node->getAsAggregate();
+    if (agg != nullptr && agg->getOp() == EOpPow)
+    {
+        ASSERT(agg->getSequence()->size() == 2);
+        return agg->getSequence()->at(1)->getAsConstantUnion() != nullptr;
+    }
+    return false;
+}
+
+// Traverser that converts all pow operations simultaneously.
+class RemovePowTraverser : public TIntermTraverser
+{
+  public:
+    RemovePowTraverser();
+
+    bool visitAggregate(Visit visit, TIntermAggregate *node) override;
+
+    void nextIteration() { mNeedAnotherIteration = false; }
+    bool needAnotherIteration() const { return mNeedAnotherIteration; }
+
+  protected:
+    bool mNeedAnotherIteration;
+};
+
+RemovePowTraverser::RemovePowTraverser()
+    : TIntermTraverser(true, false, false),
+      mNeedAnotherIteration(false)
+{
+}
+
+bool RemovePowTraverser::visitAggregate(Visit visit, TIntermAggregate *node)
+{
+    if (IsProblematicPow(node))
+    {
+        TIntermTyped *x = node->getSequence()->at(0)->getAsTyped();
+        TIntermTyped *y = node->getSequence()->at(1)->getAsTyped();
+
+        TIntermUnary *log = new TIntermUnary(EOpLog2, x);
+        log->setLine(node->getLine());
+
+        TOperator op       = TIntermBinary::GetMulOpBasedOnOperands(y->getType(), log->getType());
+        TIntermBinary *mul = new TIntermBinary(op, y, log);
+        mul->setLine(node->getLine());
+
+        TIntermUnary *exp = new TIntermUnary(EOpExp2, mul);
+        exp->setLine(node->getLine());
+
+        queueReplacement(node, exp, OriginalNode::IS_DROPPED);
+
+        // If the x parameter also needs to be replaced, we need to do that in another traversal,
+        // since it's parent node will change in a way that's not handled correctly by updateTree().
+        if (IsProblematicPow(x))
+        {
+            mNeedAnotherIteration = true;
+            return false;
+        }
+    }
+    return true;
+}
+
+} // namespace
+
+void RemovePow(TIntermNode *root)
+{
+    RemovePowTraverser traverser;
+    // Iterate as necessary, and reset the traverser between iterations.
+    do
+    {
+        traverser.nextIteration();
+        root->traverse(&traverser);
+        traverser.updateTree();
+    }
+    while (traverser.needAnotherIteration());
+}
+
+}  // namespace sh