1 files changed, 154 insertions, 0 deletions
diff --git a/gfx/angle/src/compiler/translator/ExpandIntegerPowExpressions.cpp b/gfx/angle/src/compiler/translator/ExpandIntegerPowExpressions.cpp
new file mode 100755
index 000000000..c5ff7b36b
--- /dev/null
+++ b/gfx/angle/src/compiler/translator/ExpandIntegerPowExpressions.cpp
@@ -0,0 +1,154 @@
+//
+// Copyright (c) 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.
+//
+// Implementation of the integer pow expressions HLSL bug workaround.
+// See header for more info.
+
+#include "compiler/translator/ExpandIntegerPowExpressions.h"
+
+#include <cmath>
+#include <cstdlib>
+
+#include "compiler/translator/IntermNode.h"
+
+namespace sh
+{
+
+namespace
+{
+
+class Traverser : public TIntermTraverser
+{
+  public:
+    static void Apply(TIntermNode *root, unsigned int *tempIndex);
+
+  private:
+    Traverser();
+    bool visitAggregate(Visit visit, TIntermAggregate *node) override;
+    void nextIteration();
+
+    bool mFound = false;
+};
+
+// static
+void Traverser::Apply(TIntermNode *root, unsigned int *tempIndex)
+{
+    Traverser traverser;
+    traverser.useTemporaryIndex(tempIndex);
+    do
+    {
+        traverser.nextIteration();
+        root->traverse(&traverser);
+        if (traverser.mFound)
+        {
+            traverser.updateTree();
+        }
+    } while (traverser.mFound);
+}
+
+Traverser::Traverser() : TIntermTraverser(true, false, false)
+{
+}
+
+void Traverser::nextIteration()
+{
+    mFound = false;
+    nextTemporaryIndex();
+}
+
+bool Traverser::visitAggregate(Visit visit, TIntermAggregate *node)
+{
+    if (mFound)
+    {
+        return false;
+    }
+
+    // Test 0: skip non-pow operators.
+    if (node->getOp() != EOpPow)
+    {
+        return true;
+    }
+
+    const TIntermSequence *sequence = node->getSequence();
+    ASSERT(sequence->size() == 2u);
+    const TIntermConstantUnion *constantNode = sequence->at(1)->getAsConstantUnion();
+
+    // Test 1: check for a single constant.
+    if (!constantNode || constantNode->getNominalSize() != 1)
+    {
+        return true;
+    }
+
+    const TConstantUnion *constant = constantNode->getUnionArrayPointer();
+
+    TConstantUnion asFloat;
+    asFloat.cast(EbtFloat, *constant);
+
+    float value = asFloat.getFConst();
+
+    // Test 2: value is in the problematic range.
+    if (value < -5.0f || value > 9.0f)
+    {
+        return true;
+    }
+
+    // Test 3: value is integer or pretty close to an integer.
+    float absval = std::abs(value);
+    float frac   = absval - std::round(absval);
+    if (frac > 0.0001f)
+    {
+        return true;
+    }
+
+    // Test 4: skip -1, 0, and 1
+    int exponent = static_cast<int>(value);
+    int n        = std::abs(exponent);
+    if (n < 2)
+    {
+        return true;
+    }
+
+    // Potential problem case detected, apply workaround.
+    nextTemporaryIndex();
+
+    TIntermTyped *lhs = sequence->at(0)->getAsTyped();
+    ASSERT(lhs);
+
+    TIntermDeclaration *init = createTempInitDeclaration(lhs);
+    TIntermTyped *current  = createTempSymbol(lhs->getType());
+
+    insertStatementInParentBlock(init);
+
+    // Create a chain of n-1 multiples.
+    for (int i = 1; i < n; ++i)
+    {
+        TIntermBinary *mul = new TIntermBinary(EOpMul, current, createTempSymbol(lhs->getType()));
+        mul->setLine(node->getLine());
+        current = mul;
+    }
+
+    // For negative pow, compute the reciprocal of the positive pow.
+    if (exponent < 0)
+    {
+        TConstantUnion *oneVal = new TConstantUnion();
+        oneVal->setFConst(1.0f);
+        TIntermConstantUnion *oneNode = new TIntermConstantUnion(oneVal, node->getType());
+        TIntermBinary *div            = new TIntermBinary(EOpDiv, oneNode, current);
+        current = div;
+    }
+
+    queueReplacement(node, current, OriginalNode::IS_DROPPED);
+    mFound = true;
+    return false;
+}
+
+}  // anonymous namespace
+
+void ExpandIntegerPowExpressions(TIntermNode *root, unsigned int *tempIndex)
+{
+    Traverser::Apply(root, tempIndex);
+}
+
+}  // namespace sh