// // 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); TIntermAggregate *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); mul->setLeft(current); mul->setRight(createTempSymbol(lhs->getType())); mul->setType(node->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); div->setLeft(oneNode); div->setRight(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