kc3-lang/angle/src/compiler/translator/tree_ops/ExpandIntegerPowExpressions.cpp

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• Author : Stuart Morgan
  Date : 2019-08-14 12:25:12
  Hash : 9d737966
  Message : Standardize copyright notices to project style For all "ANGLE Project" copyrights, standardize to the format specified by the style guide. Changes: - "Copyright (c)" and "Copyright(c)" changed to just "Copyright". - Removed the second half of date ranges ("Y1Y1-Y2Y2"->"Y1Y1"). - Fixed a small number of files that had no copyright date using the initial commit year from the version control history. - Fixed one instance of copyright being "The ANGLE Project" rather than "The ANGLE Project Authors" These changes are applied both to the copyright of source file, and where applicable to copyright statements that are generated by templates. BUG=angleproject:3811 Change-Id: I973dd65e4ef9deeba232d5be74c768256a0eb2e5 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1754397 Commit-Queue: Jamie Madill <jmadill@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org>

• src/compiler/translator/tree_ops/ExpandIntegerPowExpressions.cpp

• //
  // 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.
  //
  // Implementation of the integer pow expressions HLSL bug workaround.
  // See header for more info.
  
  #include "compiler/translator/tree_ops/ExpandIntegerPowExpressions.h"
  
  #include <cmath>
  #include <cstdlib>
  
  #include "compiler/translator/tree_util/IntermNode_util.h"
  #include "compiler/translator/tree_util/IntermTraverse.h"
  
  namespace sh
  {
  
  namespace
  {
  
  class Traverser : public TIntermTraverser
  {
    public:
      static void Apply(TIntermNode *root, TSymbolTable *symbolTable);
  
    private:
      Traverser(TSymbolTable *symbolTable);
      bool visitAggregate(Visit visit, TIntermAggregate *node) override;
      void nextIteration();
  
      bool mFound = false;
  };
  
  // static
  void Traverser::Apply(TIntermNode *root, TSymbolTable *symbolTable)
  {
      Traverser traverser(symbolTable);
      do
      {
          traverser.nextIteration();
          root->traverse(&traverser);
          if (traverser.mFound)
          {
              traverser.updateTree();
          }
      } while (traverser.mFound);
  }
  
  Traverser::Traverser(TSymbolTable *symbolTable) : TIntermTraverser(true, false, false, symbolTable)
  {}
  
  void Traverser::nextIteration()
  {
      mFound = false;
  }
  
  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 *constantExponent = sequence->at(1)->getAsConstantUnion();
  
      // Test 1: check for a single constant.
      if (!constantExponent || constantExponent->getNominalSize() != 1)
      {
          return true;
      }
  
      float exponentValue = constantExponent->getConstantValue()->getFConst();
  
      // Test 2: exponentValue is in the problematic range.
      if (exponentValue < -5.0f || exponentValue > 9.0f)
      {
          return true;
      }
  
      // Test 3: exponentValue is integer or pretty close to an integer.
      if (std::abs(exponentValue - std::round(exponentValue)) > 0.0001f)
      {
          return true;
      }
  
      // Test 4: skip -1, 0, and 1
      int exponent = static_cast<int>(std::round(exponentValue));
      int n        = std::abs(exponent);
      if (n < 2)
      {
          return true;
      }
  
      // Potential problem case detected, apply workaround.
  
      TIntermTyped *lhs = sequence->at(0)->getAsTyped();
      ASSERT(lhs);
  
      TIntermDeclaration *lhsVariableDeclaration = nullptr;
      TVariable *lhsVariable =
          DeclareTempVariable(mSymbolTable, lhs, EvqTemporary, &lhsVariableDeclaration);
      insertStatementInParentBlock(lhsVariableDeclaration);
  
      // Create a chain of n-1 multiples.
      TIntermTyped *current = CreateTempSymbolNode(lhsVariable);
      for (int i = 1; i < n; ++i)
      {
          TIntermBinary *mul = new TIntermBinary(EOpMul, current, CreateTempSymbolNode(lhsVariable));
          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(current, OriginalNode::IS_DROPPED);
      mFound = true;
      return false;
  }
  
  }  // anonymous namespace
  
  void ExpandIntegerPowExpressions(TIntermNode *root, TSymbolTable *symbolTable)
  {
      Traverser::Apply(root, symbolTable);
  }
  
  }  // namespace sh