kc3-lang/angle/src/compiler/DetectDiscontinuity.cpp

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• Author : shannon.woods@transgaming.com
  Date : 2013-01-25 21:56:03
  Hash : e91615cb
  Message : Treat return statements in loops as loop discontinuities. This is so that texture2D is converted to texture2DLod in loops with return statements. HLSL does not seem to allow gradient operations in loops with return statements. It considers them to be breaks. Review URL: https://codereview.appspot.com/7131057 git-svn-id: https://angleproject.googlecode.com/svn/branches/dx11proto@1788 736b8ea6-26fd-11df-bfd4-992fa37f6226

• src/compiler/DetectDiscontinuity.cpp

• //
  // Copyright (c) 2012 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.
  //
  // Contains analysis utilities for dealing with HLSL's lack of support for
  // the use of intrinsic functions which (implicitly or explicitly) compute
  // gradients of functions with discontinuities. 
  //
  
  #include "compiler/DetectDiscontinuity.h"
  
  #include "compiler/ParseHelper.h"
  
  namespace sh
  {
  bool DetectLoopDiscontinuity::traverse(TIntermNode *node)
  {
      mLoopDepth = 0;
      mLoopDiscontinuity = false;
      node->traverse(this);
      return mLoopDiscontinuity;
  }
  
  bool DetectLoopDiscontinuity::visitLoop(Visit visit, TIntermLoop *loop)
  {
      if (visit == PreVisit)
      {
          ++mLoopDepth;
      }
      else if (visit == PostVisit)
      {
          --mLoopDepth;
      }
  
      return true;
  }
  
  bool DetectLoopDiscontinuity::visitBranch(Visit visit, TIntermBranch *node)
  {
      if (mLoopDiscontinuity)
      {
          return false;
      }
  
      if (!mLoopDepth)
      {
          return true;
      }
  
      switch (node->getFlowOp())
      {
        case EOpKill:
          break;
        case EOpBreak:
        case EOpContinue:
        case EOpReturn:
          mLoopDiscontinuity = true;
          break;
        default: UNREACHABLE();
      }
  
      return !mLoopDiscontinuity;
  }
  
  bool DetectLoopDiscontinuity::visitAggregate(Visit visit, TIntermAggregate *node)
  {
      return !mLoopDiscontinuity;
  }
  
  bool containsLoopDiscontinuity(TIntermNode *node)
  {
      DetectLoopDiscontinuity detectLoopDiscontinuity;
      return detectLoopDiscontinuity.traverse(node);
  }
  
  bool DetectGradientOperation::traverse(TIntermNode *node)
  {
      mGradientOperation = false;
      node->traverse(this);
      return mGradientOperation;
  }
  
  bool DetectGradientOperation::visitUnary(Visit visit, TIntermUnary *node)
  {
      if (mGradientOperation)
      {
          return false;
      }
  
      switch (node->getOp())
      {
        case EOpDFdx:
        case EOpDFdy:
          mGradientOperation = true;
        default:
          break;
      }
  
      return !mGradientOperation;
  }
  
  bool DetectGradientOperation::visitAggregate(Visit visit, TIntermAggregate *node)
  {
      if (mGradientOperation)
      {
          return false;
      }
  
      if (node->getOp() == EOpFunctionCall)
      {
          if (!node->isUserDefined())
          {
              TString name = TFunction::unmangleName(node->getName());
  
              if (name == "texture2D" ||
                  name == "texture2DProj" ||
                  name == "textureCube")
              {
                  mGradientOperation = true;
              }
          }
          else
          {
              // When a user defined function is called, we have to
              // conservatively assume it to contain gradient operations
              mGradientOperation = true;
          }
      }
  
      return !mGradientOperation;
  }
  
  bool containsGradientOperation(TIntermNode *node)
  {
      DetectGradientOperation detectGradientOperation;
      return detectGradientOperation.traverse(node);
  }
  }