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

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• Author : Corentin Wallez
  Date : 2014-11-10 12:07:37
  Hash : 80bacde5
  Message : Use the [[flatten]] attribute only when a loop is present. Flattening branch-heavy shaders that contained no loops caused regressions. As a temporary workaround we only flatten ifs when there exists a loop. BUG=395048 Change-Id: I95c40f0249643b98c62304a0f2a4563561d1fbbc Reviewed-on: https://chromium-review.googlesource.com/228722 Reviewed-by: Shannon Woods <shannonwoods@chromium.org> Tested-by: Corentin Wallez <cwallez@chromium.org>

• src/compiler/translator/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/translator/DetectDiscontinuity.h"
  
  #include "compiler/translator/ParseContext.h"
  
  namespace sh
  {
  
  // Detect Loop Discontinuity
  
  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);
  }
  
  // Detect Any Loop
  
  bool DetectAnyLoop::traverse(TIntermNode *node)
  {
      mHasLoop = false;
      node->traverse(this);
      return mHasLoop;
  }
  
  bool DetectAnyLoop::visitLoop(Visit visit, TIntermLoop *loop)
  {
      mHasLoop = true;
      return false;
  }
  
  // The following definitions stop all traversal when we have found a loop
  bool DetectAnyLoop::visitBinary(Visit, TIntermBinary *)
  {
      return !mHasLoop;
  }
  
  bool DetectAnyLoop::visitUnary(Visit, TIntermUnary *)
  {
      return !mHasLoop;
  }
  
  bool DetectAnyLoop::visitSelection(Visit, TIntermSelection *)
  {
      return !mHasLoop;
  }
  
  bool DetectAnyLoop::visitAggregate(Visit, TIntermAggregate *)
  {
      return !mHasLoop;
  }
  
  bool DetectAnyLoop::visitBranch(Visit, TIntermBranch *)
  {
      return !mHasLoop;
  }
  
  bool containsAnyLoop(TIntermNode *node)
  {
      DetectAnyLoop detectAnyLoop;
      return detectAnyLoop.traverse(node);
  }
  
  // Detect Gradient Operation
  
  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);
  }
  }