kc3-lang/angle/src/compiler/timing/RestrictFragmentShaderTiming.h

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• Hash : 66ebd014
  Author :
  Date : 2012-05-30T22:18:11
  

  Add the SH_TIMING_RESTRICTIONS compile flag and dependency graph implementation.
  
  Description of the algorithm:
  http://code.google.com/p/mvujovic/wiki/ShaderControlFlowAnalysis
  
  This flag is one potential solution to timing attacks on textures containing cross-domain content
  or user agent data.
  This kind of analysis could be useful for both WebGL and CSS Shaders.
  
  The SH_TIMING_RESTRICTIONS flag will reject a shader if it uses texture dependent data to affect
  control flow.
  
  Other ways of affecting shader timing such as using NaNs in basic arithmetic operations or using
  built-in functions (e.g. atan) with different inputs are still under investigation.
  
  Issue=329
  Review URL: http://codereview.appspot.com/6195062/
  
  
  
  git-svn-id: https://angleproject.googlecode.com/svn/trunk@1101 736b8ea6-26fd-11df-bfd4-992fa37f6226
  

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• src/compiler/timing/RestrictFragmentShaderTiming.h

• //
  // 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.
  //
  
  #ifndef COMPILER_TIMING_RESTRICT_FRAGMENT_SHADER_TIMING_H_
  #define COMPILER_TIMING_RESTRICT_FRAGMENT_SHADER_TIMING_H_
  
  #include "GLSLANG/ShaderLang.h"
  
  #include "compiler/intermediate.h"
  #include "compiler/depgraph/DependencyGraph.h"
  
  class TInfoSinkBase;
  
  class RestrictFragmentShaderTiming : TDependencyGraphTraverser {
  public:
      RestrictFragmentShaderTiming(TInfoSinkBase& sink, const TString& restrictedSymbol)
          : mSink(sink)
          , mRestrictedSymbol(restrictedSymbol)
          , mNumErrors(0) {}
  
      void enforceRestrictions(const TDependencyGraph& graph);
      int numErrors() const { return mNumErrors; }
  
      virtual void visitArgument(TGraphArgument* parameter);
      virtual void visitSelection(TGraphSelection* selection);
      virtual void visitLoop(TGraphLoop* loop);
      virtual void visitLogicalOp(TGraphLogicalOp* logicalOp);
  
  private:
      void beginError(const TIntermNode* node);
      void validateUserDefinedFunctionCallUsage(const TDependencyGraph& graph);
  
  	TInfoSinkBase& mSink;
      const TString mRestrictedSymbol;
      int mNumErrors;
  };
  
  #endif  // COMPILER_TIMING_RESTRICT_FRAGMENT_SHADER_TIMING_H_
  

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