kc3-lang/angle/src/compiler/translator/tree_ops/vulkan/RemoveInactiveInterfaceVariables.cpp

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• Hash : 382bf288
  Author :
  Date : 2020-12-24T23:56:39
  

  Organize AST transforms per backend
  
  Most of the AST transforms are written as a workaround to an issue that
  affects a single backend.  This change identifies such transforms and
  organizes them by backend.  They are then only built if the respective
  backend is.
  
  Additionally, about half of the GL transforms are due to mac
  workarounds, including the large RewriteRowMajorMatrices transform.
  Mac-specific workarounds are additionally only built on said platform.
  
  This change reduces the ANGLE binary size:
  
  - 106KB in a Vulkan-only build on Linux
  - 27KB in a GL-only build on Android (60KB on Linux)
  
  Bug: chromium:1084580
  Bug: chromium:1161513
  Change-Id: I64b334332c0d4f848756c6538af0d8d96864c7e9
  Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2601346
  Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>
  Reviewed-by: Jamie Madill <jmadill@chromium.org>
  Reviewed-by: Tim Van Patten <timvp@google.com>
  

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• src/compiler/translator/tree_ops/vulkan/RemoveInactiveInterfaceVariables.cpp

• //
  // Copyright 2019 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.
  //
  // RemoveInactiveInterfaceVariables.h:
  //  Drop shader interface variable declarations for those that are inactive.
  //
  
  #include "compiler/translator/tree_ops/vulkan/RemoveInactiveInterfaceVariables.h"
  
  #include "compiler/translator/SymbolTable.h"
  #include "compiler/translator/tree_util/IntermTraverse.h"
  #include "compiler/translator/util.h"
  
  namespace sh
  {
  
  namespace
  {
  
  // Traverser that removes all declarations that correspond to inactive variables.
  class RemoveInactiveInterfaceVariablesTraverser : public TIntermTraverser
  {
    public:
      RemoveInactiveInterfaceVariablesTraverser(
          const std::vector<sh::ShaderVariable> &attributes,
          const std::vector<sh::ShaderVariable> &inputVaryings,
          const std::vector<sh::ShaderVariable> &outputVariables,
          const std::vector<sh::ShaderVariable> &uniforms,
          const std::vector<sh::InterfaceBlock> &interfaceBlocks);
  
      bool visitDeclaration(Visit visit, TIntermDeclaration *node) override;
  
    private:
      const std::vector<sh::ShaderVariable> &mAttributes;
      const std::vector<sh::ShaderVariable> &mInputVaryings;
      const std::vector<sh::ShaderVariable> &mOutputVariables;
      const std::vector<sh::ShaderVariable> &mUniforms;
      const std::vector<sh::InterfaceBlock> &mInterfaceBlocks;
  };
  
  RemoveInactiveInterfaceVariablesTraverser::RemoveInactiveInterfaceVariablesTraverser(
      const std::vector<sh::ShaderVariable> &attributes,
      const std::vector<sh::ShaderVariable> &inputVaryings,
      const std::vector<sh::ShaderVariable> &outputVariables,
      const std::vector<sh::ShaderVariable> &uniforms,
      const std::vector<sh::InterfaceBlock> &interfaceBlocks)
      : TIntermTraverser(true, false, false),
        mAttributes(attributes),
        mInputVaryings(inputVaryings),
        mOutputVariables(outputVariables),
        mUniforms(uniforms),
        mInterfaceBlocks(interfaceBlocks)
  {}
  
  template <typename Variable>
  bool IsVariableActive(const std::vector<Variable> &mVars, const ImmutableString &name)
  {
      for (const Variable &var : mVars)
      {
          if (name == var.name)
          {
              return var.active;
          }
      }
      UNREACHABLE();
      return true;
  }
  
  bool RemoveInactiveInterfaceVariablesTraverser::visitDeclaration(Visit visit,
                                                                   TIntermDeclaration *node)
  {
      // SeparateDeclarations should have already been run.
      ASSERT(node->getSequence()->size() == 1u);
  
      TIntermTyped *declarator = node->getSequence()->front()->getAsTyped();
      ASSERT(declarator);
  
      TIntermSymbol *asSymbol = declarator->getAsSymbolNode();
      if (!asSymbol)
      {
          return false;
      }
  
      const TType &type = declarator->getType();
  
      // Remove all shader interface variables except outputs, i.e. uniforms, interface blocks and
      // inputs.
      //
      // Imagine a situation where the VS doesn't write to a varying but the FS reads from it.  This
      // is allowed, though the value of the varying is undefined.  If the varying is removed here,
      // the situation is changed to VS not declaring the varying, but the FS reading from it, which
      // is not allowed.  That's why inactive shader outputs are not removed.
      //
      // Inactive fragment shader outputs can be removed though, as there is no next stage.
      bool removeDeclaration     = false;
      const TQualifier qualifier = type.getQualifier();
  
      if (type.isInterfaceBlock())
      {
          // When a member has an explicit location, interface block should not be removed.
          // If the member or interface would be removed, GetProgramResource could not return the
          // location.
          if (!IsShaderIoBlock(type.getQualifier()))
          {
              removeDeclaration =
                  !IsVariableActive(mInterfaceBlocks, type.getInterfaceBlock()->name());
          }
      }
      else if (qualifier == EvqUniform)
      {
          removeDeclaration = !IsVariableActive(mUniforms, asSymbol->getName());
      }
      else if (qualifier == EvqAttribute || qualifier == EvqVertexIn)
      {
          removeDeclaration = !IsVariableActive(mAttributes, asSymbol->getName());
      }
      else if (IsShaderIn(qualifier))
      {
          removeDeclaration = !IsVariableActive(mInputVaryings, asSymbol->getName());
      }
      else if (qualifier == EvqFragmentOut)
      {
          removeDeclaration = !IsVariableActive(mOutputVariables, asSymbol->getName());
      }
  
      if (removeDeclaration)
      {
          TIntermSequence emptySequence;
          mMultiReplacements.emplace_back(getParentNode()->getAsBlock(), node, emptySequence);
      }
  
      return false;
  }
  
  }  // namespace
  
  bool RemoveInactiveInterfaceVariables(TCompiler *compiler,
                                        TIntermBlock *root,
                                        const std::vector<sh::ShaderVariable> &attributes,
                                        const std::vector<sh::ShaderVariable> &inputVaryings,
                                        const std::vector<sh::ShaderVariable> &outputVariables,
                                        const std::vector<sh::ShaderVariable> &uniforms,
                                        const std::vector<sh::InterfaceBlock> &interfaceBlocks)
  {
      RemoveInactiveInterfaceVariablesTraverser traverser(attributes, inputVaryings, outputVariables,
                                                          uniforms, interfaceBlocks);
      root->traverse(&traverser);
      return traverser.updateTree(compiler, root);
  }
  
  }  // namespace sh
  

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