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

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• Hash : 472c74c6
  Author :
  Date : 2019-08-19T16:32:13
  

  Translator: Allow tree validation in children of TCompiler
  
  This is to be able to perform validation inside TranslatorVulkan, even
  if it's through ASSERTs.
  
  Additionally, every transformation is changed such that they do their
  validation themselves.  TIntermTraverser::updateTree() performs the
  validation, which indirectly validates many of three tree
  transformations.  Some of the more ancient transformations that don't
  use this function directly call TCompiler::validateAST.
  
  Bug: angleproject:2733
  Change-Id: Ie4af029d34e053c5ad1dc8c2c2568eecd625d344
  Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1761149
  Reviewed-by: Geoff Lang <geofflang@chromium.org>
  Reviewed-by: Jamie Madill <jmadill@chromium.org>
  Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>
  

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

• //
  // Copyright 2002 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.
  //
  // PruneNoOps.cpp: The PruneNoOps function prunes:
  //   1. Empty declarations "int;". Empty declarators will be pruned as well, so for example:
  //        int , a;
  //      is turned into
  //        int a;
  //   2. Literal statements: "1.0;". The ESSL output doesn't define a default precision for float,
  //      so float literal statements would end up with no precision which is invalid ESSL.
  
  #include "compiler/translator/tree_ops/PruneNoOps.h"
  
  #include "compiler/translator/Symbol.h"
  #include "compiler/translator/tree_util/IntermTraverse.h"
  
  namespace sh
  {
  
  namespace
  {
  
  bool IsNoOp(TIntermNode *node)
  {
      if (node->getAsConstantUnion() != nullptr)
      {
          return true;
      }
      bool isEmptyDeclaration = node->getAsDeclarationNode() != nullptr &&
                                node->getAsDeclarationNode()->getSequence()->empty();
      if (isEmptyDeclaration)
      {
          return true;
      }
      return false;
  }
  
  class PruneNoOpsTraverser : private TIntermTraverser
  {
    public:
      ANGLE_NO_DISCARD static bool apply(TCompiler *compiler,
                                         TIntermBlock *root,
                                         TSymbolTable *symbolTable);
  
    private:
      PruneNoOpsTraverser(TSymbolTable *symbolTable);
      bool visitDeclaration(Visit, TIntermDeclaration *node) override;
      bool visitBlock(Visit visit, TIntermBlock *node) override;
      bool visitLoop(Visit visit, TIntermLoop *loop) override;
  };
  
  bool PruneNoOpsTraverser::apply(TCompiler *compiler, TIntermBlock *root, TSymbolTable *symbolTable)
  {
      PruneNoOpsTraverser prune(symbolTable);
      root->traverse(&prune);
      return prune.updateTree(compiler, root);
  }
  
  PruneNoOpsTraverser::PruneNoOpsTraverser(TSymbolTable *symbolTable)
      : TIntermTraverser(true, false, false, symbolTable)
  {}
  
  bool PruneNoOpsTraverser::visitDeclaration(Visit, TIntermDeclaration *node)
  {
      TIntermSequence *sequence = node->getSequence();
      if (sequence->size() >= 1)
      {
          TIntermSymbol *declaratorSymbol = sequence->front()->getAsSymbolNode();
          // Prune declarations without a variable name, unless it's an interface block declaration.
          if (declaratorSymbol != nullptr &&
              declaratorSymbol->variable().symbolType() == SymbolType::Empty &&
              !declaratorSymbol->isInterfaceBlock())
          {
              if (sequence->size() > 1)
              {
                  // Generate a replacement that will remove the empty declarator in the beginning of
                  // a declarator list. Example of a declaration that will be changed:
                  // float, a;
                  // will be changed to
                  // float a;
                  // This applies also to struct declarations.
                  TIntermSequence emptyReplacement;
                  mMultiReplacements.push_back(
                      NodeReplaceWithMultipleEntry(node, declaratorSymbol, emptyReplacement));
              }
              else if (declaratorSymbol->getBasicType() != EbtStruct)
              {
                  // If there are entirely empty non-struct declarations, they result in
                  // TIntermDeclaration nodes without any children in the parsing stage. These are
                  // handled in visitBlock and visitLoop.
                  UNREACHABLE();
              }
              else if (declaratorSymbol->getQualifier() != EvqGlobal &&
                       declaratorSymbol->getQualifier() != EvqTemporary)
              {
                  // Single struct declarations may just declare the struct type and no variables, so
                  // they should not be pruned. Here we handle an empty struct declaration with a
                  // qualifier, for example like this:
                  //   const struct a { int i; };
                  // NVIDIA GL driver version 367.27 doesn't accept this kind of declarations, so we
                  // convert the declaration to a regular struct declaration. This is okay, since ESSL
                  // 1.00 spec section 4.1.8 says about structs that "The optional qualifiers only
                  // apply to any declarators, and are not part of the type being defined for name."
  
                  // Create a new variable to use in the declarator so that the variable and node
                  // types are kept consistent.
                  TType *type = new TType(declaratorSymbol->getType());
                  if (mInGlobalScope)
                  {
                      type->setQualifier(EvqGlobal);
                  }
                  else
                  {
                      type->setQualifier(EvqTemporary);
                  }
                  TVariable *variable =
                      new TVariable(mSymbolTable, kEmptyImmutableString, type, SymbolType::Empty);
                  queueReplacementWithParent(node, declaratorSymbol, new TIntermSymbol(variable),
                                             OriginalNode::IS_DROPPED);
              }
          }
      }
      return false;
  }
  
  bool PruneNoOpsTraverser::visitBlock(Visit visit, TIntermBlock *node)
  {
      TIntermSequence *statements = node->getSequence();
  
      for (TIntermNode *statement : *statements)
      {
          if (IsNoOp(statement))
          {
              TIntermSequence emptyReplacement;
              mMultiReplacements.push_back(
                  NodeReplaceWithMultipleEntry(node, statement, emptyReplacement));
          }
      }
  
      return true;
  }
  
  bool PruneNoOpsTraverser::visitLoop(Visit visit, TIntermLoop *loop)
  {
      TIntermTyped *expr = loop->getExpression();
      if (expr != nullptr && IsNoOp(expr))
      {
          loop->setExpression(nullptr);
      }
      TIntermNode *init = loop->getInit();
      if (init != nullptr && IsNoOp(init))
      {
          loop->setInit(nullptr);
      }
  
      return true;
  }
  
  }  // namespace
  
  bool PruneNoOps(TCompiler *compiler, TIntermBlock *root, TSymbolTable *symbolTable)
  {
      return PruneNoOpsTraverser::apply(compiler, root, symbolTable);
  }
  
  }  // namespace sh
  

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