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

• Show log

  Commit

• Hash : 950d054a
  Author :
  Date : 2024-01-11T00:00:00
  

  Metal: Do not defer global const initializers
  
  Since MSL supports constant global variables, they should
  not be included in the DeferGlobalInitializers operation.
  
  This reduces temporary register usage and thus makes shaders
  that use large const arrays more compatible with Apple GPUs.
  
  Fixed: angleproject:8479
  Change-Id: If1cd17a0a194173e60e6b5152297054fc384c0b2
  Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/5189165
  Reviewed-by: Kimmo Kinnunen <kkinnunen@apple.com>
  Reviewed-by: Geoff Lang <geofflang@chromium.org>
  Commit-Queue: Alexey Knyazev <lexa.knyazev@gmail.com>
  

Download

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

• //
  // Copyright 2016 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.
  //
  // DeferGlobalInitializers is an AST traverser that moves global initializers into a separate
  // function that is called in the beginning of main(). This enables initialization of globals with
  // uniforms or non-constant globals, as allowed by the WebGL spec. Some initializers referencing
  // non-constants may need to be unfolded into if statements in HLSL - this kind of steps should be
  // done after DeferGlobalInitializers is run. Note that it's important that the function definition
  // is at the end of the shader, as some globals may be declared after main().
  //
  // It can also initialize all uninitialized globals.
  //
  
  #include "compiler/translator/tree_ops/DeferGlobalInitializers.h"
  
  #include <vector>
  
  #include "compiler/translator/Compiler.h"
  #include "compiler/translator/IntermNode.h"
  #include "compiler/translator/StaticType.h"
  #include "compiler/translator/SymbolTable.h"
  #include "compiler/translator/tree_ops/InitializeVariables.h"
  #include "compiler/translator/tree_util/FindMain.h"
  #include "compiler/translator/tree_util/IntermNode_util.h"
  #include "compiler/translator/tree_util/ReplaceVariable.h"
  
  namespace sh
  {
  
  namespace
  {
  
  constexpr const ImmutableString kInitGlobalsString("initGlobals");
  
  void GetDeferredInitializers(TIntermDeclaration *declaration,
                               bool initializeUninitializedGlobals,
                               bool canUseLoopsToInitialize,
                               bool highPrecisionSupported,
                               bool forceDeferNonConstGlobalInitializers,
                               TIntermSequence *deferredInitializersOut,
                               std::vector<const TVariable *> *variablesToReplaceOut,
                               TSymbolTable *symbolTable)
  {
      // SeparateDeclarations should have already been run.
      ASSERT(declaration->getSequence()->size() == 1);
  
      TIntermNode *declarator = declaration->getSequence()->back();
      TIntermBinary *init     = declarator->getAsBinaryNode();
      if (init)
      {
          TIntermSymbol *symbolNode = init->getLeft()->getAsSymbolNode();
          ASSERT(symbolNode);
          TIntermTyped *expression = init->getRight();
  
          if (expression->getQualifier() != EvqConst || !expression->hasConstantValue() ||
              (forceDeferNonConstGlobalInitializers && symbolNode->getQualifier() != EvqConst))
          {
              // For variables which are not constant, defer their real initialization until
              // after we initialize uniforms.
              // Deferral is done also in any cases where the variable can not be converted to a
              // constant union, since otherwise there's a chance that HLSL output will generate extra
              // statements from the initializer expression.
  
              // Change const global to a regular global if its initialization is deferred.
              // This can happen if ANGLE has not been able to fold the constant expression used
              // as an initializer.
              ASSERT(symbolNode->getQualifier() == EvqConst ||
                     symbolNode->getQualifier() == EvqGlobal);
              if (symbolNode->getQualifier() == EvqConst)
              {
                  variablesToReplaceOut->push_back(&symbolNode->variable());
              }
  
              TIntermBinary *deferredInit =
                  new TIntermBinary(EOpAssign, symbolNode->deepCopy(), init->getRight());
              deferredInitializersOut->push_back(deferredInit);
  
              // Remove the initializer from the global scope and just declare the global instead.
              declaration->replaceChildNode(init, symbolNode);
          }
      }
      else if (initializeUninitializedGlobals)
      {
          TIntermSymbol *symbolNode = declarator->getAsSymbolNode();
          ASSERT(symbolNode);
  
          // Ignore ANGLE internal variables and nameless declarations.
          if (symbolNode->variable().symbolType() == SymbolType::AngleInternal ||
              symbolNode->variable().symbolType() == SymbolType::Empty)
              return;
  
          if (symbolNode->getQualifier() == EvqGlobal)
          {
              TIntermSequence initCode;
              CreateInitCode(symbolNode, canUseLoopsToInitialize, highPrecisionSupported, &initCode,
                             symbolTable);
              deferredInitializersOut->insert(deferredInitializersOut->end(), initCode.begin(),
                                              initCode.end());
          }
      }
  }
  
  void InsertInitCallToMain(TIntermBlock *root,
                            TIntermSequence *deferredInitializers,
                            TSymbolTable *symbolTable)
  {
      TIntermBlock *initGlobalsBlock = new TIntermBlock();
      initGlobalsBlock->getSequence()->swap(*deferredInitializers);
  
      TFunction *initGlobalsFunction =
          new TFunction(symbolTable, kInitGlobalsString, SymbolType::AngleInternal,
                        StaticType::GetBasic<EbtVoid, EbpUndefined>(), false);
  
      TIntermFunctionPrototype *initGlobalsFunctionPrototype =
          CreateInternalFunctionPrototypeNode(*initGlobalsFunction);
      root->getSequence()->insert(root->getSequence()->begin(), initGlobalsFunctionPrototype);
      TIntermFunctionDefinition *initGlobalsFunctionDefinition =
          CreateInternalFunctionDefinitionNode(*initGlobalsFunction, initGlobalsBlock);
      root->appendStatement(initGlobalsFunctionDefinition);
  
      TIntermSequence emptySequence;
      TIntermAggregate *initGlobalsCall =
          TIntermAggregate::CreateFunctionCall(*initGlobalsFunction, &emptySequence);
  
      TIntermBlock *mainBody = FindMainBody(root);
      mainBody->getSequence()->insert(mainBody->getSequence()->begin(), initGlobalsCall);
  }
  
  }  // namespace
  
  bool DeferGlobalInitializers(TCompiler *compiler,
                               TIntermBlock *root,
                               bool initializeUninitializedGlobals,
                               bool canUseLoopsToInitialize,
                               bool highPrecisionSupported,
                               bool forceDeferNonConstGlobalInitializers,
                               TSymbolTable *symbolTable)
  {
      TIntermSequence deferredInitializers;
      std::vector<const TVariable *> variablesToReplace;
  
      // Loop over all global statements and process the declarations. This is simpler than using a
      // traverser.
      for (TIntermNode *statement : *root->getSequence())
      {
          TIntermDeclaration *declaration = statement->getAsDeclarationNode();
          if (declaration)
          {
              GetDeferredInitializers(declaration, initializeUninitializedGlobals,
                                      canUseLoopsToInitialize, highPrecisionSupported,
                                      forceDeferNonConstGlobalInitializers, &deferredInitializers,
                                      &variablesToReplace, symbolTable);
          }
      }
  
      // Add the function with initialization and the call to that.
      if (!deferredInitializers.empty())
      {
          InsertInitCallToMain(root, &deferredInitializers, symbolTable);
      }
  
      // Replace constant variables with non-constant global variables.
      for (const TVariable *var : variablesToReplace)
      {
          TType *replacementType = new TType(var->getType());
          replacementType->setQualifier(EvqGlobal);
          TVariable *replacement =
              new TVariable(symbolTable, var->name(), replacementType, var->symbolType());
          if (!ReplaceVariable(compiler, root, var, replacement))
          {
              return false;
          }
      }
  
      return true;
  }
  
  }  // namespace sh
  

Download