kc3-lang/angle/src/compiler/ForLoopUnroll.cpp

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• Hash : 0b8d4eb2
  Author :
  Date : 2011-04-04T19:17:11
  

  Unroll for-loop if sampler array uses loop index as its index.
  
  If inside a for-loop, sampler array index is the loop index, Mac cg compiler will crash.  This CL unroll the loop in such situation.  The behavior is:
  1) If the for-loop index is a float, we reject the shader.
  2) If it is an integer, we unroll the for-loop.
  
  Things that should be done in the future are:
  1) Add line number macros.
  2) Add a limit to unroll iteration count.
  
  anglebug=94
  Review URL: http://codereview.appspot.com/4331048
  
  git-svn-id: https://angleproject.googlecode.com/svn/trunk@606 736b8ea6-26fd-11df-bfd4-992fa37f6226
  

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• src/compiler/ForLoopUnroll.cpp

• //
  // Copyright (c) 2002-2011 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.
  //
  
  #include "compiler/ForLoopUnroll.h"
  
  void ForLoopUnroll::FillLoopIndexInfo(TIntermLoop* node, TLoopIndexInfo& info)
  {
      ASSERT(node->getType() == ELoopFor);
      ASSERT(node->getUnrollFlag());
  
      TIntermNode* init = node->getInit();
      ASSERT(init != NULL);
      TIntermAggregate* decl = init->getAsAggregate();
      ASSERT((decl != NULL) && (decl->getOp() == EOpDeclaration));
      TIntermSequence& declSeq = decl->getSequence();
      ASSERT(declSeq.size() == 1);
      TIntermBinary* declInit = declSeq[0]->getAsBinaryNode();
      ASSERT((declInit != NULL) && (declInit->getOp() == EOpInitialize));
      TIntermSymbol* symbol = declInit->getLeft()->getAsSymbolNode();
      ASSERT(symbol != NULL);
      ASSERT(symbol->getBasicType() == EbtInt);
  
      info.id = symbol->getId();
  
      ASSERT(declInit->getRight() != NULL);
      TIntermConstantUnion* initNode = declInit->getRight()->getAsConstantUnion();
      ASSERT(initNode != NULL);
  
      info.initValue = evaluateIntConstant(initNode);
      info.currentValue = info.initValue;
  
      TIntermNode* cond = node->getCondition();
      ASSERT(cond != NULL);
      TIntermBinary* binOp = cond->getAsBinaryNode();
      ASSERT(binOp != NULL);
      ASSERT(binOp->getRight() != NULL);
      ASSERT(binOp->getRight()->getAsConstantUnion() != NULL);
  
      info.incrementValue = getLoopIncrement(node);
      info.stopValue = evaluateIntConstant(
          binOp->getRight()->getAsConstantUnion());
      info.op = binOp->getOp();
  }
  
  void ForLoopUnroll::Step()
  {
      ASSERT(mLoopIndexStack.size() > 0);
      TLoopIndexInfo& info = mLoopIndexStack[mLoopIndexStack.size() - 1];
      info.currentValue += info.incrementValue;
  }
  
  bool ForLoopUnroll::SatisfiesLoopCondition()
  {
      ASSERT(mLoopIndexStack.size() > 0);
      TLoopIndexInfo& info = mLoopIndexStack[mLoopIndexStack.size() - 1];
      // Relational operator is one of: > >= < <= == or !=.
      switch (info.op) {
        case EOpEqual:
          return (info.currentValue == info.stopValue);
        case EOpNotEqual:
          return (info.currentValue != info.stopValue);
        case EOpLessThan:
          return (info.currentValue < info.stopValue);
        case EOpGreaterThan:
          return (info.currentValue > info.stopValue);
        case EOpLessThanEqual:
          return (info.currentValue <= info.stopValue);
        case EOpGreaterThanEqual:
          return (info.currentValue >= info.stopValue);
        default:
          UNREACHABLE();
      }
      return false;
  }
  
  bool ForLoopUnroll::NeedsToReplaceSymbolWithValue(TIntermSymbol* symbol)
  {
      for (TVector<TLoopIndexInfo>::iterator i = mLoopIndexStack.begin();
           i != mLoopIndexStack.end();
           ++i) {
          if (i->id == symbol->getId())
              return true;
      }
      return false;
  }
  
  int ForLoopUnroll::GetLoopIndexValue(TIntermSymbol* symbol)
  {
      for (TVector<TLoopIndexInfo>::iterator i = mLoopIndexStack.begin();
           i != mLoopIndexStack.end();
           ++i) {
          if (i->id == symbol->getId())
              return i->currentValue;
      }
      UNREACHABLE();
      return false;
  }
  
  void ForLoopUnroll::Push(TLoopIndexInfo& info)
  {
      mLoopIndexStack.push_back(info);
  }
  
  void ForLoopUnroll::Pop()
  {
      mLoopIndexStack.pop_back();
  }
  
  int ForLoopUnroll::getLoopIncrement(TIntermLoop* node)
  {
      TIntermNode* expr = node->getExpression();
      ASSERT(expr != NULL);
      // for expression has one of the following forms:
      //     loop_index++
      //     loop_index--
      //     loop_index += constant_expression
      //     loop_index -= constant_expression
      //     ++loop_index
      //     --loop_index
      // The last two forms are not specified in the spec, but I am assuming
      // its an oversight.
      TIntermUnary* unOp = expr->getAsUnaryNode();
      TIntermBinary* binOp = unOp ? NULL : expr->getAsBinaryNode();
  
      TOperator op = EOpNull;
      TIntermConstantUnion* incrementNode = NULL;
      if (unOp != NULL) {
          op = unOp->getOp();
      } else if (binOp != NULL) {
          op = binOp->getOp();
          ASSERT(binOp->getRight() != NULL);
          incrementNode = binOp->getRight()->getAsConstantUnion();
          ASSERT(incrementNode != NULL);
      }
  
      int increment = 0;
      // The operator is one of: ++ -- += -=.
      switch (op) {
          case EOpPostIncrement:
          case EOpPreIncrement:
              ASSERT((unOp != NULL) && (binOp == NULL));
              increment = 1;
              break;
          case EOpPostDecrement:
          case EOpPreDecrement:
              ASSERT((unOp != NULL) && (binOp == NULL));
              increment = -1;
              break;
          case EOpAddAssign:
              ASSERT((unOp == NULL) && (binOp != NULL));
              increment = evaluateIntConstant(incrementNode);
              break;
          case EOpSubAssign:
              ASSERT((unOp == NULL) && (binOp != NULL));
              increment = - evaluateIntConstant(incrementNode);
              break;
          default:
              ASSERT(false);
      }
  
      return increment;
  }
  
  int ForLoopUnroll::evaluateIntConstant(TIntermConstantUnion* node)
  {
      ASSERT((node != NULL) && (node->getUnionArrayPointer() != NULL));
      return node->getUnionArrayPointer()->getIConst();
  }
  
  

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