1    :  // Copyright 2013 Google Inc. All Rights Reserved.
   2    :  //
   3    :  // Licensed under the Apache License, Version 2.0 (the "License");
   4    :  // you may not use this file except in compliance with the License.
   5    :  // You may obtain a copy of the License at
   6    :  //
   7    :  //     http://www.apache.org/licenses/LICENSE-2.0
   8    :  //
   9    :  // Unless required by applicable law or agreed to in writing, software
  10    :  // distributed under the License is distributed on an "AS IS" BASIS,
  11    :  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  12    :  // See the License for the specific language governing permissions and
  13    :  // limitations under the License.
  14    :  
  15    :  #include "syzygy/optimize/transforms/block_alignment_transform.h"
  16    :  
  17    :  #include "syzygy/block_graph/block_graph.h"
  18    :  
  19    :  namespace optimize {
  20    :  namespace transforms {
  21    :  
  22    :  namespace {
  23    :  using block_graph::BasicBlock;
  24    :  using block_graph::BasicCodeBlock;
  25    :  }  // namespace
  26    :  
  27    :  bool BlockAlignmentTransform::TransformBasicBlockSubGraph(
  28    :        const TransformPolicyInterface* policy,
  29    :        BlockGraph* block_graph,
  30    :        BasicBlockSubGraph* subgraph,
  31    :        ApplicationProfile* profile,
  32  E :        SubGraphProfile* subgraph_profile) {
  33  E :    DCHECK_NE(reinterpret_cast<TransformPolicyInterface*>(NULL), policy);
  34  E :    DCHECK_NE(reinterpret_cast<BlockGraph*>(NULL), block_graph);
  35  E :    DCHECK_NE(reinterpret_cast<BasicBlockSubGraph*>(NULL), subgraph);
  36  E :    DCHECK_NE(reinterpret_cast<ApplicationProfile*>(NULL), profile);
  37  E :    DCHECK_NE(reinterpret_cast<SubGraphProfile*>(NULL), subgraph_profile);
  38    :  
  39    :    // Iterates through each basic block.
  40    :    BasicBlockSubGraph::BBCollection::iterator bb_iter =
  41  E :        subgraph->basic_blocks().begin();
  42  E :    for (; bb_iter != subgraph->basic_blocks().end(); ++bb_iter) {
  43  E :      BasicCodeBlock* bb = BasicCodeBlock::Cast(*bb_iter);
  44  E :      if (bb == NULL)
  45  E :        continue;
  46    :      // TODO(etienneb): Basic block alignment based on frequencies (PGO).
  47  E :    }
  48    :  
  49    :    // Apply function alignment.
  50  E :    if (!subgraph->block_descriptions().empty()) {
  51    :      BasicBlockSubGraph::BlockDescription& description =
  52  E :          subgraph->block_descriptions().front();
  53    :      // TODO(etienneb): Function alignment based on frequencies (PGO).
  54  E :      if (description.alignment <= 1)
  55  E :        description.alignment = 32;
  56    :    }
  57    :  
  58  E :    return true;
  59  E :  }
  60    :  
  61    :  }  // namespace transforms
  62    :  }  // namespace optimize