GVN.cpp

    changed |= shouldContinue;
  }
  
  return changed;
}


// GVN::iterateOnFunction - Executes one iteration of GVN
bool GVN::iterateOnFunction(Function &F) {
  // Clean out global sets from any previous functions
  VN.clear();
  availableOut.clear();
  phiMap.clear();
 
  bool changed_function = false;
  
  DominatorTree &DT = getAnalysis<DominatorTree>();   
  
  SmallVector<Instruction*, 4> toErase;
  
  // Top-down walk of the dominator tree
  for (df_iterator<DomTreeNode*> DI = df_begin(DT.getRootNode()),
         E = df_end(DT.getRootNode()); DI != E; ++DI) {
    
    // Get the set to update for this block
    ValueNumberedSet& currAvail = availableOut[DI->getBlock()];     
    DenseMap<Value*, LoadInst*> lastSeenLoad;
    
    BasicBlock* BB = DI->getBlock();
  
    // A block inherits AVAIL_OUT from its dominator
    if (DI->getIDom() != 0)
      currAvail = availableOut[DI->getIDom()->getBlock()];

    for (BasicBlock::iterator BI = BB->begin(), BE = BB->end();
         BI != BE; ) {
      changed_function |= processInstruction(BI, currAvail,
                                             lastSeenLoad, toErase);
      
      NumGVNInstr += toErase.size();
      
      // Avoid iterator invalidation
      ++BI;
      
      for (SmallVector<Instruction*, 4>::iterator I = toErase.begin(),
           E = toErase.end(); I != E; ++I)
        (*I)->eraseFromParent();
      
      toErase.clear();
    }
  }
  
  return changed_function;
}