lib/Analysis/IPA/CallGraphSCCPass.cpp

   1 //===- CallGraphSCCPass.cpp - Pass that operates BU on call graph ---------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file was developed by the LLVM research group and is distributed under
   6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file implements the CallGraphSCCPass class, which is used for passes
  11 // which are implemented as bottom-up traversals on the call graph.  Because
  12 // there may be cycles in the call graph, passes of this type operate on the
  13 // call-graph in SCC order: that is, they process function bottom-up, except for
  14 // recursive functions, which they process all at once.
  15 //
  16 //===----------------------------------------------------------------------===//
  17
  18 #include "llvm/CallGraphSCCPass.h"
  19 #include "llvm/Analysis/CallGraph.h"
  20 #include "llvm/ADT/SCCIterator.h"
  21 using namespace llvm;
  22
  23 /// getAnalysisUsage - For this class, we declare that we require and preserve
  24 /// the call graph.  If the derived class implements this method, it should
  25 /// always explicitly call the implementation here.
  26 void CallGraphSCCPass::getAnalysisUsage(AnalysisUsage &AU) const {
  27   AU.addRequired<CallGraph>();
  28   AU.addPreserved<CallGraph>();
  29 }
  30
  31 bool CallGraphSCCPass::runOnModule(Module &M) {
  32   CallGraph &CG = getAnalysis<CallGraph>();
  33   bool Changed = doInitialization(CG);
  34   for (scc_iterator<CallGraph*> I = scc_begin(&CG), E = scc_end(&CG);
  35        I != E; ++I)
  36     Changed = runOnSCC(*I);
  37   return Changed | doFinalization(CG);
  38 }