CallGraphSCCPass.cpp revision b576c94c15af9a440f69d9d03c2afead7971118c 
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 "Support/SCCIterator.h"
21
22/// getAnalysisUsage - For this class, we declare that we require and preserve
23/// the call graph.  If the derived class implements this method, it should
24/// always explicitly call the implementation here.
25void CallGraphSCCPass::getAnalysisUsage(AnalysisUsage &AU) const {
26  AU.addRequired<CallGraph>();
27  AU.addPreserved<CallGraph>();
28}
29
30bool CallGraphSCCPass::run(Module &M) {
31  CallGraph &CG = getAnalysis<CallGraph>();
32  bool Changed = false;
33  for (scc_iterator<CallGraph*> I = scc_begin(&CG), E = scc_end(&CG);
34       I != E; ++I)
35    Changed = runOnSCC(*I);
36  return Changed;
37}
38