LoopExtractor.cpp revision c3c8703c3bf0d4fff3420ee3ce00caea992a354c 
1//===- LoopExtractor.cpp - Extract each loop into a new function ----------===//
2//
3// A pass wrapper around the ExtractLoop() scalar transformation to extract each
4// top-level loop into its own new function. If the loop is the ONLY loop in a
5// given function, it is not touched. This is a pass most useful for debugging
6// via bugpoint.
7//
8//===----------------------------------------------------------------------===//
9
10#include "llvm/Module.h"
11#include "llvm/Pass.h"
12#include "llvm/Analysis/LoopInfo.h"
13#include "llvm/Transforms/Scalar.h"
14#include "llvm/Transforms/Utils/FunctionUtils.h"
15#include <vector>
16using namespace llvm;
17
18namespace {
19
20// FIXME: PassManager should allow Module passes to require FunctionPasses
21struct LoopExtractor : public FunctionPass {
22
23public:
24  LoopExtractor() {}
25  virtual bool run(Module &M);
26  virtual bool runOnFunction(Function &F);
27
28  virtual void getAnalysisUsage(AnalysisUsage &AU) const {
29    AU.addRequired<LoopInfo>();
30  }
31
32};
33
34RegisterOpt<LoopExtractor>
35X("loop-extract", "Extract loops into new functions");
36
37bool LoopExtractor::run(Module &M) {
38  bool Changed = false;
39  for (Module::iterator i = M.begin(), e = M.end(); i != e; ++i)
40    Changed |= runOnFunction(*i);
41  return Changed;
42}
43
44bool LoopExtractor::runOnFunction(Function &F) {
45  std::cerr << F.getName() << "\n";
46
47  LoopInfo &LI = getAnalysis<LoopInfo>();
48
49  // We don't want to keep extracting the only loop of a function into a new one
50  if (LI.begin() == LI.end() || LI.begin() + 1 == LI.end())
51    return false;
52
53  bool Changed = false;
54
55  // Try to move each loop out of the code into separate function
56  for (LoopInfo::iterator i = LI.begin(), e = LI.end(); i != e; ++i)
57    Changed |= (ExtractLoop(*i) != 0);
58
59  return Changed;
60}
61
62} // End anonymous namespace
63
64/// createLoopExtractorPass
65///
66FunctionPass* llvm::createLoopExtractorPass() {
67  return new LoopExtractor();
68}
69