ConstantsScanner.h revision 36b56886974eae4f9c5ebc96befd3e7bfe5de338 
1//==- llvm/Analysis/ConstantsScanner.h - Iterate over constants -*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This class implements an iterator to walk through the constants referenced by
11// a method.  This is used by the Bitcode & Assembly writers to build constant
12// pools.
13//
14//===----------------------------------------------------------------------===//
15
16#ifndef LLVM_ANALYSIS_CONSTANTSSCANNER_H
17#define LLVM_ANALYSIS_CONSTANTSSCANNER_H
18
19#include "llvm/IR/InstIterator.h"
20
21namespace llvm {
22
23class Constant;
24
25class constant_iterator : public std::iterator<std::forward_iterator_tag,
26                                               const Constant, ptrdiff_t> {
27  const_inst_iterator InstI;                // Method instruction iterator
28  unsigned OpIdx;                           // Operand index
29
30  typedef constant_iterator _Self;
31
32  inline bool isAtConstant() const {
33    assert(!InstI.atEnd() && OpIdx < InstI->getNumOperands() &&
34           "isAtConstant called with invalid arguments!");
35    return isa<Constant>(InstI->getOperand(OpIdx));
36  }
37
38public:
39  inline constant_iterator(const Function *F) : InstI(inst_begin(F)), OpIdx(0) {
40    // Advance to first constant... if we are not already at constant or end
41    if (InstI != inst_end(F) &&                            // InstI is valid?
42        (InstI->getNumOperands() == 0 || !isAtConstant())) // Not at constant?
43      operator++();
44  }
45
46  inline constant_iterator(const Function *F, bool)   // end ctor
47    : InstI(inst_end(F)), OpIdx(0) {
48  }
49
50  inline bool operator==(const _Self& x) const { return OpIdx == x.OpIdx &&
51                                                        InstI == x.InstI; }
52  inline bool operator!=(const _Self& x) const { return !operator==(x); }
53
54  inline pointer operator*() const {
55    assert(isAtConstant() && "Dereferenced an iterator at the end!");
56    return cast<Constant>(InstI->getOperand(OpIdx));
57  }
58  inline pointer operator->() const { return operator*(); }
59
60  inline _Self& operator++() {   // Preincrement implementation
61    ++OpIdx;
62    do {
63      unsigned NumOperands = InstI->getNumOperands();
64      while (OpIdx < NumOperands && !isAtConstant()) {
65        ++OpIdx;
66      }
67
68      if (OpIdx < NumOperands) return *this;  // Found a constant!
69      ++InstI;
70      OpIdx = 0;
71    } while (!InstI.atEnd());
72
73    return *this;  // At the end of the method
74  }
75
76  inline _Self operator++(int) { // Postincrement
77    _Self tmp = *this; ++*this; return tmp;
78  }
79
80  inline bool atEnd() const { return InstI.atEnd(); }
81};
82
83inline constant_iterator constant_begin(const Function *F) {
84  return constant_iterator(F);
85}
86
87inline constant_iterator constant_end(const Function *F) {
88  return constant_iterator(F, true);
89}
90
91} // End llvm namespace
92
93#endif
94