Trace.h revision 327952 
1//===- llvm/Analysis/Trace.h - Represent one trace of LLVM code -*- 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 represents a single trace of LLVM basic blocks.  A trace is a
11// single entry, multiple exit, region of code that is often hot.  Trace-based
12// optimizations treat traces almost like they are a large, strange, basic
13// block: because the trace path is assumed to be hot, optimizations for the
14// fall-through path are made at the expense of the non-fall-through paths.
15//
16//===----------------------------------------------------------------------===//
17
18#ifndef LLVM_ANALYSIS_TRACE_H
19#define LLVM_ANALYSIS_TRACE_H
20
21#include <cassert>
22#include <vector>
23
24namespace llvm {
25
26class BasicBlock;
27class Function;
28class Module;
29class raw_ostream;
30
31class Trace {
32  using BasicBlockListType = std::vector<BasicBlock *>;
33
34  BasicBlockListType BasicBlocks;
35
36public:
37  /// Trace ctor - Make a new trace from a vector of basic blocks,
38  /// residing in the function which is the parent of the first
39  /// basic block in the vector.
40  Trace(const std::vector<BasicBlock *> &vBB) : BasicBlocks (vBB) {}
41
42  /// getEntryBasicBlock - Return the entry basic block (first block)
43  /// of the trace.
44  BasicBlock *getEntryBasicBlock () const { return BasicBlocks[0]; }
45
46  /// operator[]/getBlock - Return basic block N in the trace.
47  BasicBlock *operator[](unsigned i) const { return BasicBlocks[i]; }
48  BasicBlock *getBlock(unsigned i)   const { return BasicBlocks[i]; }
49
50  /// getFunction - Return this trace's parent function.
51  Function *getFunction () const;
52
53  /// getModule - Return this Module that contains this trace's parent
54  /// function.
55  Module *getModule () const;
56
57  /// getBlockIndex - Return the index of the specified basic block in the
58  /// trace, or -1 if it is not in the trace.
59  int getBlockIndex(const BasicBlock *X) const {
60    for (unsigned i = 0, e = BasicBlocks.size(); i != e; ++i)
61      if (BasicBlocks[i] == X)
62        return i;
63    return -1;
64  }
65
66  /// contains - Returns true if this trace contains the given basic
67  /// block.
68  bool contains(const BasicBlock *X) const {
69    return getBlockIndex(X) != -1;
70  }
71
72  /// Returns true if B1 occurs before B2 in the trace, or if it is the same
73  /// block as B2..  Both blocks must be in the trace.
74  bool dominates(const BasicBlock *B1, const BasicBlock *B2) const {
75    int B1Idx = getBlockIndex(B1), B2Idx = getBlockIndex(B2);
76    assert(B1Idx != -1 && B2Idx != -1 && "Block is not in the trace!");
77    return B1Idx <= B2Idx;
78  }
79
80  // BasicBlock iterators...
81  using iterator = BasicBlockListType::iterator;
82  using const_iterator = BasicBlockListType::const_iterator;
83  using reverse_iterator = std::reverse_iterator<iterator>;
84  using const_reverse_iterator = std::reverse_iterator<const_iterator>;
85
86  iterator                begin()       { return BasicBlocks.begin(); }
87  const_iterator          begin() const { return BasicBlocks.begin(); }
88  iterator                end  ()       { return BasicBlocks.end();   }
89  const_iterator          end  () const { return BasicBlocks.end();   }
90
91  reverse_iterator       rbegin()       { return BasicBlocks.rbegin(); }
92  const_reverse_iterator rbegin() const { return BasicBlocks.rbegin(); }
93  reverse_iterator       rend  ()       { return BasicBlocks.rend();   }
94  const_reverse_iterator rend  () const { return BasicBlocks.rend();   }
95
96  unsigned                 size() const { return BasicBlocks.size(); }
97  bool                    empty() const { return BasicBlocks.empty(); }
98
99  iterator erase(iterator q)               { return BasicBlocks.erase (q); }
100  iterator erase(iterator q1, iterator q2) { return BasicBlocks.erase (q1, q2); }
101
102  /// print - Write trace to output stream.
103  void print(raw_ostream &O) const;
104
105  /// dump - Debugger convenience method; writes trace to standard error
106  /// output stream.
107  void dump() const;
108};
109
110} // end namespace llvm
111
112#endif // LLVM_ANALYSIS_TRACE_H
113