1//===- llvm/Analysis/Trace.h - Represent one trace of LLVM code -*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This class represents a single trace of LLVM basic blocks.  A trace is a
10// single entry, multiple exit, region of code that is often hot.  Trace-based
11// optimizations treat traces almost like they are a large, strange, basic
12// block: because the trace path is assumed to be hot, optimizations for the
13// fall-through path are made at the expense of the non-fall-through paths.
14//
15//===----------------------------------------------------------------------===//
16
17#ifndef LLVM_ANALYSIS_TRACE_H
18#define LLVM_ANALYSIS_TRACE_H
19
20#include <cassert>
21#include <vector>
22
23namespace llvm {
24
25class BasicBlock;
26class Function;
27class Module;
28class raw_ostream;
29
30class Trace {
31  using BasicBlockListType = std::vector<BasicBlock *>;
32
33  BasicBlockListType BasicBlocks;
34
35public:
36  /// Trace ctor - Make a new trace from a vector of basic blocks,
37  /// residing in the function which is the parent of the first
38  /// basic block in the vector.
39  Trace(const std::vector<BasicBlock *> &vBB) : BasicBlocks (vBB) {}
40
41  /// getEntryBasicBlock - Return the entry basic block (first block)
42  /// of the trace.
43  BasicBlock *getEntryBasicBlock () const { return BasicBlocks[0]; }
44
45  /// operator[]/getBlock - Return basic block N in the trace.
46  BasicBlock *operator[](unsigned i) const { return BasicBlocks[i]; }
47  BasicBlock *getBlock(unsigned i)   const { return BasicBlocks[i]; }
48
49  /// getFunction - Return this trace's parent function.
50  Function *getFunction () const;
51
52  /// getModule - Return this Module that contains this trace's parent
53  /// function.
54  Module *getModule () const;
55
56  /// getBlockIndex - Return the index of the specified basic block in the
57  /// trace, or -1 if it is not in the trace.
58  int getBlockIndex(const BasicBlock *X) const {
59    for (unsigned i = 0, e = BasicBlocks.size(); i != e; ++i)
60      if (BasicBlocks[i] == X)
61        return i;
62    return -1;
63  }
64
65  /// contains - Returns true if this trace contains the given basic
66  /// block.
67  bool contains(const BasicBlock *X) const {
68    return getBlockIndex(X) != -1;
69  }
70
71  /// Returns true if B1 occurs before B2 in the trace, or if it is the same
72  /// block as B2..  Both blocks must be in the trace.
73  bool dominates(const BasicBlock *B1, const BasicBlock *B2) const {
74    int B1Idx = getBlockIndex(B1), B2Idx = getBlockIndex(B2);
75    assert(B1Idx != -1 && B2Idx != -1 && "Block is not in the trace!");
76    return B1Idx <= B2Idx;
77  }
78
79  // BasicBlock iterators...
80  using iterator = BasicBlockListType::iterator;
81  using const_iterator = BasicBlockListType::const_iterator;
82  using reverse_iterator = std::reverse_iterator<iterator>;
83  using const_reverse_iterator = std::reverse_iterator<const_iterator>;
84
85  iterator                begin()       { return BasicBlocks.begin(); }
86  const_iterator          begin() const { return BasicBlocks.begin(); }
87  iterator                end  ()       { return BasicBlocks.end();   }
88  const_iterator          end  () const { return BasicBlocks.end();   }
89
90  reverse_iterator       rbegin()       { return BasicBlocks.rbegin(); }
91  const_reverse_iterator rbegin() const { return BasicBlocks.rbegin(); }
92  reverse_iterator       rend  ()       { return BasicBlocks.rend();   }
93  const_reverse_iterator rend  () const { return BasicBlocks.rend();   }
94
95  unsigned                 size() const { return BasicBlocks.size(); }
96  bool                    empty() const { return BasicBlocks.empty(); }
97
98  iterator erase(iterator q)               { return BasicBlocks.erase (q); }
99  iterator erase(iterator q1, iterator q2) { return BasicBlocks.erase (q1, q2); }
100
101  /// print - Write trace to output stream.
102  void print(raw_ostream &O) const;
103
104  /// dump - Debugger convenience method; writes trace to standard error
105  /// output stream.
106  void dump() const;
107};
108
109} // end namespace llvm
110
111#endif // LLVM_ANALYSIS_TRACE_H
112