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 
24 namespace llvm {
25 
26 class BasicBlock;
27 class Function;
28 class Module;
29 class raw_ostream;
30 
31 class Trace {
32   using BasicBlockListType = std::vector<BasicBlock *>;
33 
34   BasicBlockListType BasicBlocks;
35 
36 public:
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.
Trace(const std::vector<BasicBlock * > & vBB)40   Trace(const std::vector<BasicBlock *> &vBB) : BasicBlocks (vBB) {}
41 
42   /// getEntryBasicBlock - Return the entry basic block (first block)
43   /// of the trace.
getEntryBasicBlock()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]; }
getBlock(unsigned 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.
getBlockIndex(const BasicBlock * X)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.
contains(const BasicBlock * X)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.
dominates(const BasicBlock * B1,const BasicBlock * B2)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 
begin()86   iterator                begin()       { return BasicBlocks.begin(); }
begin()87   const_iterator          begin() const { return BasicBlocks.begin(); }
end()88   iterator                end  ()       { return BasicBlocks.end();   }
end()89   const_iterator          end  () const { return BasicBlocks.end();   }
90 
rbegin()91   reverse_iterator       rbegin()       { return BasicBlocks.rbegin(); }
rbegin()92   const_reverse_iterator rbegin() const { return BasicBlocks.rbegin(); }
rend()93   reverse_iterator       rend  ()       { return BasicBlocks.rend();   }
rend()94   const_reverse_iterator rend  () const { return BasicBlocks.rend();   }
95 
size()96   unsigned                 size() const { return BasicBlocks.size(); }
empty()97   bool                    empty() const { return BasicBlocks.empty(); }
98 
erase(iterator q)99   iterator erase(iterator q)               { return BasicBlocks.erase (q); }
erase(iterator q1,iterator q2)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