include/llvm/Analysis/Trace.h

   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
  23 namespace llvm {
  24
  25 class BasicBlock;
  26 class Function;
  27 class Module;
  28 class raw_ostream;
  29
  30 class Trace {
  31   using BasicBlockListType = std::vector<BasicBlock *>;
  32
  33   BasicBlockListType BasicBlocks;
  34
  35 public:
  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