1 //===-- BasicBlockSectionsProfileReader.h - BB sections profile reader pass ==//
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 pass creates the basic block cluster info by reading the basic block
10 // sections profile. The cluster info will be used by the basic-block-sections
11 // pass to arrange basic blocks in their sections.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #ifndef LLVM_CODEGEN_BASICBLOCKSECTIONSPROFILEREADER_H
16 #define LLVM_CODEGEN_BASICBLOCKSECTIONSPROFILEREADER_H
17 
18 #include "llvm/ADT/Optional.h"
19 #include "llvm/ADT/SmallSet.h"
20 #include "llvm/ADT/SmallVector.h"
21 #include "llvm/ADT/StringMap.h"
22 #include "llvm/ADT/StringRef.h"
23 #include "llvm/InitializePasses.h"
24 #include "llvm/Pass.h"
25 #include "llvm/Support/Error.h"
26 #include "llvm/Support/LineIterator.h"
27 #include "llvm/Support/MemoryBuffer.h"
28 
29 using namespace llvm;
30 
31 namespace llvm {
32 
33 // The cluster information for a machine basic block.
34 struct BBClusterInfo {
35   // MachineBasicBlock ID.
36   unsigned MBBNumber;
37   // Cluster ID this basic block belongs to.
38   unsigned ClusterID;
39   // Position of basic block within the cluster.
40   unsigned PositionInCluster;
41 };
42 
43 using ProgramBBClusterInfoMapTy = StringMap<SmallVector<BBClusterInfo>>;
44 
45 class BasicBlockSectionsProfileReader : public ImmutablePass {
46 public:
47   static char ID;
48 
49   BasicBlockSectionsProfileReader(const MemoryBuffer *Buf)
50       : ImmutablePass(ID), MBuf(Buf) {
51     initializeBasicBlockSectionsProfileReaderPass(
52         *PassRegistry::getPassRegistry());
53   };
54 
55   BasicBlockSectionsProfileReader() : ImmutablePass(ID) {
56     initializeBasicBlockSectionsProfileReaderPass(
57         *PassRegistry::getPassRegistry());
58   }
59 
60   StringRef getPassName() const override {
61     return "Basic Block Sections Profile Reader";
62   }
63 
64   // Returns true if basic block sections profile exist for function \p
65   // FuncName.
66   bool isFunctionHot(StringRef FuncName) const;
67 
68   // Returns a pair with first element representing whether basic block sections
69   // profile exist for the function \p FuncName, and the second element
70   // representing the basic block sections profile (cluster info) for this
71   // function. If the first element is true and the second element is empty, it
72   // means unique basic block sections are desired for all basic blocks of the
73   // function.
74   std::pair<bool, SmallVector<BBClusterInfo>>
75   getBBClusterInfoForFunction(StringRef FuncName) const;
76 
77   /// Read profiles of basic blocks if available here.
78   void initializePass() override;
79 
80 private:
81   StringRef getAliasName(StringRef FuncName) const {
82     auto R = FuncAliasMap.find(FuncName);
83     return R == FuncAliasMap.end() ? FuncName : R->second;
84   }
85 
86   // This contains the basic-block-sections profile.
87   const MemoryBuffer *MBuf = nullptr;
88 
89   // This encapsulates the BB cluster information for the whole program.
90   //
91   // For every function name, it contains the cluster information for (all or
92   // some of) its basic blocks. The cluster information for every basic block
93   // includes its cluster ID along with the position of the basic block in that
94   // cluster.
95   ProgramBBClusterInfoMapTy ProgramBBClusterInfo;
96 
97   // Some functions have alias names. We use this map to find the main alias
98   // name for which we have mapping in ProgramBBClusterInfo.
99   StringMap<StringRef> FuncAliasMap;
100 };
101 
102 // Creates a BasicBlockSectionsProfileReader pass to parse the basic block
103 // sections profile. \p Buf is a memory buffer that contains the list of
104 // functions and basic block ids to selectively enable basic block sections.
105 ImmutablePass *
106 createBasicBlockSectionsProfileReaderPass(const MemoryBuffer *Buf);
107 
108 } // namespace llvm
109 #endif // LLVM_CODEGEN_BASICBLOCKSECTIONSPROFILEREADER_H
110