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