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1 //===- CodeMetrics.h - Measures the weight of a function---------*- 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 file implements various weight measurements for code, helping
11 // the Inliner and other passes decide whether to duplicate its contents.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #ifndef LLVM_ANALYSIS_CODEMETRICS_H
16 #define LLVM_ANALYSIS_CODEMETRICS_H
17 
18 #include "llvm/ADT/DenseMap.h"
19 
20 namespace llvm {
21 
22   class TargetData;
23 
24   // CodeMetrics - Calculate size and a few similar metrics for a set of
25   // basic blocks.
26   struct CodeMetrics {
27     /// NeverInline - True if this callee should never be inlined into a
28     /// caller.
29     // bool NeverInline;
30 
31     // True if this function contains a call to setjmp or _setjmp
32     bool callsSetJmp;
33 
34     // True if this function calls itself
35     bool isRecursive;
36 
37     // True if this function contains one or more indirect branches
38     bool containsIndirectBr;
39 
40     /// usesDynamicAlloca - True if this function calls alloca (in the C sense).
41     bool usesDynamicAlloca;
42 
43     /// NumInsts, NumBlocks - Keep track of how large each function is, which
44     /// is used to estimate the code size cost of inlining it.
45     unsigned NumInsts, NumBlocks;
46 
47     /// NumBBInsts - Keeps track of basic block code size estimates.
48     DenseMap<const BasicBlock *, unsigned> NumBBInsts;
49 
50     /// NumCalls - Keep track of the number of calls to 'big' functions.
51     unsigned NumCalls;
52 
53     /// NumInlineCandidates - Keep track of the number of calls to internal
54     /// functions with only a single caller.  These are likely targets for
55     /// future inlining, likely exposed by interleaved devirtualization.
56     unsigned NumInlineCandidates;
57 
58     /// NumVectorInsts - Keep track of how many instructions produce vector
59     /// values.  The inliner is being more aggressive with inlining vector
60     /// kernels.
61     unsigned NumVectorInsts;
62 
63     /// NumRets - Keep track of how many Ret instructions the block contains.
64     unsigned NumRets;
65 
CodeMetricsCodeMetrics66     CodeMetrics() : callsSetJmp(false), isRecursive(false),
67                     containsIndirectBr(false), usesDynamicAlloca(false),
68                     NumInsts(0), NumBlocks(0), NumCalls(0),
69                     NumInlineCandidates(0), NumVectorInsts(0),
70                     NumRets(0) {}
71 
72     /// analyzeBasicBlock - Add information about the specified basic block
73     /// to the current structure.
74     void analyzeBasicBlock(const BasicBlock *BB, const TargetData *TD = 0);
75 
76     /// analyzeFunction - Add information about the specified function
77     /// to the current structure.
78     void analyzeFunction(Function *F, const TargetData *TD = 0);
79 
80     /// CountCodeReductionForConstant - Figure out an approximation for how
81     /// many instructions will be constant folded if the specified value is
82     /// constant.
83     unsigned CountCodeReductionForConstant(Value *V);
84 
85     /// CountBonusForConstant - Figure out an approximation for how much
86     /// per-call performance boost we can expect if the specified value is
87     /// constant.
88     unsigned CountBonusForConstant(Value *V);
89 
90     /// CountCodeReductionForAlloca - Figure out an approximation of how much
91     /// smaller the function will be if it is inlined into a context where an
92     /// argument becomes an alloca.
93     ///
94     unsigned CountCodeReductionForAlloca(Value *V);
95   };
96 }
97 
98 #endif
99