1 //===- CodeMetrics.h - Code cost measurements -------------------*- 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 #include "llvm/Support/CallSite.h" 20 21 namespace llvm { 22 class BasicBlock; 23 class Function; 24 class Instruction; 25 class TargetData; 26 class Value; 27 28 /// \brief Check whether an instruction is likely to be "free" when lowered. 29 bool isInstructionFree(const Instruction *I, const TargetData *TD = 0); 30 31 /// \brief Check whether a call will lower to something small. 32 /// 33 /// This tests checks whether this callsite will lower to something 34 /// significantly cheaper than a traditional call, often a single 35 /// instruction. Note that if isInstructionFree(CS.getInstruction()) would 36 /// return true, so will this function. 37 bool callIsSmall(ImmutableCallSite CS); 38 39 /// \brief Utility to calculate the size and a few similar metrics for a set 40 /// of basic blocks. 41 struct CodeMetrics { 42 /// \brief True if this function contains a call to setjmp or other functions 43 /// with attribute "returns twice" without having the attribute itself. 44 bool exposesReturnsTwice; 45 46 /// \brief True if this function calls itself. 47 bool isRecursive; 48 49 /// \brief True if this function contains one or more indirect branches. 50 bool containsIndirectBr; 51 52 /// \brief True if this function calls alloca (in the C sense). 53 bool usesDynamicAlloca; 54 55 /// \brief Number of instructions in the analyzed blocks. 56 unsigned NumInsts; 57 58 /// \brief Number of analyzed blocks. 59 unsigned NumBlocks; 60 61 /// \brief Keeps track of basic block code size estimates. 62 DenseMap<const BasicBlock *, unsigned> NumBBInsts; 63 64 /// \brief Keep track of the number of calls to 'big' functions. 65 unsigned NumCalls; 66 67 /// \brief The number of calls to internal functions with a single caller. 68 /// 69 /// These are likely targets for future inlining, likely exposed by 70 /// interleaved devirtualization. 71 unsigned NumInlineCandidates; 72 73 /// \brief How many instructions produce vector values. 74 /// 75 /// The inliner is more aggressive with inlining vector kernels. 76 unsigned NumVectorInsts; 77 78 /// \brief How many 'ret' instructions the blocks contain. 79 unsigned NumRets; 80 CodeMetricsCodeMetrics81 CodeMetrics() : exposesReturnsTwice(false), isRecursive(false), 82 containsIndirectBr(false), usesDynamicAlloca(false), 83 NumInsts(0), NumBlocks(0), NumCalls(0), 84 NumInlineCandidates(0), NumVectorInsts(0), 85 NumRets(0) {} 86 87 /// \brief Add information about a block to the current state. 88 void analyzeBasicBlock(const BasicBlock *BB, const TargetData *TD = 0); 89 90 /// \brief Add information about a function to the current state. 91 void analyzeFunction(Function *F, const TargetData *TD = 0); 92 }; 93 } 94 95 #endif 96