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/ADT/SmallPtrSet.h" 20 #include "llvm/IR/CallSite.h" 21 22 namespace llvm { 23 class AssumptionCache; 24 class BasicBlock; 25 class Loop; 26 class Function; 27 class Instruction; 28 class DataLayout; 29 class TargetTransformInfo; 30 class Value; 31 32 /// \brief Check whether a call will lower to something small. 33 /// 34 /// This tests checks whether this callsite will lower to something 35 /// significantly cheaper than a traditional call, often a single 36 /// instruction. Note that if isInstructionFree(CS.getInstruction()) would 37 /// return true, so will this function. 38 bool callIsSmall(ImmutableCallSite CS); 39 40 /// \brief Utility to calculate the size and a few similar metrics for a set 41 /// of basic blocks. 42 struct CodeMetrics { 43 /// \brief True if this function contains a call to setjmp or other functions 44 /// with attribute "returns twice" without having the attribute itself. 45 bool exposesReturnsTwice; 46 47 /// \brief True if this function calls itself. 48 bool isRecursive; 49 50 /// \brief True if this function cannot be duplicated. 51 /// 52 /// True if this function contains one or more indirect branches, or it contains 53 /// one or more 'noduplicate' instructions. 54 bool notDuplicatable; 55 56 /// \brief True if this function calls alloca (in the C sense). 57 bool usesDynamicAlloca; 58 59 /// \brief Number of instructions in the analyzed blocks. 60 unsigned NumInsts; 61 62 /// \brief Number of analyzed blocks. 63 unsigned NumBlocks; 64 65 /// \brief Keeps track of basic block code size estimates. 66 DenseMap<const BasicBlock *, unsigned> NumBBInsts; 67 68 /// \brief Keep track of the number of calls to 'big' functions. 69 unsigned NumCalls; 70 71 /// \brief The number of calls to internal functions with a single caller. 72 /// 73 /// These are likely targets for future inlining, likely exposed by 74 /// interleaved devirtualization. 75 unsigned NumInlineCandidates; 76 77 /// \brief How many instructions produce vector values. 78 /// 79 /// The inliner is more aggressive with inlining vector kernels. 80 unsigned NumVectorInsts; 81 82 /// \brief How many 'ret' instructions the blocks contain. 83 unsigned NumRets; 84 CodeMetricsCodeMetrics85 CodeMetrics() 86 : exposesReturnsTwice(false), isRecursive(false), notDuplicatable(false), 87 usesDynamicAlloca(false), NumInsts(0), NumBlocks(0), NumCalls(0), 88 NumInlineCandidates(0), NumVectorInsts(0), NumRets(0) {} 89 90 /// \brief Add information about a block to the current state. 91 void analyzeBasicBlock(const BasicBlock *BB, const TargetTransformInfo &TTI, 92 SmallPtrSetImpl<const Value*> &EphValues); 93 94 /// \brief Collect a loop's ephemeral values (those used only by an assume 95 /// or similar intrinsics in the loop). 96 static void collectEphemeralValues(const Loop *L, AssumptionCache *AC, 97 SmallPtrSetImpl<const Value *> &EphValues); 98 99 /// \brief Collect a functions's ephemeral values (those used only by an 100 /// assume or similar intrinsics in the function). 101 static void collectEphemeralValues(const Function *L, AssumptionCache *AC, 102 SmallPtrSetImpl<const Value *> &EphValues); 103 }; 104 105 } 106 107 #endif 108