PrologEpilogInserter.h revision 212904
1//===-- PrologEpilogInserter.h - Prolog/Epilog code insertion -*- 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 pass is responsible for finalizing the functions frame layout, saving 11// callee saved registers, and for emitting prolog & epilog code for the 12// function. 13// 14// This pass must be run after register allocation. After this pass is 15// executed, it is illegal to construct MO_FrameIndex operands. 16// 17// This pass also implements a shrink wrapping variant of prolog/epilog 18// insertion. 19// 20//===----------------------------------------------------------------------===// 21 22#ifndef LLVM_CODEGEN_PEI_H 23#define LLVM_CODEGEN_PEI_H 24 25#include "llvm/CodeGen/Passes.h" 26#include "llvm/CodeGen/MachineFunctionPass.h" 27#include "llvm/CodeGen/MachineLoopInfo.h" 28#include "llvm/ADT/SparseBitVector.h" 29#include "llvm/ADT/DenseMap.h" 30#include "llvm/Target/TargetRegisterInfo.h" 31 32namespace llvm { 33 class RegScavenger; 34 class MachineBasicBlock; 35 36 class PEI : public MachineFunctionPass { 37 public: 38 static char ID; 39 PEI() : MachineFunctionPass(ID) {} 40 41 const char *getPassName() const { 42 return "Prolog/Epilog Insertion & Frame Finalization"; 43 } 44 45 virtual void getAnalysisUsage(AnalysisUsage &AU) const; 46 47 /// runOnMachineFunction - Insert prolog/epilog code and replace abstract 48 /// frame indexes with appropriate references. 49 /// 50 bool runOnMachineFunction(MachineFunction &Fn); 51 52 private: 53 RegScavenger *RS; 54 55 // MinCSFrameIndex, MaxCSFrameIndex - Keeps the range of callee saved 56 // stack frame indexes. 57 unsigned MinCSFrameIndex, MaxCSFrameIndex; 58 59 // Analysis info for spill/restore placement. 60 // "CSR": "callee saved register". 61 62 // CSRegSet contains indices into the Callee Saved Register Info 63 // vector built by calculateCalleeSavedRegisters() and accessed 64 // via MF.getFrameInfo()->getCalleeSavedInfo(). 65 typedef SparseBitVector<> CSRegSet; 66 67 // CSRegBlockMap maps MachineBasicBlocks to sets of callee 68 // saved register indices. 69 typedef DenseMap<MachineBasicBlock*, CSRegSet> CSRegBlockMap; 70 71 // Set and maps for computing CSR spill/restore placement: 72 // used in function (UsedCSRegs) 73 // used in a basic block (CSRUsed) 74 // anticipatable in a basic block (Antic{In,Out}) 75 // available in a basic block (Avail{In,Out}) 76 // to be spilled at the entry to a basic block (CSRSave) 77 // to be restored at the end of a basic block (CSRRestore) 78 CSRegSet UsedCSRegs; 79 CSRegBlockMap CSRUsed; 80 CSRegBlockMap AnticIn, AnticOut; 81 CSRegBlockMap AvailIn, AvailOut; 82 CSRegBlockMap CSRSave; 83 CSRegBlockMap CSRRestore; 84 85 // Entry and return blocks of the current function. 86 MachineBasicBlock* EntryBlock; 87 SmallVector<MachineBasicBlock*, 4> ReturnBlocks; 88 89 // Map of MBBs to top level MachineLoops. 90 DenseMap<MachineBasicBlock*, MachineLoop*> TLLoops; 91 92 // Flag to control shrink wrapping per-function: 93 // may choose to skip shrink wrapping for certain 94 // functions. 95 bool ShrinkWrapThisFunction; 96 97 // Flag to control whether to use the register scavenger to resolve 98 // frame index materialization registers. Set according to 99 // TRI->requiresFrameIndexScavenging() for the curren function. 100 bool FrameIndexVirtualScavenging; 101 102#ifndef NDEBUG 103 // Machine function handle. 104 MachineFunction* MF; 105 106 // Flag indicating that the current function 107 // has at least one "short" path in the machine 108 // CFG from the entry block to an exit block. 109 bool HasFastExitPath; 110#endif 111 112 bool calculateSets(MachineFunction &Fn); 113 bool calcAnticInOut(MachineBasicBlock* MBB); 114 bool calcAvailInOut(MachineBasicBlock* MBB); 115 void calculateAnticAvail(MachineFunction &Fn); 116 bool addUsesForMEMERegion(MachineBasicBlock* MBB, 117 SmallVector<MachineBasicBlock*, 4>& blks); 118 bool addUsesForTopLevelLoops(SmallVector<MachineBasicBlock*, 4>& blks); 119 bool calcSpillPlacements(MachineBasicBlock* MBB, 120 SmallVector<MachineBasicBlock*, 4> &blks, 121 CSRegBlockMap &prevSpills); 122 bool calcRestorePlacements(MachineBasicBlock* MBB, 123 SmallVector<MachineBasicBlock*, 4> &blks, 124 CSRegBlockMap &prevRestores); 125 void placeSpillsAndRestores(MachineFunction &Fn); 126 void placeCSRSpillsAndRestores(MachineFunction &Fn); 127 void calculateCallsInformation(MachineFunction &Fn); 128 void calculateCalleeSavedRegisters(MachineFunction &Fn); 129 void insertCSRSpillsAndRestores(MachineFunction &Fn); 130 void calculateFrameObjectOffsets(MachineFunction &Fn); 131 void replaceFrameIndices(MachineFunction &Fn); 132 void scavengeFrameVirtualRegs(MachineFunction &Fn); 133 void insertPrologEpilogCode(MachineFunction &Fn); 134 135 // Initialize DFA sets, called before iterations. 136 void clearAnticAvailSets(); 137 // Clear all sets constructed by shrink wrapping. 138 void clearAllSets(); 139 140 // Initialize all shrink wrapping data. 141 void initShrinkWrappingInfo(); 142 143 // Convienences for dealing with machine loops. 144 MachineBasicBlock* getTopLevelLoopPreheader(MachineLoop* LP); 145 MachineLoop* getTopLevelLoopParent(MachineLoop *LP); 146 147 // Propgate CSRs used in MBB to all MBBs of loop LP. 148 void propagateUsesAroundLoop(MachineBasicBlock* MBB, MachineLoop* LP); 149 150 // Convenience for recognizing return blocks. 151 bool isReturnBlock(MachineBasicBlock* MBB); 152 153#ifndef NDEBUG 154 // Debugging methods. 155 156 // Mark this function as having fast exit paths. 157 void findFastExitPath(); 158 159 // Verify placement of spills/restores. 160 void verifySpillRestorePlacement(); 161 162 std::string getBasicBlockName(const MachineBasicBlock* MBB); 163 std::string stringifyCSRegSet(const CSRegSet& s); 164 void dumpSet(const CSRegSet& s); 165 void dumpUsed(MachineBasicBlock* MBB); 166 void dumpAllUsed(); 167 void dumpSets(MachineBasicBlock* MBB); 168 void dumpSets1(MachineBasicBlock* MBB); 169 void dumpAllSets(); 170 void dumpSRSets(); 171#endif 172 173 }; 174} // End llvm namespace 175#endif 176