annotate lib/CodeGen/ShrinkWrap.cpp @ 120:1172e4bd9c6f

update 4.0.0
author mir3636
date Fri, 25 Nov 2016 19:14:25 +0900
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children 803732b1fca8
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1 //===-- ShrinkWrap.cpp - Compute safe point for prolog/epilog insertion ---===//
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2 //
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3 // The LLVM Compiler Infrastructure
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4 //
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5 // This file is distributed under the University of Illinois Open Source
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6 // License. See LICENSE.TXT for details.
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7 //
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8 //===----------------------------------------------------------------------===//
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9 //
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10 // This pass looks for safe point where the prologue and epilogue can be
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11 // inserted.
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12 // The safe point for the prologue (resp. epilogue) is called Save
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13 // (resp. Restore).
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14 // A point is safe for prologue (resp. epilogue) if and only if
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15 // it 1) dominates (resp. post-dominates) all the frame related operations and
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16 // between 2) two executions of the Save (resp. Restore) point there is an
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17 // execution of the Restore (resp. Save) point.
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18 //
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19 // For instance, the following points are safe:
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20 // for (int i = 0; i < 10; ++i) {
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21 // Save
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22 // ...
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23 // Restore
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24 // }
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25 // Indeed, the execution looks like Save -> Restore -> Save -> Restore ...
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26 // And the following points are not:
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27 // for (int i = 0; i < 10; ++i) {
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28 // Save
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29 // ...
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30 // }
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31 // for (int i = 0; i < 10; ++i) {
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32 // ...
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33 // Restore
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34 // }
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35 // Indeed, the execution looks like Save -> Save -> ... -> Restore -> Restore.
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36 //
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37 // This pass also ensures that the safe points are 3) cheaper than the regular
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38 // entry and exits blocks.
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39 //
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40 // Property #1 is ensured via the use of MachineDominatorTree and
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41 // MachinePostDominatorTree.
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42 // Property #2 is ensured via property #1 and MachineLoopInfo, i.e., both
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43 // points must be in the same loop.
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44 // Property #3 is ensured via the MachineBlockFrequencyInfo.
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45 //
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46 // If this pass found points matching all these properties, then
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47 // MachineFrameInfo is updated with this information.
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48 //===----------------------------------------------------------------------===//
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49 #include "llvm/ADT/BitVector.h"
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50 #include "llvm/ADT/PostOrderIterator.h"
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51 #include "llvm/ADT/SetVector.h"
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52 #include "llvm/ADT/Statistic.h"
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53 // To check for profitability.
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54 #include "llvm/CodeGen/MachineBlockFrequencyInfo.h"
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55 // For property #1 for Save.
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56 #include "llvm/CodeGen/MachineDominators.h"
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57 #include "llvm/CodeGen/MachineFunctionPass.h"
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58 // To record the result of the analysis.
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59 #include "llvm/CodeGen/MachineFrameInfo.h"
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60 // For property #2.
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61 #include "llvm/CodeGen/MachineLoopInfo.h"
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62 // For property #1 for Restore.
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63 #include "llvm/CodeGen/MachinePostDominators.h"
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64 #include "llvm/CodeGen/Passes.h"
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65 // To know about callee-saved.
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66 #include "llvm/CodeGen/RegisterClassInfo.h"
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67 #include "llvm/CodeGen/RegisterScavenging.h"
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68 #include "llvm/MC/MCAsmInfo.h"
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69 #include "llvm/Support/Debug.h"
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70 // To query the target about frame lowering.
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71 #include "llvm/Target/TargetFrameLowering.h"
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72 // To know about frame setup operation.
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73 #include "llvm/Target/TargetInstrInfo.h"
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74 #include "llvm/Target/TargetMachine.h"
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75 // To access TargetInstrInfo.
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76 #include "llvm/Target/TargetSubtargetInfo.h"
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77
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78 #define DEBUG_TYPE "shrink-wrap"
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79
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80 using namespace llvm;
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81
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82 STATISTIC(NumFunc, "Number of functions");
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83 STATISTIC(NumCandidates, "Number of shrink-wrapping candidates");
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84 STATISTIC(NumCandidatesDropped,
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85 "Number of shrink-wrapping candidates dropped because of frequency");
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86
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87 static cl::opt<cl::boolOrDefault>
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88 EnableShrinkWrapOpt("enable-shrink-wrap", cl::Hidden,
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89 cl::desc("enable the shrink-wrapping pass"));
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90
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91 namespace {
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92 /// \brief Class to determine where the safe point to insert the
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93 /// prologue and epilogue are.
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94 /// Unlike the paper from Fred C. Chow, PLDI'88, that introduces the
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95 /// shrink-wrapping term for prologue/epilogue placement, this pass
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96 /// does not rely on expensive data-flow analysis. Instead we use the
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97 /// dominance properties and loop information to decide which point
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98 /// are safe for such insertion.
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99 class ShrinkWrap : public MachineFunctionPass {
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100 /// Hold callee-saved information.
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101 RegisterClassInfo RCI;
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102 MachineDominatorTree *MDT;
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103 MachinePostDominatorTree *MPDT;
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104 /// Current safe point found for the prologue.
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105 /// The prologue will be inserted before the first instruction
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106 /// in this basic block.
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107 MachineBasicBlock *Save;
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108 /// Current safe point found for the epilogue.
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109 /// The epilogue will be inserted before the first terminator instruction
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110 /// in this basic block.
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111 MachineBasicBlock *Restore;
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112 /// Hold the information of the basic block frequency.
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113 /// Use to check the profitability of the new points.
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114 MachineBlockFrequencyInfo *MBFI;
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115 /// Hold the loop information. Used to determine if Save and Restore
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116 /// are in the same loop.
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117 MachineLoopInfo *MLI;
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118 /// Frequency of the Entry block.
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119 uint64_t EntryFreq;
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120 /// Current opcode for frame setup.
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121 unsigned FrameSetupOpcode;
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122 /// Current opcode for frame destroy.
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123 unsigned FrameDestroyOpcode;
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124 /// Entry block.
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125 const MachineBasicBlock *Entry;
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126 typedef SmallSetVector<unsigned, 16> SetOfRegs;
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127 /// Registers that need to be saved for the current function.
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128 mutable SetOfRegs CurrentCSRs;
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129 /// Current MachineFunction.
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130 MachineFunction *MachineFunc;
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131
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132 /// \brief Check if \p MI uses or defines a callee-saved register or
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133 /// a frame index. If this is the case, this means \p MI must happen
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134 /// after Save and before Restore.
100
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135 bool useOrDefCSROrFI(const MachineInstr &MI, RegScavenger *RS) const;
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136
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137 const SetOfRegs &getCurrentCSRs(RegScavenger *RS) const {
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138 if (CurrentCSRs.empty()) {
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139 BitVector SavedRegs;
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140 const TargetFrameLowering *TFI =
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141 MachineFunc->getSubtarget().getFrameLowering();
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142
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143 TFI->determineCalleeSaves(*MachineFunc, SavedRegs, RS);
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144
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145 for (int Reg = SavedRegs.find_first(); Reg != -1;
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146 Reg = SavedRegs.find_next(Reg))
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147 CurrentCSRs.insert((unsigned)Reg);
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148 }
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149 return CurrentCSRs;
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150 }
95
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151
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152 /// \brief Update the Save and Restore points such that \p MBB is in
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153 /// the region that is dominated by Save and post-dominated by Restore
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154 /// and Save and Restore still match the safe point definition.
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155 /// Such point may not exist and Save and/or Restore may be null after
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156 /// this call.
100
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157 void updateSaveRestorePoints(MachineBasicBlock &MBB, RegScavenger *RS);
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158
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159 /// \brief Initialize the pass for \p MF.
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160 void init(MachineFunction &MF) {
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161 RCI.runOnMachineFunction(MF);
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162 MDT = &getAnalysis<MachineDominatorTree>();
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163 MPDT = &getAnalysis<MachinePostDominatorTree>();
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164 Save = nullptr;
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165 Restore = nullptr;
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166 MBFI = &getAnalysis<MachineBlockFrequencyInfo>();
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167 MLI = &getAnalysis<MachineLoopInfo>();
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168 EntryFreq = MBFI->getEntryFreq();
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169 const TargetInstrInfo &TII = *MF.getSubtarget().getInstrInfo();
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170 FrameSetupOpcode = TII.getCallFrameSetupOpcode();
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171 FrameDestroyOpcode = TII.getCallFrameDestroyOpcode();
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172 Entry = &MF.front();
100
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173 CurrentCSRs.clear();
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174 MachineFunc = &MF;
95
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175
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176 ++NumFunc;
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177 }
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178
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179 /// Check whether or not Save and Restore points are still interesting for
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180 /// shrink-wrapping.
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181 bool ArePointsInteresting() const { return Save != Entry && Save && Restore; }
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182
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diff changeset
183 /// \brief Check if shrink wrapping is enabled for this target and function.
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diff changeset
184 static bool isShrinkWrapEnabled(const MachineFunction &MF);
100
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diff changeset
185
95
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186 public:
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187 static char ID;
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diff changeset
188
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diff changeset
189 ShrinkWrap() : MachineFunctionPass(ID) {
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diff changeset
190 initializeShrinkWrapPass(*PassRegistry::getPassRegistry());
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191 }
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192
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193 void getAnalysisUsage(AnalysisUsage &AU) const override {
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194 AU.setPreservesAll();
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195 AU.addRequired<MachineBlockFrequencyInfo>();
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diff changeset
196 AU.addRequired<MachineDominatorTree>();
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diff changeset
197 AU.addRequired<MachinePostDominatorTree>();
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198 AU.addRequired<MachineLoopInfo>();
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diff changeset
199 MachineFunctionPass::getAnalysisUsage(AU);
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200 }
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diff changeset
201
120
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diff changeset
202 StringRef getPassName() const override { return "Shrink Wrapping analysis"; }
95
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diff changeset
203
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diff changeset
204 /// \brief Perform the shrink-wrapping analysis and update
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diff changeset
205 /// the MachineFrameInfo attached to \p MF with the results.
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diff changeset
206 bool runOnMachineFunction(MachineFunction &MF) override;
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diff changeset
207 };
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diff changeset
208 } // End anonymous namespace.
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diff changeset
209
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diff changeset
210 char ShrinkWrap::ID = 0;
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diff changeset
211 char &llvm::ShrinkWrapID = ShrinkWrap::ID;
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diff changeset
212
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diff changeset
213 INITIALIZE_PASS_BEGIN(ShrinkWrap, "shrink-wrap", "Shrink Wrap Pass", false,
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parents:
diff changeset
214 false)
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diff changeset
215 INITIALIZE_PASS_DEPENDENCY(MachineBlockFrequencyInfo)
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diff changeset
216 INITIALIZE_PASS_DEPENDENCY(MachineDominatorTree)
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diff changeset
217 INITIALIZE_PASS_DEPENDENCY(MachinePostDominatorTree)
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diff changeset
218 INITIALIZE_PASS_DEPENDENCY(MachineLoopInfo)
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diff changeset
219 INITIALIZE_PASS_END(ShrinkWrap, "shrink-wrap", "Shrink Wrap Pass", false, false)
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diff changeset
220
100
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diff changeset
221 bool ShrinkWrap::useOrDefCSROrFI(const MachineInstr &MI,
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parents: 95
diff changeset
222 RegScavenger *RS) const {
95
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diff changeset
223 if (MI.getOpcode() == FrameSetupOpcode ||
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diff changeset
224 MI.getOpcode() == FrameDestroyOpcode) {
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parents:
diff changeset
225 DEBUG(dbgs() << "Frame instruction: " << MI << '\n');
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diff changeset
226 return true;
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parents:
diff changeset
227 }
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diff changeset
228 for (const MachineOperand &MO : MI.operands()) {
100
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diff changeset
229 bool UseOrDefCSR = false;
95
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diff changeset
230 if (MO.isReg()) {
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diff changeset
231 unsigned PhysReg = MO.getReg();
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diff changeset
232 if (!PhysReg)
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diff changeset
233 continue;
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diff changeset
234 assert(TargetRegisterInfo::isPhysicalRegister(PhysReg) &&
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diff changeset
235 "Unallocated register?!");
100
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diff changeset
236 UseOrDefCSR = RCI.getLastCalleeSavedAlias(PhysReg);
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diff changeset
237 } else if (MO.isRegMask()) {
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diff changeset
238 // Check if this regmask clobbers any of the CSRs.
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diff changeset
239 for (unsigned Reg : getCurrentCSRs(RS)) {
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diff changeset
240 if (MO.clobbersPhysReg(Reg)) {
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diff changeset
241 UseOrDefCSR = true;
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diff changeset
242 break;
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diff changeset
243 }
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diff changeset
244 }
95
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diff changeset
245 }
100
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diff changeset
246 if (UseOrDefCSR || MO.isFI()) {
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diff changeset
247 DEBUG(dbgs() << "Use or define CSR(" << UseOrDefCSR << ") or FI("
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diff changeset
248 << MO.isFI() << "): " << MI << '\n');
95
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249 return true;
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diff changeset
250 }
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diff changeset
251 }
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diff changeset
252 return false;
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diff changeset
253 }
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diff changeset
254
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diff changeset
255 /// \brief Helper function to find the immediate (post) dominator.
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diff changeset
256 template <typename ListOfBBs, typename DominanceAnalysis>
120
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diff changeset
257 static MachineBasicBlock *FindIDom(MachineBasicBlock &Block, ListOfBBs BBs,
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diff changeset
258 DominanceAnalysis &Dom) {
95
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diff changeset
259 MachineBasicBlock *IDom = &Block;
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diff changeset
260 for (MachineBasicBlock *BB : BBs) {
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diff changeset
261 IDom = Dom.findNearestCommonDominator(IDom, BB);
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parents:
diff changeset
262 if (!IDom)
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parents:
diff changeset
263 break;
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
264 }
100
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
265 if (IDom == &Block)
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
266 return nullptr;
95
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
267 return IDom;
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
268 }
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
269
100
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
270 void ShrinkWrap::updateSaveRestorePoints(MachineBasicBlock &MBB,
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
271 RegScavenger *RS) {
95
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
272 // Get rid of the easy cases first.
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
273 if (!Save)
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
274 Save = &MBB;
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
275 else
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
276 Save = MDT->findNearestCommonDominator(Save, &MBB);
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
277
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
278 if (!Save) {
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
279 DEBUG(dbgs() << "Found a block that is not reachable from Entry\n");
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
280 return;
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
281 }
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
282
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
283 if (!Restore)
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
284 Restore = &MBB;
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
285 else
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
286 Restore = MPDT->findNearestCommonDominator(Restore, &MBB);
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
287
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
288 // Make sure we would be able to insert the restore code before the
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
289 // terminator.
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
290 if (Restore == &MBB) {
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
291 for (const MachineInstr &Terminator : MBB.terminators()) {
100
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
292 if (!useOrDefCSROrFI(Terminator, RS))
95
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
293 continue;
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
294 // One of the terminator needs to happen before the restore point.
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
295 if (MBB.succ_empty()) {
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
296 Restore = nullptr;
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
297 break;
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
298 }
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
299 // Look for a restore point that post-dominates all the successors.
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
300 // The immediate post-dominator is what we are looking for.
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
301 Restore = FindIDom<>(*Restore, Restore->successors(), *MPDT);
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
302 break;
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
303 }
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
304 }
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
305
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
306 if (!Restore) {
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
307 DEBUG(dbgs() << "Restore point needs to be spanned on several blocks\n");
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
308 return;
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
309 }
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
310
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
311 // Make sure Save and Restore are suitable for shrink-wrapping:
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
312 // 1. all path from Save needs to lead to Restore before exiting.
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
313 // 2. all path to Restore needs to go through Save from Entry.
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
314 // We achieve that by making sure that:
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
315 // A. Save dominates Restore.
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
316 // B. Restore post-dominates Save.
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
317 // C. Save and Restore are in the same loop.
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
318 bool SaveDominatesRestore = false;
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
319 bool RestorePostDominatesSave = false;
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
320 while (Save && Restore &&
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
321 (!(SaveDominatesRestore = MDT->dominates(Save, Restore)) ||
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
322 !(RestorePostDominatesSave = MPDT->dominates(Restore, Save)) ||
100
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
323 // Post-dominance is not enough in loops to ensure that all uses/defs
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
324 // are after the prologue and before the epilogue at runtime.
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
325 // E.g.,
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
326 // while(1) {
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
327 // Save
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
328 // Restore
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
329 // if (...)
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
330 // break;
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
331 // use/def CSRs
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
332 // }
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
333 // All the uses/defs of CSRs are dominated by Save and post-dominated
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
334 // by Restore. However, the CSRs uses are still reachable after
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
335 // Restore and before Save are executed.
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
336 //
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
337 // For now, just push the restore/save points outside of loops.
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
338 // FIXME: Refine the criteria to still find interesting cases
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
339 // for loops.
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
340 MLI->getLoopFor(Save) || MLI->getLoopFor(Restore))) {
95
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
341 // Fix (A).
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
342 if (!SaveDominatesRestore) {
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
343 Save = MDT->findNearestCommonDominator(Save, Restore);
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
344 continue;
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
345 }
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
346 // Fix (B).
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
347 if (!RestorePostDominatesSave)
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
348 Restore = MPDT->findNearestCommonDominator(Restore, Save);
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
349
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
350 // Fix (C).
100
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
351 if (Save && Restore &&
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
352 (MLI->getLoopFor(Save) || MLI->getLoopFor(Restore))) {
95
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
353 if (MLI->getLoopDepth(Save) > MLI->getLoopDepth(Restore)) {
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
354 // Push Save outside of this loop if immediate dominator is different
100
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
355 // from save block. If immediate dominator is not different, bail out.
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
356 Save = FindIDom<>(*Save, Save->predecessors(), *MDT);
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
357 if (!Save)
95
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
358 break;
100
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
359 } else {
95
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
360 // If the loop does not exit, there is no point in looking
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
361 // for a post-dominator outside the loop.
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
362 SmallVector<MachineBasicBlock*, 4> ExitBlocks;
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
363 MLI->getLoopFor(Restore)->getExitingBlocks(ExitBlocks);
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
364 // Push Restore outside of this loop.
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
365 // Look for the immediate post-dominator of the loop exits.
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
366 MachineBasicBlock *IPdom = Restore;
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
367 for (MachineBasicBlock *LoopExitBB: ExitBlocks) {
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
368 IPdom = FindIDom<>(*IPdom, LoopExitBB->successors(), *MPDT);
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
369 if (!IPdom)
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
370 break;
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
371 }
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
372 // If the immediate post-dominator is not in a less nested loop,
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
373 // then we are stuck in a program with an infinite loop.
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
374 // In that case, we will not find a safe point, hence, bail out.
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
375 if (IPdom && MLI->getLoopDepth(IPdom) < MLI->getLoopDepth(Restore))
100
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
376 Restore = IPdom;
95
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
377 else {
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
378 Restore = nullptr;
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
379 break;
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
380 }
100
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
381 }
95
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
382 }
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
383 }
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
384 }
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
385
100
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
386 /// Check whether the edge (\p SrcBB, \p DestBB) is a backedge according to MLI.
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
387 /// I.e., check if it exists a loop that contains SrcBB and where DestBB is the
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
388 /// loop header.
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
389 static bool isProperBackedge(const MachineLoopInfo &MLI,
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
390 const MachineBasicBlock *SrcBB,
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
391 const MachineBasicBlock *DestBB) {
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
392 for (const MachineLoop *Loop = MLI.getLoopFor(SrcBB); Loop;
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
393 Loop = Loop->getParentLoop()) {
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
394 if (Loop->getHeader() == DestBB)
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
395 return true;
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
396 }
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
397 return false;
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
398 }
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
399
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
400 /// Check if the CFG of \p MF is irreducible.
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
401 static bool isIrreducibleCFG(const MachineFunction &MF,
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
402 const MachineLoopInfo &MLI) {
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
403 const MachineBasicBlock *Entry = &*MF.begin();
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
404 ReversePostOrderTraversal<const MachineBasicBlock *> RPOT(Entry);
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
405 BitVector VisitedBB(MF.getNumBlockIDs());
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
406 for (const MachineBasicBlock *MBB : RPOT) {
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
407 VisitedBB.set(MBB->getNumber());
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
408 for (const MachineBasicBlock *SuccBB : MBB->successors()) {
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
409 if (!VisitedBB.test(SuccBB->getNumber()))
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
410 continue;
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
411 // We already visited SuccBB, thus MBB->SuccBB must be a backedge.
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
412 // Check that the head matches what we have in the loop information.
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
413 // Otherwise, we have an irreducible graph.
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
414 if (!isProperBackedge(MLI, MBB, SuccBB))
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
415 return true;
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
416 }
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
417 }
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
418 return false;
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
419 }
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
420
95
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
421 bool ShrinkWrap::runOnMachineFunction(MachineFunction &MF) {
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
422 if (MF.empty() || !isShrinkWrapEnabled(MF))
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
423 return false;
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
424
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
425 DEBUG(dbgs() << "**** Analysing " << MF.getName() << '\n');
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
426
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
427 init(MF);
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
428
100
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
429 if (isIrreducibleCFG(MF, *MLI)) {
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
430 // If MF is irreducible, a block may be in a loop without
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
431 // MachineLoopInfo reporting it. I.e., we may use the
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
432 // post-dominance property in loops, which lead to incorrect
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
433 // results. Moreover, we may miss that the prologue and
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
434 // epilogue are not in the same loop, leading to unbalanced
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
435 // construction/deconstruction of the stack frame.
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
436 DEBUG(dbgs() << "Irreducible CFGs are not supported yet\n");
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
437 return false;
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
438 }
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
439
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
440 const TargetRegisterInfo *TRI = MF.getSubtarget().getRegisterInfo();
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
441 std::unique_ptr<RegScavenger> RS(
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
442 TRI->requiresRegisterScavenging(MF) ? new RegScavenger() : nullptr);
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
443
95
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
444 for (MachineBasicBlock &MBB : MF) {
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
445 DEBUG(dbgs() << "Look into: " << MBB.getNumber() << ' ' << MBB.getName()
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
446 << '\n');
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
447
100
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
448 if (MBB.isEHFuncletEntry()) {
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
449 DEBUG(dbgs() << "EH Funclets are not supported yet.\n");
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
450 return false;
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
451 }
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
452
95
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
453 for (const MachineInstr &MI : MBB) {
100
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
454 if (!useOrDefCSROrFI(MI, RS.get()))
95
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
455 continue;
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
456 // Save (resp. restore) point must dominate (resp. post dominate)
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
457 // MI. Look for the proper basic block for those.
100
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
458 updateSaveRestorePoints(MBB, RS.get());
95
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
459 // If we are at a point where we cannot improve the placement of
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
460 // save/restore instructions, just give up.
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
461 if (!ArePointsInteresting()) {
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
462 DEBUG(dbgs() << "No Shrink wrap candidate found\n");
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
463 return false;
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
464 }
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
465 // No need to look for other instructions, this basic block
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
466 // will already be part of the handled region.
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
467 break;
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
468 }
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
469 }
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
470 if (!ArePointsInteresting()) {
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
471 // If the points are not interesting at this point, then they must be null
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
472 // because it means we did not encounter any frame/CSR related code.
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
473 // Otherwise, we would have returned from the previous loop.
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
474 assert(!Save && !Restore && "We miss a shrink-wrap opportunity?!");
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
475 DEBUG(dbgs() << "Nothing to shrink-wrap\n");
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
476 return false;
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
477 }
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
478
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
479 DEBUG(dbgs() << "\n ** Results **\nFrequency of the Entry: " << EntryFreq
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
480 << '\n');
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
481
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
482 const TargetFrameLowering *TFI = MF.getSubtarget().getFrameLowering();
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
483 do {
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
484 DEBUG(dbgs() << "Shrink wrap candidates (#, Name, Freq):\nSave: "
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
485 << Save->getNumber() << ' ' << Save->getName() << ' '
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
486 << MBFI->getBlockFreq(Save).getFrequency() << "\nRestore: "
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
487 << Restore->getNumber() << ' ' << Restore->getName() << ' '
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
488 << MBFI->getBlockFreq(Restore).getFrequency() << '\n');
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
489
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
490 bool IsSaveCheap, TargetCanUseSaveAsPrologue = false;
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
491 if (((IsSaveCheap = EntryFreq >= MBFI->getBlockFreq(Save).getFrequency()) &&
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
492 EntryFreq >= MBFI->getBlockFreq(Restore).getFrequency()) &&
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
493 ((TargetCanUseSaveAsPrologue = TFI->canUseAsPrologue(*Save)) &&
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
494 TFI->canUseAsEpilogue(*Restore)))
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
495 break;
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
496 DEBUG(dbgs() << "New points are too expensive or invalid for the target\n");
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
497 MachineBasicBlock *NewBB;
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
498 if (!IsSaveCheap || !TargetCanUseSaveAsPrologue) {
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
499 Save = FindIDom<>(*Save, Save->predecessors(), *MDT);
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
500 if (!Save)
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
501 break;
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
502 NewBB = Save;
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
503 } else {
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
504 // Restore is expensive.
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
505 Restore = FindIDom<>(*Restore, Restore->successors(), *MPDT);
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
506 if (!Restore)
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
507 break;
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
508 NewBB = Restore;
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
509 }
100
7d135dc70f03 LLVM 3.9
Miyagi Mitsuki <e135756@ie.u-ryukyu.ac.jp>
parents: 95
diff changeset
510 updateSaveRestorePoints(*NewBB, RS.get());
95
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
511 } while (Save && Restore);
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
512
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
513 if (!ArePointsInteresting()) {
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
514 ++NumCandidatesDropped;
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
515 return false;
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
516 }
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
517
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
518 DEBUG(dbgs() << "Final shrink wrap candidates:\nSave: " << Save->getNumber()
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
519 << ' ' << Save->getName() << "\nRestore: "
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
520 << Restore->getNumber() << ' ' << Restore->getName() << '\n');
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
521
120
1172e4bd9c6f update 4.0.0
mir3636
parents: 100
diff changeset
522 MachineFrameInfo &MFI = MF.getFrameInfo();
1172e4bd9c6f update 4.0.0
mir3636
parents: 100
diff changeset
523 MFI.setSavePoint(Save);
1172e4bd9c6f update 4.0.0
mir3636
parents: 100
diff changeset
524 MFI.setRestorePoint(Restore);
95
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
525 ++NumCandidates;
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
526 return false;
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
527 }
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
528
afa8332a0e37 LLVM 3.8
Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
parents:
diff changeset
529 bool ShrinkWrap::isShrinkWrapEnabled(const MachineFunction &MF) {
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530 const TargetFrameLowering *TFI = MF.getSubtarget().getFrameLowering();
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531
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532 switch (EnableShrinkWrapOpt) {
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533 case cl::BOU_UNSET:
100
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534 return TFI->enableShrinkWrapping(MF) &&
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535 // Windows with CFI has some limitations that make it impossible
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536 // to use shrink-wrapping.
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537 !MF.getTarget().getMCAsmInfo()->usesWindowsCFI() &&
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538 // Sanitizers look at the value of the stack at the location
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539 // of the crash. Since a crash can happen anywhere, the
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540 // frame must be lowered before anything else happen for the
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541 // sanitizers to be able to get a correct stack frame.
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542 !(MF.getFunction()->hasFnAttribute(Attribute::SanitizeAddress) ||
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543 MF.getFunction()->hasFnAttribute(Attribute::SanitizeThread) ||
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544 MF.getFunction()->hasFnAttribute(Attribute::SanitizeMemory));
95
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545 // If EnableShrinkWrap is set, it takes precedence on whatever the
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546 // target sets. The rational is that we assume we want to test
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547 // something related to shrink-wrapping.
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548 case cl::BOU_TRUE:
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549 return true;
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550 case cl::BOU_FALSE:
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551 return false;
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552 }
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553 llvm_unreachable("Invalid shrink-wrapping state");
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554 }