lib/Target/X86/X86FrameLowering.h

   1 //===-- X86TargetFrameLowering.h - Define frame lowering for X86 -*- C++ -*-==//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This class implements X86-specific bits of TargetFrameLowering class.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #ifndef LLVM_LIB_TARGET_X86_X86FRAMELOWERING_H
  14 #define LLVM_LIB_TARGET_X86_X86FRAMELOWERING_H
  15
  16 #include "llvm/CodeGen/TargetFrameLowering.h"
  17
  18 namespace llvm {
  19
  20 class MachineInstrBuilder;
  21 class MCCFIInstruction;
  22 class X86InstrInfo;
  23 class X86Subtarget;
  24 class X86RegisterInfo;
  25
  26 class X86FrameLowering : public TargetFrameLowering {
  27 public:
  28   X86FrameLowering(const X86Subtarget &STI, unsigned StackAlignOverride);
  29
  30   // Cached subtarget predicates.
  31
  32   const X86Subtarget &STI;
  33   const X86InstrInfo &TII;
  34   const X86RegisterInfo *TRI;
  35
  36   unsigned SlotSize;
  37
  38   /// Is64Bit implies that x86_64 instructions are available.
  39   bool Is64Bit;
  40
  41   bool IsLP64;
  42
  43   /// True if the 64-bit frame or stack pointer should be used. True for most
  44   /// 64-bit targets with the exception of x32. If this is false, 32-bit
  45   /// instruction operands should be used to manipulate StackPtr and FramePtr.
  46   bool Uses64BitFramePtr;
  47
  48   unsigned StackPtr;
  49
  50   /// Emit target stack probe code. This is required for all
  51   /// large stack allocations on Windows. The caller is required to materialize
  52   /// the number of bytes to probe in RAX/EAX.
  53   void emitStackProbe(MachineFunction &MF, MachineBasicBlock &MBB,
  54                       MachineBasicBlock::iterator MBBI, const DebugLoc &DL,
  55                       bool InProlog) const;
  56
  57   /// Replace a StackProbe inline-stub with the actual probe code inline.
  58   void inlineStackProbe(MachineFunction &MF,
  59                         MachineBasicBlock &PrologMBB) const override;
  60
  61   void emitCalleeSavedFrameMoves(MachineBasicBlock &MBB,
  62                                  MachineBasicBlock::iterator MBBI,
  63                                  const DebugLoc &DL) const;
  64
  65   /// emitProlog/emitEpilog - These methods insert prolog and epilog code into
  66   /// the function.
  67   void emitPrologue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
  68   void emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
  69
  70   void adjustForSegmentedStacks(MachineFunction &MF,
  71                                 MachineBasicBlock &PrologueMBB) const override;
  72
  73   void adjustForHiPEPrologue(MachineFunction &MF,
  74                              MachineBasicBlock &PrologueMBB) const override;
  75
  76   void determineCalleeSaves(MachineFunction &MF, BitVector &SavedRegs,
  77                             RegScavenger *RS = nullptr) const override;
  78
  79   bool
  80   assignCalleeSavedSpillSlots(MachineFunction &MF,
  81                               const TargetRegisterInfo *TRI,
  82                               std::vector<CalleeSavedInfo> &CSI) const override;
  83
  84   bool spillCalleeSavedRegisters(MachineBasicBlock &MBB,
  85                                  MachineBasicBlock::iterator MI,
  86                                  const std::vector<CalleeSavedInfo> &CSI,
  87                                  const TargetRegisterInfo *TRI) const override;
  88
  89   bool restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
  90                                   MachineBasicBlock::iterator MI,
  91                                   std::vector<CalleeSavedInfo> &CSI,
  92                                   const TargetRegisterInfo *TRI) const override;
  93
  94   bool hasFP(const MachineFunction &MF) const override;
  95   bool hasReservedCallFrame(const MachineFunction &MF) const override;
  96   bool canSimplifyCallFramePseudos(const MachineFunction &MF) const override;
  97   bool needsFrameIndexResolution(const MachineFunction &MF) const override;
  98
  99   int getFrameIndexReference(const MachineFunction &MF, int FI,
 100                              unsigned &FrameReg) const override;
 101
 102   int getFrameIndexReferenceSP(const MachineFunction &MF,
 103                                int FI, unsigned &SPReg, int Adjustment) const;
 104   int getFrameIndexReferencePreferSP(const MachineFunction &MF, int FI,
 105                                      unsigned &FrameReg,
 106                                      bool IgnoreSPUpdates) const override;
 107
 108   MachineBasicBlock::iterator
 109   eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
 110                                 MachineBasicBlock::iterator MI) const override;
 111
 112   unsigned getWinEHParentFrameOffset(const MachineFunction &MF) const override;
 113
 114   void processFunctionBeforeFrameFinalized(MachineFunction &MF,
 115                                            RegScavenger *RS) const override;
 116
 117   /// Check the instruction before/after the passed instruction. If
 118   /// it is an ADD/SUB/LEA instruction it is deleted argument and the
 119   /// stack adjustment is returned as a positive value for ADD/LEA and
 120   /// a negative for SUB.
 121   int mergeSPUpdates(MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI,
 122                      bool doMergeWithPrevious) const;
 123
 124   /// Emit a series of instructions to increment / decrement the stack
 125   /// pointer by a constant value.
 126   void emitSPUpdate(MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI,
 127                     const DebugLoc &DL, int64_t NumBytes, bool InEpilogue) const;
 128
 129   /// Check that LEA can be used on SP in an epilogue sequence for \p MF.
 130   bool canUseLEAForSPInEpilogue(const MachineFunction &MF) const;
 131
 132   /// Check whether or not the given \p MBB can be used as a prologue
 133   /// for the target.
 134   /// The prologue will be inserted first in this basic block.
 135   /// This method is used by the shrink-wrapping pass to decide if
 136   /// \p MBB will be correctly handled by the target.
 137   /// As soon as the target enable shrink-wrapping without overriding
 138   /// this method, we assume that each basic block is a valid
 139   /// prologue.
 140   bool canUseAsPrologue(const MachineBasicBlock &MBB) const override;
 141
 142   /// Check whether or not the given \p MBB can be used as a epilogue
 143   /// for the target.
 144   /// The epilogue will be inserted before the first terminator of that block.
 145   /// This method is used by the shrink-wrapping pass to decide if
 146   /// \p MBB will be correctly handled by the target.
 147   bool canUseAsEpilogue(const MachineBasicBlock &MBB) const override;
 148
 149   /// Returns true if the target will correctly handle shrink wrapping.
 150   bool enableShrinkWrapping(const MachineFunction &MF) const override;
 151
 152   /// Order the symbols in the local stack.
 153   /// We want to place the local stack objects in some sort of sensible order.
 154   /// The heuristic we use is to try and pack them according to static number
 155   /// of uses and size in order to minimize code size.
 156   void orderFrameObjects(const MachineFunction &MF,
 157                          SmallVectorImpl<int> &ObjectsToAllocate) const override;
 158
 159   /// Wraps up getting a CFI index and building a MachineInstr for it.
 160   void BuildCFI(MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI,
 161                 const DebugLoc &DL, const MCCFIInstruction &CFIInst) const;
 162
 163   /// Sets up EBP and optionally ESI based on the incoming EBP value.  Only
 164   /// needed for 32-bit. Used in funclet prologues and at catchret destinations.
 165   MachineBasicBlock::iterator
 166   restoreWin32EHStackPointers(MachineBasicBlock &MBB,
 167                               MachineBasicBlock::iterator MBBI,
 168                               const DebugLoc &DL, bool RestoreSP = false) const;
 169
 170   int getInitialCFAOffset(const MachineFunction &MF) const override;
 171
 172   unsigned getInitialCFARegister(const MachineFunction &MF) const override;
 173
 174   /// Return true if the function has a redzone (accessible bytes past the
 175   /// frame of the top of stack function) as part of it's ABI.
 176   bool has128ByteRedZone(const MachineFunction& MF) const;
 177
 178 private:
 179   uint64_t calculateMaxStackAlign(const MachineFunction &MF) const;
 180
 181   /// Emit target stack probe as a call to a helper function
 182   void emitStackProbeCall(MachineFunction &MF, MachineBasicBlock &MBB,
 183                           MachineBasicBlock::iterator MBBI, const DebugLoc &DL,
 184                           bool InProlog) const;
 185
 186   /// Emit target stack probe as an inline sequence.
 187   void emitStackProbeInline(MachineFunction &MF, MachineBasicBlock &MBB,
 188                             MachineBasicBlock::iterator MBBI,
 189                             const DebugLoc &DL, bool InProlog) const;
 190
 191   /// Emit a stub to later inline the target stack probe.
 192   void emitStackProbeInlineStub(MachineFunction &MF, MachineBasicBlock &MBB,
 193                                 MachineBasicBlock::iterator MBBI,
 194                                 const DebugLoc &DL, bool InProlog) const;
 195
 196   /// Aligns the stack pointer by ANDing it with -MaxAlign.
 197   void BuildStackAlignAND(MachineBasicBlock &MBB,
 198                           MachineBasicBlock::iterator MBBI, const DebugLoc &DL,
 199                           unsigned Reg, uint64_t MaxAlign) const;
 200
 201   /// Make small positive stack adjustments using POPs.
 202   bool adjustStackWithPops(MachineBasicBlock &MBB,
 203                            MachineBasicBlock::iterator MBBI, const DebugLoc &DL,
 204                            int Offset) const;
 205
 206   /// Adjusts the stack pointer using LEA, SUB, or ADD.
 207   MachineInstrBuilder BuildStackAdjustment(MachineBasicBlock &MBB,
 208                                            MachineBasicBlock::iterator MBBI,
 209                                            const DebugLoc &DL, int64_t Offset,
 210                                            bool InEpilogue) const;
 211
 212   unsigned getPSPSlotOffsetFromSP(const MachineFunction &MF) const;
 213
 214   unsigned getWinEHFuncletFrameSize(const MachineFunction &MF) const;
 215
 216   /// Materialize the catchret target MBB in RAX.
 217   void emitCatchRetReturnValue(MachineBasicBlock &MBB,
 218                                MachineBasicBlock::iterator MBBI,
 219                                MachineInstr *CatchRet) const;
 220 };
 221
 222 } // End llvm namespace
 223
 224 #endif