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