X86FrameLowering.h revision 360784 
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
18namespace llvm {
19
20class MachineInstrBuilder;
21class MCCFIInstruction;
22class X86InstrInfo;
23class X86Subtarget;
24class X86RegisterInfo;
25
26class X86FrameLowering : public TargetFrameLowering {
27public:
28  X86FrameLowering(const X86Subtarget &STI, MaybeAlign 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 getWin64EHFrameIndexRef(const MachineFunction &MF,
103                              int FI, unsigned &SPReg) const;
104  int getFrameIndexReferenceSP(const MachineFunction &MF,
105                               int FI, unsigned &SPReg, int Adjustment) const;
106  int getFrameIndexReferencePreferSP(const MachineFunction &MF, int FI,
107                                     unsigned &FrameReg,
108                                     bool IgnoreSPUpdates) const override;
109
110  MachineBasicBlock::iterator
111  eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
112                                MachineBasicBlock::iterator MI) const override;
113
114  unsigned getWinEHParentFrameOffset(const MachineFunction &MF) const override;
115
116  void processFunctionBeforeFrameFinalized(MachineFunction &MF,
117                                           RegScavenger *RS) const override;
118
119  /// Check the instruction before/after the passed instruction. If
120  /// it is an ADD/SUB/LEA instruction it is deleted argument and the
121  /// stack adjustment is returned as a positive value for ADD/LEA and
122  /// a negative for SUB.
123  int mergeSPUpdates(MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI,
124                     bool doMergeWithPrevious) const;
125
126  /// Emit a series of instructions to increment / decrement the stack
127  /// pointer by a constant value.
128  void emitSPUpdate(MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI,
129                    const DebugLoc &DL, int64_t NumBytes, bool InEpilogue) const;
130
131  /// Check that LEA can be used on SP in an epilogue sequence for \p MF.
132  bool canUseLEAForSPInEpilogue(const MachineFunction &MF) const;
133
134  /// Check whether or not the given \p MBB can be used as a prologue
135  /// for the target.
136  /// The prologue will be inserted first in this basic block.
137  /// This method is used by the shrink-wrapping pass to decide if
138  /// \p MBB will be correctly handled by the target.
139  /// As soon as the target enable shrink-wrapping without overriding
140  /// this method, we assume that each basic block is a valid
141  /// prologue.
142  bool canUseAsPrologue(const MachineBasicBlock &MBB) const override;
143
144  /// Check whether or not the given \p MBB can be used as a epilogue
145  /// for the target.
146  /// The epilogue will be inserted before the first terminator of that block.
147  /// This method is used by the shrink-wrapping pass to decide if
148  /// \p MBB will be correctly handled by the target.
149  bool canUseAsEpilogue(const MachineBasicBlock &MBB) const override;
150
151  /// Returns true if the target will correctly handle shrink wrapping.
152  bool enableShrinkWrapping(const MachineFunction &MF) const override;
153
154  /// Order the symbols in the local stack.
155  /// We want to place the local stack objects in some sort of sensible order.
156  /// The heuristic we use is to try and pack them according to static number
157  /// of uses and size in order to minimize code size.
158  void orderFrameObjects(const MachineFunction &MF,
159                         SmallVectorImpl<int> &ObjectsToAllocate) const override;
160
161  /// Wraps up getting a CFI index and building a MachineInstr for it.
162  void BuildCFI(MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI,
163                const DebugLoc &DL, const MCCFIInstruction &CFIInst) const;
164
165  /// Sets up EBP and optionally ESI based on the incoming EBP value.  Only
166  /// needed for 32-bit. Used in funclet prologues and at catchret destinations.
167  MachineBasicBlock::iterator
168  restoreWin32EHStackPointers(MachineBasicBlock &MBB,
169                              MachineBasicBlock::iterator MBBI,
170                              const DebugLoc &DL, bool RestoreSP = false) const;
171
172  int getInitialCFAOffset(const MachineFunction &MF) const override;
173
174  unsigned getInitialCFARegister(const MachineFunction &MF) const override;
175
176  /// Return true if the function has a redzone (accessible bytes past the
177  /// frame of the top of stack function) as part of it's ABI.
178  bool has128ByteRedZone(const MachineFunction& MF) const;
179
180private:
181  uint64_t calculateMaxStackAlign(const MachineFunction &MF) const;
182
183  /// Emit target stack probe as a call to a helper function
184  void emitStackProbeCall(MachineFunction &MF, MachineBasicBlock &MBB,
185                          MachineBasicBlock::iterator MBBI, const DebugLoc &DL,
186                          bool InProlog) const;
187
188  /// Emit target stack probe as an inline sequence.
189  void emitStackProbeInline(MachineFunction &MF, MachineBasicBlock &MBB,
190                            MachineBasicBlock::iterator MBBI,
191                            const DebugLoc &DL, bool InProlog) const;
192
193  /// Emit a stub to later inline the target stack probe.
194  void emitStackProbeInlineStub(MachineFunction &MF, MachineBasicBlock &MBB,
195                                MachineBasicBlock::iterator MBBI,
196                                const DebugLoc &DL, bool InProlog) const;
197
198  /// Aligns the stack pointer by ANDing it with -MaxAlign.
199  void BuildStackAlignAND(MachineBasicBlock &MBB,
200                          MachineBasicBlock::iterator MBBI, const DebugLoc &DL,
201                          unsigned Reg, uint64_t MaxAlign) const;
202
203  /// Make small positive stack adjustments using POPs.
204  bool adjustStackWithPops(MachineBasicBlock &MBB,
205                           MachineBasicBlock::iterator MBBI, const DebugLoc &DL,
206                           int Offset) const;
207
208  /// Adjusts the stack pointer using LEA, SUB, or ADD.
209  MachineInstrBuilder BuildStackAdjustment(MachineBasicBlock &MBB,
210                                           MachineBasicBlock::iterator MBBI,
211                                           const DebugLoc &DL, int64_t Offset,
212                                           bool InEpilogue) const;
213
214  unsigned getPSPSlotOffsetFromSP(const MachineFunction &MF) const;
215
216  unsigned getWinEHFuncletFrameSize(const MachineFunction &MF) const;
217
218  /// Materialize the catchret target MBB in RAX.
219  void emitCatchRetReturnValue(MachineBasicBlock &MBB,
220                               MachineBasicBlock::iterator MBBI,
221                               MachineInstr *CatchRet) const;
222};
223
224} // End llvm namespace
225
226#endif
227