LLVM  4.0.0
X86FrameLowering.h
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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 
18 
19 namespace llvm {
20 
21 class MachineInstrBuilder;
22 class MCCFIInstruction;
23 class X86Subtarget;
24 class X86RegisterInfo;
25 
27 public:
28  X86FrameLowering(const X86Subtarget &STI, unsigned StackAlignOverride);
29 
30  // Cached subtarget predicates.
31 
32  const X86Subtarget &STI;
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.
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.
54  MachineBasicBlock::iterator MBBI, const DebugLoc &DL,
55  bool InProlog) const;
56 
57  /// Replace a StackProbe inline-stub with the actual probe code inline.
59  MachineBasicBlock &PrologMBB) const override;
60 
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 
71  MachineBasicBlock &PrologueMBB) const override;
72 
74  MachineBasicBlock &PrologueMBB) const override;
75 
76  void determineCalleeSaves(MachineFunction &MF, BitVector &SavedRegs,
77  RegScavenger *RS = nullptr) const override;
78 
79  bool
81  const TargetRegisterInfo *TRI,
82  std::vector<CalleeSavedInfo> &CSI) const override;
83 
86  const std::vector<CalleeSavedInfo> &CSI,
87  const TargetRegisterInfo *TRI) const override;
88 
91  const 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 getFrameIndexReferencePreferSP(const MachineFunction &MF, int FI,
103  unsigned &FrameReg,
104  bool IgnoreSPUpdates) const override;
105 
108  MachineBasicBlock::iterator MI) const override;
109 
110  unsigned getWinEHParentFrameOffset(const MachineFunction &MF) const override;
111 
113  RegScavenger *RS) const override;
114 
115  /// Check the instruction before/after the passed instruction. If
116  /// it is an ADD/SUB/LEA instruction it is deleted argument and the
117  /// stack adjustment is returned as a positive value for ADD/LEA and
118  /// a negative for SUB.
120  bool doMergeWithPrevious) const;
121 
122  /// Emit a series of instructions to increment / decrement the stack
123  /// pointer by a constant value.
125  int64_t NumBytes, bool InEpilogue) const;
126 
127  /// Check that LEA can be used on SP in an epilogue sequence for \p MF.
128  bool canUseLEAForSPInEpilogue(const MachineFunction &MF) const;
129 
130  /// Check whether or not the given \p MBB can be used as a prologue
131  /// for the target.
132  /// The prologue will be inserted first in this basic block.
133  /// This method is used by the shrink-wrapping pass to decide if
134  /// \p MBB will be correctly handled by the target.
135  /// As soon as the target enable shrink-wrapping without overriding
136  /// this method, we assume that each basic block is a valid
137  /// prologue.
138  bool canUseAsPrologue(const MachineBasicBlock &MBB) const override;
139 
140  /// Check whether or not the given \p MBB can be used as a epilogue
141  /// for the target.
142  /// The epilogue will be inserted before the first terminator of that block.
143  /// This method is used by the shrink-wrapping pass to decide if
144  /// \p MBB will be correctly handled by the target.
145  bool canUseAsEpilogue(const MachineBasicBlock &MBB) const override;
146 
147  /// Returns true if the target will correctly handle shrink wrapping.
148  bool enableShrinkWrapping(const MachineFunction &MF) const override;
149 
150  /// Order the symbols in the local stack.
151  /// We want to place the local stack objects in some sort of sensible order.
152  /// The heuristic we use is to try and pack them according to static number
153  /// of uses and size in order to minimize code size.
154  void orderFrameObjects(const MachineFunction &MF,
155  SmallVectorImpl<int> &ObjectsToAllocate) const override;
156 
157  /// convertArgMovsToPushes - This method tries to convert a call sequence
158  /// that uses sub and mov instructions to put the argument onto the stack
159  /// into a series of pushes.
160  /// Returns true if the transformation succeeded, false if not.
164  uint64_t Amount) const;
165 
166  /// Wraps up getting a CFI index and building a MachineInstr for it.
168  const DebugLoc &DL, const MCCFIInstruction &CFIInst) const;
169 
170  /// Sets up EBP and optionally ESI based on the incoming EBP value. Only
171  /// needed for 32-bit. Used in funclet prologues and at catchret destinations.
175  const DebugLoc &DL, bool RestoreSP = false) const;
176 
177 private:
178  uint64_t calculateMaxStackAlign(const MachineFunction &MF) const;
179 
180  /// Emit target stack probe as a call to a helper function
181  void emitStackProbeCall(MachineFunction &MF, MachineBasicBlock &MBB,
182  MachineBasicBlock::iterator MBBI, const DebugLoc &DL,
183  bool InProlog) const;
184 
185  /// Emit target stack probe as an inline sequence.
186  void emitStackProbeInline(MachineFunction &MF, MachineBasicBlock &MBB,
188  const DebugLoc &DL, bool InProlog) const;
189 
190  /// Emit a stub to later inline the target stack probe.
191  void emitStackProbeInlineStub(MachineFunction &MF, MachineBasicBlock &MBB,
193  const DebugLoc &DL, bool InProlog) const;
194 
195  /// Aligns the stack pointer by ANDing it with -MaxAlign.
196  void BuildStackAlignAND(MachineBasicBlock &MBB,
197  MachineBasicBlock::iterator MBBI, const DebugLoc &DL,
198  unsigned Reg, uint64_t MaxAlign) const;
199 
200  /// Make small positive stack adjustments using POPs.
201  bool adjustStackWithPops(MachineBasicBlock &MBB,
202  MachineBasicBlock::iterator MBBI, const DebugLoc &DL,
203  int Offset) const;
204 
205  /// Adjusts the stack pointer using LEA, SUB, or ADD.
206  MachineInstrBuilder BuildStackAdjustment(MachineBasicBlock &MBB,
208  const DebugLoc &DL, int64_t Offset,
209  bool InEpilogue) const;
210 
211  unsigned getPSPSlotOffsetFromSP(const MachineFunction &MF) const;
212 
213  unsigned getWinEHFuncletFrameSize(const MachineFunction &MF) const;
214 };
215 
216 } // End llvm namespace
217 
218 #endif
MachineBasicBlock::iterator restoreWin32EHStackPointers(MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI, const DebugLoc &DL, bool RestoreSP=false) const
Sets up EBP and optionally ESI based on the incoming EBP value.
bool restoreCalleeSavedRegisters(MachineBasicBlock &MBB, MachineBasicBlock::iterator MI, const std::vector< CalleeSavedInfo > &CSI, const TargetRegisterInfo *TRI) const override
restoreCalleeSavedRegisters - Issues instruction(s) to restore all callee saved registers and returns...
bool convertArgMovsToPushes(MachineFunction &MF, MachineBasicBlock &MBB, MachineBasicBlock::iterator I, uint64_t Amount) const
convertArgMovsToPushes - This method tries to convert a call sequence that uses sub and mov instructi...
A debug info location.
Definition: DebugLoc.h:34
X86FrameLowering(const X86Subtarget &STI, unsigned StackAlignOverride)
bool Uses64BitFramePtr
True if the 64-bit frame or stack pointer should be used.
Reg
All possible values of the reg field in the ModR/M byte.
void BuildCFI(MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI, const DebugLoc &DL, const MCCFIInstruction &CFIInst) const
Wraps up getting a CFI index and building a MachineInstr for it.
void adjustForHiPEPrologue(MachineFunction &MF, MachineBasicBlock &PrologueMBB) const override
Erlang programs may need a special prologue to handle the stack size they might need at runtime...
void processFunctionBeforeFrameFinalized(MachineFunction &MF, RegScavenger *RS) const override
processFunctionBeforeFrameFinalized - This method is called immediately before the specified function...
unsigned getWinEHParentFrameOffset(const MachineFunction &MF) const override
bool hasFP(const MachineFunction &MF) const override
hasFP - Return true if the specified function should have a dedicated frame pointer register...
bool needsFrameIndexResolution(const MachineFunction &MF) const override
MachineBasicBlock::iterator eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB, MachineBasicBlock::iterator MI) const override
This method is called during prolog/epilog code insertion to eliminate call frame setup and destroy p...
void inlineStackProbe(MachineFunction &MF, MachineBasicBlock &PrologMBB) const override
Replace a StackProbe inline-stub with the actual probe code inline.
MachineBasicBlock * MBB
bool Is64Bit
Is64Bit implies that x86_64 instructions are available.
TargetInstrInfo - Interface to description of machine instruction set.
bool canUseAsPrologue(const MachineBasicBlock &MBB) const override
Check whether or not the given MBB can be used as a prologue for the target.
void determineCalleeSaves(MachineFunction &MF, BitVector &SavedRegs, RegScavenger *RS=nullptr) const override
This method determines which of the registers reported by TargetRegisterInfo::getCalleeSavedRegs() sh...
void emitCalleeSavedFrameMoves(MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI, const DebugLoc &DL) const
bool canUseAsEpilogue(const MachineBasicBlock &MBB) const override
Check whether or not the given MBB can be used as a epilogue for the target.
uint32_t Offset
int mergeSPUpdates(MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI, bool doMergeWithPrevious) const
Check the instruction before/after the passed instruction.
bool enableShrinkWrapping(const MachineFunction &MF) const override
Returns true if the target will correctly handle shrink wrapping.
TargetRegisterInfo base class - We assume that the target defines a static array of TargetRegisterDes...
const X86Subtarget & STI
bool hasReservedCallFrame(const MachineFunction &MF) const override
hasReservedCallFrame - Under normal circumstances, when a frame pointer is not required, we reserve argument space for call sites in the function immediately on entry to the current function.
void emitStackProbe(MachineFunction &MF, MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI, const DebugLoc &DL, bool InProlog) const
Emit target stack probe code.
Information about stack frame layout on the target.
int getFrameIndexReferencePreferSP(const MachineFunction &MF, int FI, unsigned &FrameReg, bool IgnoreSPUpdates) const override
Same as getFrameIndexReference, except that the stack pointer (as opposed to the frame pointer) will ...
bool canSimplifyCallFramePseudos(const MachineFunction &MF) const override
canSimplifyCallFramePseudos - If there is a reserved call frame, the call frame pseudos can be simpli...
const TargetInstrInfo & TII
void emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const override
void emitPrologue(MachineFunction &MF, MachineBasicBlock &MBB) const override
emitProlog/emitEpilog - These methods insert prolog and epilog code into the function.
bool canUseLEAForSPInEpilogue(const MachineFunction &MF) const
Check that LEA can be used on SP in an epilogue sequence for MF.
bool assignCalleeSavedSpillSlots(MachineFunction &MF, const TargetRegisterInfo *TRI, std::vector< CalleeSavedInfo > &CSI) const override
assignCalleeSavedSpillSlots - Allows target to override spill slot assignment logic.
void adjustForSegmentedStacks(MachineFunction &MF, MachineBasicBlock &PrologueMBB) const override
Adjust the prologue to have the function use segmented stacks.
#define I(x, y, z)
Definition: MD5.cpp:54
const X86RegisterInfo * TRI
void emitSPUpdate(MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI, int64_t NumBytes, bool InEpilogue) const
Emit a series of instructions to increment / decrement the stack pointer by a constant value...
int getFrameIndexReference(const MachineFunction &MF, int FI, unsigned &FrameReg) const override
getFrameIndexReference - This method should return the base register and offset used to reference a f...
IRTranslator LLVM IR MI
bool spillCalleeSavedRegisters(MachineBasicBlock &MBB, MachineBasicBlock::iterator MI, const std::vector< CalleeSavedInfo > &CSI, const TargetRegisterInfo *TRI) const override
spillCalleeSavedRegisters - Issues instruction(s) to spill all callee saved registers and returns tru...
void orderFrameObjects(const MachineFunction &MF, SmallVectorImpl< int > &ObjectsToAllocate) const override
Order the symbols in the local stack.