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/MachineFunction.h"
17#include "llvm/CodeGen/TargetFrameLowering.h"
18#include "llvm/Support/TypeSize.h"
19
20namespace llvm {
21
22class MachineInstrBuilder;
23class MCCFIInstruction;
24class X86InstrInfo;
25class X86Subtarget;
26class X86RegisterInfo;
27
28class X86FrameLowering : public TargetFrameLowering {
29public:
30 X86FrameLowering(const X86Subtarget &STI, MaybeAlign StackAlignOverride);
31
32 // Cached subtarget predicates.
33
34 const X86Subtarget &STI;
35 const X86InstrInfo &TII;
36 const X86RegisterInfo *TRI;
37
38 unsigned SlotSize;
39
40 /// Is64Bit implies that x86_64 instructions are available.
41 bool Is64Bit;
42
43 bool IsLP64;
44
45 /// True if the 64-bit frame or stack pointer should be used. True for most
46 /// 64-bit targets with the exception of x32. If this is false, 32-bit
47 /// instruction operands should be used to manipulate StackPtr and FramePtr.
48 bool Uses64BitFramePtr;
49
50 unsigned StackPtr;
51
52 /// Emit target stack probe code. This is required for all
53 /// large stack allocations on Windows. The caller is required to materialize
54 /// the number of bytes to probe in RAX/EAX.
55 /// \p InstrNum optionally contains a debug-info instruction number for the
56 /// new stack pointer.
57 void emitStackProbe(MachineFunction &MF, MachineBasicBlock &MBB,
58 MachineBasicBlock::iterator MBBI, const DebugLoc &DL,
59 bool InProlog,
60 std::optional<MachineFunction::DebugInstrOperandPair>
61 InstrNum = std::nullopt) const;
62
63 bool stackProbeFunctionModifiesSP() const override;
64
65 /// Replace a StackProbe inline-stub with the actual probe code inline.
66 void inlineStackProbe(MachineFunction &MF,
67 MachineBasicBlock &PrologMBB) const override;
68
69 void emitCalleeSavedFrameMovesFullCFA(
70 MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI) const override;
71
72 void emitCalleeSavedFrameMoves(MachineBasicBlock &MBB,
73 MachineBasicBlock::iterator MBBI,
74 const DebugLoc &DL, bool IsPrologue) const;
75
76 /// emitProlog/emitEpilog - These methods insert prolog and epilog code into
77 /// the function.
78 void emitPrologue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
79 void emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
80
81 void adjustForSegmentedStacks(MachineFunction &MF,
82 MachineBasicBlock &PrologueMBB) const override;
83
84 void adjustForHiPEPrologue(MachineFunction &MF,
85 MachineBasicBlock &PrologueMBB) const override;
86
87 void determineCalleeSaves(MachineFunction &MF, BitVector &SavedRegs,
88 RegScavenger *RS = nullptr) const override;
89
90 bool
91 assignCalleeSavedSpillSlots(MachineFunction &MF,
92 const TargetRegisterInfo *TRI,
93 std::vector<CalleeSavedInfo> &CSI) const override;
94
95 bool spillCalleeSavedRegisters(MachineBasicBlock &MBB,
96 MachineBasicBlock::iterator MI,
97 ArrayRef<CalleeSavedInfo> CSI,
98 const TargetRegisterInfo *TRI) const override;
99
100 bool
101 restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
102 MachineBasicBlock::iterator MI,
103 MutableArrayRef<CalleeSavedInfo> CSI,
104 const TargetRegisterInfo *TRI) const override;
105
106 bool hasFP(const MachineFunction &MF) const override;
107 bool hasReservedCallFrame(const MachineFunction &MF) const override;
108 bool canSimplifyCallFramePseudos(const MachineFunction &MF) const override;
109 bool needsFrameIndexResolution(const MachineFunction &MF) const override;
110
111 StackOffset getFrameIndexReference(const MachineFunction &MF, int FI,
112 Register &FrameReg) const override;
113
114 int getWin64EHFrameIndexRef(const MachineFunction &MF, int FI,
115 Register &SPReg) const;
116 StackOffset getFrameIndexReferenceSP(const MachineFunction &MF, int FI,
117 Register &SPReg, int Adjustment) const;
118 StackOffset
119 getFrameIndexReferencePreferSP(const MachineFunction &MF, int FI,
120 Register &FrameReg,
121 bool IgnoreSPUpdates) const override;
122
123 MachineBasicBlock::iterator
124 eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
125 MachineBasicBlock::iterator MI) const override;
126
127 unsigned getWinEHParentFrameOffset(const MachineFunction &MF) const override;
128
129 void processFunctionBeforeFrameFinalized(MachineFunction &MF,
130 RegScavenger *RS) const override;
131
132 void
133 processFunctionBeforeFrameIndicesReplaced(MachineFunction &MF,
134 RegScavenger *RS) const override;
135
136 /// Check the instruction before/after the passed instruction. If
137 /// it is an ADD/SUB/LEA instruction it is deleted argument and the
138 /// stack adjustment is returned as a positive value for ADD/LEA and
139 /// a negative for SUB.
140 int mergeSPUpdates(MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI,
141 bool doMergeWithPrevious) const;
142
143 /// Emit a series of instructions to increment / decrement the stack
144 /// pointer by a constant value.
145 void emitSPUpdate(MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI,
146 const DebugLoc &DL, int64_t NumBytes, bool InEpilogue) const;
147
148 /// Check that LEA can be used on SP in an epilogue sequence for \p MF.
149 bool canUseLEAForSPInEpilogue(const MachineFunction &MF) const;
150
151 /// Check whether or not the given \p MBB can be used as a prologue
152 /// for the target.
153 /// The prologue will be inserted first in this basic block.
154 /// This method is used by the shrink-wrapping pass to decide if
155 /// \p MBB will be correctly handled by the target.
156 /// As soon as the target enable shrink-wrapping without overriding
157 /// this method, we assume that each basic block is a valid
158 /// prologue.
159 bool canUseAsPrologue(const MachineBasicBlock &MBB) const override;
160
161 /// Check whether or not the given \p MBB can be used as a epilogue
162 /// for the target.
163 /// The epilogue will be inserted before the first terminator of that block.
164 /// This method is used by the shrink-wrapping pass to decide if
165 /// \p MBB will be correctly handled by the target.
166 bool canUseAsEpilogue(const MachineBasicBlock &MBB) const override;
167
168 /// Returns true if the target will correctly handle shrink wrapping.
169 bool enableShrinkWrapping(const MachineFunction &MF) const override;
170
171 /// Order the symbols in the local stack.
172 /// We want to place the local stack objects in some sort of sensible order.
173 /// The heuristic we use is to try and pack them according to static number
174 /// of uses and size in order to minimize code size.
175 void orderFrameObjects(const MachineFunction &MF,
176 SmallVectorImpl<int> &ObjectsToAllocate) const override;
177
178 /// Wraps up getting a CFI index and building a MachineInstr for it.
179 void BuildCFI(MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI,
180 const DebugLoc &DL, const MCCFIInstruction &CFIInst,
181 MachineInstr::MIFlag Flag = MachineInstr::NoFlags) const;
182
183 /// Sets up EBP and optionally ESI based on the incoming EBP value. Only
184 /// needed for 32-bit. Used in funclet prologues and at catchret destinations.
185 MachineBasicBlock::iterator
186 restoreWin32EHStackPointers(MachineBasicBlock &MBB,
187 MachineBasicBlock::iterator MBBI,
188 const DebugLoc &DL, bool RestoreSP = false) const;
189
190 void restoreWinEHStackPointersInParent(MachineFunction &MF) const;
191
192 int getInitialCFAOffset(const MachineFunction &MF) const override;
193
194 Register getInitialCFARegister(const MachineFunction &MF) const override;
195
196 DwarfFrameBase getDwarfFrameBase(const MachineFunction &MF) const override;
197
198 /// Return true if the function has a redzone (accessible bytes past the
199 /// frame of the top of stack function) as part of it's ABI.
200 bool has128ByteRedZone(const MachineFunction& MF) const;
201
202private:
203 bool isWin64Prologue(const MachineFunction &MF) const;
204
205 bool needsDwarfCFI(const MachineFunction &MF) const;
206
207 uint64_t calculateMaxStackAlign(const MachineFunction &MF) const;
208
209 /// Emit target stack probe as a call to a helper function
210 void emitStackProbeCall(
211 MachineFunction &MF, MachineBasicBlock &MBB,
212 MachineBasicBlock::iterator MBBI, const DebugLoc &DL, bool InProlog,
213 std::optional<MachineFunction::DebugInstrOperandPair> InstrNum) const;
214
215 /// Emit target stack probe as an inline sequence.
216 void emitStackProbeInline(MachineFunction &MF, MachineBasicBlock &MBB,
217 MachineBasicBlock::iterator MBBI,
218 const DebugLoc &DL, bool InProlog) const;
219 void emitStackProbeInlineWindowsCoreCLR64(MachineFunction &MF,
220 MachineBasicBlock &MBB,
221 MachineBasicBlock::iterator MBBI,
222 const DebugLoc &DL,
223 bool InProlog) const;
224 void emitStackProbeInlineGeneric(MachineFunction &MF, MachineBasicBlock &MBB,
225 MachineBasicBlock::iterator MBBI,
226 const DebugLoc &DL, bool InProlog) const;
227
228 void emitStackProbeInlineGenericBlock(MachineFunction &MF,
229 MachineBasicBlock &MBB,
230 MachineBasicBlock::iterator MBBI,
231 const DebugLoc &DL, uint64_t Offset,
232 uint64_t Align) const;
233
234 void emitStackProbeInlineGenericLoop(MachineFunction &MF,
235 MachineBasicBlock &MBB,
236 MachineBasicBlock::iterator MBBI,
237 const DebugLoc &DL, uint64_t Offset,
238 uint64_t Align) const;
239
240 /// Emit target zero call-used regs.
241 void emitZeroCallUsedRegs(BitVector RegsToZero,
242 MachineBasicBlock &MBB) const override;
243
244 void adjustFrameForMsvcCxxEh(MachineFunction &MF) const;
245
246 /// Aligns the stack pointer by ANDing it with -MaxAlign.
247 void BuildStackAlignAND(MachineBasicBlock &MBB,
248 MachineBasicBlock::iterator MBBI, const DebugLoc &DL,
249 unsigned Reg, uint64_t MaxAlign) const;
250
251 /// Make small positive stack adjustments using POPs.
252 bool adjustStackWithPops(MachineBasicBlock &MBB,
253 MachineBasicBlock::iterator MBBI, const DebugLoc &DL,
254 int Offset) const;
255
256 /// Adjusts the stack pointer using LEA, SUB, or ADD.
257 MachineInstrBuilder BuildStackAdjustment(MachineBasicBlock &MBB,
258 MachineBasicBlock::iterator MBBI,
259 const DebugLoc &DL, int64_t Offset,
260 bool InEpilogue) const;
261
262 unsigned getPSPSlotOffsetFromSP(const MachineFunction &MF) const;
263
264 unsigned getWinEHFuncletFrameSize(const MachineFunction &MF) const;
265
266 /// Materialize the catchret target MBB in RAX.
267 void emitCatchRetReturnValue(MachineBasicBlock &MBB,
268 MachineBasicBlock::iterator MBBI,
269 MachineInstr *CatchRet) const;
270};
271
272} // End llvm namespace
273
274#endif
275