1 //===- X86RegisterInfo.cpp - X86 Register Information -----------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file contains the X86 implementation of the MRegisterInfo class. This
11 // file is responsible for the frame pointer elimination optimization on X86.
13 //===----------------------------------------------------------------------===//
16 #include "X86RegisterInfo.h"
17 #include "X86InstrBuilder.h"
18 #include "llvm/Constants.h"
19 #include "llvm/Type.h"
20 #include "llvm/CodeGen/ValueTypes.h"
21 #include "llvm/CodeGen/MachineInstrBuilder.h"
22 #include "llvm/CodeGen/MachineFunction.h"
23 #include "llvm/CodeGen/MachineFrameInfo.h"
24 #include "llvm/Target/TargetMachine.h"
25 #include "llvm/Target/TargetFrameInfo.h"
26 #include "Support/CommandLine.h"
27 #include "Support/STLExtras.h"
32 NoFPElim("disable-fp-elim",
33 cl::desc("Disable frame pointer elimination optimization"));
35 NoFusing("disable-spill-fusing",
36 cl::desc("Disable fusing of spill code into instructions"));
38 PrintFailedFusing("print-failed-fuse-candidates",
39 cl::desc("Print instructions that the allocator wants to"
40 " fuse, but the X86 backend currently can't"),
44 X86RegisterInfo::X86RegisterInfo()
45 : X86GenRegisterInfo(X86::ADJCALLSTACKDOWN, X86::ADJCALLSTACKUP) {}
47 static unsigned getIdx(const TargetRegisterClass *RC) {
48 switch (RC->getSize()) {
49 default: assert(0 && "Invalid data size!");
57 int X86RegisterInfo::storeRegToStackSlot(MachineBasicBlock &MBB,
58 MachineBasicBlock::iterator MI,
59 unsigned SrcReg, int FrameIdx,
60 const TargetRegisterClass *RC) const {
61 static const unsigned Opcode[] =
62 { X86::MOVmr8, X86::MOVmr16, X86::MOVmr32, X86::FSTPr80 };
63 MachineInstr *I = addFrameReference(BuildMI(Opcode[getIdx(RC)], 5),
64 FrameIdx).addReg(SrcReg);
69 int X86RegisterInfo::loadRegFromStackSlot(MachineBasicBlock &MBB,
70 MachineBasicBlock::iterator MI,
71 unsigned DestReg, int FrameIdx,
72 const TargetRegisterClass *RC) const{
73 static const unsigned Opcode[] =
74 { X86::MOVrm8, X86::MOVrm16, X86::MOVrm32, X86::FLDr80 };
75 unsigned OC = Opcode[getIdx(RC)];
76 MBB.insert(MI, addFrameReference(BuildMI(OC, 4, DestReg), FrameIdx));
80 int X86RegisterInfo::copyRegToReg(MachineBasicBlock &MBB,
81 MachineBasicBlock::iterator MI,
82 unsigned DestReg, unsigned SrcReg,
83 const TargetRegisterClass *RC) const {
84 static const unsigned Opcode[] =
85 { X86::MOVrr8, X86::MOVrr16, X86::MOVrr32, X86::FpMOV };
86 MBB.insert(MI, BuildMI(Opcode[getIdx(RC)],1,DestReg).addReg(SrcReg));
90 static MachineInstr *MakeMInst(unsigned Opcode, unsigned FrameIndex,
92 return addFrameReference(BuildMI(Opcode, 1, MI->getOperand(0).getReg()),
96 static MachineInstr *MakeMRInst(unsigned Opcode, unsigned FrameIndex,
98 return addFrameReference(BuildMI(Opcode, 5), FrameIndex)
99 .addReg(MI->getOperand(1).getReg());
102 static MachineInstr *MakeMIInst(unsigned Opcode, unsigned FrameIndex,
104 return addFrameReference(BuildMI(Opcode, 5), FrameIndex)
105 .addZImm(MI->getOperand(1).getImmedValue());
108 static MachineInstr *MakeRMInst(unsigned Opcode, unsigned FrameIndex,
110 return addFrameReference(BuildMI(Opcode, 5, MI->getOperand(0).getReg()),
114 static MachineInstr *MakeRMIInst(unsigned Opcode, unsigned FrameIndex,
116 return addFrameReference(BuildMI(Opcode, 5, MI->getOperand(0).getReg()),
117 FrameIndex).addZImm(MI->getOperand(2).getImmedValue());
121 bool X86RegisterInfo::foldMemoryOperand(MachineBasicBlock::iterator &MI,
122 unsigned i, int FrameIndex) const {
123 if (NoFusing) return false;
125 /// FIXME: This should obviously be autogenerated by tablegen when patterns
127 MachineBasicBlock& MBB = *MI->getParent();
128 MachineInstr* NI = 0;
130 switch(MI->getOpcode()) {
131 case X86::MOVrr8: NI = MakeMRInst(X86::MOVmr8 , FrameIndex, MI); break;
132 case X86::MOVrr16: NI = MakeMRInst(X86::MOVmr16, FrameIndex, MI); break;
133 case X86::MOVrr32: NI = MakeMRInst(X86::MOVmr32, FrameIndex, MI); break;
134 case X86::MOVri8: NI = MakeMIInst(X86::MOVmi8 , FrameIndex, MI); break;
135 case X86::MOVri16: NI = MakeMIInst(X86::MOVmi16, FrameIndex, MI); break;
136 case X86::MOVri32: NI = MakeMIInst(X86::MOVmi32, FrameIndex, MI); break;
137 case X86::MULr8: NI = MakeMInst(X86::MULm8 , FrameIndex, MI); break;
138 case X86::MULr16: NI = MakeMInst(X86::MULm16, FrameIndex, MI); break;
139 case X86::MULr32: NI = MakeMInst(X86::MULm32, FrameIndex, MI); break;
140 case X86::DIVr8: NI = MakeMInst(X86::DIVm8 , FrameIndex, MI); break;
141 case X86::DIVr16: NI = MakeMInst(X86::DIVm16, FrameIndex, MI); break;
142 case X86::DIVr32: NI = MakeMInst(X86::DIVm32, FrameIndex, MI); break;
143 case X86::IDIVr8: NI = MakeMInst(X86::IDIVm8 , FrameIndex, MI); break;
144 case X86::IDIVr16: NI = MakeMInst(X86::IDIVm16, FrameIndex, MI); break;
145 case X86::IDIVr32: NI = MakeMInst(X86::IDIVm32, FrameIndex, MI); break;
146 case X86::NEGr8: NI = MakeMInst(X86::NEGm8 , FrameIndex, MI); break;
147 case X86::NEGr16: NI = MakeMInst(X86::NEGm16, FrameIndex, MI); break;
148 case X86::NEGr32: NI = MakeMInst(X86::NEGm32, FrameIndex, MI); break;
149 case X86::NOTr8: NI = MakeMInst(X86::NOTm8 , FrameIndex, MI); break;
150 case X86::NOTr16: NI = MakeMInst(X86::NOTm16, FrameIndex, MI); break;
151 case X86::NOTr32: NI = MakeMInst(X86::NOTm32, FrameIndex, MI); break;
152 case X86::INCr8: NI = MakeMInst(X86::INCm8 , FrameIndex, MI); break;
153 case X86::INCr16: NI = MakeMInst(X86::INCm16, FrameIndex, MI); break;
154 case X86::INCr32: NI = MakeMInst(X86::INCm32, FrameIndex, MI); break;
155 case X86::DECr8: NI = MakeMInst(X86::DECm8 , FrameIndex, MI); break;
156 case X86::DECr16: NI = MakeMInst(X86::DECm16, FrameIndex, MI); break;
157 case X86::DECr32: NI = MakeMInst(X86::DECm32, FrameIndex, MI); break;
158 case X86::ADDrr8: NI = MakeMRInst(X86::ADDmr8 , FrameIndex, MI); break;
159 case X86::ADDrr16: NI = MakeMRInst(X86::ADDmr16, FrameIndex, MI); break;
160 case X86::ADDrr32: NI = MakeMRInst(X86::ADDmr32, FrameIndex, MI); break;
161 case X86::ADCrr32: NI = MakeMRInst(X86::ADCmr32, FrameIndex, MI); break;
162 case X86::ADDri8: NI = MakeMIInst(X86::ADDmi8 , FrameIndex, MI); break;
163 case X86::ADDri16: NI = MakeMIInst(X86::ADDmi16, FrameIndex, MI); break;
164 case X86::ADDri32: NI = MakeMIInst(X86::ADDmi32, FrameIndex, MI); break;
165 case X86::SUBrr8: NI = MakeMRInst(X86::SUBmr8 , FrameIndex, MI); break;
166 case X86::SUBrr16: NI = MakeMRInst(X86::SUBmr16, FrameIndex, MI); break;
167 case X86::SUBrr32: NI = MakeMRInst(X86::SUBmr32, FrameIndex, MI); break;
168 case X86::SBBrr32: NI = MakeMRInst(X86::SBBmr32, FrameIndex, MI); break;
169 case X86::SUBri8: NI = MakeMIInst(X86::SUBmi8 , FrameIndex, MI); break;
170 case X86::SUBri16: NI = MakeMIInst(X86::SUBmi16, FrameIndex, MI); break;
171 case X86::SUBri32: NI = MakeMIInst(X86::SUBmi32, FrameIndex, MI); break;
172 case X86::ANDrr8: NI = MakeMRInst(X86::ANDmr8 , FrameIndex, MI); break;
173 case X86::ANDrr16: NI = MakeMRInst(X86::ANDmr16, FrameIndex, MI); break;
174 case X86::ANDrr32: NI = MakeMRInst(X86::ANDmr32, FrameIndex, MI); break;
175 case X86::ANDri8: NI = MakeMIInst(X86::ANDmi8 , FrameIndex, MI); break;
176 case X86::ANDri16: NI = MakeMIInst(X86::ANDmi16, FrameIndex, MI); break;
177 case X86::ANDri32: NI = MakeMIInst(X86::ANDmi32, FrameIndex, MI); break;
178 case X86::CMPrr8: NI = MakeMRInst(X86::CMPmr8 , FrameIndex, MI); break;
179 case X86::CMPrr16: NI = MakeMRInst(X86::CMPmr16, FrameIndex, MI); break;
180 case X86::CMPrr32: NI = MakeMRInst(X86::CMPmr32, FrameIndex, MI); break;
181 case X86::CMPri8: NI = MakeMIInst(X86::CMPmi8 , FrameIndex, MI); break;
182 case X86::CMPri16: NI = MakeMIInst(X86::CMPmi16, FrameIndex, MI); break;
183 case X86::CMPri32: NI = MakeMIInst(X86::CMPmi32, FrameIndex, MI); break;
184 default: break; // Cannot fold
187 switch(MI->getOpcode()) {
188 case X86::MOVrr8: NI = MakeRMInst(X86::MOVrm8 , FrameIndex, MI); break;
189 case X86::MOVrr16: NI = MakeRMInst(X86::MOVrm16, FrameIndex, MI); break;
190 case X86::MOVrr32: NI = MakeRMInst(X86::MOVrm32, FrameIndex, MI); break;
191 case X86::ADDrr8: NI = MakeRMInst(X86::ADDrm8 , FrameIndex, MI); break;
192 case X86::ADDrr16: NI = MakeRMInst(X86::ADDrm16, FrameIndex, MI); break;
193 case X86::ADDrr32: NI = MakeRMInst(X86::ADDrm32, FrameIndex, MI); break;
194 case X86::ADCrr32: NI = MakeRMInst(X86::ADCrm32, FrameIndex, MI); break;
195 case X86::SUBrr8: NI = MakeRMInst(X86::SUBrm8 , FrameIndex, MI); break;
196 case X86::SUBrr16: NI = MakeRMInst(X86::SUBrm16, FrameIndex, MI); break;
197 case X86::SUBrr32: NI = MakeRMInst(X86::SUBrm32, FrameIndex, MI); break;
198 case X86::SBBrr32: NI = MakeRMInst(X86::SBBrm32, FrameIndex, MI); break;
199 case X86::ANDrr8: NI = MakeRMInst(X86::ANDrm8 , FrameIndex, MI); break;
200 case X86::ANDrr16: NI = MakeRMInst(X86::ANDrm16, FrameIndex, MI); break;
201 case X86::ANDrr32: NI = MakeRMInst(X86::ANDrm32, FrameIndex, MI); break;
202 case X86::IMULrr16:NI = MakeRMInst(X86::IMULrm16, FrameIndex, MI); break;
203 case X86::IMULrr32:NI = MakeRMInst(X86::IMULrm32, FrameIndex, MI); break;
204 case X86::IMULrri16: NI = MakeRMIInst(X86::IMULrmi16, FrameIndex, MI);break;
205 case X86::IMULrri32: NI = MakeRMIInst(X86::IMULrmi32, FrameIndex, MI);break;
206 case X86::CMPrr8: NI = MakeRMInst(X86::CMPrm8 , FrameIndex, MI); break;
207 case X86::CMPrr16: NI = MakeRMInst(X86::CMPrm16, FrameIndex, MI); break;
208 case X86::CMPrr32: NI = MakeRMInst(X86::CMPrm32, FrameIndex, MI); break;
210 case X86::MOVSXr16r8: NI = MakeRMInst(X86::MOVSXr16m8 , FrameIndex, MI); break;
211 case X86::MOVSXr32r8: NI = MakeRMInst(X86::MOVSXr32m8, FrameIndex, MI); break;
212 case X86::MOVSXr32r16:NI = MakeRMInst(X86::MOVSXr32m16, FrameIndex, MI); break;
213 case X86::MOVZXr16r8: NI = MakeRMInst(X86::MOVZXr16m8 , FrameIndex, MI); break;
214 case X86::MOVZXr32r8: NI = MakeRMInst(X86::MOVZXr32m8, FrameIndex, MI); break;
215 case X86::MOVZXr32r16:NI = MakeRMInst(X86::MOVZXr32m16, FrameIndex, MI); break;
220 MI = MBB.insert(MBB.erase(MI), NI);
223 if (PrintFailedFusing)
224 std::cerr << "We failed to fuse: " << *MI;
229 //===----------------------------------------------------------------------===//
230 // Stack Frame Processing methods
231 //===----------------------------------------------------------------------===//
233 // hasFP - Return true if the specified function should have a dedicated frame
234 // pointer register. This is true if the function has variable sized allocas or
235 // if frame pointer elimination is disabled.
237 static bool hasFP(MachineFunction &MF) {
238 return NoFPElim || MF.getFrameInfo()->hasVarSizedObjects();
241 void X86RegisterInfo::
242 eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
243 MachineBasicBlock::iterator I) const {
245 // If we have a frame pointer, turn the adjcallstackup instruction into a
246 // 'sub ESP, <amt>' and the adjcallstackdown instruction into 'add ESP,
248 MachineInstr *Old = I;
249 unsigned Amount = Old->getOperand(0).getImmedValue();
251 // We need to keep the stack aligned properly. To do this, we round the
252 // amount of space needed for the outgoing arguments up to the next
253 // alignment boundary.
254 unsigned Align = MF.getTarget().getFrameInfo().getStackAlignment();
255 Amount = (Amount+Align-1)/Align*Align;
258 if (Old->getOpcode() == X86::ADJCALLSTACKDOWN) {
259 New=BuildMI(X86::SUBri32, 1, X86::ESP, MOTy::UseAndDef).addZImm(Amount);
261 assert(Old->getOpcode() == X86::ADJCALLSTACKUP);
262 New=BuildMI(X86::ADDri32, 1, X86::ESP, MOTy::UseAndDef).addZImm(Amount);
265 // Replace the pseudo instruction with a new instruction...
273 void X86RegisterInfo::eliminateFrameIndex(MachineFunction &MF,
274 MachineBasicBlock::iterator II) const {
276 MachineInstr &MI = *II;
277 while (!MI.getOperand(i).isFrameIndex()) {
279 assert(i < MI.getNumOperands() && "Instr doesn't have FrameIndex operand!");
282 int FrameIndex = MI.getOperand(i).getFrameIndex();
284 // This must be part of a four operand memory reference. Replace the
285 // FrameIndex with base register with EBP. Add add an offset to the offset.
286 MI.SetMachineOperandReg(i, hasFP(MF) ? X86::EBP : X86::ESP);
288 // Now add the frame object offset to the offset from EBP.
289 int Offset = MF.getFrameInfo()->getObjectOffset(FrameIndex) +
290 MI.getOperand(i+3).getImmedValue()+4;
293 Offset += MF.getFrameInfo()->getStackSize();
295 Offset += 4; // Skip the saved EBP
297 MI.SetMachineOperandConst(i+3, MachineOperand::MO_SignExtendedImmed, Offset);
301 X86RegisterInfo::processFunctionBeforeFrameFinalized(MachineFunction &MF) const{
303 // Create a frame entry for the EBP register that must be saved.
304 int FrameIdx = MF.getFrameInfo()->CreateFixedObject(4, -8);
305 assert(FrameIdx == MF.getFrameInfo()->getObjectIndexBegin() &&
306 "Slot for EBP register must be last in order to be found!");
310 void X86RegisterInfo::emitPrologue(MachineFunction &MF) const {
311 MachineBasicBlock &MBB = MF.front(); // Prolog goes in entry BB
312 MachineBasicBlock::iterator MBBI = MBB.begin();
313 MachineFrameInfo *MFI = MF.getFrameInfo();
316 // Get the number of bytes to allocate from the FrameInfo
317 unsigned NumBytes = MFI->getStackSize();
319 // Get the offset of the stack slot for the EBP register... which is
320 // guaranteed to be the last slot by processFunctionBeforeFrameFinalized.
321 int EBPOffset = MFI->getObjectOffset(MFI->getObjectIndexBegin())+4;
323 if (NumBytes) { // adjust stack pointer: ESP -= numbytes
324 MI= BuildMI(X86::SUBri32, 1, X86::ESP, MOTy::UseAndDef).addZImm(NumBytes);
325 MBB.insert(MBBI, MI);
328 // Save EBP into the appropriate stack slot...
329 MI = addRegOffset(BuildMI(X86::MOVmr32, 5), // mov [ESP-<offset>], EBP
330 X86::ESP, EBPOffset+NumBytes).addReg(X86::EBP);
331 MBB.insert(MBBI, MI);
333 // Update EBP with the new base value...
334 if (NumBytes == 4) // mov EBP, ESP
335 MI = BuildMI(X86::MOVrr32, 2, X86::EBP).addReg(X86::ESP);
336 else // lea EBP, [ESP+StackSize]
337 MI = addRegOffset(BuildMI(X86::LEAr32, 5, X86::EBP), X86::ESP,NumBytes-4);
339 MBB.insert(MBBI, MI);
342 if (MFI->hasCalls()) {
343 // When we have no frame pointer, we reserve argument space for call sites
344 // in the function immediately on entry to the current function. This
345 // eliminates the need for add/sub ESP brackets around call sites.
347 NumBytes += MFI->getMaxCallFrameSize();
349 // Round the size to a multiple of the alignment (don't forget the 4 byte
351 unsigned Align = MF.getTarget().getFrameInfo().getStackAlignment();
352 NumBytes = ((NumBytes+4)+Align-1)/Align*Align - 4;
355 // Update frame info to pretend that this is part of the stack...
356 MFI->setStackSize(NumBytes);
359 // adjust stack pointer: ESP -= numbytes
360 MI= BuildMI(X86::SUBri32, 1, X86::ESP, MOTy::UseAndDef).addZImm(NumBytes);
361 MBB.insert(MBBI, MI);
366 void X86RegisterInfo::emitEpilogue(MachineFunction &MF,
367 MachineBasicBlock &MBB) const {
368 const MachineFrameInfo *MFI = MF.getFrameInfo();
369 MachineBasicBlock::iterator MBBI = prior(MBB.end());
371 assert(MBBI->getOpcode() == X86::RET &&
372 "Can only insert epilog into returning blocks");
375 // Get the offset of the stack slot for the EBP register... which is
376 // guaranteed to be the last slot by processFunctionBeforeFrameFinalized.
377 int EBPOffset = MFI->getObjectOffset(MFI->getObjectIndexEnd()-1)+4;
380 MI = BuildMI(X86::MOVrr32, 1,X86::ESP).addReg(X86::EBP);
381 MBB.insert(MBBI, MI);
384 MI = BuildMI(X86::POPr32, 0, X86::EBP);
385 MBB.insert(MBBI, MI);
387 // Get the number of bytes allocated from the FrameInfo...
388 unsigned NumBytes = MFI->getStackSize();
390 if (NumBytes) { // adjust stack pointer back: ESP += numbytes
391 MI =BuildMI(X86::ADDri32, 1, X86::ESP, MOTy::UseAndDef).addZImm(NumBytes);
392 MBB.insert(MBBI, MI);
397 #include "X86GenRegisterInfo.inc"
399 const TargetRegisterClass*
400 X86RegisterInfo::getRegClassForType(const Type* Ty) const {
401 switch (Ty->getPrimitiveID()) {
403 case Type::ULongTyID: assert(0 && "Long values can't fit in registers!");
404 default: assert(0 && "Invalid type to getClass!");
406 case Type::SByteTyID:
407 case Type::UByteTyID: return &R8Instance;
408 case Type::ShortTyID:
409 case Type::UShortTyID: return &R16Instance;
412 case Type::PointerTyID: return &R32Instance;
414 case Type::FloatTyID:
415 case Type::DoubleTyID: return &RFPInstance;