1 //===-- PPCRegisterInfo.cpp - PowerPC Register Information ----------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file contains the PowerPC implementation of the TargetRegisterInfo
13 //===----------------------------------------------------------------------===//
15 #define DEBUG_TYPE "reginfo"
16 #include "PPCRegisterInfo.h"
18 #include "PPCFrameLowering.h"
19 #include "PPCInstrBuilder.h"
20 #include "PPCMachineFunctionInfo.h"
21 #include "PPCSubtarget.h"
22 #include "llvm/ADT/BitVector.h"
23 #include "llvm/ADT/STLExtras.h"
24 #include "llvm/CodeGen/MachineFrameInfo.h"
25 #include "llvm/CodeGen/MachineFunction.h"
26 #include "llvm/CodeGen/MachineInstrBuilder.h"
27 #include "llvm/CodeGen/MachineModuleInfo.h"
28 #include "llvm/CodeGen/MachineRegisterInfo.h"
29 #include "llvm/CodeGen/RegisterScavenging.h"
30 #include "llvm/CodeGen/ValueTypes.h"
31 #include "llvm/IR/CallingConv.h"
32 #include "llvm/IR/Constants.h"
33 #include "llvm/IR/Function.h"
34 #include "llvm/IR/Type.h"
35 #include "llvm/Support/CommandLine.h"
36 #include "llvm/Support/Debug.h"
37 #include "llvm/Support/ErrorHandling.h"
38 #include "llvm/Support/MathExtras.h"
39 #include "llvm/Support/raw_ostream.h"
40 #include "llvm/Target/TargetFrameLowering.h"
41 #include "llvm/Target/TargetInstrInfo.h"
42 #include "llvm/Target/TargetMachine.h"
43 #include "llvm/Target/TargetOptions.h"
46 #define GET_REGINFO_TARGET_DESC
47 #include "PPCGenRegisterInfo.inc"
51 PPCRegisterInfo::PPCRegisterInfo(const PPCSubtarget &ST,
52 const TargetInstrInfo &tii)
53 : PPCGenRegisterInfo(ST.isPPC64() ? PPC::LR8 : PPC::LR,
55 ST.isPPC64() ? 0 : 1),
56 Subtarget(ST), TII(tii) {
57 ImmToIdxMap[PPC::LD] = PPC::LDX; ImmToIdxMap[PPC::STD] = PPC::STDX;
58 ImmToIdxMap[PPC::LBZ] = PPC::LBZX; ImmToIdxMap[PPC::STB] = PPC::STBX;
59 ImmToIdxMap[PPC::LHZ] = PPC::LHZX; ImmToIdxMap[PPC::LHA] = PPC::LHAX;
60 ImmToIdxMap[PPC::LWZ] = PPC::LWZX; ImmToIdxMap[PPC::LWA] = PPC::LWAX;
61 ImmToIdxMap[PPC::LFS] = PPC::LFSX; ImmToIdxMap[PPC::LFD] = PPC::LFDX;
62 ImmToIdxMap[PPC::STH] = PPC::STHX; ImmToIdxMap[PPC::STW] = PPC::STWX;
63 ImmToIdxMap[PPC::STFS] = PPC::STFSX; ImmToIdxMap[PPC::STFD] = PPC::STFDX;
64 ImmToIdxMap[PPC::ADDI] = PPC::ADD4;
67 ImmToIdxMap[PPC::LHA8] = PPC::LHAX8; ImmToIdxMap[PPC::LBZ8] = PPC::LBZX8;
68 ImmToIdxMap[PPC::LHZ8] = PPC::LHZX8; ImmToIdxMap[PPC::LWZ8] = PPC::LWZX8;
69 ImmToIdxMap[PPC::STB8] = PPC::STBX8; ImmToIdxMap[PPC::STH8] = PPC::STHX8;
70 ImmToIdxMap[PPC::STW8] = PPC::STWX8; ImmToIdxMap[PPC::STDU] = PPC::STDUX;
71 ImmToIdxMap[PPC::ADDI8] = PPC::ADD8; ImmToIdxMap[PPC::STD_32] = PPC::STDX_32;
75 PPCRegisterInfo::trackLivenessAfterRegAlloc(const MachineFunction &MF) const {
76 return requiresRegisterScavenging(MF);
80 /// getPointerRegClass - Return the register class to use to hold pointers.
81 /// This is used for addressing modes.
82 const TargetRegisterClass *
83 PPCRegisterInfo::getPointerRegClass(const MachineFunction &MF, unsigned Kind)
85 if (Subtarget.isPPC64())
86 return &PPC::G8RCRegClass;
87 return &PPC::GPRCRegClass;
91 PPCRegisterInfo::getCalleeSavedRegs(const MachineFunction *MF) const {
92 if (Subtarget.isDarwinABI())
93 return Subtarget.isPPC64() ? CSR_Darwin64_SaveList :
94 CSR_Darwin32_SaveList;
96 return Subtarget.isPPC64() ? CSR_SVR464_SaveList : CSR_SVR432_SaveList;
100 PPCRegisterInfo::getCallPreservedMask(CallingConv::ID CC) const {
101 if (Subtarget.isDarwinABI())
102 return Subtarget.isPPC64() ? CSR_Darwin64_RegMask :
103 CSR_Darwin32_RegMask;
105 return Subtarget.isPPC64() ? CSR_SVR464_RegMask : CSR_SVR432_RegMask;
108 BitVector PPCRegisterInfo::getReservedRegs(const MachineFunction &MF) const {
109 BitVector Reserved(getNumRegs());
110 const PPCFrameLowering *PPCFI =
111 static_cast<const PPCFrameLowering*>(MF.getTarget().getFrameLowering());
113 Reserved.set(PPC::R0);
114 Reserved.set(PPC::R1);
115 Reserved.set(PPC::LR);
116 Reserved.set(PPC::LR8);
117 Reserved.set(PPC::RM);
119 // The SVR4 ABI reserves r2 and r13
120 if (Subtarget.isSVR4ABI()) {
121 Reserved.set(PPC::R2); // System-reserved register
122 Reserved.set(PPC::R13); // Small Data Area pointer register
125 // On PPC64, r13 is the thread pointer. Never allocate this register.
126 // Note that this is over conservative, as it also prevents allocation of R31
127 // when the FP is not needed.
128 if (Subtarget.isPPC64()) {
129 Reserved.set(PPC::R13);
130 Reserved.set(PPC::R31);
132 Reserved.set(PPC::X0);
133 Reserved.set(PPC::X1);
134 Reserved.set(PPC::X13);
135 Reserved.set(PPC::X31);
137 // The 64-bit SVR4 ABI reserves r2 for the TOC pointer.
138 if (Subtarget.isSVR4ABI()) {
139 Reserved.set(PPC::X2);
143 if (PPCFI->needsFP(MF))
144 Reserved.set(PPC::R31);
150 PPCRegisterInfo::getRegPressureLimit(const TargetRegisterClass *RC,
151 MachineFunction &MF) const {
152 const TargetFrameLowering *TFI = MF.getTarget().getFrameLowering();
153 const unsigned DefaultSafety = 1;
155 switch (RC->getID()) {
158 case PPC::G8RCRegClassID:
159 case PPC::GPRCRegClassID: {
160 unsigned FP = TFI->hasFP(MF) ? 1 : 0;
161 return 32 - FP - DefaultSafety;
163 case PPC::F8RCRegClassID:
164 case PPC::F4RCRegClassID:
165 case PPC::VRRCRegClassID:
166 return 32 - DefaultSafety;
167 case PPC::CRRCRegClassID:
168 return 8 - DefaultSafety;
173 PPCRegisterInfo::avoidWriteAfterWrite(const TargetRegisterClass *RC) const {
174 switch (RC->getID()) {
175 case PPC::G8RCRegClassID:
176 case PPC::GPRCRegClassID:
177 case PPC::F8RCRegClassID:
178 case PPC::F4RCRegClassID:
179 case PPC::VRRCRegClassID:
186 //===----------------------------------------------------------------------===//
187 // Stack Frame Processing methods
188 //===----------------------------------------------------------------------===//
190 /// findScratchRegister - Find a 'free' PPC register. Try for a call-clobbered
191 /// register first and then a spilled callee-saved register if that fails.
193 unsigned findScratchRegister(MachineBasicBlock::iterator II, RegScavenger *RS,
194 const TargetRegisterClass *RC, int SPAdj) {
195 assert(RS && "Register scavenging must be on");
196 unsigned Reg = RS->FindUnusedReg(RC);
197 // FIXME: move ARM callee-saved reg scan to target independent code, then
198 // search for already spilled CS register here.
200 Reg = RS->scavengeRegister(RC, II, SPAdj);
204 /// lowerDynamicAlloc - Generate the code for allocating an object in the
205 /// current frame. The sequence of code with be in the general form
207 /// addi R0, SP, \#frameSize ; get the address of the previous frame
208 /// stwxu R0, SP, Rnegsize ; add and update the SP with the negated size
209 /// addi Rnew, SP, \#maxCalFrameSize ; get the top of the allocation
211 void PPCRegisterInfo::lowerDynamicAlloc(MachineBasicBlock::iterator II,
212 int SPAdj, RegScavenger *RS) const {
213 // Get the instruction.
214 MachineInstr &MI = *II;
215 // Get the instruction's basic block.
216 MachineBasicBlock &MBB = *MI.getParent();
217 // Get the basic block's function.
218 MachineFunction &MF = *MBB.getParent();
219 // Get the frame info.
220 MachineFrameInfo *MFI = MF.getFrameInfo();
221 // Determine whether 64-bit pointers are used.
222 bool LP64 = Subtarget.isPPC64();
223 DebugLoc dl = MI.getDebugLoc();
225 // Get the maximum call stack size.
226 unsigned maxCallFrameSize = MFI->getMaxCallFrameSize();
227 // Get the total frame size.
228 unsigned FrameSize = MFI->getStackSize();
230 // Get stack alignments.
231 unsigned TargetAlign = MF.getTarget().getFrameLowering()->getStackAlignment();
232 unsigned MaxAlign = MFI->getMaxAlignment();
233 if (MaxAlign > TargetAlign)
234 report_fatal_error("Dynamic alloca with large aligns not supported");
236 // Determine the previous frame's address. If FrameSize can't be
237 // represented as 16 bits or we need special alignment, then we load the
238 // previous frame's address from 0(SP). Why not do an addis of the hi?
239 // Because R0 is our only safe tmp register and addi/addis treat R0 as zero.
240 // Constructing the constant and adding would take 3 instructions.
241 // Fortunately, a frame greater than 32K is rare.
242 const TargetRegisterClass *G8RC = &PPC::G8RCRegClass;
243 const TargetRegisterClass *GPRC = &PPC::GPRCRegClass;
244 const TargetRegisterClass *RC = LP64 ? G8RC : GPRC;
246 unsigned Reg = findScratchRegister(II, RS, RC, SPAdj);
248 if (MaxAlign < TargetAlign && isInt<16>(FrameSize)) {
249 BuildMI(MBB, II, dl, TII.get(PPC::ADDI), Reg)
253 BuildMI(MBB, II, dl, TII.get(PPC::LD), Reg)
257 BuildMI(MBB, II, dl, TII.get(PPC::LWZ), Reg)
262 // Grow the stack and update the stack pointer link, then determine the
263 // address of new allocated space.
265 BuildMI(MBB, II, dl, TII.get(PPC::STDUX), PPC::X1)
266 .addReg(Reg, RegState::Kill)
268 .addReg(MI.getOperand(1).getReg());
269 if (!MI.getOperand(1).isKill())
270 BuildMI(MBB, II, dl, TII.get(PPC::ADDI8), MI.getOperand(0).getReg())
272 .addImm(maxCallFrameSize);
274 // Implicitly kill the register.
275 BuildMI(MBB, II, dl, TII.get(PPC::ADDI8), MI.getOperand(0).getReg())
277 .addImm(maxCallFrameSize)
278 .addReg(MI.getOperand(1).getReg(), RegState::ImplicitKill);
280 BuildMI(MBB, II, dl, TII.get(PPC::STWUX), PPC::R1)
281 .addReg(Reg, RegState::Kill)
283 .addReg(MI.getOperand(1).getReg());
285 if (!MI.getOperand(1).isKill())
286 BuildMI(MBB, II, dl, TII.get(PPC::ADDI), MI.getOperand(0).getReg())
288 .addImm(maxCallFrameSize);
290 // Implicitly kill the register.
291 BuildMI(MBB, II, dl, TII.get(PPC::ADDI), MI.getOperand(0).getReg())
293 .addImm(maxCallFrameSize)
294 .addReg(MI.getOperand(1).getReg(), RegState::ImplicitKill);
297 // Discard the DYNALLOC instruction.
301 /// lowerCRSpilling - Generate the code for spilling a CR register. Instead of
302 /// reserving a whole register (R0), we scrounge for one here. This generates
305 /// mfcr rA ; Move the conditional register into GPR rA.
306 /// rlwinm rA, rA, SB, 0, 31 ; Shift the bits left so they are in CR0's slot.
307 /// stw rA, FI ; Store rA to the frame.
309 void PPCRegisterInfo::lowerCRSpilling(MachineBasicBlock::iterator II,
310 unsigned FrameIndex, int SPAdj,
311 RegScavenger *RS) const {
312 // Get the instruction.
313 MachineInstr &MI = *II; // ; SPILL_CR <SrcReg>, <offset>
314 // Get the instruction's basic block.
315 MachineBasicBlock &MBB = *MI.getParent();
316 DebugLoc dl = MI.getDebugLoc();
318 // FIXME: Once LLVM supports creating virtual registers here, or the register
319 // scavenger can return multiple registers, stop using reserved registers
324 bool LP64 = Subtarget.isPPC64();
325 unsigned Reg = LP64 ? PPC::X0 : PPC::R0;
326 unsigned SrcReg = MI.getOperand(0).getReg();
328 // We need to store the CR in the low 4-bits of the saved value. First, issue
329 // an MFCRpsued to save all of the CRBits and, if needed, kill the SrcReg.
330 BuildMI(MBB, II, dl, TII.get(LP64 ? PPC::MFCR8pseud : PPC::MFCRpseud), Reg)
331 .addReg(SrcReg, getKillRegState(MI.getOperand(0).isKill()));
333 // If the saved register wasn't CR0, shift the bits left so that they are in
335 if (SrcReg != PPC::CR0)
336 // rlwinm rA, rA, ShiftBits, 0, 31.
337 BuildMI(MBB, II, dl, TII.get(LP64 ? PPC::RLWINM8 : PPC::RLWINM), Reg)
338 .addReg(Reg, RegState::Kill)
339 .addImm(getPPCRegisterNumbering(SrcReg) * 4)
343 addFrameReference(BuildMI(MBB, II, dl, TII.get(LP64 ? PPC::STW8 : PPC::STW))
344 .addReg(Reg, getKillRegState(MI.getOperand(1).getImm())),
347 // Discard the pseudo instruction.
351 void PPCRegisterInfo::lowerCRRestore(MachineBasicBlock::iterator II,
352 unsigned FrameIndex, int SPAdj,
353 RegScavenger *RS) const {
354 // Get the instruction.
355 MachineInstr &MI = *II; // ; <DestReg> = RESTORE_CR <offset>
356 // Get the instruction's basic block.
357 MachineBasicBlock &MBB = *MI.getParent();
358 DebugLoc dl = MI.getDebugLoc();
360 // FIXME: Once LLVM supports creating virtual registers here, or the register
361 // scavenger can return multiple registers, stop using reserved registers
366 bool LP64 = Subtarget.isPPC64();
367 unsigned Reg = LP64 ? PPC::X0 : PPC::R0;
368 unsigned DestReg = MI.getOperand(0).getReg();
369 assert(MI.definesRegister(DestReg) &&
370 "RESTORE_CR does not define its destination");
372 addFrameReference(BuildMI(MBB, II, dl, TII.get(LP64 ? PPC::LWZ8 : PPC::LWZ),
375 // If the reloaded register isn't CR0, shift the bits right so that they are
376 // in the right CR's slot.
377 if (DestReg != PPC::CR0) {
378 unsigned ShiftBits = getPPCRegisterNumbering(DestReg)*4;
379 // rlwinm r11, r11, 32-ShiftBits, 0, 31.
380 BuildMI(MBB, II, dl, TII.get(LP64 ? PPC::RLWINM8 : PPC::RLWINM), Reg)
381 .addReg(Reg).addImm(32-ShiftBits).addImm(0)
385 BuildMI(MBB, II, dl, TII.get(LP64 ? PPC::MTCRF8 : PPC::MTCRF), DestReg)
388 // Discard the pseudo instruction.
393 PPCRegisterInfo::hasReservedSpillSlot(const MachineFunction &MF,
394 unsigned Reg, int &FrameIdx) const {
396 // For the nonvolatile condition registers (CR2, CR3, CR4) in an SVR4
397 // ABI, return true to prevent allocating an additional frame slot.
398 // For 64-bit, the CR save area is at SP+8; the value of FrameIdx = 0
399 // is arbitrary and will be subsequently ignored. For 32-bit, we have
400 // previously created the stack slot if needed, so return its FrameIdx.
401 if (Subtarget.isSVR4ABI() && PPC::CR2 <= Reg && Reg <= PPC::CR4) {
402 if (Subtarget.isPPC64())
405 const PPCFunctionInfo *FI = MF.getInfo<PPCFunctionInfo>();
406 FrameIdx = FI->getCRSpillFrameIndex();
414 PPCRegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
415 int SPAdj, unsigned FIOperandNum,
416 RegScavenger *RS) const {
417 assert(SPAdj == 0 && "Unexpected");
419 // Get the instruction.
420 MachineInstr &MI = *II;
421 // Get the instruction's basic block.
422 MachineBasicBlock &MBB = *MI.getParent();
423 // Get the basic block's function.
424 MachineFunction &MF = *MBB.getParent();
425 // Get the frame info.
426 MachineFrameInfo *MFI = MF.getFrameInfo();
427 const TargetFrameLowering *TFI = MF.getTarget().getFrameLowering();
428 DebugLoc dl = MI.getDebugLoc();
430 // Take into account whether it's an add or mem instruction
431 unsigned OffsetOperandNo = (FIOperandNum == 2) ? 1 : 2;
432 if (MI.isInlineAsm())
433 OffsetOperandNo = FIOperandNum-1;
435 // Get the frame index.
436 int FrameIndex = MI.getOperand(FIOperandNum).getIndex();
438 // Get the frame pointer save index. Users of this index are primarily
439 // DYNALLOC instructions.
440 PPCFunctionInfo *FI = MF.getInfo<PPCFunctionInfo>();
441 int FPSI = FI->getFramePointerSaveIndex();
442 // Get the instruction opcode.
443 unsigned OpC = MI.getOpcode();
445 // Special case for dynamic alloca.
446 if (FPSI && FrameIndex == FPSI &&
447 (OpC == PPC::DYNALLOC || OpC == PPC::DYNALLOC8)) {
448 lowerDynamicAlloc(II, SPAdj, RS);
452 // Special case for pseudo-ops SPILL_CR and RESTORE_CR.
453 if (OpC == PPC::SPILL_CR) {
454 lowerCRSpilling(II, FrameIndex, SPAdj, RS);
456 } else if (OpC == PPC::RESTORE_CR) {
457 lowerCRRestore(II, FrameIndex, SPAdj, RS);
461 // Replace the FrameIndex with base register with GPR1 (SP) or GPR31 (FP).
463 bool is64Bit = Subtarget.isPPC64();
464 MI.getOperand(FIOperandNum).ChangeToRegister(TFI->hasFP(MF) ?
465 (is64Bit ? PPC::X31 : PPC::R31) :
466 (is64Bit ? PPC::X1 : PPC::R1),
469 // Figure out if the offset in the instruction is shifted right two bits. This
470 // is true for instructions like "STD", which the machine implicitly adds two
472 bool isIXAddr = false;
482 // Now add the frame object offset to the offset from r1.
483 int Offset = MFI->getObjectOffset(FrameIndex);
485 Offset += MI.getOperand(OffsetOperandNo).getImm();
487 Offset += MI.getOperand(OffsetOperandNo).getImm() << 2;
489 // If we're not using a Frame Pointer that has been set to the value of the
490 // SP before having the stack size subtracted from it, then add the stack size
491 // to Offset to get the correct offset.
492 // Naked functions have stack size 0, although getStackSize may not reflect that
493 // because we didn't call all the pieces that compute it for naked functions.
494 if (!MF.getFunction()->getAttributes().
495 hasAttribute(AttributeSet::FunctionIndex, Attribute::Naked))
496 Offset += MFI->getStackSize();
498 // If we can, encode the offset directly into the instruction. If this is a
499 // normal PPC "ri" instruction, any 16-bit value can be safely encoded. If
500 // this is a PPC64 "ix" instruction, only a 16-bit value with the low two bits
501 // clear can be encoded. This is extremely uncommon, because normally you
502 // only "std" to a stack slot that is at least 4-byte aligned, but it can
503 // happen in invalid code.
504 if (OpC == PPC::DBG_VALUE || // DBG_VALUE is always Reg+Imm
505 (isInt<16>(Offset) && (!isIXAddr || (Offset & 3) == 0))) {
507 Offset >>= 2; // The actual encoded value has the low two bits zero.
508 MI.getOperand(OffsetOperandNo).ChangeToImmediate(Offset);
512 // The offset doesn't fit into a single register, scavenge one to build the
515 const TargetRegisterClass *G8RC = &PPC::G8RCRegClass;
516 const TargetRegisterClass *GPRC = &PPC::GPRCRegClass;
517 unsigned SReg = findScratchRegister(II, RS, is64Bit ? G8RC : GPRC, SPAdj);
519 // Insert a set of rA with the full offset value before the ld, st, or add
520 BuildMI(MBB, II, dl, TII.get(is64Bit ? PPC::LIS8 : PPC::LIS), SReg)
521 .addImm(Offset >> 16);
522 BuildMI(MBB, II, dl, TII.get(is64Bit ? PPC::ORI8 : PPC::ORI), SReg)
523 .addReg(SReg, RegState::Kill)
526 // Convert into indexed form of the instruction:
528 // sth 0:rA, 1:imm 2:(rB) ==> sthx 0:rA, 2:rB, 1:r0
529 // addi 0:rA 1:rB, 2, imm ==> add 0:rA, 1:rB, 2:r0
530 unsigned OperandBase;
532 if (OpC != TargetOpcode::INLINEASM) {
533 assert(ImmToIdxMap.count(OpC) &&
534 "No indexed form of load or store available!");
535 unsigned NewOpcode = ImmToIdxMap.find(OpC)->second;
536 MI.setDesc(TII.get(NewOpcode));
539 OperandBase = OffsetOperandNo;
542 unsigned StackReg = MI.getOperand(FIOperandNum).getReg();
543 MI.getOperand(OperandBase).ChangeToRegister(StackReg, false);
544 MI.getOperand(OperandBase + 1).ChangeToRegister(SReg, false, false, true);
547 unsigned PPCRegisterInfo::getFrameRegister(const MachineFunction &MF) const {
548 const TargetFrameLowering *TFI = MF.getTarget().getFrameLowering();
550 if (!Subtarget.isPPC64())
551 return TFI->hasFP(MF) ? PPC::R31 : PPC::R1;
553 return TFI->hasFP(MF) ? PPC::X31 : PPC::X1;
556 unsigned PPCRegisterInfo::getEHExceptionRegister() const {
557 return !Subtarget.isPPC64() ? PPC::R3 : PPC::X3;
560 unsigned PPCRegisterInfo::getEHHandlerRegister() const {
561 return !Subtarget.isPPC64() ? PPC::R4 : PPC::X4;