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
124 // Reserve R2 on Darwin to hack around the problem of save/restore of CR
125 // when the stack frame is too big to address directly; we need two regs.
127 if (Subtarget.isDarwinABI()) {
128 Reserved.set(PPC::R2);
131 // On PPC64, r13 is the thread pointer. Never allocate this register.
132 // Note that this is over conservative, as it also prevents allocation of R31
133 // when the FP is not needed.
134 if (Subtarget.isPPC64()) {
135 Reserved.set(PPC::R13);
136 Reserved.set(PPC::R31);
138 Reserved.set(PPC::X0);
139 Reserved.set(PPC::X1);
140 Reserved.set(PPC::X13);
141 Reserved.set(PPC::X31);
143 // The 64-bit SVR4 ABI reserves r2 for the TOC pointer.
144 if (Subtarget.isSVR4ABI()) {
145 Reserved.set(PPC::X2);
147 // Reserve X2 on Darwin to hack around the problem of save/restore of CR
148 // when the stack frame is too big to address directly; we need two regs.
150 if (Subtarget.isDarwinABI()) {
151 Reserved.set(PPC::X2);
155 if (PPCFI->needsFP(MF))
156 Reserved.set(PPC::R31);
162 PPCRegisterInfo::getRegPressureLimit(const TargetRegisterClass *RC,
163 MachineFunction &MF) const {
164 const TargetFrameLowering *TFI = MF.getTarget().getFrameLowering();
165 const unsigned DefaultSafety = 1;
167 switch (RC->getID()) {
170 case PPC::G8RCRegClassID:
171 case PPC::GPRCRegClassID: {
172 unsigned FP = TFI->hasFP(MF) ? 1 : 0;
173 return 32 - FP - DefaultSafety;
175 case PPC::F8RCRegClassID:
176 case PPC::F4RCRegClassID:
177 case PPC::VRRCRegClassID:
178 return 32 - DefaultSafety;
179 case PPC::CRRCRegClassID:
180 return 8 - DefaultSafety;
185 PPCRegisterInfo::avoidWriteAfterWrite(const TargetRegisterClass *RC) const {
186 switch (RC->getID()) {
187 case PPC::G8RCRegClassID:
188 case PPC::GPRCRegClassID:
189 case PPC::F8RCRegClassID:
190 case PPC::F4RCRegClassID:
191 case PPC::VRRCRegClassID:
198 //===----------------------------------------------------------------------===//
199 // Stack Frame Processing methods
200 //===----------------------------------------------------------------------===//
202 /// findScratchRegister - Find a 'free' PPC register. Try for a call-clobbered
203 /// register first and then a spilled callee-saved register if that fails.
205 unsigned findScratchRegister(MachineBasicBlock::iterator II, RegScavenger *RS,
206 const TargetRegisterClass *RC, int SPAdj) {
207 assert(RS && "Register scavenging must be on");
208 unsigned Reg = RS->FindUnusedReg(RC);
209 // FIXME: move ARM callee-saved reg scan to target independent code, then
210 // search for already spilled CS register here.
212 Reg = RS->scavengeRegister(RC, II, SPAdj);
216 /// lowerDynamicAlloc - Generate the code for allocating an object in the
217 /// current frame. The sequence of code with be in the general form
219 /// addi R0, SP, \#frameSize ; get the address of the previous frame
220 /// stwxu R0, SP, Rnegsize ; add and update the SP with the negated size
221 /// addi Rnew, SP, \#maxCalFrameSize ; get the top of the allocation
223 void PPCRegisterInfo::lowerDynamicAlloc(MachineBasicBlock::iterator II,
224 int SPAdj, RegScavenger *RS) const {
225 // Get the instruction.
226 MachineInstr &MI = *II;
227 // Get the instruction's basic block.
228 MachineBasicBlock &MBB = *MI.getParent();
229 // Get the basic block's function.
230 MachineFunction &MF = *MBB.getParent();
231 // Get the frame info.
232 MachineFrameInfo *MFI = MF.getFrameInfo();
233 // Determine whether 64-bit pointers are used.
234 bool LP64 = Subtarget.isPPC64();
235 DebugLoc dl = MI.getDebugLoc();
237 // Get the maximum call stack size.
238 unsigned maxCallFrameSize = MFI->getMaxCallFrameSize();
239 // Get the total frame size.
240 unsigned FrameSize = MFI->getStackSize();
242 // Get stack alignments.
243 unsigned TargetAlign = MF.getTarget().getFrameLowering()->getStackAlignment();
244 unsigned MaxAlign = MFI->getMaxAlignment();
245 if (MaxAlign > TargetAlign)
246 report_fatal_error("Dynamic alloca with large aligns not supported");
248 // Determine the previous frame's address. If FrameSize can't be
249 // represented as 16 bits or we need special alignment, then we load the
250 // previous frame's address from 0(SP). Why not do an addis of the hi?
251 // Because R0 is our only safe tmp register and addi/addis treat R0 as zero.
252 // Constructing the constant and adding would take 3 instructions.
253 // Fortunately, a frame greater than 32K is rare.
254 const TargetRegisterClass *G8RC = &PPC::G8RCRegClass;
255 const TargetRegisterClass *GPRC = &PPC::GPRCRegClass;
256 const TargetRegisterClass *RC = LP64 ? G8RC : GPRC;
258 unsigned Reg = findScratchRegister(II, RS, RC, SPAdj);
260 if (MaxAlign < TargetAlign && isInt<16>(FrameSize)) {
261 BuildMI(MBB, II, dl, TII.get(PPC::ADDI), Reg)
265 BuildMI(MBB, II, dl, TII.get(PPC::LD), Reg)
269 BuildMI(MBB, II, dl, TII.get(PPC::LWZ), Reg)
274 // Grow the stack and update the stack pointer link, then determine the
275 // address of new allocated space.
277 BuildMI(MBB, II, dl, TII.get(PPC::STDUX), PPC::X1)
278 .addReg(Reg, RegState::Kill)
280 .addReg(MI.getOperand(1).getReg());
281 if (!MI.getOperand(1).isKill())
282 BuildMI(MBB, II, dl, TII.get(PPC::ADDI8), MI.getOperand(0).getReg())
284 .addImm(maxCallFrameSize);
286 // Implicitly kill the register.
287 BuildMI(MBB, II, dl, TII.get(PPC::ADDI8), MI.getOperand(0).getReg())
289 .addImm(maxCallFrameSize)
290 .addReg(MI.getOperand(1).getReg(), RegState::ImplicitKill);
292 BuildMI(MBB, II, dl, TII.get(PPC::STWUX), PPC::R1)
293 .addReg(Reg, RegState::Kill)
295 .addReg(MI.getOperand(1).getReg());
297 if (!MI.getOperand(1).isKill())
298 BuildMI(MBB, II, dl, TII.get(PPC::ADDI), MI.getOperand(0).getReg())
300 .addImm(maxCallFrameSize);
302 // Implicitly kill the register.
303 BuildMI(MBB, II, dl, TII.get(PPC::ADDI), MI.getOperand(0).getReg())
305 .addImm(maxCallFrameSize)
306 .addReg(MI.getOperand(1).getReg(), RegState::ImplicitKill);
309 // Discard the DYNALLOC instruction.
313 /// lowerCRSpilling - Generate the code for spilling a CR register. Instead of
314 /// reserving a whole register (R0), we scrounge for one here. This generates
317 /// mfcr rA ; Move the conditional register into GPR rA.
318 /// rlwinm rA, rA, SB, 0, 31 ; Shift the bits left so they are in CR0's slot.
319 /// stw rA, FI ; Store rA to the frame.
321 void PPCRegisterInfo::lowerCRSpilling(MachineBasicBlock::iterator II,
322 unsigned FrameIndex, int SPAdj,
323 RegScavenger *RS) const {
324 // Get the instruction.
325 MachineInstr &MI = *II; // ; SPILL_CR <SrcReg>, <offset>
326 // Get the instruction's basic block.
327 MachineBasicBlock &MBB = *MI.getParent();
328 DebugLoc dl = MI.getDebugLoc();
330 // FIXME: Once LLVM supports creating virtual registers here, or the register
331 // scavenger can return multiple registers, stop using reserved registers
336 bool LP64 = Subtarget.isPPC64();
337 unsigned Reg = Subtarget.isDarwinABI() ? (LP64 ? PPC::X2 : PPC::R2) :
338 (LP64 ? PPC::X0 : PPC::R0);
339 unsigned SrcReg = MI.getOperand(0).getReg();
341 // We need to store the CR in the low 4-bits of the saved value. First, issue
342 // an MFCRpsued to save all of the CRBits and, if needed, kill the SrcReg.
343 BuildMI(MBB, II, dl, TII.get(LP64 ? PPC::MFCR8pseud : PPC::MFCRpseud), Reg)
344 .addReg(SrcReg, getKillRegState(MI.getOperand(0).isKill()));
346 // If the saved register wasn't CR0, shift the bits left so that they are in
348 if (SrcReg != PPC::CR0)
349 // rlwinm rA, rA, ShiftBits, 0, 31.
350 BuildMI(MBB, II, dl, TII.get(LP64 ? PPC::RLWINM8 : PPC::RLWINM), Reg)
351 .addReg(Reg, RegState::Kill)
352 .addImm(getPPCRegisterNumbering(SrcReg) * 4)
356 addFrameReference(BuildMI(MBB, II, dl, TII.get(LP64 ? PPC::STW8 : PPC::STW))
357 .addReg(Reg, getKillRegState(MI.getOperand(1).getImm())),
360 // Discard the pseudo instruction.
364 void PPCRegisterInfo::lowerCRRestore(MachineBasicBlock::iterator II,
365 unsigned FrameIndex, int SPAdj,
366 RegScavenger *RS) const {
367 // Get the instruction.
368 MachineInstr &MI = *II; // ; <DestReg> = RESTORE_CR <offset>
369 // Get the instruction's basic block.
370 MachineBasicBlock &MBB = *MI.getParent();
371 DebugLoc dl = MI.getDebugLoc();
373 // FIXME: Once LLVM supports creating virtual registers here, or the register
374 // scavenger can return multiple registers, stop using reserved registers
379 bool LP64 = Subtarget.isPPC64();
380 unsigned Reg = Subtarget.isDarwinABI() ? (LP64 ? PPC::X2 : PPC::R2) :
381 (LP64 ? PPC::X0 : PPC::R0);
382 unsigned DestReg = MI.getOperand(0).getReg();
383 assert(MI.definesRegister(DestReg) &&
384 "RESTORE_CR does not define its destination");
386 addFrameReference(BuildMI(MBB, II, dl, TII.get(LP64 ? PPC::LWZ8 : PPC::LWZ),
389 // If the reloaded register isn't CR0, shift the bits right so that they are
390 // in the right CR's slot.
391 if (DestReg != PPC::CR0) {
392 unsigned ShiftBits = getPPCRegisterNumbering(DestReg)*4;
393 // rlwinm r11, r11, 32-ShiftBits, 0, 31.
394 BuildMI(MBB, II, dl, TII.get(LP64 ? PPC::RLWINM8 : PPC::RLWINM), Reg)
395 .addReg(Reg).addImm(32-ShiftBits).addImm(0)
399 BuildMI(MBB, II, dl, TII.get(LP64 ? PPC::MTCRF8 : PPC::MTCRF), DestReg)
402 // Discard the pseudo instruction.
407 PPCRegisterInfo::hasReservedSpillSlot(const MachineFunction &MF,
408 unsigned Reg, int &FrameIdx) const {
410 // For the nonvolatile condition registers (CR2, CR3, CR4) in an SVR4
411 // ABI, return true to prevent allocating an additional frame slot.
412 // For 64-bit, the CR save area is at SP+8; the value of FrameIdx = 0
413 // is arbitrary and will be subsequently ignored. For 32-bit, we have
414 // previously created the stack slot if needed, so return its FrameIdx.
415 if (Subtarget.isSVR4ABI() && PPC::CR2 <= Reg && Reg <= PPC::CR4) {
416 if (Subtarget.isPPC64())
419 const PPCFunctionInfo *FI = MF.getInfo<PPCFunctionInfo>();
420 FrameIdx = FI->getCRSpillFrameIndex();
428 PPCRegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
429 int SPAdj, unsigned FIOperandNum,
430 RegScavenger *RS) const {
431 assert(SPAdj == 0 && "Unexpected");
433 // Get the instruction.
434 MachineInstr &MI = *II;
435 // Get the instruction's basic block.
436 MachineBasicBlock &MBB = *MI.getParent();
437 // Get the basic block's function.
438 MachineFunction &MF = *MBB.getParent();
439 // Get the frame info.
440 MachineFrameInfo *MFI = MF.getFrameInfo();
441 const TargetFrameLowering *TFI = MF.getTarget().getFrameLowering();
442 DebugLoc dl = MI.getDebugLoc();
444 // Take into account whether it's an add or mem instruction
445 unsigned OffsetOperandNo = (FIOperandNum == 2) ? 1 : 2;
446 if (MI.isInlineAsm())
447 OffsetOperandNo = FIOperandNum-1;
449 // Get the frame index.
450 int FrameIndex = MI.getOperand(FIOperandNum).getIndex();
452 // Get the frame pointer save index. Users of this index are primarily
453 // DYNALLOC instructions.
454 PPCFunctionInfo *FI = MF.getInfo<PPCFunctionInfo>();
455 int FPSI = FI->getFramePointerSaveIndex();
456 // Get the instruction opcode.
457 unsigned OpC = MI.getOpcode();
459 // Special case for dynamic alloca.
460 if (FPSI && FrameIndex == FPSI &&
461 (OpC == PPC::DYNALLOC || OpC == PPC::DYNALLOC8)) {
462 lowerDynamicAlloc(II, SPAdj, RS);
466 // Special case for pseudo-ops SPILL_CR and RESTORE_CR.
467 if (OpC == PPC::SPILL_CR) {
468 lowerCRSpilling(II, FrameIndex, SPAdj, RS);
470 } else if (OpC == PPC::RESTORE_CR) {
471 lowerCRRestore(II, FrameIndex, SPAdj, RS);
475 // Replace the FrameIndex with base register with GPR1 (SP) or GPR31 (FP).
477 bool is64Bit = Subtarget.isPPC64();
478 MI.getOperand(FIOperandNum).ChangeToRegister(TFI->hasFP(MF) ?
479 (is64Bit ? PPC::X31 : PPC::R31) :
480 (is64Bit ? PPC::X1 : PPC::R1),
483 // Figure out if the offset in the instruction is shifted right two bits. This
484 // is true for instructions like "STD", which the machine implicitly adds two
486 bool isIXAddr = false;
496 // Now add the frame object offset to the offset from r1.
497 int Offset = MFI->getObjectOffset(FrameIndex);
499 Offset += MI.getOperand(OffsetOperandNo).getImm();
501 Offset += MI.getOperand(OffsetOperandNo).getImm() << 2;
503 // If we're not using a Frame Pointer that has been set to the value of the
504 // SP before having the stack size subtracted from it, then add the stack size
505 // to Offset to get the correct offset.
506 // Naked functions have stack size 0, although getStackSize may not reflect that
507 // because we didn't call all the pieces that compute it for naked functions.
508 if (!MF.getFunction()->getAttributes().
509 hasAttribute(AttributeSet::FunctionIndex, Attribute::Naked))
510 Offset += MFI->getStackSize();
512 // If we can, encode the offset directly into the instruction. If this is a
513 // normal PPC "ri" instruction, any 16-bit value can be safely encoded. If
514 // this is a PPC64 "ix" instruction, only a 16-bit value with the low two bits
515 // clear can be encoded. This is extremely uncommon, because normally you
516 // only "std" to a stack slot that is at least 4-byte aligned, but it can
517 // happen in invalid code.
518 if (OpC == PPC::DBG_VALUE || // DBG_VALUE is always Reg+Imm
519 (isInt<16>(Offset) && (!isIXAddr || (Offset & 3) == 0))) {
521 Offset >>= 2; // The actual encoded value has the low two bits zero.
522 MI.getOperand(OffsetOperandNo).ChangeToImmediate(Offset);
526 // The offset doesn't fit into a single register, scavenge one to build the
529 const TargetRegisterClass *G8RC = &PPC::G8RCRegClass;
530 const TargetRegisterClass *GPRC = &PPC::GPRCRegClass;
531 unsigned SReg = findScratchRegister(II, RS, is64Bit ? G8RC : GPRC, SPAdj);
533 // Insert a set of rA with the full offset value before the ld, st, or add
534 BuildMI(MBB, II, dl, TII.get(is64Bit ? PPC::LIS8 : PPC::LIS), SReg)
535 .addImm(Offset >> 16);
536 BuildMI(MBB, II, dl, TII.get(is64Bit ? PPC::ORI8 : PPC::ORI), SReg)
537 .addReg(SReg, RegState::Kill)
540 // Convert into indexed form of the instruction:
542 // sth 0:rA, 1:imm 2:(rB) ==> sthx 0:rA, 2:rB, 1:r0
543 // addi 0:rA 1:rB, 2, imm ==> add 0:rA, 1:rB, 2:r0
544 unsigned OperandBase;
546 if (OpC != TargetOpcode::INLINEASM) {
547 assert(ImmToIdxMap.count(OpC) &&
548 "No indexed form of load or store available!");
549 unsigned NewOpcode = ImmToIdxMap.find(OpC)->second;
550 MI.setDesc(TII.get(NewOpcode));
553 OperandBase = OffsetOperandNo;
556 unsigned StackReg = MI.getOperand(FIOperandNum).getReg();
557 MI.getOperand(OperandBase).ChangeToRegister(StackReg, false);
558 MI.getOperand(OperandBase + 1).ChangeToRegister(SReg, false, false, true);
561 unsigned PPCRegisterInfo::getFrameRegister(const MachineFunction &MF) const {
562 const TargetFrameLowering *TFI = MF.getTarget().getFrameLowering();
564 if (!Subtarget.isPPC64())
565 return TFI->hasFP(MF) ? PPC::R31 : PPC::R1;
567 return TFI->hasFP(MF) ? PPC::X31 : PPC::X1;
570 unsigned PPCRegisterInfo::getEHExceptionRegister() const {
571 return !Subtarget.isPPC64() ? PPC::R3 : PPC::X3;
574 unsigned PPCRegisterInfo::getEHHandlerRegister() const {
575 return !Subtarget.isPPC64() ? PPC::R4 : PPC::X4;