1 //==- TargetRegisterInfo.cpp - Target Register Information Implementation --==//
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 implements the TargetRegisterInfo interface.
12 //===----------------------------------------------------------------------===//
14 #include "llvm/CodeGen/TargetRegisterInfo.h"
15 #include "llvm/ADT/ArrayRef.h"
16 #include "llvm/ADT/BitVector.h"
17 #include "llvm/ADT/SmallSet.h"
18 #include "llvm/ADT/STLExtras.h"
19 #include "llvm/ADT/StringExtras.h"
20 #include "llvm/CodeGen/MachineFrameInfo.h"
21 #include "llvm/CodeGen/MachineFunction.h"
22 #include "llvm/CodeGen/MachineRegisterInfo.h"
23 #include "llvm/CodeGen/TargetFrameLowering.h"
24 #include "llvm/CodeGen/TargetSubtargetInfo.h"
25 #include "llvm/CodeGen/VirtRegMap.h"
26 #include "llvm/Config/llvm-config.h"
27 #include "llvm/IR/Attributes.h"
28 #include "llvm/IR/Function.h"
29 #include "llvm/MC/MCRegisterInfo.h"
30 #include "llvm/Support/Compiler.h"
31 #include "llvm/Support/Debug.h"
32 #include "llvm/Support/MachineValueType.h"
33 #include "llvm/Support/MathExtras.h"
34 #include "llvm/Support/Printable.h"
35 #include "llvm/Support/raw_ostream.h"
39 #define DEBUG_TYPE "target-reg-info"
43 TargetRegisterInfo::TargetRegisterInfo(const TargetRegisterInfoDesc *ID,
44 regclass_iterator RCB, regclass_iterator RCE,
45 const char *const *SRINames,
46 const LaneBitmask *SRILaneMasks,
47 LaneBitmask SRICoveringLanes,
48 const RegClassInfo *const RCIs,
50 : InfoDesc(ID), SubRegIndexNames(SRINames),
51 SubRegIndexLaneMasks(SRILaneMasks),
52 RegClassBegin(RCB), RegClassEnd(RCE),
53 CoveringLanes(SRICoveringLanes),
54 RCInfos(RCIs), HwMode(Mode) {
57 TargetRegisterInfo::~TargetRegisterInfo() = default;
59 void TargetRegisterInfo::markSuperRegs(BitVector &RegisterSet, unsigned Reg)
61 for (MCSuperRegIterator AI(Reg, this, true); AI.isValid(); ++AI)
65 bool TargetRegisterInfo::checkAllSuperRegsMarked(const BitVector &RegisterSet,
66 ArrayRef<MCPhysReg> Exceptions) const {
67 // Check that all super registers of reserved regs are reserved as well.
68 BitVector Checked(getNumRegs());
69 for (unsigned Reg : RegisterSet.set_bits()) {
72 for (MCSuperRegIterator SR(Reg, this); SR.isValid(); ++SR) {
73 if (!RegisterSet[*SR] && !is_contained(Exceptions, Reg)) {
74 dbgs() << "Error: Super register " << printReg(*SR, this)
75 << " of reserved register " << printReg(Reg, this)
76 << " is not reserved.\n";
80 // We transitively check superregs. So we can remember this for later
81 // to avoid compiletime explosion in deep register hierarchies.
90 Printable printReg(unsigned Reg, const TargetRegisterInfo *TRI,
91 unsigned SubIdx, const MachineRegisterInfo *MRI) {
92 return Printable([Reg, TRI, SubIdx, MRI](raw_ostream &OS) {
95 else if (TargetRegisterInfo::isStackSlot(Reg))
96 OS << "SS#" << TargetRegisterInfo::stackSlot2Index(Reg);
97 else if (TargetRegisterInfo::isVirtualRegister(Reg)) {
98 StringRef Name = MRI ? MRI->getVRegName(Reg) : "";
102 OS << '%' << TargetRegisterInfo::virtReg2Index(Reg);
106 OS << '$' << "physreg" << Reg;
107 else if (Reg < TRI->getNumRegs()) {
109 printLowerCase(TRI->getName(Reg), OS);
111 llvm_unreachable("Register kind is unsupported.");
115 OS << ':' << TRI->getSubRegIndexName(SubIdx);
117 OS << ":sub(" << SubIdx << ')';
122 Printable printRegUnit(unsigned Unit, const TargetRegisterInfo *TRI) {
123 return Printable([Unit, TRI](raw_ostream &OS) {
124 // Generic printout when TRI is missing.
126 OS << "Unit~" << Unit;
130 // Check for invalid register units.
131 if (Unit >= TRI->getNumRegUnits()) {
132 OS << "BadUnit~" << Unit;
136 // Normal units have at least one root.
137 MCRegUnitRootIterator Roots(Unit, TRI);
138 assert(Roots.isValid() && "Unit has no roots.");
139 OS << TRI->getName(*Roots);
140 for (++Roots; Roots.isValid(); ++Roots)
141 OS << '~' << TRI->getName(*Roots);
145 Printable printVRegOrUnit(unsigned Unit, const TargetRegisterInfo *TRI) {
146 return Printable([Unit, TRI](raw_ostream &OS) {
147 if (TRI && TRI->isVirtualRegister(Unit)) {
148 OS << '%' << TargetRegisterInfo::virtReg2Index(Unit);
150 OS << printRegUnit(Unit, TRI);
155 Printable printRegClassOrBank(unsigned Reg, const MachineRegisterInfo &RegInfo,
156 const TargetRegisterInfo *TRI) {
157 return Printable([Reg, &RegInfo, TRI](raw_ostream &OS) {
158 if (RegInfo.getRegClassOrNull(Reg))
159 OS << StringRef(TRI->getRegClassName(RegInfo.getRegClass(Reg))).lower();
160 else if (RegInfo.getRegBankOrNull(Reg))
161 OS << StringRef(RegInfo.getRegBankOrNull(Reg)->getName()).lower();
164 assert((RegInfo.def_empty(Reg) || RegInfo.getType(Reg).isValid()) &&
165 "Generic registers must have a valid type");
170 } // end namespace llvm
172 /// getAllocatableClass - Return the maximal subclass of the given register
173 /// class that is alloctable, or NULL.
174 const TargetRegisterClass *
175 TargetRegisterInfo::getAllocatableClass(const TargetRegisterClass *RC) const {
176 if (!RC || RC->isAllocatable())
179 for (BitMaskClassIterator It(RC->getSubClassMask(), *this); It.isValid();
181 const TargetRegisterClass *SubRC = getRegClass(It.getID());
182 if (SubRC->isAllocatable())
188 /// getMinimalPhysRegClass - Returns the Register Class of a physical
189 /// register of the given type, picking the most sub register class of
190 /// the right type that contains this physreg.
191 const TargetRegisterClass *
192 TargetRegisterInfo::getMinimalPhysRegClass(unsigned reg, MVT VT) const {
193 assert(isPhysicalRegister(reg) && "reg must be a physical register");
195 // Pick the most sub register class of the right type that contains
197 const TargetRegisterClass* BestRC = nullptr;
198 for (const TargetRegisterClass* RC : regclasses()) {
199 if ((VT == MVT::Other || isTypeLegalForClass(*RC, VT)) &&
200 RC->contains(reg) && (!BestRC || BestRC->hasSubClass(RC)))
204 assert(BestRC && "Couldn't find the register class");
208 /// getAllocatableSetForRC - Toggle the bits that represent allocatable
209 /// registers for the specific register class.
210 static void getAllocatableSetForRC(const MachineFunction &MF,
211 const TargetRegisterClass *RC, BitVector &R){
212 assert(RC->isAllocatable() && "invalid for nonallocatable sets");
213 ArrayRef<MCPhysReg> Order = RC->getRawAllocationOrder(MF);
214 for (unsigned i = 0; i != Order.size(); ++i)
218 BitVector TargetRegisterInfo::getAllocatableSet(const MachineFunction &MF,
219 const TargetRegisterClass *RC) const {
220 BitVector Allocatable(getNumRegs());
222 // A register class with no allocatable subclass returns an empty set.
223 const TargetRegisterClass *SubClass = getAllocatableClass(RC);
225 getAllocatableSetForRC(MF, SubClass, Allocatable);
227 for (const TargetRegisterClass *C : regclasses())
228 if (C->isAllocatable())
229 getAllocatableSetForRC(MF, C, Allocatable);
232 // Mask out the reserved registers
233 BitVector Reserved = getReservedRegs(MF);
234 Allocatable &= Reserved.flip();
240 const TargetRegisterClass *firstCommonClass(const uint32_t *A,
242 const TargetRegisterInfo *TRI,
243 const MVT::SimpleValueType SVT =
244 MVT::SimpleValueType::Any) {
246 for (unsigned I = 0, E = TRI->getNumRegClasses(); I < E; I += 32)
247 if (unsigned Common = *A++ & *B++) {
248 const TargetRegisterClass *RC =
249 TRI->getRegClass(I + countTrailingZeros(Common));
250 if (SVT == MVT::SimpleValueType::Any || TRI->isTypeLegalForClass(*RC, VT))
256 const TargetRegisterClass *
257 TargetRegisterInfo::getCommonSubClass(const TargetRegisterClass *A,
258 const TargetRegisterClass *B,
259 const MVT::SimpleValueType SVT) const {
260 // First take care of the trivial cases.
266 // Register classes are ordered topologically, so the largest common
267 // sub-class it the common sub-class with the smallest ID.
268 return firstCommonClass(A->getSubClassMask(), B->getSubClassMask(), this, SVT);
271 const TargetRegisterClass *
272 TargetRegisterInfo::getMatchingSuperRegClass(const TargetRegisterClass *A,
273 const TargetRegisterClass *B,
274 unsigned Idx) const {
275 assert(A && B && "Missing register class");
276 assert(Idx && "Bad sub-register index");
278 // Find Idx in the list of super-register indices.
279 for (SuperRegClassIterator RCI(B, this); RCI.isValid(); ++RCI)
280 if (RCI.getSubReg() == Idx)
281 // The bit mask contains all register classes that are projected into B
282 // by Idx. Find a class that is also a sub-class of A.
283 return firstCommonClass(RCI.getMask(), A->getSubClassMask(), this);
287 const TargetRegisterClass *TargetRegisterInfo::
288 getCommonSuperRegClass(const TargetRegisterClass *RCA, unsigned SubA,
289 const TargetRegisterClass *RCB, unsigned SubB,
290 unsigned &PreA, unsigned &PreB) const {
291 assert(RCA && SubA && RCB && SubB && "Invalid arguments");
293 // Search all pairs of sub-register indices that project into RCA and RCB
294 // respectively. This is quadratic, but usually the sets are very small. On
295 // most targets like X86, there will only be a single sub-register index
296 // (e.g., sub_16bit projecting into GR16).
298 // The worst case is a register class like DPR on ARM.
299 // We have indices dsub_0..dsub_7 projecting into that class.
301 // It is very common that one register class is a sub-register of the other.
302 // Arrange for RCA to be the larger register so the answer will be found in
303 // the first iteration. This makes the search linear for the most common
305 const TargetRegisterClass *BestRC = nullptr;
306 unsigned *BestPreA = &PreA;
307 unsigned *BestPreB = &PreB;
308 if (getRegSizeInBits(*RCA) < getRegSizeInBits(*RCB)) {
310 std::swap(SubA, SubB);
311 std::swap(BestPreA, BestPreB);
314 // Also terminate the search one we have found a register class as small as
316 unsigned MinSize = getRegSizeInBits(*RCA);
318 for (SuperRegClassIterator IA(RCA, this, true); IA.isValid(); ++IA) {
319 unsigned FinalA = composeSubRegIndices(IA.getSubReg(), SubA);
320 for (SuperRegClassIterator IB(RCB, this, true); IB.isValid(); ++IB) {
321 // Check if a common super-register class exists for this index pair.
322 const TargetRegisterClass *RC =
323 firstCommonClass(IA.getMask(), IB.getMask(), this);
324 if (!RC || getRegSizeInBits(*RC) < MinSize)
327 // The indexes must compose identically: PreA+SubA == PreB+SubB.
328 unsigned FinalB = composeSubRegIndices(IB.getSubReg(), SubB);
329 if (FinalA != FinalB)
332 // Is RC a better candidate than BestRC?
333 if (BestRC && getRegSizeInBits(*RC) >= getRegSizeInBits(*BestRC))
336 // Yes, RC is the smallest super-register seen so far.
338 *BestPreA = IA.getSubReg();
339 *BestPreB = IB.getSubReg();
341 // Bail early if we reached MinSize. We won't find a better candidate.
342 if (getRegSizeInBits(*BestRC) == MinSize)
349 /// Check if the registers defined by the pair (RegisterClass, SubReg)
350 /// share the same register file.
351 static bool shareSameRegisterFile(const TargetRegisterInfo &TRI,
352 const TargetRegisterClass *DefRC,
354 const TargetRegisterClass *SrcRC,
355 unsigned SrcSubReg) {
356 // Same register class.
360 // Both operands are sub registers. Check if they share a register class.
361 unsigned SrcIdx, DefIdx;
362 if (SrcSubReg && DefSubReg) {
363 return TRI.getCommonSuperRegClass(SrcRC, SrcSubReg, DefRC, DefSubReg,
364 SrcIdx, DefIdx) != nullptr;
367 // At most one of the register is a sub register, make it Src to avoid
368 // duplicating the test.
370 std::swap(DefSubReg, SrcSubReg);
371 std::swap(DefRC, SrcRC);
374 // One of the register is a sub register, check if we can get a superclass.
376 return TRI.getMatchingSuperRegClass(SrcRC, DefRC, SrcSubReg) != nullptr;
379 return TRI.getCommonSubClass(DefRC, SrcRC) != nullptr;
382 bool TargetRegisterInfo::shouldRewriteCopySrc(const TargetRegisterClass *DefRC,
384 const TargetRegisterClass *SrcRC,
385 unsigned SrcSubReg) const {
386 // If this source does not incur a cross register bank copy, use it.
387 return shareSameRegisterFile(*this, DefRC, DefSubReg, SrcRC, SrcSubReg);
390 // Compute target-independent register allocator hints to help eliminate copies.
392 TargetRegisterInfo::getRegAllocationHints(unsigned VirtReg,
393 ArrayRef<MCPhysReg> Order,
394 SmallVectorImpl<MCPhysReg> &Hints,
395 const MachineFunction &MF,
396 const VirtRegMap *VRM,
397 const LiveRegMatrix *Matrix) const {
398 const MachineRegisterInfo &MRI = MF.getRegInfo();
399 const std::pair<unsigned, SmallVector<unsigned, 4>> &Hints_MRI =
400 MRI.getRegAllocationHints(VirtReg);
402 SmallSet<unsigned, 32> HintedRegs;
403 // First hint may be a target hint.
404 bool Skip = (Hints_MRI.first != 0);
405 for (auto Reg : Hints_MRI.second) {
411 // Target-independent hints are either a physical or a virtual register.
413 if (VRM && isVirtualRegister(Phys))
414 Phys = VRM->getPhys(Phys);
416 // Don't add the same reg twice (Hints_MRI may contain multiple virtual
417 // registers allocated to the same physreg).
418 if (!HintedRegs.insert(Phys).second)
420 // Check that Phys is a valid hint in VirtReg's register class.
421 if (!isPhysicalRegister(Phys))
423 if (MRI.isReserved(Phys))
425 // Check that Phys is in the allocation order. We shouldn't heed hints
426 // from VirtReg's register class if they aren't in the allocation order. The
427 // target probably has a reason for removing the register.
428 if (!is_contained(Order, Phys))
431 // All clear, tell the register allocator to prefer this register.
432 Hints.push_back(Phys);
437 bool TargetRegisterInfo::canRealignStack(const MachineFunction &MF) const {
438 return !MF.getFunction().hasFnAttribute("no-realign-stack");
441 bool TargetRegisterInfo::needsStackRealignment(
442 const MachineFunction &MF) const {
443 const MachineFrameInfo &MFI = MF.getFrameInfo();
444 const TargetFrameLowering *TFI = MF.getSubtarget().getFrameLowering();
445 const Function &F = MF.getFunction();
446 unsigned StackAlign = TFI->getStackAlignment();
447 bool requiresRealignment = ((MFI.getMaxAlignment() > StackAlign) ||
448 F.hasFnAttribute(Attribute::StackAlignment));
449 if (F.hasFnAttribute("stackrealign") || requiresRealignment) {
450 if (canRealignStack(MF))
452 LLVM_DEBUG(dbgs() << "Can't realign function's stack: " << F.getName()
458 bool TargetRegisterInfo::regmaskSubsetEqual(const uint32_t *mask0,
459 const uint32_t *mask1) const {
460 unsigned N = (getNumRegs()+31) / 32;
461 for (unsigned I = 0; I < N; ++I)
462 if ((mask0[I] & mask1[I]) != mask0[I])
467 unsigned TargetRegisterInfo::getRegSizeInBits(unsigned Reg,
468 const MachineRegisterInfo &MRI) const {
469 const TargetRegisterClass *RC{};
470 if (isPhysicalRegister(Reg)) {
471 // The size is not directly available for physical registers.
472 // Instead, we need to access a register class that contains Reg and
473 // get the size of that register class.
474 RC = getMinimalPhysRegClass(Reg);
476 LLT Ty = MRI.getType(Reg);
477 unsigned RegSize = Ty.isValid() ? Ty.getSizeInBits() : 0;
478 // If Reg is not a generic register, query the register class to
482 // Since Reg is not a generic register, it must have a register class.
483 RC = MRI.getRegClass(Reg);
485 assert(RC && "Unable to deduce the register class");
486 return getRegSizeInBits(*RC);
490 TargetRegisterInfo::lookThruCopyLike(unsigned SrcReg,
491 const MachineRegisterInfo *MRI) const {
493 const MachineInstr *MI = MRI->getVRegDef(SrcReg);
494 if (!MI->isCopyLike())
499 CopySrcReg = MI->getOperand(1).getReg();
501 assert(MI->isSubregToReg() && "Bad opcode for lookThruCopyLike");
502 CopySrcReg = MI->getOperand(2).getReg();
505 if (!isVirtualRegister(CopySrcReg))
512 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
514 void TargetRegisterInfo::dumpReg(unsigned Reg, unsigned SubRegIndex,
515 const TargetRegisterInfo *TRI) {
516 dbgs() << printReg(Reg, TRI, SubRegIndex) << "\n";