#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/IR/Function.h"
+#include "llvm/Support/raw_os_ostream.h"
#include "llvm/Target/TargetInstrInfo.h"
-#include "llvm/Support/CommandLine.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetSubtargetInfo.h"
+
using namespace llvm;
-MachineRegisterInfo::MachineRegisterInfo(const TargetRegisterInfo &TRI) {
+// Pin the vtable to this file.
+void MachineRegisterInfo::Delegate::anchor() {}
+
+MachineRegisterInfo::MachineRegisterInfo(const MachineFunction *MF)
+ : MF(MF), TheDelegate(nullptr), IsSSA(true), TracksLiveness(true),
+ TracksSubRegLiveness(false) {
VRegInfo.reserve(256);
RegAllocHints.reserve(256);
- RegClass2VRegMap.resize(TRI.getNumRegClasses()+1); // RC ID starts at 1.
- UsedPhysRegs.resize(TRI.getNumRegs());
-
- // Create the physreg use/def lists.
- PhysRegUseDefLists = new MachineOperand*[TRI.getNumRegs()];
- memset(PhysRegUseDefLists, 0, sizeof(MachineOperand*)*TRI.getNumRegs());
-}
+ UsedPhysRegMask.resize(getTargetRegisterInfo()->getNumRegs());
-MachineRegisterInfo::~MachineRegisterInfo() {
-#ifndef NDEBUG
- for (unsigned i = 0, e = VRegInfo.size(); i != e; ++i)
- assert(VRegInfo[i].second == 0 && "Vreg use list non-empty still?");
- for (unsigned i = 0, e = UsedPhysRegs.size(); i != e; ++i)
- assert(!PhysRegUseDefLists[i] &&
- "PhysRegUseDefLists has entries after all instructions are deleted");
-#endif
- delete [] PhysRegUseDefLists;
+ // Create the physreg use/def lists.
+ PhysRegUseDefLists.resize(getTargetRegisterInfo()->getNumRegs(), nullptr);
}
/// setRegClass - Set the register class of the specified virtual register.
///
void
MachineRegisterInfo::setRegClass(unsigned Reg, const TargetRegisterClass *RC) {
- unsigned VR = Reg;
- Reg -= TargetRegisterInfo::FirstVirtualRegister;
- assert(Reg < VRegInfo.size() && "Invalid vreg!");
- const TargetRegisterClass *OldRC = VRegInfo[Reg].first;
+ assert(RC && RC->isAllocatable() && "Invalid RC for virtual register");
VRegInfo[Reg].first = RC;
+}
+
+const TargetRegisterClass *
+MachineRegisterInfo::constrainRegClass(unsigned Reg,
+ const TargetRegisterClass *RC,
+ unsigned MinNumRegs) {
+ const TargetRegisterClass *OldRC = getRegClass(Reg);
+ if (OldRC == RC)
+ return RC;
+ const TargetRegisterClass *NewRC =
+ getTargetRegisterInfo()->getCommonSubClass(OldRC, RC);
+ if (!NewRC || NewRC == OldRC)
+ return NewRC;
+ if (NewRC->getNumRegs() < MinNumRegs)
+ return nullptr;
+ setRegClass(Reg, NewRC);
+ return NewRC;
+}
+
+bool
+MachineRegisterInfo::recomputeRegClass(unsigned Reg) {
+ const TargetInstrInfo *TII = MF->getSubtarget().getInstrInfo();
+ const TargetRegisterClass *OldRC = getRegClass(Reg);
+ const TargetRegisterClass *NewRC =
+ getTargetRegisterInfo()->getLargestLegalSuperClass(OldRC, *MF);
- // Remove from old register class's vregs list. This may be slow but
- // fortunately this operation is rarely needed.
- std::vector<unsigned> &VRegs = RegClass2VRegMap[OldRC->getID()];
- std::vector<unsigned>::iterator I=std::find(VRegs.begin(), VRegs.end(), VR);
- VRegs.erase(I);
+ // Stop early if there is no room to grow.
+ if (NewRC == OldRC)
+ return false;
- // Add to new register class's vregs list.
- RegClass2VRegMap[RC->getID()].push_back(VR);
+ // Accumulate constraints from all uses.
+ for (MachineOperand &MO : reg_nodbg_operands(Reg)) {
+ // Apply the effect of the given operand to NewRC.
+ MachineInstr *MI = MO.getParent();
+ unsigned OpNo = &MO - &MI->getOperand(0);
+ NewRC = MI->getRegClassConstraintEffect(OpNo, NewRC, TII,
+ getTargetRegisterInfo());
+ if (!NewRC || NewRC == OldRC)
+ return false;
+ }
+ setRegClass(Reg, NewRC);
+ return true;
}
/// createVirtualRegister - Create and return a new virtual register in the
unsigned
MachineRegisterInfo::createVirtualRegister(const TargetRegisterClass *RegClass){
assert(RegClass && "Cannot create register without RegClass!");
- // Add a reg, but keep track of whether the vector reallocated or not.
- void *ArrayBase = VRegInfo.empty() ? 0 : &VRegInfo[0];
- VRegInfo.push_back(std::make_pair(RegClass, (MachineOperand*)0));
- RegAllocHints.push_back(std::make_pair(0, 0));
-
- if (!((&VRegInfo[0] == ArrayBase || VRegInfo.size() == 1)))
- // The vector reallocated, handle this now.
- HandleVRegListReallocation();
- unsigned VR = getLastVirtReg();
- RegClass2VRegMap[RegClass->getID()].push_back(VR);
- return VR;
+ assert(RegClass->isAllocatable() &&
+ "Virtual register RegClass must be allocatable.");
+
+ // New virtual register number.
+ unsigned Reg = TargetRegisterInfo::index2VirtReg(getNumVirtRegs());
+ VRegInfo.grow(Reg);
+ VRegInfo[Reg].first = RegClass;
+ RegAllocHints.grow(Reg);
+ if (TheDelegate)
+ TheDelegate->MRI_NoteNewVirtualRegister(Reg);
+ return Reg;
+}
+
+/// clearVirtRegs - Remove all virtual registers (after physreg assignment).
+void MachineRegisterInfo::clearVirtRegs() {
+#ifndef NDEBUG
+ for (unsigned i = 0, e = getNumVirtRegs(); i != e; ++i) {
+ unsigned Reg = TargetRegisterInfo::index2VirtReg(i);
+ if (!VRegInfo[Reg].second)
+ continue;
+ verifyUseList(Reg);
+ llvm_unreachable("Remaining virtual register operands");
+ }
+#endif
+ VRegInfo.clear();
+ for (auto &I : LiveIns)
+ I.second = 0;
+}
+
+void MachineRegisterInfo::verifyUseList(unsigned Reg) const {
+#ifndef NDEBUG
+ bool Valid = true;
+ for (MachineOperand &M : reg_operands(Reg)) {
+ MachineOperand *MO = &M;
+ MachineInstr *MI = MO->getParent();
+ if (!MI) {
+ errs() << PrintReg(Reg, getTargetRegisterInfo())
+ << " use list MachineOperand " << MO
+ << " has no parent instruction.\n";
+ Valid = false;
+ continue;
+ }
+ MachineOperand *MO0 = &MI->getOperand(0);
+ unsigned NumOps = MI->getNumOperands();
+ if (!(MO >= MO0 && MO < MO0+NumOps)) {
+ errs() << PrintReg(Reg, getTargetRegisterInfo())
+ << " use list MachineOperand " << MO
+ << " doesn't belong to parent MI: " << *MI;
+ Valid = false;
+ }
+ if (!MO->isReg()) {
+ errs() << PrintReg(Reg, getTargetRegisterInfo())
+ << " MachineOperand " << MO << ": " << *MO
+ << " is not a register\n";
+ Valid = false;
+ }
+ if (MO->getReg() != Reg) {
+ errs() << PrintReg(Reg, getTargetRegisterInfo())
+ << " use-list MachineOperand " << MO << ": "
+ << *MO << " is the wrong register\n";
+ Valid = false;
+ }
+ }
+ assert(Valid && "Invalid use list");
+#endif
+}
+
+void MachineRegisterInfo::verifyUseLists() const {
+#ifndef NDEBUG
+ for (unsigned i = 0, e = getNumVirtRegs(); i != e; ++i)
+ verifyUseList(TargetRegisterInfo::index2VirtReg(i));
+ for (unsigned i = 1, e = getTargetRegisterInfo()->getNumRegs(); i != e; ++i)
+ verifyUseList(i);
+#endif
+}
+
+/// Add MO to the linked list of operands for its register.
+void MachineRegisterInfo::addRegOperandToUseList(MachineOperand *MO) {
+ assert(!MO->isOnRegUseList() && "Already on list");
+ MachineOperand *&HeadRef = getRegUseDefListHead(MO->getReg());
+ MachineOperand *const Head = HeadRef;
+
+ // Head points to the first list element.
+ // Next is NULL on the last list element.
+ // Prev pointers are circular, so Head->Prev == Last.
+
+ // Head is NULL for an empty list.
+ if (!Head) {
+ MO->Contents.Reg.Prev = MO;
+ MO->Contents.Reg.Next = nullptr;
+ HeadRef = MO;
+ return;
+ }
+ assert(MO->getReg() == Head->getReg() && "Different regs on the same list!");
+
+ // Insert MO between Last and Head in the circular Prev chain.
+ MachineOperand *Last = Head->Contents.Reg.Prev;
+ assert(Last && "Inconsistent use list");
+ assert(MO->getReg() == Last->getReg() && "Different regs on the same list!");
+ Head->Contents.Reg.Prev = MO;
+ MO->Contents.Reg.Prev = Last;
+
+ // Def operands always precede uses. This allows def_iterator to stop early.
+ // Insert def operands at the front, and use operands at the back.
+ if (MO->isDef()) {
+ // Insert def at the front.
+ MO->Contents.Reg.Next = Head;
+ HeadRef = MO;
+ } else {
+ // Insert use at the end.
+ MO->Contents.Reg.Next = nullptr;
+ Last->Contents.Reg.Next = MO;
+ }
+}
+
+/// Remove MO from its use-def list.
+void MachineRegisterInfo::removeRegOperandFromUseList(MachineOperand *MO) {
+ assert(MO->isOnRegUseList() && "Operand not on use list");
+ MachineOperand *&HeadRef = getRegUseDefListHead(MO->getReg());
+ MachineOperand *const Head = HeadRef;
+ assert(Head && "List already empty");
+
+ // Unlink this from the doubly linked list of operands.
+ MachineOperand *Next = MO->Contents.Reg.Next;
+ MachineOperand *Prev = MO->Contents.Reg.Prev;
+
+ // Prev links are circular, next link is NULL instead of looping back to Head.
+ if (MO == Head)
+ HeadRef = Next;
+ else
+ Prev->Contents.Reg.Next = Next;
+
+ (Next ? Next : Head)->Contents.Reg.Prev = Prev;
+
+ MO->Contents.Reg.Prev = nullptr;
+ MO->Contents.Reg.Next = nullptr;
}
-/// HandleVRegListReallocation - We just added a virtual register to the
-/// VRegInfo info list and it reallocated. Update the use/def lists info
-/// pointers.
-void MachineRegisterInfo::HandleVRegListReallocation() {
- // The back pointers for the vreg lists point into the previous vector.
- // Update them to point to their correct slots.
- for (unsigned i = 0, e = VRegInfo.size(); i != e; ++i) {
- MachineOperand *List = VRegInfo[i].second;
- if (!List) continue;
- // Update the back-pointer to be accurate once more.
- List->Contents.Reg.Prev = &VRegInfo[i].second;
+/// Move NumOps operands from Src to Dst, updating use-def lists as needed.
+///
+/// The Dst range is assumed to be uninitialized memory. (Or it may contain
+/// operands that won't be destroyed, which is OK because the MO destructor is
+/// trivial anyway).
+///
+/// The Src and Dst ranges may overlap.
+void MachineRegisterInfo::moveOperands(MachineOperand *Dst,
+ MachineOperand *Src,
+ unsigned NumOps) {
+ assert(Src != Dst && NumOps && "Noop moveOperands");
+
+ // Copy backwards if Dst is within the Src range.
+ int Stride = 1;
+ if (Dst >= Src && Dst < Src + NumOps) {
+ Stride = -1;
+ Dst += NumOps - 1;
+ Src += NumOps - 1;
}
+
+ // Copy one operand at a time.
+ do {
+ new (Dst) MachineOperand(*Src);
+
+ // Dst takes Src's place in the use-def chain.
+ if (Src->isReg()) {
+ MachineOperand *&Head = getRegUseDefListHead(Src->getReg());
+ MachineOperand *Prev = Src->Contents.Reg.Prev;
+ MachineOperand *Next = Src->Contents.Reg.Next;
+ assert(Head && "List empty, but operand is chained");
+ assert(Prev && "Operand was not on use-def list");
+
+ // Prev links are circular, next link is NULL instead of looping back to
+ // Head.
+ if (Src == Head)
+ Head = Dst;
+ else
+ Prev->Contents.Reg.Next = Dst;
+
+ // Update Prev pointer. This also works when Src was pointing to itself
+ // in a 1-element list. In that case Head == Dst.
+ (Next ? Next : Head)->Contents.Reg.Prev = Dst;
+ }
+
+ Dst += Stride;
+ Src += Stride;
+ } while (--NumOps);
}
/// replaceRegWith - Replace all instances of FromReg with ToReg in the
/// machine function. This is like llvm-level X->replaceAllUsesWith(Y),
/// except that it also changes any definitions of the register as well.
+/// If ToReg is a physical register we apply the sub register to obtain the
+/// final/proper physical register.
void MachineRegisterInfo::replaceRegWith(unsigned FromReg, unsigned ToReg) {
assert(FromReg != ToReg && "Cannot replace a reg with itself");
+ const TargetRegisterInfo *TRI = getTargetRegisterInfo();
+
// TODO: This could be more efficient by bulk changing the operands.
for (reg_iterator I = reg_begin(FromReg), E = reg_end(); I != E; ) {
- MachineOperand &O = I.getOperand();
+ MachineOperand &O = *I;
++I;
- O.setReg(ToReg);
+ if (TargetRegisterInfo::isPhysicalRegister(ToReg)) {
+ O.substPhysReg(ToReg, *TRI);
+ } else {
+ O.setReg(ToReg);
+ }
}
}
-
/// getVRegDef - Return the machine instr that defines the specified virtual
/// register or null if none is found. This assumes that the code is in SSA
/// form, so there should only be one definition.
MachineInstr *MachineRegisterInfo::getVRegDef(unsigned Reg) const {
- assert(Reg-TargetRegisterInfo::FirstVirtualRegister < VRegInfo.size() &&
- "Invalid vreg!");
// Since we are in SSA form, we can use the first definition.
- if (!def_empty(Reg))
- return &*def_begin(Reg);
- return 0;
+ def_instr_iterator I = def_instr_begin(Reg);
+ assert((I.atEnd() || std::next(I) == def_instr_end()) &&
+ "getVRegDef assumes a single definition or no definition");
+ return !I.atEnd() ? &*I : nullptr;
}
-bool MachineRegisterInfo::hasOneUse(unsigned RegNo) const {
- use_iterator UI = use_begin(RegNo);
- if (UI == use_end())
- return false;
- return ++UI == use_end();
+/// getUniqueVRegDef - Return the unique machine instr that defines the
+/// specified virtual register or null if none is found. If there are
+/// multiple definitions or no definition, return null.
+MachineInstr *MachineRegisterInfo::getUniqueVRegDef(unsigned Reg) const {
+ if (def_empty(Reg)) return nullptr;
+ def_instr_iterator I = def_instr_begin(Reg);
+ if (std::next(I) != def_instr_end())
+ return nullptr;
+ return &*I;
}
bool MachineRegisterInfo::hasOneNonDBGUse(unsigned RegNo) const {
return ++UI == use_nodbg_end();
}
+/// clearKillFlags - Iterate over all the uses of the given register and
+/// clear the kill flag from the MachineOperand. This function is used by
+/// optimization passes which extend register lifetimes and need only
+/// preserve conservative kill flag information.
+void MachineRegisterInfo::clearKillFlags(unsigned Reg) const {
+ for (MachineOperand &MO : use_operands(Reg))
+ MO.setIsKill(false);
+}
+
bool MachineRegisterInfo::isLiveIn(unsigned Reg) const {
for (livein_iterator I = livein_begin(), E = livein_end(); I != E; ++I)
if (I->first == Reg || I->second == Reg)
return false;
}
-bool MachineRegisterInfo::isLiveOut(unsigned Reg) const {
- for (liveout_iterator I = liveout_begin(), E = liveout_end(); I != E; ++I)
- if (*I == Reg)
- return true;
- return false;
-}
-
/// getLiveInPhysReg - If VReg is a live-in virtual register, return the
/// corresponding live-in physical register.
unsigned MachineRegisterInfo::getLiveInPhysReg(unsigned VReg) const {
return 0;
}
-static cl::opt<bool>
-SchedLiveInCopies("schedule-livein-copies", cl::Hidden,
- cl::desc("Schedule copies of livein registers"),
- cl::init(false));
-
-/// EmitLiveInCopy - Emit a copy for a live in physical register. If the
-/// physical register has only a single copy use, then coalesced the copy
-/// if possible.
-static void EmitLiveInCopy(MachineBasicBlock *MBB,
- MachineBasicBlock::iterator &InsertPos,
- unsigned VirtReg, unsigned PhysReg,
- const TargetRegisterClass *RC,
- DenseMap<MachineInstr*, unsigned> &CopyRegMap,
- const MachineRegisterInfo &MRI,
- const TargetRegisterInfo &TRI,
- const TargetInstrInfo &TII) {
- unsigned NumUses = 0;
- MachineInstr *UseMI = NULL;
- for (MachineRegisterInfo::use_iterator UI = MRI.use_begin(VirtReg),
- UE = MRI.use_end(); UI != UE; ++UI) {
- UseMI = &*UI;
- if (++NumUses > 1)
- break;
- }
-
- // If the number of uses is not one, or the use is not a move instruction,
- // don't coalesce. Also, only coalesce away a virtual register to virtual
- // register copy.
- bool Coalesced = false;
- unsigned SrcReg, DstReg, SrcSubReg, DstSubReg;
- if (NumUses == 1 &&
- TII.isMoveInstr(*UseMI, SrcReg, DstReg, SrcSubReg, DstSubReg) &&
- TargetRegisterInfo::isVirtualRegister(DstReg)) {
- VirtReg = DstReg;
- Coalesced = true;
- }
-
- // Now find an ideal location to insert the copy.
- MachineBasicBlock::iterator Pos = InsertPos;
- while (Pos != MBB->begin()) {
- MachineInstr *PrevMI = prior(Pos);
- DenseMap<MachineInstr*, unsigned>::iterator RI = CopyRegMap.find(PrevMI);
- // copyRegToReg might emit multiple instructions to do a copy.
- unsigned CopyDstReg = (RI == CopyRegMap.end()) ? 0 : RI->second;
- if (CopyDstReg && !TRI.regsOverlap(CopyDstReg, PhysReg))
- // This is what the BB looks like right now:
- // r1024 = mov r0
- // ...
- // r1 = mov r1024
- //
- // We want to insert "r1025 = mov r1". Inserting this copy below the
- // move to r1024 makes it impossible for that move to be coalesced.
- //
- // r1025 = mov r1
- // r1024 = mov r0
- // ...
- // r1 = mov 1024
- // r2 = mov 1025
- break; // Woot! Found a good location.
- --Pos;
- }
-
- bool Emitted = TII.copyRegToReg(*MBB, Pos, VirtReg, PhysReg, RC, RC,
- DebugLoc());
- assert(Emitted && "Unable to issue a live-in copy instruction!\n");
- (void) Emitted;
-
- CopyRegMap.insert(std::make_pair(prior(Pos), VirtReg));
- if (Coalesced) {
- if (&*InsertPos == UseMI) ++InsertPos;
- MBB->erase(UseMI);
- }
+/// getLiveInVirtReg - If PReg is a live-in physical register, return the
+/// corresponding live-in physical register.
+unsigned MachineRegisterInfo::getLiveInVirtReg(unsigned PReg) const {
+ for (livein_iterator I = livein_begin(), E = livein_end(); I != E; ++I)
+ if (I->first == PReg)
+ return I->second;
+ return 0;
}
/// EmitLiveInCopies - Emit copies to initialize livein virtual registers
MachineRegisterInfo::EmitLiveInCopies(MachineBasicBlock *EntryMBB,
const TargetRegisterInfo &TRI,
const TargetInstrInfo &TII) {
- if (SchedLiveInCopies) {
- // Emit the copies at a heuristically-determined location in the block.
- DenseMap<MachineInstr*, unsigned> CopyRegMap;
- MachineBasicBlock::iterator InsertPos = EntryMBB->begin();
- for (MachineRegisterInfo::livein_iterator LI = livein_begin(),
- E = livein_end(); LI != E; ++LI)
- if (LI->second) {
- const TargetRegisterClass *RC = getRegClass(LI->second);
- EmitLiveInCopy(EntryMBB, InsertPos, LI->second, LI->first,
- RC, CopyRegMap, *this, TRI, TII);
- }
- } else {
- // Emit the copies into the top of the block.
- for (MachineRegisterInfo::livein_iterator LI = livein_begin(),
- E = livein_end(); LI != E; ++LI)
- if (LI->second) {
- const TargetRegisterClass *RC = getRegClass(LI->second);
- bool Emitted = TII.copyRegToReg(*EntryMBB, EntryMBB->begin(),
- LI->second, LI->first, RC, RC,
- DebugLoc());
- assert(Emitted && "Unable to issue a live-in copy instruction!\n");
- (void) Emitted;
+ // Emit the copies into the top of the block.
+ for (unsigned i = 0, e = LiveIns.size(); i != e; ++i)
+ if (LiveIns[i].second) {
+ if (use_empty(LiveIns[i].second)) {
+ // The livein has no uses. Drop it.
+ //
+ // It would be preferable to have isel avoid creating live-in
+ // records for unused arguments in the first place, but it's
+ // complicated by the debug info code for arguments.
+ LiveIns.erase(LiveIns.begin() + i);
+ --i; --e;
+ } else {
+ // Emit a copy.
+ BuildMI(*EntryMBB, EntryMBB->begin(), DebugLoc(),
+ TII.get(TargetOpcode::COPY), LiveIns[i].second)
+ .addReg(LiveIns[i].first);
+
+ // Add the register to the entry block live-in set.
+ EntryMBB->addLiveIn(LiveIns[i].first);
}
- }
+ } else {
+ // Add the register to the entry block live-in set.
+ EntryMBB->addLiveIn(LiveIns[i].first);
+ }
+}
- // Add function live-ins to entry block live-in set.
- for (MachineRegisterInfo::livein_iterator I = livein_begin(),
- E = livein_end(); I != E; ++I)
- EntryMBB->addLiveIn(I->first);
+LaneBitmask MachineRegisterInfo::getMaxLaneMaskForVReg(unsigned Reg) const {
+ // Lane masks are only defined for vregs.
+ assert(TargetRegisterInfo::isVirtualRegister(Reg));
+ const TargetRegisterClass &TRC = *getRegClass(Reg);
+ return TRC.getLaneMask();
}
#ifndef NDEBUG
void MachineRegisterInfo::dumpUses(unsigned Reg) const {
- for (use_iterator I = use_begin(Reg), E = use_end(); I != E; ++I)
- I.getOperand().getParent()->dump();
+ for (MachineInstr &I : use_instructions(Reg))
+ I.dump();
}
#endif
+
+void MachineRegisterInfo::freezeReservedRegs(const MachineFunction &MF) {
+ ReservedRegs = getTargetRegisterInfo()->getReservedRegs(MF);
+ assert(ReservedRegs.size() == getTargetRegisterInfo()->getNumRegs() &&
+ "Invalid ReservedRegs vector from target");
+}
+
+bool MachineRegisterInfo::isConstantPhysReg(unsigned PhysReg,
+ const MachineFunction &MF) const {
+ assert(TargetRegisterInfo::isPhysicalRegister(PhysReg));
+
+ // Check if any overlapping register is modified, or allocatable so it may be
+ // used later.
+ for (MCRegAliasIterator AI(PhysReg, getTargetRegisterInfo(), true);
+ AI.isValid(); ++AI)
+ if (!def_empty(*AI) || isAllocatable(*AI))
+ return false;
+ return true;
+}
+
+/// markUsesInDebugValueAsUndef - Mark every DBG_VALUE referencing the
+/// specified register as undefined which causes the DBG_VALUE to be
+/// deleted during LiveDebugVariables analysis.
+void MachineRegisterInfo::markUsesInDebugValueAsUndef(unsigned Reg) const {
+ // Mark any DBG_VALUE that uses Reg as undef (but don't delete it.)
+ MachineRegisterInfo::use_instr_iterator nextI;
+ for (use_instr_iterator I = use_instr_begin(Reg), E = use_instr_end();
+ I != E; I = nextI) {
+ nextI = std::next(I); // I is invalidated by the setReg
+ MachineInstr *UseMI = &*I;
+ if (UseMI->isDebugValue())
+ UseMI->getOperand(0).setReg(0U);
+ }
+}
+
+static const Function *getCalledFunction(const MachineInstr &MI) {
+ for (const MachineOperand &MO : MI.operands()) {
+ if (!MO.isGlobal())
+ continue;
+ const Function *Func = dyn_cast<Function>(MO.getGlobal());
+ if (Func != nullptr)
+ return Func;
+ }
+ return nullptr;
+}
+
+static bool isNoReturnDef(const MachineOperand &MO) {
+ // Anything which is not a noreturn function is a real def.
+ const MachineInstr &MI = *MO.getParent();
+ if (!MI.isCall())
+ return false;
+ const MachineBasicBlock &MBB = *MI.getParent();
+ if (!MBB.succ_empty())
+ return false;
+ const MachineFunction &MF = *MBB.getParent();
+ // We need to keep correct unwind information even if the function will
+ // not return, since the runtime may need it.
+ if (MF.getFunction()->hasFnAttribute(Attribute::UWTable))
+ return false;
+ const Function *Called = getCalledFunction(MI);
+ return !(Called == nullptr || !Called->hasFnAttribute(Attribute::NoReturn) ||
+ !Called->hasFnAttribute(Attribute::NoUnwind));
+}
+
+bool MachineRegisterInfo::isPhysRegModified(unsigned PhysReg) const {
+ if (UsedPhysRegMask.test(PhysReg))
+ return true;
+ const TargetRegisterInfo *TRI = getTargetRegisterInfo();
+ for (MCRegAliasIterator AI(PhysReg, TRI, true); AI.isValid(); ++AI) {
+ for (const MachineOperand &MO : make_range(def_begin(*AI), def_end())) {
+ if (isNoReturnDef(MO))
+ continue;
+ return true;
+ }
+ }
+ return false;
+}
+
+bool MachineRegisterInfo::isPhysRegUsed(unsigned PhysReg) const {
+ if (UsedPhysRegMask.test(PhysReg))
+ return true;
+ const TargetRegisterInfo *TRI = getTargetRegisterInfo();
+ for (MCRegAliasIterator AliasReg(PhysReg, TRI, true); AliasReg.isValid();
+ ++AliasReg) {
+ if (!reg_nodbg_empty(*AliasReg))
+ return true;
+ }
+ return false;
+}
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