-//===-- MachineRegisterInfo.cpp -------------------------------------------===//
+//===-- lib/Codegen/MachineRegisterInfo.cpp -------------------------------===//
//
// The LLVM Compiler Infrastructure
//
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Target/TargetInstrInfo.h"
using namespace llvm;
-MachineRegisterInfo::MachineRegisterInfo(const MRegisterInfo &MRI) {
+MachineRegisterInfo::MachineRegisterInfo(const TargetRegisterInfo &TRI) {
VRegInfo.reserve(256);
- UsedPhysRegs.resize(MRI.getNumRegs());
+ 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());
}
+
+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;
+}
+
+/// 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;
+ VRegInfo[Reg].first = RC;
+
+ // 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);
+
+ // Add to new register class's vregs list.
+ RegClass2VRegMap[RC->getID()].push_back(VR);
+}
+
+/// createVirtualRegister - Create and return a new virtual register in the
+/// function with the specified register class.
+///
+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;
+}
+
+/// 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;
+ }
+}
+
+/// 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.
+void MachineRegisterInfo::replaceRegWith(unsigned FromReg, unsigned ToReg) {
+ assert(FromReg != ToReg && "Cannot replace a reg with itself");
+
+ // 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();
+ ++I;
+ 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;
+}
+
+bool MachineRegisterInfo::hasOneUse(unsigned RegNo) const {
+ use_iterator UI = use_begin(RegNo);
+ if (UI == use_end())
+ return false;
+ return ++UI == use_end();
+}
+
+bool MachineRegisterInfo::hasOneNonDBGUse(unsigned RegNo) const {
+ use_nodbg_iterator UI = use_nodbg_begin(RegNo);
+ if (UI == use_nodbg_end())
+ return false;
+ return ++UI == use_nodbg_end();
+}
+
+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 true;
+ 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;
+}
+
+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);
+ 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);
+ }
+}
+
+/// EmitLiveInCopies - Emit copies to initialize livein virtual registers
+/// into the given entry block.
+void
+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);
+ assert(Emitted && "Unable to issue a live-in copy instruction!\n");
+ (void) Emitted;
+ }
+ }
+
+ // 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);
+}
+
+#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();
+}
+#endif
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