#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/SlotIndexes.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetRegisterInfo.h"
using namespace llvm;
STATISTIC(NumSpills , "Number of register spills");
+STATISTIC(NumIdCopies, "Number of identity moves eliminated after rewriting");
//===----------------------------------------------------------------------===//
// VirtRegMap implementation
unsigned VirtRegMap::getRegAllocPref(unsigned virtReg) {
std::pair<unsigned, unsigned> Hint = MRI->getRegAllocationHint(virtReg);
unsigned physReg = Hint.second;
- if (physReg &&
- TargetRegisterInfo::isVirtualRegister(physReg) && hasPhys(physReg))
+ if (TargetRegisterInfo::isVirtualRegister(physReg) && hasPhys(physReg))
physReg = getPhys(physReg);
if (Hint.first == 0)
- return (physReg && TargetRegisterInfo::isPhysicalRegister(physReg))
+ return (TargetRegisterInfo::isPhysicalRegister(physReg))
? physReg : 0;
return TRI->ResolveRegAllocHint(Hint.first, physReg, *MF);
}
return AnyUnused;
}
+void VirtRegMap::rewrite(SlotIndexes *Indexes) {
+ DEBUG(dbgs() << "********** REWRITE VIRTUAL REGISTERS **********\n"
+ << "********** Function: "
+ << MF->getFunction()->getName() << '\n');
+ DEBUG(dump());
+ SmallVector<unsigned, 8> SuperDeads;
+ SmallVector<unsigned, 8> SuperDefs;
+ SmallVector<unsigned, 8> SuperKills;
+
+ for (MachineFunction::iterator MBBI = MF->begin(), MBBE = MF->end();
+ MBBI != MBBE; ++MBBI) {
+ DEBUG(MBBI->print(dbgs(), Indexes));
+ for (MachineBasicBlock::iterator MII = MBBI->begin(), MIE = MBBI->end();
+ MII != MIE;) {
+ MachineInstr *MI = MII;
+ ++MII;
+
+ for (MachineInstr::mop_iterator MOI = MI->operands_begin(),
+ MOE = MI->operands_end(); MOI != MOE; ++MOI) {
+ MachineOperand &MO = *MOI;
+ if (!MO.isReg() || !TargetRegisterInfo::isVirtualRegister(MO.getReg()))
+ continue;
+ unsigned VirtReg = MO.getReg();
+ unsigned PhysReg = getPhys(VirtReg);
+ assert(PhysReg != NO_PHYS_REG && "Instruction uses unmapped VirtReg");
+
+ // Preserve semantics of sub-register operands.
+ if (MO.getSubReg()) {
+ // A virtual register kill refers to the whole register, so we may
+ // have to add <imp-use,kill> operands for the super-register.
+ if (MO.isUse()) {
+ if (MO.isKill() && !MO.isUndef())
+ SuperKills.push_back(PhysReg);
+ } else if (MO.isDead())
+ SuperDeads.push_back(PhysReg);
+ else
+ SuperDefs.push_back(PhysReg);
+
+ // PhysReg operands cannot have subregister indexes.
+ PhysReg = TRI->getSubReg(PhysReg, MO.getSubReg());
+ assert(PhysReg && "Invalid SubReg for physical register");
+ MO.setSubReg(0);
+ }
+ // Rewrite. Note we could have used MachineOperand::substPhysReg(), but
+ // we need the inlining here.
+ MO.setReg(PhysReg);
+ }
+
+ // Add any missing super-register kills after rewriting the whole
+ // instruction.
+ while (!SuperKills.empty())
+ MI->addRegisterKilled(SuperKills.pop_back_val(), TRI, true);
+
+ while (!SuperDeads.empty())
+ MI->addRegisterDead(SuperDeads.pop_back_val(), TRI, true);
+
+ while (!SuperDefs.empty())
+ MI->addRegisterDefined(SuperDefs.pop_back_val(), TRI);
+
+ DEBUG(dbgs() << "> " << *MI);
+
+ // Finally, remove any identity copies.
+ if (MI->isIdentityCopy()) {
+ ++NumIdCopies;
+ if (MI->getNumOperands() == 2) {
+ DEBUG(dbgs() << "Deleting identity copy.\n");
+ RemoveMachineInstrFromMaps(MI);
+ if (Indexes)
+ Indexes->removeMachineInstrFromMaps(MI);
+ // It's safe to erase MI because MII has already been incremented.
+ MI->eraseFromParent();
+ } else {
+ // Transform identity copy to a KILL to deal with subregisters.
+ MI->setDesc(TII->get(TargetOpcode::KILL));
+ DEBUG(dbgs() << "Identity copy: " << *MI);
+ }
+ }
+ }
+ }
+
+ // Tell MRI about physical registers in use.
+ for (unsigned Reg = 1, RegE = TRI->getNumRegs(); Reg != RegE; ++Reg)
+ if (!MRI->reg_nodbg_empty(Reg))
+ MRI->setPhysRegUsed(Reg);
+}
+
void VirtRegMap::print(raw_ostream &OS, const Module* M) const {
const TargetRegisterInfo* TRI = MF->getTarget().getRegisterInfo();
const MachineRegisterInfo &MRI = MF->getRegInfo();