[llvm-commits] [llvm] r47862 - /llvm/trunk/lib/CodeGen/MachineInstr.cpp

[Bill Wendling]

On Mon, Mar 3, 2008 at 3:14 PM, Evan Cheng <evan.cheng at apple.com> wrote:
>  > --- llvm/trunk/lib/CodeGen/MachineInstr.cpp (original)
>  > +++ llvm/trunk/lib/CodeGen/MachineInstr.cpp Mon Mar  3 16:14:33 2008
>  > @@ -678,34 +678,74 @@
>  > bool MachineInstr::addRegisterKilled(unsigned IncomingReg,
>  >                                      const TargetRegisterInfo
>  > *RegInfo,
>  >                                      bool AddIfNotFound) {
>  > -  bool Found = false;
>  > -  for (unsigned i = 0, e = getNumOperands(); i != e; ++i) {
>  > +  // Go through the machine instruction's operands to eliminate any
>  > potentially
>  > +  // illegal conditions. I.e., a super- and sub-register both
>  > marked "kill".
>  > + Restart:
>  > +  for (unsigned i = 0, e = getNumOperands(); i < e; ++i) {
>  >     MachineOperand &MO = getOperand(i);
>  > +
>  >     if (MO.isRegister() && MO.isUse()) {
>  >       unsigned Reg = MO.getReg();
>  > -      if (!Reg)
>  > +
>  > +      if (!Reg || IncomingReg == Reg ||
>  > +          !TargetRegisterInfo::isPhysicalRegister(Reg) ||
>  > +          !TargetRegisterInfo::isPhysicalRegister(IncomingReg))
>  >         continue;
>  > +
>  > +      if (RegInfo->isSubRegister(IncomingReg, Reg)) {
>  > +        if (MO.isKill()) {
>  > +          if (MO.isImplicit()) {
>  >
>  > +            // Remove this implicit use that marks the sub-register
>  > "kill". Let
>  > +            // the super-register take care of this information.
>  > +            RemoveOperand(i);
>  > +            goto Restart;       // Instruction was modified, redo
>  > checking.
>
>  Seems like this may increase compile time unnecessarily? Do you have
>  to restart from first operand? Can you simply recompute 'e' and make
>  sure i isn't incremented?
>
Okay. (I'm the only one who likes gotos ;-)

>  > +          } else {
>  > +            // The super-register is going to take care of this kill
>  > +            // information.
>  > +            MO.setIsKill(false);
>  > +          }
>  > +        }
>  > +      } else if (RegInfo->isSuperRegister(IncomingReg, Reg) &&
>  > MO.isKill()) {
>  > +        // The kill information is already handled by a super-
>  > register. Don't
>  > +        // add this sub-register as a kill.
>  > +        return true;
>  > +      }
>
>  Check this first so we can take advantage of the early exit to avoid
>  nesting.
>
Okay.

>
>  >
>  > +    }
>  > +  }
>  > +
>  > +  // If the register already exists, then make sure it or its super-
>  > register is
>  > +  // marked "kill".
>  > +  for (unsigned i = 0, e = getNumOperands(); i != e; ++i) {
>  > +    MachineOperand &MO = getOperand(i);
>  > +
>  > +    if (MO.isRegister() && MO.isUse()) {
>  > +      unsigned Reg = MO.getReg();
>  > +      if (!Reg) continue;
>  > +
>  >       if (Reg == IncomingReg) {
>  >         MO.setIsKill();
>  > -        Found = true;
>  > -        break;
>  > +        return true;
>  >
>  >       } else if (TargetRegisterInfo::isPhysicalRegister(Reg) &&
>
>  No need for else here.
>
Okay.

-bw