[llvm-commits] [llvm] r48003 - in /llvm/trunk: include/llvm/CodeGen/RegisterScavenging.h lib/CodeGen/RegisterScavenging.cpp

[Bill Wendling]

On Fri, Mar 7, 2008 at 2:32 PM, Evan Cheng <evan.cheng at apple.com> wrote:
>
>  On Mar 6, 2008, at 3:22 PM, Bill Wendling wrote:
>
>  > void RegScavenger::enterBasicBlock(MachineBasicBlock *mbb) {
>  > @@ -138,9 +161,12 @@
>  >     if (MO.isKill() && !isReserved(Reg)) {
>  >       ChangedRegs.set(Reg);
>  >
>  > +      // Mark sub-registers as changed if they aren't defined in
>  > the same
>  > +      // instruction.
>  >       for (const unsigned *SubRegs = TRI->getSubRegisters(Reg);
>  >            unsigned SubReg = *SubRegs; ++SubRegs)
>  > -        ChangedRegs.set(SubReg);
>  > +        if (!RedefinesSuperRegPart(MI, Reg, TRI))
>
>  Why is this necessary? Something that kills a super-register also
>  kills the sub-register.
>
Okay, sure.

>  > @@ -194,7 +224,7 @@
>  >     unsigned Reg = MO.getReg();
>  >     assert(isUsed(Reg));
>  >     if (!isReserved(Reg))
>  > -      setUnused(Reg);
>  > +      setUnused(Reg, MI);
>
>  What about the sub-registers?
>
The setUnused method sets that information, right?

-bw