[llvm] r175688 - Kill of TransferDeadFlag - Dead copies and subreg-to-reg instructions should

[Alexey Samsonov]

Hi, Lang!

I think this is causing http://llvm.org/bugs/show_bug.cgi?id=15320. Could
you please take a look?


On Thu, Feb 21, 2013 at 3:36 AM, Lang Hames <lhames at gmail.com> wrote:

> Author: lhames
> Date: Wed Feb 20 17:36:57 2013
> New Revision: 175688
>
> URL: http://llvm.org/viewvc/llvm-project?rev=175688&view=rev
> Log:
> Kill of TransferDeadFlag - Dead copies and subreg-to-reg instructions
> should
> just be turned into kills on the spot.
>
>
> Modified:
>     llvm/trunk/lib/CodeGen/ExpandPostRAPseudos.cpp
>
> Modified: llvm/trunk/lib/CodeGen/ExpandPostRAPseudos.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/ExpandPostRAPseudos.cpp?rev=175688&r1=175687&r2=175688&view=diff
>
> ==============================================================================
> --- llvm/trunk/lib/CodeGen/ExpandPostRAPseudos.cpp (original)
> +++ llvm/trunk/lib/CodeGen/ExpandPostRAPseudos.cpp Wed Feb 20 17:36:57 2013
> @@ -49,8 +49,6 @@ private:
>    bool LowerSubregToReg(MachineInstr *MI);
>    bool LowerCopy(MachineInstr *MI);
>
> -  void TransferDeadFlag(MachineInstr *MI, unsigned DstReg,
> -                        const TargetRegisterInfo *TRI);
>    void TransferImplicitDefs(MachineInstr *MI);
>  };
>  } // end anonymous namespace
> @@ -61,21 +59,6 @@ char &llvm::ExpandPostRAPseudosID = Expa
>  INITIALIZE_PASS(ExpandPostRA, "postrapseudos",
>                  "Post-RA pseudo instruction expansion pass", false, false)
>
> -/// TransferDeadFlag - MI is a pseudo-instruction with DstReg dead,
> -/// and the lowered replacement instructions immediately precede it.
> -/// Mark the replacement instructions with the dead flag.
> -void
> -ExpandPostRA::TransferDeadFlag(MachineInstr *MI, unsigned DstReg,
> -                               const TargetRegisterInfo *TRI) {
> -  for (MachineBasicBlock::iterator MII =
> -        prior(MachineBasicBlock::iterator(MI)); ; --MII) {
> -    if (MII->addRegisterDead(DstReg, TRI))
> -      break;
> -    assert(MII != MI->getParent()->begin() &&
> -           "copyPhysReg output doesn't reference destination register!");
> -  }
> -}
> -
>  /// TransferImplicitDefs - MI is a pseudo-instruction, and the lowered
>  /// replacement instructions immediately precede it.  Copy any
> implicit-def
>  /// operands from MI to the replacement instruction.
> @@ -128,17 +111,17 @@ bool ExpandPostRA::LowerSubregToReg(Mach
>      }
>      DEBUG(dbgs() << "subreg: eliminated!");
>    } else {
> +    if (MI->getOperand(0).isDead()) {
> +      MI->setDesc(TII->get(TargetOpcode::KILL));
> +      DEBUG(dbgs() << "subreg: replaced by: " << *MI);
> +      return true;
> +    }
>      TII->copyPhysReg(*MBB, MI, MI->getDebugLoc(), DstSubReg, InsReg,
>                       MI->getOperand(2).isKill());
> -
>      // Implicitly define DstReg for subsequent uses.
>      MachineBasicBlock::iterator CopyMI = MI;
>      --CopyMI;
>      CopyMI->addRegisterDefined(DstReg);
> -
> -    // Transfer the kill/dead flags, if needed.
> -    if (MI->getOperand(0).isDead())
> -      TransferDeadFlag(MI, DstSubReg, TRI);
>      DEBUG(dbgs() << "subreg: " << *CopyMI);
>    }
>
> @@ -151,11 +134,18 @@ bool ExpandPostRA::LowerCopy(MachineInst
>    MachineOperand &DstMO = MI->getOperand(0);
>    MachineOperand &SrcMO = MI->getOperand(1);
>
> +  if (DstMO.isDead()) {
> +    DEBUG(dbgs() << "dead copy: " << *MI);
> +    MI->setDesc(TII->get(TargetOpcode::KILL));
> +    DEBUG(dbgs() << "replaced by: " << *MI);
> +    return true;
> +  }
> +
>    if (SrcMO.getReg() == DstMO.getReg()) {
>      DEBUG(dbgs() << "identity copy: " << *MI);
>      // No need to insert an identity copy instruction, but replace with a
> KILL
>      // if liveness is changed.
> -    if (DstMO.isDead() || SrcMO.isUndef() || MI->getNumOperands() > 2) {
> +    if (SrcMO.isUndef() || MI->getNumOperands() > 2) {
>        // We must make sure the super-register gets killed. Replace the
>        // instruction with KILL.
>        MI->setDesc(TII->get(TargetOpcode::KILL));
> @@ -171,8 +161,6 @@ bool ExpandPostRA::LowerCopy(MachineInst
>    TII->copyPhysReg(*MI->getParent(), MI, MI->getDebugLoc(),
>                     DstMO.getReg(), SrcMO.getReg(), SrcMO.isKill());
>
> -  if (DstMO.isDead())
> -    TransferDeadFlag(MI, DstMO.getReg(), TRI);
>    if (MI->getNumOperands() > 2)
>      TransferImplicitDefs(MI);
>    DEBUG({
>
>
> _______________________________________________
> llvm-commits mailing list
> llvm-commits at cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
>



-- 
Alexey Samsonov, MSK
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20130221/11315da6/attachment.html>