[llvm-commits] [llvm] r126956 - in /llvm/trunk: include/llvm/Target/TargetRegisterInfo.h lib/CodeGen/PrologEpilogInserter.cpp

[Evan Cheng]

Hi Jim,

Is this target hook really necessary? Can it be subsumed by hasFP? Isn't there a target hook for creating the emergency slot? Can you explain what the patch is doing?

Thanks,

Evan

On Mar 3, 2011, at 12:01 PM, Jim Grosbach <grosbach at apple.com> wrote:

> Author: grosbach
> Date: Thu Mar  3 14:01:52 2011
> New Revision: 126956
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=126956&view=rev
> Log:
> Allow a target to choose whether to prefer the scavenger emergency spill slot
> be next to the frame pointer or the stack pointer.
> 
> 
> Modified:
>    llvm/trunk/include/llvm/Target/TargetRegisterInfo.h
>    llvm/trunk/lib/CodeGen/PrologEpilogInserter.cpp
> 
> Modified: llvm/trunk/include/llvm/Target/TargetRegisterInfo.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Target/TargetRegisterInfo.h?rev=126956&r1=126955&r2=126956&view=diff
> ==============================================================================
> --- llvm/trunk/include/llvm/Target/TargetRegisterInfo.h (original)
> +++ llvm/trunk/include/llvm/Target/TargetRegisterInfo.h Thu Mar  3 14:01:52 2011
> @@ -631,6 +631,13 @@
>     return false;
>   }
> 
> +  /// useFPForScavengingIndex - returns true if the target wants to use
> +  /// frame pointer based accesses to spill to the scavenger emergency spill
> +  /// slot.
> +  virtual bool useFPForScavengingIndex(const MachineFunction &MF) const {
> +    return true;
> +  }
> +
>   /// requiresFrameIndexScavenging - returns true if the target requires post
>   /// PEI scavenging of registers for materializing frame index constants.
>   virtual bool requiresFrameIndexScavenging(const MachineFunction &MF) const {
> 
> Modified: llvm/trunk/lib/CodeGen/PrologEpilogInserter.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/PrologEpilogInserter.cpp?rev=126956&r1=126955&r2=126956&view=diff
> ==============================================================================
> --- llvm/trunk/lib/CodeGen/PrologEpilogInserter.cpp (original)
> +++ llvm/trunk/lib/CodeGen/PrologEpilogInserter.cpp Thu Mar  3 14:01:52 2011
> @@ -559,7 +559,8 @@
>   // Make sure the special register scavenging spill slot is closest to the
>   // frame pointer if a frame pointer is required.
>   const TargetRegisterInfo *RegInfo = Fn.getTarget().getRegisterInfo();
> -  if (RS && TFI.hasFP(Fn) && !RegInfo->needsStackRealignment(Fn)) {
> +  if (RS && TFI.hasFP(Fn) && RegInfo->useFPForScavengingIndex(Fn) &&
> +      !RegInfo->needsStackRealignment(Fn)) {
>     int SFI = RS->getScavengingFrameIndex();
>     if (SFI >= 0)
>       AdjustStackOffset(MFI, SFI, StackGrowsDown, Offset, MaxAlign);
> @@ -641,7 +642,8 @@
> 
>   // Make sure the special register scavenging spill slot is closest to the
>   // stack pointer.
> -  if (RS && (!TFI.hasFP(Fn) || RegInfo->needsStackRealignment(Fn))) {
> +  if (RS && (!TFI.hasFP(Fn) || RegInfo->needsStackRealignment(Fn) ||
> +             !RegInfo->useFPForScavengingIndex(Fn))) {
>     int SFI = RS->getScavengingFrameIndex();
>     if (SFI >= 0)
>       AdjustStackOffset(MFI, SFI, StackGrowsDown, Offset, MaxAlign);
> @@ -811,7 +813,6 @@
>     // directly.
>     for (MachineBasicBlock::iterator I = BB->begin(); I != BB->end(); ) {
>       MachineInstr *MI = I;
> -      bool DoIncr = true;
>       for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
>         if (MI->getOperand(i).isReg()) {
>           MachineOperand &MO = MI->getOperand(i);
> @@ -842,10 +843,8 @@
> 
>         }
>       }
> -      if (DoIncr) {
> -        RS->forward(I);
> -        ++I;
> -      }
> +      RS->forward(I);
> +      ++I;
>     }
>   }
> }
> 
> 
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