[llvm-commits] [llvm] r43805 - /llvm/trunk/lib/CodeGen/StrongPHIElimination.cpp

[Evan Cheng]

Hi Owen,

Please use SmallPtrSet and / or SmallSet instead of std::set.

Thanks,

Evan

On Nov 6, 2007, at 9:17 PM, Owen Anderson wrote:

> Author: resistor
> Date: Tue Nov  6 23:17:15 2007
> New Revision: 43805
>
> URL: http://llvm.org/viewvc/llvm-project?rev=43805&view=rev
> Log:
> Add some more of StrongPHIElim.
>
> Modified:
>     llvm/trunk/lib/CodeGen/StrongPHIElimination.cpp
>
> Modified: llvm/trunk/lib/CodeGen/StrongPHIElimination.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/ 
> StrongPHIElimination.cpp?rev=43805&r1=43804&r2=43805&view=diff
>
> ====================================================================== 
> ========
> --- llvm/trunk/lib/CodeGen/StrongPHIElimination.cpp (original)
> +++ llvm/trunk/lib/CodeGen/StrongPHIElimination.cpp Tue Nov  6  
> 23:17:15 2007
> @@ -89,7 +89,7 @@
>
>
>      void computeDFS(MachineFunction& MF);
> -    void processPHI(MachineInstr* P);
> +    void processBlock(MachineBasicBlock* MBB);
>
>      std::vector<DomForestNode*> computeDomForest 
> (std::set<unsigned>& instrs);
>
> @@ -219,23 +219,85 @@
>    return ret;
>  }
>
> -/// processPHI - Eliminate the given PHI node
> -void StrongPHIElimination::processPHI(MachineInstr* P) {
> +/// isLiveIn - helper method that determines, from a VarInfo, if a  
> register
> +/// is live into a block
> +bool isLiveIn(LiveVariables::VarInfo& V, MachineBasicBlock* MBB) {
> +  if (V.AliveBlocks.test(MBB->getNumber()))
> +    return true;
> +
> +  for (std::vector<MachineInstr*>::iterator I = V.Kills.begin(),
> +       E = V.Kills.end(); I != E; ++I)
> +    if ((*I)->getParent() == MBB)
> +      return true;
>
> +  return false;
>  }
>
> -bool StrongPHIElimination::runOnMachineFunction(MachineFunction  
> &Fn) {
> -  computeDFS(Fn);
> +/// isLiveOut - help method that determines, from a VarInfo, if a  
> register is
> +/// live out of a block.
> +bool isLiveOut(LiveVariables::VarInfo& V, MachineBasicBlock* MBB) {
> +  if (V.AliveBlocks.test(MBB->getNumber()))
> +    return true;
>
> -  for (MachineFunction::iterator I = Fn.begin(), E = Fn.end(); I ! 
> = E; ++I) {
> -    for (MachineBasicBlock::iterator BI = I->begin(), BE = I->end 
> (); BI != BE;
> -         ++BI) {
> -      if (BI->getOpcode() == TargetInstrInfo::PHI)
> -        processPHI(BI);
> -      else
> -        break;
> +  if (V.DefInst->getParent() == MBB)
> +    return true;
> +
> +  return false;
> +}
> +
> +/// processBlock - Eliminate PHIs in the given block
> +void StrongPHIElimination::processBlock(MachineBasicBlock* MBB) {
> +  LiveVariables& LV = getAnalysis<LiveVariables>();
> +
> +  // Holds names that have been added to a set in any PHI within  
> this block
> +  // before the current one.
> +  std::set<unsigned> ProcessedNames;
> +
> +  MachineBasicBlock::iterator P = MBB->begin();
> +  while (P->getOpcode() == TargetInstrInfo::PHI) {
> +    LiveVariables::VarInfo& PHIInfo = LV.getVarInfo(P->getOperand 
> (0).getReg());
> +
> +    // Hold the names that are currently in the candidate set.
> +    std::set<unsigned> PHIUnion;
> +    std::set<MachineBasicBlock*> UnionedBlocks;
> +
> +    for (int i = P->getNumOperands() - 1; i >= 2; i-=2) {
> +      unsigned SrcReg = P->getOperand(i-1).getReg();
> +      LiveVariables::VarInfo& SrcInfo = LV.getVarInfo(SrcReg);
> +
> +      if (isLiveIn(SrcInfo, P->getParent())) {
> +        // add a copy from a_i to p in Waiting[From[a_i]]
> +      } else if (isLiveOut(PHIInfo, SrcInfo.DefInst->getParent())) {
> +        // add a copy to Waiting[From[a_i]]
> +      } else if (PHIInfo.DefInst->getOpcode() ==  
> TargetInstrInfo::PHI &&
> +                 isLiveIn(PHIInfo, SrcInfo.DefInst->getParent())) {
> +        // add a copy to Waiting[From[a_i]]
> +      } else if (ProcessedNames.count(SrcReg)) {
> +        // add a copy to Waiting[From[a_i]]
> +      } else if (UnionedBlocks.count(SrcInfo.DefInst->getParent())) {
> +        // add a copy to Waiting[From[a_i]]
> +      } else {
> +        PHIUnion.insert(SrcReg);
> +        UnionedBlocks.insert(SrcInfo.DefInst->getParent());
> +
> +        // DO STUFF HERE
> +
> +      }
> +
> +      ProcessedNames.insert(PHIUnion.begin(), PHIUnion.end());
>      }
> +
> +    ++P;
>    }
> +}
> +
> +bool StrongPHIElimination::runOnMachineFunction(MachineFunction  
> &Fn) {
> +  computeDFS(Fn);
> +
> +  for (MachineFunction::iterator I = Fn.begin(), E = Fn.end(); I ! 
> = E; ++I)
> +    if (!I->empty() &&
> +        I->begin()->getOpcode() == TargetInstrInfo::PHI)
> +      processBlock(I);
>
>    return false;
>  }
>
>
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