[llvm-commits] [llvm] r58726 - /llvm/trunk/lib/CodeGen/PreAllocSplitting.cpp

[Evan Cheng]

Thanks. Please add comment to createsNewJoin. Also, the function name  
sounds like it's creating a new join. How about SplitWillCreateNewJoin?

Evan

On Nov 4, 2008, at 2:22 PM, Owen Anderson wrote:

> Author: resistor
> Date: Tue Nov  4 16:22:41 2008
> New Revision: 58726
>
> URL: http://llvm.org/viewvc/llvm-project?rev=58726&view=rev
> Log:
> First pass at checking for the creation of a new join point when  
> doing pre-alloc splitting.  This is not turned on yet.
>
> Modified:
>    llvm/trunk/lib/CodeGen/PreAllocSplitting.cpp
>
> Modified: llvm/trunk/lib/CodeGen/PreAllocSplitting.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/PreAllocSplitting.cpp?rev=58726&r1=58725&r2=58726&view=diff
>
> = 
> = 
> = 
> = 
> = 
> = 
> = 
> = 
> ======================================================================
> --- llvm/trunk/lib/CodeGen/PreAllocSplitting.cpp (original)
> +++ llvm/trunk/lib/CodeGen/PreAllocSplitting.cpp Tue Nov  4 16:22:41  
> 2008
> @@ -17,6 +17,7 @@
> #define DEBUG_TYPE "pre-alloc-split"
> #include "llvm/CodeGen/LiveIntervalAnalysis.h"
> #include "llvm/CodeGen/LiveStackAnalysis.h"
> +#include "llvm/CodeGen/MachineDominators.h"
> #include "llvm/CodeGen/MachineFrameInfo.h"
> #include "llvm/CodeGen/MachineFunctionPass.h"
> #include "llvm/CodeGen/MachineLoopInfo.h"
> @@ -89,6 +90,10 @@
>         AU.addPreservedID(StrongPHIEliminationID);
>       else
>         AU.addPreservedID(PHIEliminationID);
> +      AU.addRequired<MachineDominatorTree>();
> +      AU.addRequired<MachineLoopInfo>();
> +      AU.addPreserved<MachineDominatorTree>();
> +      AU.addPreserved<MachineLoopInfo>();
>       MachineFunctionPass::getAnalysisUsage(AU);
>     }
>
> @@ -145,6 +150,9 @@
>     bool SplitRegLiveInterval(LiveInterval*);
>
>     bool SplitRegLiveIntervals(const TargetRegisterClass **);
> +
> +    bool createsNewJoin(LiveRange* LR, MachineBasicBlock* DefMBB,
> +                        MachineBasicBlock* BarrierMBB);
>   };
> } // end anonymous namespace
>
> @@ -817,6 +825,71 @@
>   return Change;
> }
>
> +bool PreAllocSplitting::createsNewJoin(LiveRange* LR,
> +                                       MachineBasicBlock* DefMBB,
> +                                       MachineBasicBlock*  
> BarrierMBB) {
> +  if (DefMBB == BarrierMBB)
> +    return false;
> +
> +  if (LR->valno->hasPHIKill)
> +    return false;
> +
> +  unsigned MBBEnd = LIs->getMBBEndIdx(BarrierMBB);
> +  if (LR->end < MBBEnd)
> +    return false;
> +
> +  MachineLoopInfo& MLI = getAnalysis<MachineLoopInfo>();
> +  if (MLI.getLoopFor(DefMBB) != MLI.getLoopFor(BarrierMBB))
> +    return true;
> +
> +  MachineDominatorTree& MDT = getAnalysis<MachineDominatorTree>();
> +  SmallPtrSet<MachineBasicBlock*, 4> Visited;
> +  typedef std::pair<MachineBasicBlock*,
> +                    MachineBasicBlock::succ_iterator> ItPair;
> +  SmallVector<ItPair, 4> Stack;
> +  Stack.push_back(std::make_pair(BarrierMBB, BarrierMBB- 
> >succ_begin()));
> +
> +  while (!Stack.empty()) {
> +    ItPair P = Stack.back();
> +    Stack.pop_back();
> +
> +    MachineBasicBlock* PredMBB = P.first;
> +    MachineBasicBlock::succ_iterator S = P.second;
> +
> +    if (S == PredMBB->succ_end())
> +      continue;
> +    else if (Visited.count(*S)) {
> +      Stack.push_back(std::make_pair(PredMBB, ++S));
> +      continue;
> +    } else
> +      Stack.push_back(std::make_pair(PredMBB, ++S));
> +
> +    MachineBasicBlock* MBB = *S;
> +    Visited.insert(MBB);
> +
> +    if (MBB == BarrierMBB)
> +      return true;
> +
> +    MachineDomTreeNode* DefMDTN = MDT.getNode(DefMBB);
> +    MachineDomTreeNode* BarrierMDTN = MDT.getNode(BarrierMBB);
> +    MachineDomTreeNode* MDTN = MDT.getNode(MBB)->getIDom();
> +    while (MDTN) {
> +      if (MDTN == DefMDTN)
> +        return true;
> +      else if (MDTN == BarrierMDTN)
> +        break;
> +      MDTN = MDTN->getIDom();
> +    }
> +
> +    MBBEnd = LIs->getMBBEndIdx(MBB);
> +    if (LR->end > MBBEnd)
> +      Stack.push_back(std::make_pair(MBB, MBB->succ_begin()));
> +  }
> +
> +  return false;
> +}
> +
> +
> bool PreAllocSplitting::runOnMachineFunction(MachineFunction &MF) {
>   CurrMF = &MF;
>   TM     = &MF.getTarget();
>
>
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