[llvm-commits] [llvm] r61802 - /llvm/trunk/lib/CodeGen/PreAllocSplitting.cpp

[Evan Cheng]

Can you add some test cases to the various pre-splitting features you  
are adding?

Thanks,

Evan

On Jan 5, 2009, at 11:53 PM, Owen Anderson wrote:

> Author: resistor
> Date: Tue Jan  6 01:53:32 2009
> New Revision: 61802
>
> URL: http://llvm.org/viewvc/llvm-project?rev=61802&view=rev
> Log:
> The phi construction algorithm used for interval reconstruction is  
> complicated by
> two address instructions.  We need to keep track of things we've  
> processed AS USES
> independetly of whether we've processed them as defs.
>
> This fixes all known miscompilations when reconstruction is turned on.
>
> 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=61802&r1=61801&r2=61802&view=diff
>
> = 
> = 
> = 
> = 
> = 
> = 
> = 
> = 
> ======================================================================
> --- llvm/trunk/lib/CodeGen/PreAllocSplitting.cpp (original)
> +++ llvm/trunk/lib/CodeGen/PreAllocSplitting.cpp Tue Jan  6 01:53:32  
> 2009
> @@ -175,6 +175,7 @@
>     VNInfo* PerformPHIConstruction(MachineBasicBlock::iterator use,
>                                    MachineBasicBlock* MBB,
>                                    LiveInterval* LI,
> +                                   SmallPtrSet<MachineInstr*, 4>&  
> Visited,
>             DenseMap<MachineBasicBlock*, SmallPtrSet<MachineInstr*,  
> 2> >& Defs,
>             DenseMap<MachineBasicBlock*, SmallPtrSet<MachineInstr*,  
> 2> >& Uses,
>                                       DenseMap<MachineInstr*,  
> VNInfo*>& NewVNs,
> @@ -593,6 +594,7 @@
>                                                  
> MachineBasicBlock::iterator use,
>                                                           
> MachineBasicBlock* MBB,
>                                                                 
> LiveInterval* LI,
> +                                       SmallPtrSet<MachineInstr*,  
> 4>& Visited,
>              DenseMap<MachineBasicBlock*, SmallPtrSet<MachineInstr*,  
> 2> >& Defs,
>              DenseMap<MachineBasicBlock*, SmallPtrSet<MachineInstr*,  
> 2> >& Uses,
>                                        DenseMap<MachineInstr*,  
> VNInfo*>& NewVNs,
> @@ -600,7 +602,9 @@
>                                  DenseMap<MachineBasicBlock*,  
> VNInfo*>& Phis,
>                                               bool toplevel, bool  
> intrablock) {
>   // Return memoized result if it's available.
> -  if (intrablock && NewVNs.count(use))
> +  if (toplevel && Visited.count(use) && NewVNs.count(use))
> +    return NewVNs[use];
> +  else if (!toplevel && intrablock && NewVNs.count(use))
>     return NewVNs[use];
>   else if (!intrablock && LiveOut.count(MBB))
>     return LiveOut[MBB];
> @@ -624,8 +628,8 @@
>
>     if (MBB->pred_size() == 1) {
>       Phis[MBB] = ret = PerformPHIConstruction((*MBB->pred_begin())- 
> >end(),
> -                                          *(MBB->pred_begin()), LI,  
> Defs,
> -                                          Uses, NewVNs, LiveOut,  
> Phis,
> +                                          *(MBB->pred_begin()), LI,  
> Visited,
> +                                          Defs, Uses, NewVNs,  
> LiveOut, Phis,
>                                           false, false);
>       unsigned EndIndex = 0;
>       if (intrablock) {
> @@ -646,9 +650,9 @@
>       DenseMap<MachineBasicBlock*, VNInfo*> IncomingVNs;
>       for (MachineBasicBlock::pred_iterator PI = MBB->pred_begin(),
>            PE = MBB->pred_end(); PI != PE; ++PI) {
> -        VNInfo* Incoming = PerformPHIConstruction((*PI)->end(),  
> *PI, LI, Defs,
> -                                            Uses, NewVNs, LiveOut,  
> Phis,
> -                                            false, false);
> +        VNInfo* Incoming = PerformPHIConstruction((*PI)->end(),  
> *PI, LI,
> +                                            Visited, Defs, Uses,  
> NewVNs,
> +                                            LiveOut, Phis, false,  
> false);
>         if (Incoming != 0)
>           IncomingVNs[*PI] = Incoming;
>       }
> @@ -732,7 +736,7 @@
>
>     // Now, recursively phi construct the VNInfo for the use we found,
>     // and then extend it to include the instruction we care about
> -    ret = PerformPHIConstruction(walker, MBB, LI, Defs, Uses,
> +    ret = PerformPHIConstruction(walker, MBB, LI, Visited, Defs,  
> Uses,
>                                  NewVNs, LiveOut, Phis, false, true);
>
>     // FIXME: Need to set kills properly for inter-block stuff.
> @@ -789,7 +793,7 @@
>     if (foundDef)
>       ret = NewVNs[walker];
>     else
> -      ret = PerformPHIConstruction(walker, MBB, LI, Defs, Uses,
> +      ret = PerformPHIConstruction(walker, MBB, LI, Visited, Defs,  
> Uses,
>                                    NewVNs, LiveOut, Phis, false,  
> true);
>
>     if (foundUse && LI->isKill(ret, StartIndex))
> @@ -803,8 +807,11 @@
>
>   // Memoize results so we don't have to recompute them.
>   if (!intrablock) LiveOut[MBB] = ret;
> -  else NewVNs[use] = ret;
> -
> +  else {
> +    NewVNs[use] = ret;
> +    Visited.insert(use);
> +  }
> +
>   return ret;
> }
>
> @@ -831,7 +838,14 @@
>     unsigned DefIdx = LIs->getInstructionIndex(&*DI);
>     DefIdx = LiveIntervals::getDefIndex(DefIdx);
>
> -    VNInfo* NewVN = LI->getNextValue(DefIdx, /*FIXME*/ 0, Alloc);
> +    VNInfo* NewVN = LI->getNextValue(DefIdx, 0, Alloc);
> +
> +    // If the def is a move, set the copy field.
> +    unsigned source, dest;
> +    if (TII->isMoveInstr(*DI, source, dest))
> +      if (dest == LI->reg)
> +        NewVN->copy = &*DI;
> +
>     NewVNs[&*DI] = NewVN;
>   }
>
> @@ -845,9 +859,10 @@
>   // the way.
>   DenseMap<MachineBasicBlock*, VNInfo*> LiveOut;
>   DenseMap<MachineBasicBlock*, VNInfo*> Phis;
> +  SmallPtrSet<MachineInstr*, 4> Visited;
>   for (MachineRegisterInfo::use_iterator UI = MRI->use_begin(LI->reg),
>        UE = MRI->use_end(); UI != UE; ++UI) {
> -    PerformPHIConstruction(&*UI, UI->getParent(), LI, Defs,
> +    PerformPHIConstruction(&*UI, UI->getParent(), LI, Visited, Defs,
>                            Uses, NewVNs, LiveOut, Phis, true, true);
>   }
>
> @@ -1116,7 +1131,6 @@
>   }
>
>   RepairLiveInterval(CurrLI, ValNo, DefMI, RestoreIdx);
> -
>   ++NumSplits;
>   ++NumRemats;
>   return true;
>
>
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