[llvm-commits] [llvm] r52475 - /llvm/trunk/lib/CodeGen/LiveIntervalAnalysis.cpp

[Evan Cheng]

On Jun 18, 2008, at 5:10 PM, Owen Anderson wrote:

> Author: resistor
> Date: Wed Jun 18 19:10:49 2008
> New Revision: 52475
>
> URL: http://llvm.org/viewvc/llvm-project?rev=52475&view=rev
> Log:
> Insert empty slots into the instruction numbering in live intervals,  
> so that we can more easily
> add new instructions.
>
> Modified:
>    llvm/trunk/lib/CodeGen/LiveIntervalAnalysis.cpp
>
> Modified: llvm/trunk/lib/CodeGen/LiveIntervalAnalysis.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/LiveIntervalAnalysis.cpp?rev=52475&r1=52474&r2=52475&view=diff
>
> = 
> = 
> = 
> = 
> = 
> = 
> = 
> = 
> ======================================================================
> --- llvm/trunk/lib/CodeGen/LiveIntervalAnalysis.cpp (original)
> +++ llvm/trunk/lib/CodeGen/LiveIntervalAnalysis.cpp Wed Jun 18  
> 19:10:49 2008
> @@ -78,6 +78,7 @@
>
> void LiveIntervals::computeNumbering() {
>   Index2MiMap OldI2MI = i2miMap_;
> +  std::vector<IdxMBBPair> OldI2MBB = Idx2MBBMap;
>
>   Idx2MBBMap.clear();
>   MBB2IdxMap.clear();
> @@ -93,19 +94,22 @@
>        MBB != E; ++MBB) {
>     unsigned StartIdx = MIIndex;
>
> +    // Insert an empty slot at the beginning of each block.
> +    MIIndex += InstrSlots::NUM;
> +    i2miMap_.push_back(0);
> +
>     for (MachineBasicBlock::iterator I = MBB->begin(), E = MBB->end();
>          I != E; ++I) {
>       bool inserted = mi2iMap_.insert(std::make_pair(I,  
> MIIndex)).second;
>       assert(inserted && "multiple MachineInstr -> index mappings");
>       i2miMap_.push_back(I);
>       MIIndex += InstrSlots::NUM;
> -    }
> -
> -    if (StartIdx == MIIndex) {
> -      // Empty MBB
> +
> +      // Insert an empty slot after every instruction.
>       MIIndex += InstrSlots::NUM;
>       i2miMap_.push_back(0);
>     }
> +
>     // Set the MBB2IdxMap entry for this MBB.
>     MBB2IdxMap[MBB->getNumber()] = std::make_pair(StartIdx, MIIndex  
> - 1);
>     Idx2MBBMap.push_back(std::make_pair(StartIdx, MBB));
> @@ -113,90 +117,82 @@
>   std::sort(Idx2MBBMap.begin(), Idx2MBBMap.end(), Idx2MBBCompare());
>
>   if (!OldI2MI.empty())
> -    for (iterator I = begin(), E = end(); I != E; ++I)
> -      for (LiveInterval::iterator LI = I->second.begin(), LE = I- 
> >second.end();
> -           LI != LE; ++LI) {
> +    for (iterator OI = begin(), OE = end(); OI != OE; ++OI)
> +      for (LiveInterval::iterator LI = OI->second.begin(),
> +           LE = OI->second.end(); LI != LE; ++LI) {
>
>         // Remap the start index of the live range to the  
> corresponding new
>         // number, or our best guess at what it _should_ correspond  
> to if the
>         // original instruction has been erased.  This is either the  
> following
>         // instruction or its predecessor.
> +        unsigned index = LI->start / InstrSlots::NUM;
>         unsigned offset = LI->start % InstrSlots::NUM;
> -        if (OldI2MI[LI->start / InstrSlots::NUM])
> -          LI->start = mi2iMap_[OldI2MI[LI->start /  
> InstrSlots::NUM]] + offset;
> -        else {
> -          unsigned i = 0;
> -          MachineInstr* newInstr = 0;
> -          do {
> -            newInstr = OldI2MI[LI->start / InstrSlots::NUM + i];
> -            i++;
> -          } while (!newInstr);
> +        if (offset == InstrSlots::LOAD) {
> +          std::vector<IdxMBBPair>::const_iterator I =
> +                  std::lower_bound(OldI2MBB.begin(),  
> OldI2MBB.end(), index);
> +          // Take the pair containing the index
> +          std::vector<IdxMBBPair>::const_iterator J =
> +                    ((I != OldI2MBB.end() && I->first > index) ||
> +                    (I == OldI2MBB.end() && OldI2MBB.size()>0)) ?  
> (I-1): I;

I have hard time following this. The code was so easy to understand  
before! :-) Can you factor these 6-7 lines out and add a bit of  
comments? I see it's used at at least two places.

Thanks.

Evan

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