[llvm-commits] [llvm] r53390 - /llvm/trunk/lib/CodeGen/RegAllocLocal.cpp

[Chris Lattner]

On Jul 9, 2008, at 6:56 PM, Owen Anderson wrote:

> Author: resistor
> Date: Wed Jul  9 20:56:35 2008
> New Revision: 53390
>
> URL: http://llvm.org/viewvc/llvm-project?rev=53390&view=rev
> Log:
> Use DenseMap instead of std::map in local register allocation.  This  
> improves the time on instcombine from .31s to .22s

nice!

>       if (MO.isReg() && MO.getReg() && MO.isDef()) {
> -        std::map<unsigned, std::pair<MachineInstr*, unsigned>  
> >::iterator
> +        DenseMap<unsigned, std::pair<MachineInstr*, unsigned>  
> >::iterator
>           last = LastUseDef.find(MO.getReg());

Neither of these loops will care that iteration will be non- 
deterministic, will they?

-Chris

>
>         if (last != LastUseDef.end()) {
>           // Check if this is a two address instruction.  If so, then
> @@ -633,7 +646,7 @@
>
>   // Finally, loop over the final use/def of each reg
>   // in the block and determine if it is dead.
> -  for (std::map<unsigned, std::pair<MachineInstr*, unsigned>  
> >::iterator
> +  for (DenseMap<unsigned, std::pair<MachineInstr*, unsigned>  
> >::iterator
>        I = LastUseDef.begin(), E = LastUseDef.end(); I != E; ++I) {
>     MachineInstr* MI = I->second.first;
>     unsigned idx = I->second.second;
>
>
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