[llvm-commits] [llvm] r52951 - in /llvm/trunk: include/llvm/Target/TargetRegisterInfo.h utils/TableGen/RegisterInfoEmitter.cpp

[Chris Lattner]

On Jul 1, 2008, at 12:02 AM, Owen Anderson wrote:

> Author: resistor
> Date: Tue Jul  1 02:02:30 2008
> New Revision: 52951
>
> URL: http://llvm.org/viewvc/llvm-project?rev=52951&view=rev
> Log:
> Implement suggestions from Chris:
>  - Use a more accurate heuristic for the size of the hashtable.
>  - Use bitwise and instead of modulo since the size is a power of two.
>  - Use new[] instead of malloc().

Thanks Owen!  BTW, is there a reason you use malloc/free (now new/ 
delete) instead of a std::vector?

-Chris

>
>
> Modified:
>    llvm/trunk/include/llvm/Target/TargetRegisterInfo.h
>    llvm/trunk/utils/TableGen/RegisterInfoEmitter.cpp
>
> Modified: llvm/trunk/include/llvm/Target/TargetRegisterInfo.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Target/TargetRegisterInfo.h?rev=52951&r1=52950&r2=52951&view=diff
>
> = 
> = 
> = 
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> ======================================================================
> --- llvm/trunk/include/llvm/Target/TargetRegisterInfo.h (original)
> +++ llvm/trunk/include/llvm/Target/TargetRegisterInfo.h Tue Jul  1  
> 02:02:30 2008
> @@ -413,14 +413,14 @@
>   ///
>   bool isSubRegister(unsigned regA, unsigned regB) const {
>     // SubregHash is a simple quadratically probed hash table.
> -    size_t index = (regA + regB * 37) % SubregHashSize;
> +    size_t index = (regA + regB * 37) & (SubregHashSize-1);
>     unsigned ProbeAmt = 2;
>     while (SubregHash[index*2] != 0 &&
>            SubregHash[index*2+1] != 0) {
>       if (SubregHash[index*2] == regA && SubregHash[index*2+1] ==  
> regB)
>         return true;
>
> -      index = (index + ProbeAmt) % SubregHashSize;
> +      index = (index + ProbeAmt) & (SubregHashSize-1);
>       ProbeAmt += 2;
>     }
>
>
> Modified: llvm/trunk/utils/TableGen/RegisterInfoEmitter.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/utils/TableGen/RegisterInfoEmitter.cpp?rev=52951&r1=52950&r2=52951&view=diff
>
> = 
> = 
> = 
> = 
> = 
> = 
> = 
> = 
> ======================================================================
> --- llvm/trunk/utils/TableGen/RegisterInfoEmitter.cpp (original)
> +++ llvm/trunk/utils/TableGen/RegisterInfoEmitter.cpp Tue Jul  1  
> 02:02:30 2008
> @@ -466,15 +466,16 @@
>   // Print the SubregHashTable, a simple quadratically probed
>   // hash table for determining if a register is a subregister
>   // of another register.
> -  unsigned SubregHashTableSize = NextPowerOf2(2 * Regs.size());
> -  unsigned* SubregHashTable =
> -                  (unsigned*)malloc(2 * SubregHashTableSize *  
> sizeof(unsigned));
> -  for (unsigned i = 0; i < SubregHashTableSize * 2; ++i)
> -    SubregHashTable[i] = ~0U;
> -
> +  unsigned NumSubRegs = 0;
>   std::map<Record*, unsigned> RegNo;
> -  for (unsigned i = 0, e = Regs.size(); i != e; ++i)
> +  for (unsigned i = 0, e = Regs.size(); i != e; ++i) {
>     RegNo[Regs[i].TheDef] = i;
> +    NumSubRegs += RegisterSubRegs[Regs[i].TheDef].size();
> +  }
> +
> +  unsigned SubregHashTableSize = NextPowerOf2(2 * NumSubRegs);
> +  unsigned* SubregHashTable = new unsigned[2 * SubregHashTableSize];
> +  std::fill(SubregHashTable, SubregHashTable + 2 *  
> SubregHashTableSize, ~0U);
>
>   for (unsigned i = 0, e = Regs.size(); i != e; ++i) {
>     Record* R = Regs[i].TheDef;
> @@ -484,11 +485,11 @@
>       // We have to increase the indices of both registers by one when
>       // computing the hash because, in the generated code, there
>       // will be an extra empty slot at register 0.
> -      size_t index = ((i+1) + (RegNo[RJ]+1) * 37) %  
> SubregHashTableSize;
> +      size_t index = ((i+1) + (RegNo[RJ]+1) * 37) &  
> (SubregHashTableSize-1);
>       unsigned ProbeAmt = 2;
>       while (SubregHashTable[index*2] != ~0U &&
>              SubregHashTable[index*2+1] != ~0U) {
> -        index = (index + ProbeAmt) % SubregHashTableSize;
> +        index = (index + ProbeAmt) & (SubregHashTableSize-1);
>         ProbeAmt += 2;
>       }
>
>
>
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