[PATCH][Review Requested][Compilation Time]

[Craig Topper]

SmallPtrSet only does a linear scan when the space is small. Once the set
grows beyond the small size then it should be O(log n). So I would wonder
if the SmallPtrSets that have a size of 16 actually see a real performance
increase from this change. I also wonder if shrinking the existing
SmallPtrSets to less than 64 might show gains since they would fall over to
logarithmic behavior sooner.

On Thu, Jan 31, 2013 at 8:15 PM, Craig Topper <craig.topper at gmail.com>wrote:

> I haven't looked in detail, but there are many 80 column violations in
> this patch.
>
> On Thu, Jan 31, 2013 at 6:28 PM, Nowicki, Tyler <tyler.nowicki at intel.com>wrote:
>
>>  Hi,****
>>
>> ** **
>>
>> This patch aims to improve compile time performance by replacing uses of
>> SmallPtrSet in SelectionDAG with a new class called FlagVector. The
>> SmallPtrSet is used for keeping track of SDNode pointers. For example, in
>> DAGCombiner.cpp it is used to keep a track of each unique SDNode in the
>> working list. Performing an insert into a SmallPtrSet causes it to loop
>> over all entries to determine if the pointer has been stored before. This
>> patch avoids this O(N) operation by given each SDNode a unique number that
>> is then used to index into the FlagVector. Since a SelectionDAG is
>> instantiated for each function, its FlagVector doesn’t grow prohibitively
>> large.****
>>
>> ** **
>>
>> Although FlagVector may appear similar to SmallVector it differs slightly
>> in the semantics of its array operator which will grow the vector to
>> contain the SDNode index. Suggestions are welcome on potential reuses of
>> SmallVector, however, it is very convenient to have an array operator which
>> automatically grows the vector. We have another patch coming which uses the
>> FlagVector in the same manner.****
>>
>> ** **
>>
>> This patch is part of a series of compile time improvements. Although
>> these were originally produced by our colleague Wan Xiaofei, our team
>> consisting of preston.gurd at intel.com; sriram.murali at intel.com and
>> myself, are assuming all responsibility for this work.****
>>
>> ** **
>>
>> PLEASE REVIEW. Thanks!****
>>
>> ** **
>>
>> Tyler Nowicki****
>>
>> Intel****
>>
>> ** **
>>
>> *Benchmark*
>>
>> *Trunk*
>>
>> *Numbering.SD*
>>
>> *401.bzip2*
>>
>> 74.21 ****
>>
>> 72.34
>>
>> *403.gcc*
>>
>> 73.88 ****
>>
>> 72.01
>>
>> *429.mcf*
>>
>> 72.80 ****
>>
>> 71.22
>>
>> *433.milc*
>>
>> 78.78 ****
>>
>> 76.75
>>
>> *444.namd*
>>
>> 94.73 ****
>>
>> 93.37
>>
>> *445.gobmk*
>>
>> 36.28 ****
>>
>> 35.38
>>
>> *450.soplex*
>>
>> 71.41 ****
>>
>> 69.66
>>
>> *456.hmmer*
>>
>> 86.80 ****
>>
>> 84.78
>>
>> *458.sjeng*
>>
>> 96.38 ****
>>
>> 94.44
>>
>> *464.h264ref*
>>
>> 87.61 ****
>>
>> 85.93
>>
>> *470.lbm*
>>
>> 68.95 ****
>>
>> 67.97
>>
>> *471.omnetpp*
>>
>> 89.07 ****
>>
>> 86.91
>>
>> *bitmnp01*
>>
>> 84.06 ****
>>
>> 82.61
>>
>> *cjpegv2data6*
>>
>> 59.70 ****
>>
>> 58.42
>>
>> *idctrn01*
>>
>> 40.18 ****
>>
>> 39.08
>>
>> *libquake2*
>>
>> 48.48 ****
>>
>> 47.10
>>
>> *libquake_portable*
>>
>> 63.54 ****
>>
>> 62.03
>>
>> *libxcsoar*
>>
>> 47.44 ****
>>
>> 45.92
>>
>> *linpack*
>>
>> 142.14 ****
>>
>> 140.99
>>
>> *matrix01*
>>
>> 24.75 ****
>>
>> 24.11
>>
>> *nbench*
>>
>> 108.04 ****
>>
>> 106.59
>>
>> *tblook01*
>>
>> 44.03 ****
>>
>> 43.30
>>
>> *ttsprk01*
>>
>> 39.23 ****
>>
>> 38.23
>>
>> *Geomean*
>>
>> 65.85 ****
>>
>> 64.41
>>
>> ** **
>>
>> *401.bzip2*
>>
>> 100.00 ****
>>
>> 102.59
>>
>> *403.gcc*
>>
>> 100.00 ****
>>
>> 102.60
>>
>> *429.mcf*
>>
>> 100.00 ****
>>
>> 102.22
>>
>> *433.milc*
>>
>> 100.00 ****
>>
>> 102.64
>>
>> *444.namd*
>>
>> 100.00 ****
>>
>> 101.46
>>
>> *445.gobmk*
>>
>> 100.00 ****
>>
>> 102.54
>>
>> *450.soplex*
>>
>> 100.00 ****
>>
>> 102.51
>>
>> *456.hmmer*
>>
>> 100.00 ****
>>
>> 102.38
>>
>> *458.sjeng*
>>
>> 100.00 ****
>>
>> 102.05
>>
>> *464.h264ref*
>>
>> 100.00 ****
>>
>> 101.96
>>
>> *470.lbm*
>>
>> 100.00 ****
>>
>> 101.44
>>
>> *471.omnetpp*
>>
>> 100.00 ****
>>
>> 102.49
>>
>> *bitmnp01*
>>
>> 100.00 ****
>>
>> 101.76
>>
>> *cjpegv2data6*
>>
>> 100.00 ****
>>
>> 102.19
>>
>> *idctrn01*
>>
>> 100.00 ****
>>
>> 102.81
>>
>> *libquake2*
>>
>> 100.00 ****
>>
>> 102.93
>>
>> *libquake_portable*
>>
>> 100.00 ****
>>
>> 102.43
>>
>> *libxcsoar*
>>
>> 100.00 ****
>>
>> 103.31
>>
>> *linpack*
>>
>> 100.00 ****
>>
>> 100.82
>>
>> *matrix01*
>>
>> 100.00 ****
>>
>> 102.65
>>
>> *nbench*
>>
>> 100.00 ****
>>
>> 101.36
>>
>> *tblook01*
>>
>> 100.00 ****
>>
>> 101.69
>>
>> *ttsprk01*
>>
>> 100.00 ****
>>
>> 102.62
>>
>> *Geomean*
>>
>> 100.00 ****
>>
>> 102.24
>>
>> ** **
>>
>> _______________________________________________
>> llvm-commits mailing list
>> llvm-commits at cs.uiuc.edu
>> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
>>
>>
>
>
> --
> ~Craig




-- 
~Craig
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