compiler/nativeGen/RegAlloc/Graph/TrivColorable.hs¶
Note [accSqueeze]¶
BL 2007/09 Doing a nice fold over the UniqSet makes trivColorable use 32% of total compile time and 42% of total alloc when compiling SHA1.hs from darcs. Therefore the UniqFM is made non-abstract and we use custom fold.
MS 2010/04 When converting UniqFM to use Data.IntMap, the fold cannot use UniqFM internal representation any more. But it is imperative that the accSqueeze stops the folding if the count gets greater or equal to maxCount. We thus convert UniqFM to a (lazy) list, do the fold and stops if necessary, which was the most efficient variant tried. Benchmark compiling 10-times SHA1.hs follows. (original = previous implementation, folding = fold of the whole UFM,
lazyFold = the current implementation, hackFold = using internal representation of Data.IntMap)
original folding hackFold lazyFold
- -O -fasm (used everywhere) 31.509s 30.387s 30.791s 30.603s
- 100.00% 96.44% 97.72% 97.12%
-fregs-graph 67.938s 74.875s 62.673s 64.679s 100.00% 110.21% 92.25% 95.20% -fregs-iterative 89.761s 143.913s 81.075s 86.912s 100.00% 160.33% 90.32% 96.83% -fnew-codegen 38.225s 37.142s 37.551s 37.119s 100.00% 97.17% 98.24% 97.11%
- -fnew-codegen -fregs-graph 91.786s 91.51s 87.368s 86.88s
- 100.00% 99.70% 95.19% 94.65%
- -fnew-codegen -fregs-iterative 206.72s 343.632s 194.694s 208.677s
- 100.00% 166.23% 94.18% 100.95%
