寻找一个函数的GHC程序集(finding GHC assembly for a function)

 我想确定GHC为给定函数生成的组件。 
 
 这里，例如，是一些代码（应该）在一个字中旋转位 - 它将位0移动到位12，位12到14，位14移回0，类似地位置1,18,13和6。 
 
 在ghc -O2 -S ...生成的.S文件中查找为rot0cw生成的汇编的最佳方法是什么？ 
 
 我读过这个答案 ，但是在程序集输出中没有看到... ..._rot0cw_closure 。 
 
import Data.Bits
import Data.Int (Int64)
import Text.Printf
import System.Environment

{-# INLINE maskbits #-}
-- set in word v the bits of b corresponding to the mask m
-- assume a bit in b is zero if not in the mask
maskbits v m b = (v .&. (complement m) .|. b)

{-# INLINE tb #-}
-- transfer bit i of word v to bit j of word m; assume bit j of m is 0
tb v i j m =  m .|. (rotate  (v .&. (bit i)) (j-i))

rot0cw :: Int64 -> Int64
rot0cw v = maskbits (maskbits v m1 b1) m2 b2
  where
    m1 = 0x0000005005
    b1 = tb v 0 2 . tb v 2 14 . tb v 14 12 . tb v 12 0 $ 0
    m2 = 0x0000002142
    b2 = tb v 1 8 . tb v 8 13 . tb v 13 6 . tb v 6 1 $ 0

showBits v = 
  let set = [ i | i <- [0..35], testBit v i ]
  in "bits set: " ++ (unwords $ map show set)

main = do
  (arg0:_) <- getArgs
  let v = read arg0 
  -- let v = 0x0000000005
  let v' = rot0cw v
  putStrLn $ printf "v  = 0x%010x = %12d %s" v v (showBits v)
  putStrLn $ printf "v' = 0x%010x = %12d %s" v' v' (showBits v')

I'd like to identify what assembly GHC produces for a given function.
 
Here, for example, is some code which (should) rotate bits around in a word - it moves bit 0 to bit 12, bit 12 to 14, bit 14 back to 0 and similarly for the positions 1, 18, 13 and 6.
 
What's the best way to go about finding the assembly generated for rot0cw in the .S file produced by ghc -O2 -S ...?
 
I've read this answer, but I don't see any ..._rot0cw_closure in the assembly output.
 
import Data.Bits
import Data.Int (Int64)
import Text.Printf
import System.Environment

{-# INLINE maskbits #-}
-- set in word v the bits of b corresponding to the mask m
-- assume a bit in b is zero if not in the mask
maskbits v m b = (v .&. (complement m) .|. b)

{-# INLINE tb #-}
-- transfer bit i of word v to bit j of word m; assume bit j of m is 0
tb v i j m =  m .|. (rotate  (v .&. (bit i)) (j-i))

rot0cw :: Int64 -> Int64
rot0cw v = maskbits (maskbits v m1 b1) m2 b2
  where
    m1 = 0x0000005005
    b1 = tb v 0 2 . tb v 2 14 . tb v 14 12 . tb v 12 0 $ 0
    m2 = 0x0000002142
    b2 = tb v 1 8 . tb v 8 13 . tb v 13 6 . tb v 6 1 $ 0

showBits v = 
  let set = [ i | i <- [0..35], testBit v i ]
  in "bits set: " ++ (unwords $ map show set)

main = do
  (arg0:_) <- getArgs
  let v = read arg0 
  -- let v = 0x0000000005
  let v' = rot0cw v
  putStrLn $ printf "v  = 0x%010x = %12d %s" v v (showBits v)
  putStrLn $ printf "v' = 0x%010x = %12d %s" v' v' (showBits v')

原文：https://stackoverflow.com/questions/27495041