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|
--
-- (c) The University of Glasgow 2003-2006
--
-- Functions for constructing bitmaps, which are used in various
-- places in generated code (stack frame liveness masks, function
-- argument liveness masks, SRT bitmaps).
{-# OPTIONS -fno-warn-tabs #-}
-- The above warning supression flag is a temporary kludge.
-- While working on this module you are encouraged to remove it and
-- detab the module (please do the detabbing in a separate patch). See
-- http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#TabsvsSpaces
-- for details
module Bitmap (
Bitmap, mkBitmap,
intsToBitmap, intsToReverseBitmap,
mAX_SMALL_BITMAP_SIZE,
seqBitmap,
) where
#include "HsVersions.h"
#include "../includes/MachDeps.h"
import SMRep
import DynFlags
import Util
import Data.Bits
{-|
A bitmap represented by a sequence of 'StgWord's on the /target/
architecture. These are used for bitmaps in info tables and other
generated code which need to be emitted as sequences of StgWords.
-}
type Bitmap = [StgWord]
-- | Make a bitmap from a sequence of bits
mkBitmap :: DynFlags -> [Bool] -> Bitmap
mkBitmap _ [] = []
mkBitmap dflags stuff = chunkToBitmap dflags chunk : mkBitmap dflags rest
where (chunk, rest) = splitAt (wORD_SIZE_IN_BITS dflags) stuff
chunkToBitmap :: DynFlags -> [Bool] -> StgWord
chunkToBitmap dflags chunk =
foldr (.|.) (toStgWord dflags 0) [ toStgWord dflags 1 `shiftL` n | (True,n) <- zip chunk [0..] ]
-- | Make a bitmap where the slots specified are the /ones/ in the bitmap.
-- eg. @[0,1,3], size 4 ==> 0xb@.
--
-- The list of @Int@s /must/ be already sorted.
intsToBitmap :: DynFlags -> Int -> [Int] -> Bitmap
intsToBitmap dflags size slots{- must be sorted -}
| size <= 0 = []
| otherwise =
(foldr (.|.) (toStgWord dflags 0) (map (toStgWord dflags 1 `shiftL`) these)) :
intsToBitmap dflags (size - wORD_SIZE_IN_BITS dflags)
(map (\x -> x - wORD_SIZE_IN_BITS dflags) rest)
where (these,rest) = span (< wORD_SIZE_IN_BITS dflags) slots
-- | Make a bitmap where the slots specified are the /zeros/ in the bitmap.
-- eg. @[0,1,3], size 4 ==> 0x4@ (we leave any bits outside the size as zero,
-- just to make the bitmap easier to read).
--
-- The list of @Int@s /must/ be already sorted and duplicate-free.
intsToReverseBitmap :: DynFlags -> Int -> [Int] -> Bitmap
intsToReverseBitmap dflags size slots{- must be sorted -}
| size <= 0 = []
| otherwise =
(foldr xor (toStgWord dflags init) (map (toStgWord dflags 1 `shiftL`) these)) :
intsToReverseBitmap dflags (size - wORD_SIZE_IN_BITS dflags)
(map (\x -> x - wORD_SIZE_IN_BITS dflags) rest)
where (these,rest) = span (< wORD_SIZE_IN_BITS dflags) slots
init
| size >= wORD_SIZE_IN_BITS dflags = -1
| otherwise = (1 `shiftL` size) - 1
{- |
Magic number, must agree with @BITMAP_BITS_SHIFT@ in InfoTables.h.
Some kinds of bitmap pack a size\/bitmap into a single word if
possible, or fall back to an external pointer when the bitmap is too
large. This value represents the largest size of bitmap that can be
packed into a single word.
-}
mAX_SMALL_BITMAP_SIZE :: DynFlags -> Int
mAX_SMALL_BITMAP_SIZE dflags
| wORD_SIZE dflags == 4 = 27
| otherwise = 58
seqBitmap :: Bitmap -> a -> a
seqBitmap = seqList
|
