1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
|
--
-- (c) The University of Glasgow 2003
--
-- Functions for constructing bitmaps, which are used in various
-- places in generated code (stack frame liveness masks, function
-- argument liveness masks, SRT bitmaps).
module Bitmap (
Bitmap, mkBitmap,
intsToBitmap, intsToReverseBitmap,
mAX_SMALL_BITMAP_SIZE
) where
#include "HsVersions.h"
#include "../includes/MachDeps.h"
import SMRep
import Constants
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 :: [Bool] -> Bitmap
mkBitmap [] = []
mkBitmap stuff = chunkToBitmap chunk : mkBitmap rest
where (chunk, rest) = splitAt wORD_SIZE_IN_BITS stuff
chunkToBitmap :: [Bool] -> StgWord
chunkToBitmap chunk =
foldr (.|.) 0 [ 1 `shiftL` n | (True,n) <- zip chunk [0..] ]
-- | Make a bitmap where the slots specified are the /ones/ in the bitmap.
-- eg. @[1,2,4], size 4 ==> 0xb@.
--
-- The list of @Int@s /must/ be already sorted.
intsToBitmap :: Int -> [Int] -> Bitmap
intsToBitmap size slots{- must be sorted -}
| size <= 0 = []
| otherwise =
(foldr (.|.) 0 (map (1 `shiftL`) these)) :
intsToBitmap (size - wORD_SIZE_IN_BITS)
(map (\x -> x - wORD_SIZE_IN_BITS) rest)
where (these,rest) = span (<wORD_SIZE_IN_BITS) slots
-- | Make a bitmap where the slots specified are the /zeros/ in the bitmap.
-- eg. @[1,2,4], size 4 ==> 0x8@ (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.
intsToReverseBitmap :: Int -> [Int] -> Bitmap
intsToReverseBitmap size slots{- must be sorted -}
| size <= 0 = []
| otherwise =
(foldr xor init (map (1 `shiftL`) these)) :
intsToReverseBitmap (size - wORD_SIZE_IN_BITS)
(map (\x -> x - wORD_SIZE_IN_BITS) rest)
where (these,rest) = span (<wORD_SIZE_IN_BITS) slots
init
| size >= wORD_SIZE_IN_BITS = complement 0
| 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 :: Int
mAX_SMALL_BITMAP_SIZE | wORD_SIZE == 4 = 27
| otherwise = 58
|
