Produce new-style Cmm from the Cmm parser
[ghc.git] / includes / rts / Constants.h
1 /* ----------------------------------------------------------------------------
2 *
3 * (c) The GHC Team, 1998-2009
4 *
5 * Constants
6 *
7 * NOTE: this information is used by both the compiler and the RTS.
8 * Some of it is tweakable, and some of it must be kept up to date
9 * with various other parts of the system.
10 *
11 * Constants which are derived automatically from other definitions in
12 * the system (eg. structure sizes) are generated into the file
13 * DerivedConstants.h by a C program (mkDerivedConstantsHdr).
14 *
15 * To understand the structure of the RTS headers, see the wiki:
16 * http://hackage.haskell.org/trac/ghc/wiki/Commentary/SourceTree/Includes
17 *
18 * -------------------------------------------------------------------------- */
19
20 #ifndef RTS_CONSTANTS_H
21 #define RTS_CONSTANTS_H
22
23 /* -----------------------------------------------------------------------------
24 Minimum closure sizes
25
26 This is the minimum number of words in the payload of a
27 heap-allocated closure, so that the closure has enough room to be
28 overwritten with a forwarding pointer during garbage collection.
29 -------------------------------------------------------------------------- */
30
31 #define MIN_PAYLOAD_SIZE 1
32
33 /* -----------------------------------------------------------------------------
34 Constants to do with specialised closure types.
35 -------------------------------------------------------------------------- */
36
37 /* We have some pre-compiled selector thunks defined in rts/StgStdThunks.hc.
38 * This constant defines the highest selectee index that we can replace with a
39 * reference to the pre-compiled code.
40 */
41
42 #define MAX_SPEC_SELECTEE_SIZE 15
43
44 /* Vector-apply thunks. These thunks just push their free variables
45 * on the stack and enter the first one. They're a bit like PAPs, but
46 * don't have a dynamic size. We've pre-compiled a few to save
47 * space.
48 */
49
50 #define MAX_SPEC_AP_SIZE 7
51
52 /* Specialised FUN/THUNK/CONSTR closure types */
53
54 #define MAX_SPEC_THUNK_SIZE 2
55 #define MAX_SPEC_FUN_SIZE 2
56 #define MAX_SPEC_CONSTR_SIZE 2
57
58 /* Range of built-in table of static small int-like and char-like closures.
59 *
60 * NB. This corresponds with the number of actual INTLIKE/CHARLIKE
61 * closures defined in rts/StgMiscClosures.cmm.
62 */
63 #define MAX_INTLIKE 16
64 #define MIN_INTLIKE (-16)
65
66 #define MAX_CHARLIKE 255
67 #define MIN_CHARLIKE 0
68
69 /* Each byte in the card table for an StgMutaArrPtrs covers
70 * (1<<MUT_ARR_PTRS_CARD_BITS) elements in the array. To find a good
71 * value for this, I used the benchmarks nofib/gc/hash,
72 * nofib/gc/graph, and nofib/gc/gc_bench.
73 */
74 #define MUT_ARR_PTRS_CARD_BITS 7
75
76 /* -----------------------------------------------------------------------------
77 STG Registers.
78
79 Note that in MachRegs.h we define how many of these registers are
80 *real* machine registers, and not just offsets in the Register Table.
81 -------------------------------------------------------------------------- */
82
83 #define MAX_VANILLA_REG 10
84 #define MAX_FLOAT_REG 4
85 #define MAX_DOUBLE_REG 2
86 #define MAX_LONG_REG 1
87
88 /* -----------------------------------------------------------------------------
89 Semi-Tagging constants
90
91 Old Comments about this stuff:
92
93 Tags for indirection nodes and ``other'' (probably unevaluated) nodes;
94 normal-form values of algebraic data types will have tags 0, 1, ...
95
96 @INFO_IND_TAG@ is different from @INFO_OTHER_TAG@ just so we can count
97 how often we bang into indirection nodes; that's all. (WDP 95/11)
98
99 ToDo: find out if we need any of this.
100 -------------------------------------------------------------------------- */
101
102 #define INFO_OTHER_TAG (-1)
103 #define INFO_IND_TAG (-2)
104 #define INFO_FIRST_TAG 0
105
106 /* -----------------------------------------------------------------------------
107 How much C stack to reserve for local temporaries when in the STG
108 world. Used in StgCRun.c.
109 -------------------------------------------------------------------------- */
110
111 #define RESERVED_C_STACK_BYTES (2048 * SIZEOF_LONG)
112
113 /* -----------------------------------------------------------------------------
114 How much Haskell stack space to reserve for the saving of registers
115 etc. in the case of a stack/heap overflow.
116
117 This must be large enough to accomodate the largest stack frame
118 pushed in one of the heap check fragments in HeapStackCheck.hc
119 (ie. currently the generic heap checks - 3 words for StgRetDyn,
120 18 words for the saved registers, see StgMacros.h).
121 -------------------------------------------------------------------------- */
122
123 #define RESERVED_STACK_WORDS 21
124
125 /* -----------------------------------------------------------------------------
126 The limit on the size of the stack check performed when we enter an
127 AP_STACK, in words. See raiseAsync() and bug #1466.
128 -------------------------------------------------------------------------- */
129
130 #define AP_STACK_SPLIM 1024
131
132 /* -----------------------------------------------------------------------------
133 Storage manager constants
134 -------------------------------------------------------------------------- */
135
136 /* The size of a block (2^BLOCK_SHIFT bytes) */
137 #define BLOCK_SHIFT 12
138
139 /* The size of a megablock (2^MBLOCK_SHIFT bytes) */
140 #define MBLOCK_SHIFT 20
141
142 /* -----------------------------------------------------------------------------
143 Bitmap/size fields (used in info tables)
144 -------------------------------------------------------------------------- */
145
146 /* In a 32-bit bitmap field, we use 5 bits for the size, and 27 bits
147 * for the bitmap. If the bitmap requires more than 27 bits, then we
148 * store it in a separate array, and leave a pointer in the bitmap
149 * field. On a 64-bit machine, the sizes are extended accordingly.
150 */
151 #if SIZEOF_VOID_P == 4
152 #define BITMAP_SIZE_MASK 0x1f
153 #define BITMAP_BITS_SHIFT 5
154 #elif SIZEOF_VOID_P == 8
155 #define BITMAP_SIZE_MASK 0x3f
156 #define BITMAP_BITS_SHIFT 6
157 #else
158 #error unknown SIZEOF_VOID_P
159 #endif
160
161 /* -----------------------------------------------------------------------------
162 Lag/Drag/Void constants
163 -------------------------------------------------------------------------- */
164
165 /*
166 An LDV word is divided into 3 parts: state bits (LDV_STATE_MASK), creation
167 time bits (LDV_CREATE_MASK), and last use time bits (LDV_LAST_MASK).
168 */
169 #if SIZEOF_VOID_P == 8
170 #define LDV_SHIFT 30
171 #define LDV_STATE_MASK 0x1000000000000000
172 #define LDV_CREATE_MASK 0x0FFFFFFFC0000000
173 #define LDV_LAST_MASK 0x000000003FFFFFFF
174 #define LDV_STATE_CREATE 0x0000000000000000
175 #define LDV_STATE_USE 0x1000000000000000
176 #else
177 #define LDV_SHIFT 15
178 #define LDV_STATE_MASK 0x40000000
179 #define LDV_CREATE_MASK 0x3FFF8000
180 #define LDV_LAST_MASK 0x00007FFF
181 #define LDV_STATE_CREATE 0x00000000
182 #define LDV_STATE_USE 0x40000000
183 #endif /* SIZEOF_VOID_P */
184
185 /* -----------------------------------------------------------------------------
186 TSO related constants
187 -------------------------------------------------------------------------- */
188
189 /*
190 * Constants for the what_next field of a TSO, which indicates how it
191 * is to be run.
192 */
193 #define ThreadRunGHC 1 /* return to address on top of stack */
194 #define ThreadInterpret 2 /* interpret this thread */
195 #define ThreadKilled 3 /* thread has died, don't run it */
196 #define ThreadComplete 4 /* thread has finished */
197
198 /*
199 * Constants for the why_blocked field of a TSO
200 * NB. keep these in sync with GHC/Conc.lhs: threadStatus
201 */
202 #define NotBlocked 0
203 #define BlockedOnMVar 1
204 #define BlockedOnBlackHole 2
205 #define BlockedOnRead 3
206 #define BlockedOnWrite 4
207 #define BlockedOnDelay 5
208 #define BlockedOnSTM 6
209
210 /* Win32 only: */
211 #define BlockedOnDoProc 7
212
213 /* Only relevant for PAR: */
214 /* blocked on a remote closure represented by a Global Address: */
215 #define BlockedOnGA 8
216 /* same as above but without sending a Fetch message */
217 #define BlockedOnGA_NoSend 9
218 /* Only relevant for THREADED_RTS: */
219 #define BlockedOnCCall 10
220 #define BlockedOnCCall_Interruptible 11
221 /* same as above but permit killing the worker thread */
222
223 /* Involved in a message sent to tso->msg_cap */
224 #define BlockedOnMsgThrowTo 12
225
226 /* The thread is not on any run queues, but can be woken up
227 by tryWakeupThread() */
228 #define ThreadMigrating 13
229
230 /*
231 * These constants are returned to the scheduler by a thread that has
232 * stopped for one reason or another. See typedef StgThreadReturnCode
233 * in TSO.h.
234 */
235 #define HeapOverflow 1 /* might also be StackOverflow */
236 #define StackOverflow 2
237 #define ThreadYielding 3
238 #define ThreadBlocked 4
239 #define ThreadFinished 5
240
241 /*
242 * Flags for the tso->flags field.
243 */
244
245 /*
246 * TSO_LOCKED is set when a TSO is locked to a particular Capability.
247 */
248 #define TSO_LOCKED 2
249
250 /*
251 * TSO_BLOCKEX: the TSO is blocking exceptions
252 *
253 * TSO_INTERRUPTIBLE: the TSO can be interrupted if it blocks
254 * interruptibly (eg. with BlockedOnMVar).
255 *
256 * TSO_STOPPED_ON_BREAKPOINT: the thread is currently stopped in a breakpoint
257 */
258 #define TSO_BLOCKEX 4
259 #define TSO_INTERRUPTIBLE 8
260 #define TSO_STOPPED_ON_BREAKPOINT 16
261
262 /*
263 * Used by the sanity checker to check whether TSOs are on the correct
264 * mutable list.
265 */
266 #define TSO_MARKED 64
267
268 /*
269 * Used to communicate between stackSqueeze() and
270 * threadStackOverflow() that a thread's stack was squeezed and the
271 * stack may not need to be expanded.
272 */
273 #define TSO_SQUEEZED 128
274
275 /*
276 * The number of times we spin in a spin lock before yielding (see
277 * #3758). To tune this value, use the benchmark in #3758: run the
278 * server with -N2 and the client both on a dual-core. Also make sure
279 * that the chosen value doesn't slow down any of the parallel
280 * benchmarks in nofib/parallel.
281 */
282 #define SPIN_COUNT 1000
283
284 /* -----------------------------------------------------------------------------
285 Spare workers per Capability in the threaded RTS
286
287 No more than MAX_SPARE_WORKERS will be kept in the thread pool
288 associated with each Capability.
289 -------------------------------------------------------------------------- */
290
291 #define MAX_SPARE_WORKERS 6
292
293 #endif /* RTS_CONSTANTS_H */