cpp: Use #pragma once instead of #ifndef guards
[ghc.git] / includes / Stg.h
1 /* -----------------------------------------------------------------------------
2 *
3 * (c) The GHC Team, 1998-2009
4 *
5 * Top-level include file for everything required when compiling .hc
6 * code. NOTE: in .hc files, Stg.h must be included *before* any
7 * other headers, because we define some register variables which must
8 * be done before any inline functions are defined (some system
9 * headers have been known to define the odd inline function).
10 *
11 * We generally try to keep as little visible as possible when
12 * compiling .hc files. So for example the definitions of the
13 * InfoTable structs, closure structs and other RTS types are not
14 * visible here. The compiler knows enough about the representations
15 * of these types to generate code which manipulates them directly
16 * with pointer arithmetic.
17 *
18 * In ordinary C code, do not #include this file directly: #include
19 * "Rts.h" instead.
20 *
21 * To understand the structure of the RTS headers, see the wiki:
22 * http://ghc.haskell.org/trac/ghc/wiki/Commentary/SourceTree/Includes
23 *
24 * ---------------------------------------------------------------------------*/
25
26 #pragma once
27
28 #if !(__STDC_VERSION__ >= 199901L)
29 # error __STDC_VERSION__ does not advertise C99 or later
30 #endif
31
32 /*
33 * If we are compiling a .hc file, then we want all the register
34 * variables. This is the what happens if you #include "Stg.h" first:
35 * we assume this is a .hc file, and set IN_STG_CODE==1, which later
36 * causes the register variables to be enabled in stg/Regs.h.
37 *
38 * If instead "Rts.h" is included first, then we are compiling a
39 * vanilla C file. Everything from Stg.h is provided, except that
40 * IN_STG_CODE is not defined, and the register variables will not be
41 * active.
42 */
43 #ifndef IN_STG_CODE
44 # define IN_STG_CODE 1
45
46 // Turn on C99 for .hc code. This gives us the INFINITY and NAN
47 // constants from math.h, which we occasionally need to use in .hc (#1861)
48 # define _ISOC99_SOURCE
49
50 // We need _BSD_SOURCE so that math.h defines things like gamma
51 // on Linux
52 # define _BSD_SOURCE
53
54 // On AIX we need _BSD defined, otherwise <math.h> includes <stdlib.h>
55 # if defined(_AIX)
56 # define _BSD 1
57 # endif
58
59 // '_BSD_SOURCE' is deprecated since glibc-2.20
60 // in favour of '_DEFAULT_SOURCE'
61 # define _DEFAULT_SOURCE
62 #endif
63
64 #if IN_STG_CODE == 0 || defined(llvm_CC_FLAVOR)
65 // C compilers that use an LLVM back end (clang or llvm-gcc) do not
66 // correctly support global register variables so we make sure that
67 // we do not declare them for these compilers.
68 # define NO_GLOBAL_REG_DECLS /* don't define fixed registers */
69 #endif
70
71 /* Configuration */
72 #include "ghcconfig.h"
73
74 /* The code generator calls the math functions directly in .hc code.
75 NB. after configuration stuff above, because this sets #defines
76 that depend on config info, such as __USE_FILE_OFFSET64 */
77 #include <math.h>
78
79 // On Solaris, we don't get the INFINITY and NAN constants unless we
80 // #define _STDC_C99, and we can't do that unless we also use -std=c99,
81 // because _STDC_C99 causes the headers to use C99 syntax (e.g. restrict).
82 // We aren't ready for -std=c99 yet, so define INFINITY/NAN by hand using
83 // the gcc builtins.
84 #if !defined(INFINITY)
85 #if defined(__GNUC__)
86 #define INFINITY __builtin_inf()
87 #else
88 #error No definition for INFINITY
89 #endif
90 #endif
91
92 #if !defined(NAN)
93 #if defined(__GNUC__)
94 #define NAN __builtin_nan("")
95 #else
96 #error No definition for NAN
97 #endif
98 #endif
99
100 /* -----------------------------------------------------------------------------
101 Useful definitions
102 -------------------------------------------------------------------------- */
103
104 /*
105 * The C backend likes to refer to labels by just mentioning their
106 * names. However, when a symbol is declared as a variable in C, the
107 * C compiler will implicitly dereference it when it occurs in source.
108 * So we must subvert this behaviour for .hc files by declaring
109 * variables as arrays, which eliminates the implicit dereference.
110 */
111 #if IN_STG_CODE
112 #define RTS_VAR(x) (x)[]
113 #define RTS_DEREF(x) (*(x))
114 #else
115 #define RTS_VAR(x) x
116 #define RTS_DEREF(x) x
117 #endif
118
119 /* bit macros
120 */
121 #define BITS_PER_BYTE 8
122 #define BITS_IN(x) (BITS_PER_BYTE * sizeof(x))
123
124 /* Compute offsets of struct fields
125 */
126 #define STG_FIELD_OFFSET(s_type, field) ((StgWord)&(((s_type*)0)->field))
127
128 /*
129 * 'Portable' inlining:
130 * INLINE_HEADER is for inline functions in header files (macros)
131 * STATIC_INLINE is for inline functions in source files
132 * EXTERN_INLINE is for functions that we want to inline sometimes
133 * (we also compile a static version of the function; see Inlines.c)
134 */
135
136 // We generally assume C99 semantics albeit these two definitions work fine even
137 // when gnu90 semantics are active (i.e. when __GNUC_GNU_INLINE__ is defined or
138 // when a GCC older than 4.2 is used)
139 //
140 // The problem, however, is with 'extern inline' whose semantics significantly
141 // differs between gnu90 and C99
142 #define INLINE_HEADER static inline
143 #define STATIC_INLINE static inline
144
145 // Figure out whether `__attributes__((gnu_inline))` is needed
146 // to force gnu90-style 'external inline' semantics.
147 #if defined(FORCE_GNU_INLINE)
148 // disable auto-detection since HAVE_GNU_INLINE has been defined externally
149 #elif __GNUC_GNU_INLINE__ && __GNUC__ == 4 && __GNUC_MINOR__ == 2
150 // GCC 4.2.x didn't properly support C99 inline semantics (GCC 4.3 was the first
151 // release to properly support C99 inline semantics), and therefore warned when
152 // using 'extern inline' while in C99 mode unless `__attributes__((gnu_inline))`
153 // was explicitly set.
154 # define FORCE_GNU_INLINE 1
155 #endif
156
157 #if FORCE_GNU_INLINE
158 // Force compiler into gnu90 semantics
159 # if defined(KEEP_INLINES)
160 # define EXTERN_INLINE inline __attribute__((gnu_inline))
161 # else
162 # define EXTERN_INLINE extern inline __attribute__((gnu_inline))
163 # endif
164 #elif __GNUC_GNU_INLINE__
165 // we're currently in gnu90 inline mode by default and
166 // __attribute__((gnu_inline)) may not be supported, so better leave it off
167 # if defined(KEEP_INLINES)
168 # define EXTERN_INLINE inline
169 # else
170 # define EXTERN_INLINE extern inline
171 # endif
172 #else
173 // Assume C99 semantics (yes, this curiously results in swapped definitions!)
174 // This is the preferred branch, and at some point we may drop support for
175 // compilers not supporting C99 semantics altogether.
176 # if defined(KEEP_INLINES)
177 # define EXTERN_INLINE extern inline
178 # else
179 # define EXTERN_INLINE inline
180 # endif
181 #endif
182
183
184 /*
185 * GCC attributes
186 */
187 #if defined(__GNUC__)
188 #define GNU_ATTRIBUTE(at) __attribute__((at))
189 #else
190 #define GNU_ATTRIBUTE(at)
191 #endif
192
193 #if __GNUC__ >= 3
194 #define GNUC3_ATTRIBUTE(at) __attribute__((at))
195 #else
196 #define GNUC3_ATTRIBUTE(at)
197 #endif
198
199 #if __GNUC__ > 4 || __GNUC__ == 4 && __GNUC_MINOR__ >= 3
200 #define GNUC_ATTR_HOT __attribute__((hot))
201 #else
202 #define GNUC_ATTR_HOT /* nothing */
203 #endif
204
205 #define STG_UNUSED GNUC3_ATTRIBUTE(__unused__)
206
207 /* -----------------------------------------------------------------------------
208 Global type definitions
209 -------------------------------------------------------------------------- */
210
211 #include "MachDeps.h"
212 #include "stg/Types.h"
213
214 /* -----------------------------------------------------------------------------
215 Shorthand forms
216 -------------------------------------------------------------------------- */
217
218 typedef StgChar C_;
219 typedef StgWord W_;
220 typedef StgWord* P_;
221 typedef StgInt I_;
222 typedef StgWord StgWordArray[];
223 typedef StgFunPtr F_;
224
225 #define EB_(X) extern char X[]
226 #define IB_(X) static char X[]
227 #define EI_(X) extern StgWordArray (X) GNU_ATTRIBUTE(aligned (8))
228 #define II_(X) static StgWordArray (X) GNU_ATTRIBUTE(aligned (8))
229 #define IF_(f) static StgFunPtr GNUC3_ATTRIBUTE(used) f(void)
230 #define FN_(f) StgFunPtr f(void)
231 #define EF_(f) StgFunPtr f(void) /* External Cmm functions */
232 #define EFF_(f) void f() /* See Note [External function prototypes] */
233
234 /* Note [External function prototypes] See Trac #8965, #11395
235 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
236 In generated C code we need to distinct between two types
237 of external symbols:
238 1. Cmm functions declared by 'EF_' macro (External Functions)
239 2. C functions declared by 'EFF_' macro (External Foreign Functions)
240
241 Cmm functions are simple as they are internal to GHC.
242
243 C functions are trickier:
244
245 The external-function macro EFF_(F) used to be defined as
246 extern StgFunPtr f(void)
247 i.e a function of zero arguments. On most platforms this doesn't
248 matter very much: calls to these functions put the parameters in the
249 usual places anyway, and (with the exception of varargs) things just
250 work.
251
252 However, the ELFv2 ABI on ppc64 optimises stack allocation
253 (http://gcc.gnu.org/ml/gcc-patches/2013-11/msg01149.html): a call to a
254 function that has a prototype, is not varargs, and receives all parameters
255 in registers rather than on the stack does not require the caller to
256 allocate an argument save area. The incorrect prototypes cause GCC to
257 believe that all functions declared this way can be called without an
258 argument save area, but if the callee has sufficiently many arguments then
259 it will expect that area to be present, and will thus corrupt the caller's
260 stack. This happens in particular with calls to runInteractiveProcess in
261 libraries/process/cbits/runProcess.c, and led to Trac #8965.
262
263 The simplest fix appears to be to declare these external functions with an
264 unspecified argument list rather than a void argument list. This is no
265 worse for platforms that don't care either way, and allows a successful
266 bootstrap of GHC 7.8 on little-endian Linux ppc64 (which uses the ELFv2
267 ABI).
268
269 Another case is m68k ABI where 'void*' return type is returned by 'a0'
270 register while 'long' return type is returned by 'd0'. Thus we trick
271 external prototype return neither of these types to workaround #11395.
272 */
273
274
275 /* -----------------------------------------------------------------------------
276 Tail calls
277 -------------------------------------------------------------------------- */
278
279 #define JMP_(cont) return((StgFunPtr)(cont))
280
281 /* -----------------------------------------------------------------------------
282 Other Stg stuff...
283 -------------------------------------------------------------------------- */
284
285 #include "stg/DLL.h"
286 #include "stg/RtsMachRegs.h"
287 #include "stg/Regs.h"
288 #include "stg/Ticky.h"
289
290 #if IN_STG_CODE
291 /*
292 * This is included later for RTS sources, after definitions of
293 * StgInfoTable, StgClosure and so on.
294 */
295 #include "stg/MiscClosures.h"
296 #endif
297
298 #include "stg/Prim.h" /* ghc-prim fallbacks */
299 #include "stg/SMP.h" // write_barrier() inline is required
300
301 /* -----------------------------------------------------------------------------
302 Moving Floats and Doubles
303
304 ASSIGN_FLT is for assigning a float to memory (usually the
305 stack/heap). The memory address is guaranteed to be
306 StgWord aligned (currently == sizeof(void *)).
307
308 PK_FLT is for pulling a float out of memory. The memory is
309 guaranteed to be StgWord aligned.
310 -------------------------------------------------------------------------- */
311
312 INLINE_HEADER void ASSIGN_FLT (W_ [], StgFloat);
313 INLINE_HEADER StgFloat PK_FLT (W_ []);
314
315 #if ALIGNMENT_FLOAT <= ALIGNMENT_VOID_P
316
317 INLINE_HEADER void ASSIGN_FLT(W_ p_dest[], StgFloat src) { *(StgFloat *)p_dest = src; }
318 INLINE_HEADER StgFloat PK_FLT (W_ p_src[]) { return *(StgFloat *)p_src; }
319
320 #else /* ALIGNMENT_FLOAT > ALIGNMENT_UNSIGNED_INT */
321
322 INLINE_HEADER void ASSIGN_FLT(W_ p_dest[], StgFloat src)
323 {
324 float_thing y;
325 y.f = src;
326 *p_dest = y.fu;
327 }
328
329 INLINE_HEADER StgFloat PK_FLT(W_ p_src[])
330 {
331 float_thing y;
332 y.fu = *p_src;
333 return(y.f);
334 }
335
336 #endif /* ALIGNMENT_FLOAT > ALIGNMENT_VOID_P */
337
338 #if ALIGNMENT_DOUBLE <= ALIGNMENT_VOID_P
339
340 INLINE_HEADER void ASSIGN_DBL (W_ [], StgDouble);
341 INLINE_HEADER StgDouble PK_DBL (W_ []);
342
343 INLINE_HEADER void ASSIGN_DBL(W_ p_dest[], StgDouble src) { *(StgDouble *)p_dest = src; }
344 INLINE_HEADER StgDouble PK_DBL (W_ p_src[]) { return *(StgDouble *)p_src; }
345
346 #else /* ALIGNMENT_DOUBLE > ALIGNMENT_VOID_P */
347
348 /* Sparc uses two floating point registers to hold a double. We can
349 * write ASSIGN_DBL and PK_DBL by directly accessing the registers
350 * independently - unfortunately this code isn't writable in C, we
351 * have to use inline assembler.
352 */
353 #if sparc_HOST_ARCH
354
355 #define ASSIGN_DBL(dst0,src) \
356 { StgPtr dst = (StgPtr)(dst0); \
357 __asm__("st %2,%0\n\tst %R2,%1" : "=m" (((P_)(dst))[0]), \
358 "=m" (((P_)(dst))[1]) : "f" (src)); \
359 }
360
361 #define PK_DBL(src0) \
362 ( { StgPtr src = (StgPtr)(src0); \
363 register double d; \
364 __asm__("ld %1,%0\n\tld %2,%R0" : "=f" (d) : \
365 "m" (((P_)(src))[0]), "m" (((P_)(src))[1])); d; \
366 } )
367
368 #else /* ! sparc_HOST_ARCH */
369
370 INLINE_HEADER void ASSIGN_DBL (W_ [], StgDouble);
371 INLINE_HEADER StgDouble PK_DBL (W_ []);
372
373 typedef struct
374 { StgWord dhi;
375 StgWord dlo;
376 } unpacked_double;
377
378 typedef union
379 { StgDouble d;
380 unpacked_double du;
381 } double_thing;
382
383 INLINE_HEADER void ASSIGN_DBL(W_ p_dest[], StgDouble src)
384 {
385 double_thing y;
386 y.d = src;
387 p_dest[0] = y.du.dhi;
388 p_dest[1] = y.du.dlo;
389 }
390
391 /* GCC also works with this version, but it generates
392 the same code as the previous one, and is not ANSI
393
394 #define ASSIGN_DBL( p_dest, src ) \
395 *p_dest = ((double_thing) src).du.dhi; \
396 *(p_dest+1) = ((double_thing) src).du.dlo \
397 */
398
399 INLINE_HEADER StgDouble PK_DBL(W_ p_src[])
400 {
401 double_thing y;
402 y.du.dhi = p_src[0];
403 y.du.dlo = p_src[1];
404 return(y.d);
405 }
406
407 #endif /* ! sparc_HOST_ARCH */
408
409 #endif /* ALIGNMENT_DOUBLE > ALIGNMENT_UNSIGNED_INT */
410
411
412 /* -----------------------------------------------------------------------------
413 Moving 64-bit quantities around
414
415 ASSIGN_Word64 assign an StgWord64/StgInt64 to a memory location
416 PK_Word64 load an StgWord64/StgInt64 from a amemory location
417
418 In both cases the memory location might not be 64-bit aligned.
419 -------------------------------------------------------------------------- */
420
421 #if SIZEOF_HSWORD == 4
422
423 typedef struct
424 { StgWord dhi;
425 StgWord dlo;
426 } unpacked_double_word;
427
428 typedef union
429 { StgInt64 i;
430 unpacked_double_word iu;
431 } int64_thing;
432
433 typedef union
434 { StgWord64 w;
435 unpacked_double_word wu;
436 } word64_thing;
437
438 INLINE_HEADER void ASSIGN_Word64(W_ p_dest[], StgWord64 src)
439 {
440 word64_thing y;
441 y.w = src;
442 p_dest[0] = y.wu.dhi;
443 p_dest[1] = y.wu.dlo;
444 }
445
446 INLINE_HEADER StgWord64 PK_Word64(W_ p_src[])
447 {
448 word64_thing y;
449 y.wu.dhi = p_src[0];
450 y.wu.dlo = p_src[1];
451 return(y.w);
452 }
453
454 INLINE_HEADER void ASSIGN_Int64(W_ p_dest[], StgInt64 src)
455 {
456 int64_thing y;
457 y.i = src;
458 p_dest[0] = y.iu.dhi;
459 p_dest[1] = y.iu.dlo;
460 }
461
462 INLINE_HEADER StgInt64 PK_Int64(W_ p_src[])
463 {
464 int64_thing y;
465 y.iu.dhi = p_src[0];
466 y.iu.dlo = p_src[1];
467 return(y.i);
468 }
469
470 #elif SIZEOF_VOID_P == 8
471
472 INLINE_HEADER void ASSIGN_Word64(W_ p_dest[], StgWord64 src)
473 {
474 p_dest[0] = src;
475 }
476
477 INLINE_HEADER StgWord64 PK_Word64(W_ p_src[])
478 {
479 return p_src[0];
480 }
481
482 INLINE_HEADER void ASSIGN_Int64(W_ p_dest[], StgInt64 src)
483 {
484 p_dest[0] = src;
485 }
486
487 INLINE_HEADER StgInt64 PK_Int64(W_ p_src[])
488 {
489 return p_src[0];
490 }
491
492 #endif /* SIZEOF_HSWORD == 4 */
493
494 /* -----------------------------------------------------------------------------
495 Integer multiply with overflow
496 -------------------------------------------------------------------------- */
497
498 /* Multiply with overflow checking.
499 *
500 * This is tricky - the usual sign rules for add/subtract don't apply.
501 *
502 * On 32-bit machines we use gcc's 'long long' types, finding
503 * overflow with some careful bit-twiddling.
504 *
505 * On 64-bit machines where gcc's 'long long' type is also 64-bits,
506 * we use a crude approximation, testing whether either operand is
507 * larger than 32-bits; if neither is, then we go ahead with the
508 * multiplication.
509 *
510 * Return non-zero if there is any possibility that the signed multiply
511 * of a and b might overflow. Return zero only if you are absolutely sure
512 * that it won't overflow. If in doubt, return non-zero.
513 */
514
515 #if SIZEOF_VOID_P == 4
516
517 #ifdef WORDS_BIGENDIAN
518 #define RTS_CARRY_IDX__ 0
519 #define RTS_REM_IDX__ 1
520 #else
521 #define RTS_CARRY_IDX__ 1
522 #define RTS_REM_IDX__ 0
523 #endif
524
525 typedef union {
526 StgInt64 l;
527 StgInt32 i[2];
528 } long_long_u ;
529
530 #define mulIntMayOflo(a,b) \
531 ({ \
532 StgInt32 r, c; \
533 long_long_u z; \
534 z.l = (StgInt64)a * (StgInt64)b; \
535 r = z.i[RTS_REM_IDX__]; \
536 c = z.i[RTS_CARRY_IDX__]; \
537 if (c == 0 || c == -1) { \
538 c = ((StgWord)((a^b) ^ r)) \
539 >> (BITS_IN (I_) - 1); \
540 } \
541 c; \
542 })
543
544 /* Careful: the carry calculation above is extremely delicate. Make sure
545 * you test it thoroughly after changing it.
546 */
547
548 #else
549
550 /* Approximate version when we don't have long arithmetic (on 64-bit archs) */
551
552 /* If we have n-bit words then we have n-1 bits after accounting for the
553 * sign bit, so we can fit the result of multiplying 2 (n-1)/2-bit numbers */
554 #define HALF_POS_INT (((I_)1) << ((BITS_IN (I_) - 1) / 2))
555 #define HALF_NEG_INT (-HALF_POS_INT)
556
557 #define mulIntMayOflo(a,b) \
558 ({ \
559 I_ c; \
560 if ((I_)a <= HALF_NEG_INT || a >= HALF_POS_INT \
561 || (I_)b <= HALF_NEG_INT || b >= HALF_POS_INT) {\
562 c = 1; \
563 } else { \
564 c = 0; \
565 } \
566 c; \
567 })
568 #endif