Enable new warning for fragile/incorrect CPP #if usage
[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 defined(__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 #ifdef 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 defined(__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 /* byte arrays (and strings): */
226 #define EB_(X) extern const char X[]
227 #define IB_(X) static const char X[]
228 /* static (non-heap) closures (requires alignment for pointer tagging): */
229 #define EC_(X) extern StgWordArray (X) GNU_ATTRIBUTE(aligned (8))
230 #define IC_(X) static StgWordArray (X) GNU_ATTRIBUTE(aligned (8))
231 /* writable data (does not require alignment): */
232 #define ERW_(X) extern StgWordArray (X)
233 #define IRW_(X) static StgWordArray (X)
234 /* read-only data (does not require alignment): */
235 #define ERO_(X) extern const StgWordArray (X)
236 #define IRO_(X) static const StgWordArray (X)
237 /* stg-native functions: */
238 #define IF_(f) static StgFunPtr GNUC3_ATTRIBUTE(used) f(void)
239 #define FN_(f) StgFunPtr f(void)
240 #define EF_(f) StgFunPtr f(void) /* External Cmm functions */
241 /* foreign functions: */
242 #define EFF_(f) void f() /* See Note [External function prototypes] */
243
244 /* Note [External function prototypes] See Trac #8965, #11395
245 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
246 In generated C code we need to distinct between two types
247 of external symbols:
248 1. Cmm functions declared by 'EF_' macro (External Functions)
249 2. C functions declared by 'EFF_' macro (External Foreign Functions)
250
251 Cmm functions are simple as they are internal to GHC.
252
253 C functions are trickier:
254
255 The external-function macro EFF_(F) used to be defined as
256 extern StgFunPtr f(void)
257 i.e a function of zero arguments. On most platforms this doesn't
258 matter very much: calls to these functions put the parameters in the
259 usual places anyway, and (with the exception of varargs) things just
260 work.
261
262 However, the ELFv2 ABI on ppc64 optimises stack allocation
263 (http://gcc.gnu.org/ml/gcc-patches/2013-11/msg01149.html): a call to a
264 function that has a prototype, is not varargs, and receives all parameters
265 in registers rather than on the stack does not require the caller to
266 allocate an argument save area. The incorrect prototypes cause GCC to
267 believe that all functions declared this way can be called without an
268 argument save area, but if the callee has sufficiently many arguments then
269 it will expect that area to be present, and will thus corrupt the caller's
270 stack. This happens in particular with calls to runInteractiveProcess in
271 libraries/process/cbits/runProcess.c, and led to Trac #8965.
272
273 The simplest fix appears to be to declare these external functions with an
274 unspecified argument list rather than a void argument list. This is no
275 worse for platforms that don't care either way, and allows a successful
276 bootstrap of GHC 7.8 on little-endian Linux ppc64 (which uses the ELFv2
277 ABI).
278
279 Another case is m68k ABI where 'void*' return type is returned by 'a0'
280 register while 'long' return type is returned by 'd0'. Thus we trick
281 external prototype return neither of these types to workaround #11395.
282 */
283
284
285 /* -----------------------------------------------------------------------------
286 Tail calls
287 -------------------------------------------------------------------------- */
288
289 #define JMP_(cont) return((StgFunPtr)(cont))
290
291 /* -----------------------------------------------------------------------------
292 Other Stg stuff...
293 -------------------------------------------------------------------------- */
294
295 #include "stg/DLL.h"
296 #include "stg/RtsMachRegs.h"
297 #include "stg/Regs.h"
298 #include "stg/Ticky.h"
299
300 #if IN_STG_CODE
301 /*
302 * This is included later for RTS sources, after definitions of
303 * StgInfoTable, StgClosure and so on.
304 */
305 #include "stg/MiscClosures.h"
306 #endif
307
308 #include "stg/Prim.h" /* ghc-prim fallbacks */
309 #include "stg/SMP.h" // write_barrier() inline is required
310
311 /* -----------------------------------------------------------------------------
312 Moving Floats and Doubles
313
314 ASSIGN_FLT is for assigning a float to memory (usually the
315 stack/heap). The memory address is guaranteed to be
316 StgWord aligned (currently == sizeof(void *)).
317
318 PK_FLT is for pulling a float out of memory. The memory is
319 guaranteed to be StgWord aligned.
320 -------------------------------------------------------------------------- */
321
322 INLINE_HEADER void ASSIGN_FLT (W_ [], StgFloat);
323 INLINE_HEADER StgFloat PK_FLT (W_ []);
324
325 #if ALIGNMENT_FLOAT <= ALIGNMENT_VOID_P
326
327 INLINE_HEADER void ASSIGN_FLT(W_ p_dest[], StgFloat src) { *(StgFloat *)p_dest = src; }
328 INLINE_HEADER StgFloat PK_FLT (W_ p_src[]) { return *(StgFloat *)p_src; }
329
330 #else /* ALIGNMENT_FLOAT > ALIGNMENT_UNSIGNED_INT */
331
332 INLINE_HEADER void ASSIGN_FLT(W_ p_dest[], StgFloat src)
333 {
334 float_thing y;
335 y.f = src;
336 *p_dest = y.fu;
337 }
338
339 INLINE_HEADER StgFloat PK_FLT(W_ p_src[])
340 {
341 float_thing y;
342 y.fu = *p_src;
343 return(y.f);
344 }
345
346 #endif /* ALIGNMENT_FLOAT > ALIGNMENT_VOID_P */
347
348 #if ALIGNMENT_DOUBLE <= ALIGNMENT_VOID_P
349
350 INLINE_HEADER void ASSIGN_DBL (W_ [], StgDouble);
351 INLINE_HEADER StgDouble PK_DBL (W_ []);
352
353 INLINE_HEADER void ASSIGN_DBL(W_ p_dest[], StgDouble src) { *(StgDouble *)p_dest = src; }
354 INLINE_HEADER StgDouble PK_DBL (W_ p_src[]) { return *(StgDouble *)p_src; }
355
356 #else /* ALIGNMENT_DOUBLE > ALIGNMENT_VOID_P */
357
358 /* Sparc uses two floating point registers to hold a double. We can
359 * write ASSIGN_DBL and PK_DBL by directly accessing the registers
360 * independently - unfortunately this code isn't writable in C, we
361 * have to use inline assembler.
362 */
363 #if sparc_HOST_ARCH
364
365 #define ASSIGN_DBL(dst0,src) \
366 { StgPtr dst = (StgPtr)(dst0); \
367 __asm__("st %2,%0\n\tst %R2,%1" : "=m" (((P_)(dst))[0]), \
368 "=m" (((P_)(dst))[1]) : "f" (src)); \
369 }
370
371 #define PK_DBL(src0) \
372 ( { StgPtr src = (StgPtr)(src0); \
373 register double d; \
374 __asm__("ld %1,%0\n\tld %2,%R0" : "=f" (d) : \
375 "m" (((P_)(src))[0]), "m" (((P_)(src))[1])); d; \
376 } )
377
378 #else /* ! sparc_HOST_ARCH */
379
380 INLINE_HEADER void ASSIGN_DBL (W_ [], StgDouble);
381 INLINE_HEADER StgDouble PK_DBL (W_ []);
382
383 typedef struct
384 { StgWord dhi;
385 StgWord dlo;
386 } unpacked_double;
387
388 typedef union
389 { StgDouble d;
390 unpacked_double du;
391 } double_thing;
392
393 INLINE_HEADER void ASSIGN_DBL(W_ p_dest[], StgDouble src)
394 {
395 double_thing y;
396 y.d = src;
397 p_dest[0] = y.du.dhi;
398 p_dest[1] = y.du.dlo;
399 }
400
401 /* GCC also works with this version, but it generates
402 the same code as the previous one, and is not ANSI
403
404 #define ASSIGN_DBL( p_dest, src ) \
405 *p_dest = ((double_thing) src).du.dhi; \
406 *(p_dest+1) = ((double_thing) src).du.dlo \
407 */
408
409 INLINE_HEADER StgDouble PK_DBL(W_ p_src[])
410 {
411 double_thing y;
412 y.du.dhi = p_src[0];
413 y.du.dlo = p_src[1];
414 return(y.d);
415 }
416
417 #endif /* ! sparc_HOST_ARCH */
418
419 #endif /* ALIGNMENT_DOUBLE > ALIGNMENT_UNSIGNED_INT */
420
421
422 /* -----------------------------------------------------------------------------
423 Moving 64-bit quantities around
424
425 ASSIGN_Word64 assign an StgWord64/StgInt64 to a memory location
426 PK_Word64 load an StgWord64/StgInt64 from a amemory location
427
428 In both cases the memory location might not be 64-bit aligned.
429 -------------------------------------------------------------------------- */
430
431 #if SIZEOF_HSWORD == 4
432
433 typedef struct
434 { StgWord dhi;
435 StgWord dlo;
436 } unpacked_double_word;
437
438 typedef union
439 { StgInt64 i;
440 unpacked_double_word iu;
441 } int64_thing;
442
443 typedef union
444 { StgWord64 w;
445 unpacked_double_word wu;
446 } word64_thing;
447
448 INLINE_HEADER void ASSIGN_Word64(W_ p_dest[], StgWord64 src)
449 {
450 word64_thing y;
451 y.w = src;
452 p_dest[0] = y.wu.dhi;
453 p_dest[1] = y.wu.dlo;
454 }
455
456 INLINE_HEADER StgWord64 PK_Word64(W_ p_src[])
457 {
458 word64_thing y;
459 y.wu.dhi = p_src[0];
460 y.wu.dlo = p_src[1];
461 return(y.w);
462 }
463
464 INLINE_HEADER void ASSIGN_Int64(W_ p_dest[], StgInt64 src)
465 {
466 int64_thing y;
467 y.i = src;
468 p_dest[0] = y.iu.dhi;
469 p_dest[1] = y.iu.dlo;
470 }
471
472 INLINE_HEADER StgInt64 PK_Int64(W_ p_src[])
473 {
474 int64_thing y;
475 y.iu.dhi = p_src[0];
476 y.iu.dlo = p_src[1];
477 return(y.i);
478 }
479
480 #elif SIZEOF_VOID_P == 8
481
482 INLINE_HEADER void ASSIGN_Word64(W_ p_dest[], StgWord64 src)
483 {
484 p_dest[0] = src;
485 }
486
487 INLINE_HEADER StgWord64 PK_Word64(W_ p_src[])
488 {
489 return p_src[0];
490 }
491
492 INLINE_HEADER void ASSIGN_Int64(W_ p_dest[], StgInt64 src)
493 {
494 p_dest[0] = src;
495 }
496
497 INLINE_HEADER StgInt64 PK_Int64(W_ p_src[])
498 {
499 return p_src[0];
500 }
501
502 #endif /* SIZEOF_HSWORD == 4 */
503
504 /* -----------------------------------------------------------------------------
505 Integer multiply with overflow
506 -------------------------------------------------------------------------- */
507
508 /* Multiply with overflow checking.
509 *
510 * This is tricky - the usual sign rules for add/subtract don't apply.
511 *
512 * On 32-bit machines we use gcc's 'long long' types, finding
513 * overflow with some careful bit-twiddling.
514 *
515 * On 64-bit machines where gcc's 'long long' type is also 64-bits,
516 * we use a crude approximation, testing whether either operand is
517 * larger than 32-bits; if neither is, then we go ahead with the
518 * multiplication.
519 *
520 * Return non-zero if there is any possibility that the signed multiply
521 * of a and b might overflow. Return zero only if you are absolutely sure
522 * that it won't overflow. If in doubt, return non-zero.
523 */
524
525 #if SIZEOF_VOID_P == 4
526
527 #ifdef WORDS_BIGENDIAN
528 #define RTS_CARRY_IDX__ 0
529 #define RTS_REM_IDX__ 1
530 #else
531 #define RTS_CARRY_IDX__ 1
532 #define RTS_REM_IDX__ 0
533 #endif
534
535 typedef union {
536 StgInt64 l;
537 StgInt32 i[2];
538 } long_long_u ;
539
540 #define mulIntMayOflo(a,b) \
541 ({ \
542 StgInt32 r, c; \
543 long_long_u z; \
544 z.l = (StgInt64)a * (StgInt64)b; \
545 r = z.i[RTS_REM_IDX__]; \
546 c = z.i[RTS_CARRY_IDX__]; \
547 if (c == 0 || c == -1) { \
548 c = ((StgWord)((a^b) ^ r)) \
549 >> (BITS_IN (I_) - 1); \
550 } \
551 c; \
552 })
553
554 /* Careful: the carry calculation above is extremely delicate. Make sure
555 * you test it thoroughly after changing it.
556 */
557
558 #else
559
560 /* Approximate version when we don't have long arithmetic (on 64-bit archs) */
561
562 /* If we have n-bit words then we have n-1 bits after accounting for the
563 * sign bit, so we can fit the result of multiplying 2 (n-1)/2-bit numbers */
564 #define HALF_POS_INT (((I_)1) << ((BITS_IN (I_) - 1) / 2))
565 #define HALF_NEG_INT (-HALF_POS_INT)
566
567 #define mulIntMayOflo(a,b) \
568 ({ \
569 I_ c; \
570 if ((I_)a <= HALF_NEG_INT || a >= HALF_POS_INT \
571 || (I_)b <= HALF_NEG_INT || b >= HALF_POS_INT) {\
572 c = 1; \
573 } else { \
574 c = 0; \
575 } \
576 c; \
577 })
578 #endif