1 /* -----------------------------------------------------------------------
2    ffi64.c - Copyright (c) 2013  The Written Word, Inc.
3              Copyright (c) 2011  Anthony Green
4              Copyright (c) 2008, 2010  Red Hat, Inc.
5              Copyright (c) 2002, 2007  Bo Thorsen <bo@suse.de>
6 
7    x86-64 Foreign Function Interface
8 
9    Permission is hereby granted, free of charge, to any person obtaining
10    a copy of this software and associated documentation files (the
11    ``Software''), to deal in the Software without restriction, including
12    without limitation the rights to use, copy, modify, merge, publish,
13    distribute, sublicense, and/or sell copies of the Software, and to
14    permit persons to whom the Software is furnished to do so, subject to
15    the following conditions:
16 
17    The above copyright notice and this permission notice shall be included
18    in all copies or substantial portions of the Software.
19 
20    THE SOFTWARE IS PROVIDED ``AS IS'', WITHOUT WARRANTY OF ANY KIND,
21    EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
22    MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
23    NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
24    HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
25    WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
26    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
27    DEALINGS IN THE SOFTWARE.
28    ----------------------------------------------------------------------- */
29 
30 #include <ffi.h>
31 #include <ffi_common.h>
32 
33 #include <stdlib.h>
34 #include <stdarg.h>
35 
36 #ifdef __x86_64__
37 
38 #define MAX_GPR_REGS 6
39 #define MAX_SSE_REGS 8
40 
41 #if defined(__INTEL_COMPILER)
42 #include "xmmintrin.h"
43 #define UINT128 __m128
44 #else
45 #if defined(__SUNPRO_C)
46 #include <sunmedia_types.h>
47 #define UINT128 __m128i
48 #else
49 #define UINT128 __int128_t
50 #endif
51 #endif
52 
53 union big_int_union
54 {
55   UINT32 i32;
56   UINT64 i64;
57   UINT128 i128;
58 };
59 
60 struct register_args
61 {
62   /* Registers for argument passing.  */
63   UINT64 gpr[MAX_GPR_REGS];
64   union big_int_union sse[MAX_SSE_REGS];
65 };
66 
67 extern void ffi_call_unix64 (void *args, unsigned long bytes, unsigned flags,
68 			     void *raddr, void (*fnaddr)(void), unsigned ssecount);
69 
70 /* All reference to register classes here is identical to the code in
71    gcc/config/i386/i386.c. Do *not* change one without the other.  */
72 
73 /* Register class used for passing given 64bit part of the argument.
74    These represent classes as documented by the PS ABI, with the
75    exception of SSESF, SSEDF classes, that are basically SSE class,
76    just gcc will use SF or DFmode move instead of DImode to avoid
77    reformatting penalties.
78 
79    Similary we play games with INTEGERSI_CLASS to use cheaper SImode moves
80    whenever possible (upper half does contain padding).  */
81 enum x86_64_reg_class
82   {
83     X86_64_NO_CLASS,
84     X86_64_INTEGER_CLASS,
85     X86_64_INTEGERSI_CLASS,
86     X86_64_SSE_CLASS,
87     X86_64_SSESF_CLASS,
88     X86_64_SSEDF_CLASS,
89     X86_64_SSEUP_CLASS,
90     X86_64_X87_CLASS,
91     X86_64_X87UP_CLASS,
92     X86_64_COMPLEX_X87_CLASS,
93     X86_64_MEMORY_CLASS
94   };
95 
96 #define MAX_CLASSES 4
97 
98 #define SSE_CLASS_P(X)	((X) >= X86_64_SSE_CLASS && X <= X86_64_SSEUP_CLASS)
99 
100 /* x86-64 register passing implementation.  See x86-64 ABI for details.  Goal
101    of this code is to classify each 8bytes of incoming argument by the register
102    class and assign registers accordingly.  */
103 
104 /* Return the union class of CLASS1 and CLASS2.
105    See the x86-64 PS ABI for details.  */
106 
107 static enum x86_64_reg_class
merge_classes(enum x86_64_reg_class class1,enum x86_64_reg_class class2)108 merge_classes (enum x86_64_reg_class class1, enum x86_64_reg_class class2)
109 {
110   /* Rule #1: If both classes are equal, this is the resulting class.  */
111   if (class1 == class2)
112     return class1;
113 
114   /* Rule #2: If one of the classes is NO_CLASS, the resulting class is
115      the other class.  */
116   if (class1 == X86_64_NO_CLASS)
117     return class2;
118   if (class2 == X86_64_NO_CLASS)
119     return class1;
120 
121   /* Rule #3: If one of the classes is MEMORY, the result is MEMORY.  */
122   if (class1 == X86_64_MEMORY_CLASS || class2 == X86_64_MEMORY_CLASS)
123     return X86_64_MEMORY_CLASS;
124 
125   /* Rule #4: If one of the classes is INTEGER, the result is INTEGER.  */
126   if ((class1 == X86_64_INTEGERSI_CLASS && class2 == X86_64_SSESF_CLASS)
127       || (class2 == X86_64_INTEGERSI_CLASS && class1 == X86_64_SSESF_CLASS))
128     return X86_64_INTEGERSI_CLASS;
129   if (class1 == X86_64_INTEGER_CLASS || class1 == X86_64_INTEGERSI_CLASS
130       || class2 == X86_64_INTEGER_CLASS || class2 == X86_64_INTEGERSI_CLASS)
131     return X86_64_INTEGER_CLASS;
132 
133   /* Rule #5: If one of the classes is X87, X87UP, or COMPLEX_X87 class,
134      MEMORY is used.  */
135   if (class1 == X86_64_X87_CLASS
136       || class1 == X86_64_X87UP_CLASS
137       || class1 == X86_64_COMPLEX_X87_CLASS
138       || class2 == X86_64_X87_CLASS
139       || class2 == X86_64_X87UP_CLASS
140       || class2 == X86_64_COMPLEX_X87_CLASS)
141     return X86_64_MEMORY_CLASS;
142 
143   /* Rule #6: Otherwise class SSE is used.  */
144   return X86_64_SSE_CLASS;
145 }
146 
147 /* Classify the argument of type TYPE and mode MODE.
148    CLASSES will be filled by the register class used to pass each word
149    of the operand.  The number of words is returned.  In case the parameter
150    should be passed in memory, 0 is returned. As a special case for zero
151    sized containers, classes[0] will be NO_CLASS and 1 is returned.
152 
153    See the x86-64 PS ABI for details.
154 */
155 static size_t
classify_argument(ffi_type * type,enum x86_64_reg_class classes[],size_t byte_offset)156 classify_argument (ffi_type *type, enum x86_64_reg_class classes[],
157 		   size_t byte_offset)
158 {
159   switch (type->type)
160     {
161     case FFI_TYPE_UINT8:
162     case FFI_TYPE_SINT8:
163     case FFI_TYPE_UINT16:
164     case FFI_TYPE_SINT16:
165     case FFI_TYPE_UINT32:
166     case FFI_TYPE_SINT32:
167     case FFI_TYPE_UINT64:
168     case FFI_TYPE_SINT64:
169     case FFI_TYPE_POINTER:
170       {
171 	size_t size = byte_offset + type->size;
172 
173 	if (size <= 4)
174 	  {
175 	    classes[0] = X86_64_INTEGERSI_CLASS;
176 	    return 1;
177 	  }
178 	else if (size <= 8)
179 	  {
180 	    classes[0] = X86_64_INTEGER_CLASS;
181 	    return 1;
182 	  }
183 	else if (size <= 12)
184 	  {
185 	    classes[0] = X86_64_INTEGER_CLASS;
186 	    classes[1] = X86_64_INTEGERSI_CLASS;
187 	    return 2;
188 	  }
189 	else if (size <= 16)
190 	  {
191 	    classes[0] = classes[1] = X86_64_INTEGERSI_CLASS;
192 	    return 2;
193 	  }
194 	else
195 	  FFI_ASSERT (0);
196       }
197     case FFI_TYPE_FLOAT:
198       if (!(byte_offset % 8))
199 	classes[0] = X86_64_SSESF_CLASS;
200       else
201 	classes[0] = X86_64_SSE_CLASS;
202       return 1;
203     case FFI_TYPE_DOUBLE:
204       classes[0] = X86_64_SSEDF_CLASS;
205       return 1;
206 #if FFI_TYPE_LONGDOUBLE != FFI_TYPE_DOUBLE
207     case FFI_TYPE_LONGDOUBLE:
208       classes[0] = X86_64_X87_CLASS;
209       classes[1] = X86_64_X87UP_CLASS;
210       return 2;
211 #endif
212     case FFI_TYPE_STRUCT:
213       {
214 	const size_t UNITS_PER_WORD = 8;
215 	size_t words = (type->size + UNITS_PER_WORD - 1) / UNITS_PER_WORD;
216 	ffi_type **ptr;
217 	int i;
218 	enum x86_64_reg_class subclasses[MAX_CLASSES];
219 
220 	/* If the struct is larger than 32 bytes, pass it on the stack.  */
221 	if (type->size > 32)
222 	  return 0;
223 
224 	for (i = 0; i < words; i++)
225 	  classes[i] = X86_64_NO_CLASS;
226 
227 	/* Zero sized arrays or structures are NO_CLASS.  We return 0 to
228 	   signalize memory class, so handle it as special case.  */
229 	if (!words)
230 	  {
231 	    classes[0] = X86_64_NO_CLASS;
232 	    return 1;
233 	  }
234 
235 	/* Merge the fields of structure.  */
236 	for (ptr = type->elements; *ptr != NULL; ptr++)
237 	  {
238 	    size_t num;
239 
240 	    byte_offset = ALIGN (byte_offset, (*ptr)->alignment);
241 
242 	    num = classify_argument (*ptr, subclasses, byte_offset % 8);
243 	    if (num == 0)
244 	      return 0;
245 	    for (i = 0; i < num; i++)
246 	      {
247 		size_t pos = byte_offset / 8;
248 		classes[i + pos] =
249 		  merge_classes (subclasses[i], classes[i + pos]);
250 	      }
251 
252 	    byte_offset += (*ptr)->size;
253 	  }
254 
255 	if (words > 2)
256 	  {
257 	    /* When size > 16 bytes, if the first one isn't
258 	       X86_64_SSE_CLASS or any other ones aren't
259 	       X86_64_SSEUP_CLASS, everything should be passed in
260 	       memory.  */
261 	    if (classes[0] != X86_64_SSE_CLASS)
262 	      return 0;
263 
264 	    for (i = 1; i < words; i++)
265 	      if (classes[i] != X86_64_SSEUP_CLASS)
266 		return 0;
267 	  }
268 
269 	/* Final merger cleanup.  */
270 	for (i = 0; i < words; i++)
271 	  {
272 	    /* If one class is MEMORY, everything should be passed in
273 	       memory.  */
274 	    if (classes[i] == X86_64_MEMORY_CLASS)
275 	      return 0;
276 
277 	    /* The X86_64_SSEUP_CLASS should be always preceded by
278 	       X86_64_SSE_CLASS or X86_64_SSEUP_CLASS.  */
279 	    if (classes[i] == X86_64_SSEUP_CLASS
280 		&& classes[i - 1] != X86_64_SSE_CLASS
281 		&& classes[i - 1] != X86_64_SSEUP_CLASS)
282 	      {
283 		/* The first one should never be X86_64_SSEUP_CLASS.  */
284 		FFI_ASSERT (i != 0);
285 		classes[i] = X86_64_SSE_CLASS;
286 	      }
287 
288 	    /*  If X86_64_X87UP_CLASS isn't preceded by X86_64_X87_CLASS,
289 		everything should be passed in memory.  */
290 	    if (classes[i] == X86_64_X87UP_CLASS
291 		&& (classes[i - 1] != X86_64_X87_CLASS))
292 	      {
293 		/* The first one should never be X86_64_X87UP_CLASS.  */
294 		FFI_ASSERT (i != 0);
295 		return 0;
296 	      }
297 	  }
298 	return words;
299       }
300 
301     default:
302       FFI_ASSERT(0);
303     }
304   return 0; /* Never reached.  */
305 }
306 
307 /* Examine the argument and return set number of register required in each
308    class.  Return zero iff parameter should be passed in memory, otherwise
309    the number of registers.  */
310 
311 static size_t
examine_argument(ffi_type * type,enum x86_64_reg_class classes[MAX_CLASSES],_Bool in_return,int * pngpr,int * pnsse)312 examine_argument (ffi_type *type, enum x86_64_reg_class classes[MAX_CLASSES],
313 		  _Bool in_return, int *pngpr, int *pnsse)
314 {
315   size_t n;
316   int i, ngpr, nsse;
317 
318   n = classify_argument (type, classes, 0);
319   if (n == 0)
320     return 0;
321 
322   ngpr = nsse = 0;
323   for (i = 0; i < n; ++i)
324     switch (classes[i])
325       {
326       case X86_64_INTEGER_CLASS:
327       case X86_64_INTEGERSI_CLASS:
328 	ngpr++;
329 	break;
330       case X86_64_SSE_CLASS:
331       case X86_64_SSESF_CLASS:
332       case X86_64_SSEDF_CLASS:
333 	nsse++;
334 	break;
335       case X86_64_NO_CLASS:
336       case X86_64_SSEUP_CLASS:
337 	break;
338       case X86_64_X87_CLASS:
339       case X86_64_X87UP_CLASS:
340       case X86_64_COMPLEX_X87_CLASS:
341 	return in_return != 0;
342       default:
343 	abort ();
344       }
345 
346   *pngpr = ngpr;
347   *pnsse = nsse;
348 
349   return n;
350 }
351 
352 /* Perform machine dependent cif processing.  */
353 
354 ffi_status
ffi_prep_cif_machdep(ffi_cif * cif)355 ffi_prep_cif_machdep (ffi_cif *cif)
356 {
357   int gprcount, ssecount, i, avn, ngpr, nsse, flags;
358   enum x86_64_reg_class classes[MAX_CLASSES];
359   size_t bytes, n;
360 
361   gprcount = ssecount = 0;
362 
363   flags = cif->rtype->type;
364   if (flags != FFI_TYPE_VOID)
365     {
366       n = examine_argument (cif->rtype, classes, 1, &ngpr, &nsse);
367       if (n == 0)
368 	{
369 	  /* The return value is passed in memory.  A pointer to that
370 	     memory is the first argument.  Allocate a register for it.  */
371 	  gprcount++;
372 	  /* We don't have to do anything in asm for the return.  */
373 	  flags = FFI_TYPE_VOID;
374 	}
375       else if (flags == FFI_TYPE_STRUCT)
376 	{
377 	  /* Mark which registers the result appears in.  */
378 	  _Bool sse0 = SSE_CLASS_P (classes[0]);
379 	  _Bool sse1 = n == 2 && SSE_CLASS_P (classes[1]);
380 	  if (sse0 && !sse1)
381 	    flags |= 1 << 8;
382 	  else if (!sse0 && sse1)
383 	    flags |= 1 << 9;
384 	  else if (sse0 && sse1)
385 	    flags |= 1 << 10;
386 	  /* Mark the true size of the structure.  */
387 	  flags |= cif->rtype->size << 12;
388 	}
389     }
390 
391   /* Go over all arguments and determine the way they should be passed.
392      If it's in a register and there is space for it, let that be so. If
393      not, add it's size to the stack byte count.  */
394   for (bytes = 0, i = 0, avn = cif->nargs; i < avn; i++)
395     {
396       if (examine_argument (cif->arg_types[i], classes, 0, &ngpr, &nsse) == 0
397 	  || gprcount + ngpr > MAX_GPR_REGS
398 	  || ssecount + nsse > MAX_SSE_REGS)
399 	{
400 	  long align = cif->arg_types[i]->alignment;
401 
402 	  if (align < 8)
403 	    align = 8;
404 
405 	  bytes = ALIGN (bytes, align);
406 	  bytes += cif->arg_types[i]->size;
407 	}
408       else
409 	{
410 	  gprcount += ngpr;
411 	  ssecount += nsse;
412 	}
413     }
414   if (ssecount)
415     flags |= 1 << 11;
416   cif->flags = flags;
417   cif->bytes = (unsigned)ALIGN (bytes, 8);
418 
419   return FFI_OK;
420 }
421 
422 #ifndef __SANITIZE_ADDRESS__
423 # ifdef __clang__
424 #  if __has_feature(address_sanitizer)
425 #   define __SANITIZE_ADDRESS__
426 #  endif
427 # endif
428 #endif
429 #ifdef __SANITIZE_ADDRESS__
430 __attribute__((noinline,no_sanitize_address))
431 #endif
432 void
ffi_call(ffi_cif * cif,void (* fn)(void),void * rvalue,void ** avalue)433 ffi_call (ffi_cif *cif, void (*fn)(void), void *rvalue, void **avalue)
434 {
435   enum x86_64_reg_class classes[MAX_CLASSES];
436   char *stack, *argp;
437   ffi_type **arg_types;
438   int gprcount, ssecount, ngpr, nsse, i, avn;
439   _Bool ret_in_memory;
440   struct register_args *reg_args;
441 
442   /* Can't call 32-bit mode from 64-bit mode.  */
443   FFI_ASSERT (cif->abi == FFI_UNIX64);
444 
445   /* If the return value is a struct and we don't have a return value
446      address then we need to make one.  Note the setting of flags to
447      VOID above in ffi_prep_cif_machdep.  */
448   ret_in_memory = (cif->rtype->type == FFI_TYPE_STRUCT
449 		   && (cif->flags & 0xff) == FFI_TYPE_VOID);
450   if (rvalue == NULL && ret_in_memory)
451     rvalue = alloca (cif->rtype->size);
452 
453   /* Allocate the space for the arguments, plus 4 words of temp space.  */
454   stack = alloca (sizeof (struct register_args) + cif->bytes + 4*8);
455   reg_args = (struct register_args *) stack;
456   argp = stack + sizeof (struct register_args);
457 
458   gprcount = ssecount = 0;
459 
460   /* If the return value is passed in memory, add the pointer as the
461      first integer argument.  */
462   if (ret_in_memory)
463     reg_args->gpr[gprcount++] = (unsigned long) rvalue;
464 
465   avn = cif->nargs;
466   arg_types = cif->arg_types;
467 
468   for (i = 0; i < avn; ++i)
469     {
470       size_t n, size = arg_types[i]->size;
471 
472       n = examine_argument (arg_types[i], classes, 0, &ngpr, &nsse);
473       if (n == 0
474 	  || gprcount + ngpr > MAX_GPR_REGS
475 	  || ssecount + nsse > MAX_SSE_REGS)
476 	{
477 	  long align = arg_types[i]->alignment;
478 
479 	  /* Stack arguments are *always* at least 8 byte aligned.  */
480 	  if (align < 8)
481 	    align = 8;
482 
483 	  /* Pass this argument in memory.  */
484 	  argp = (void *) ALIGN (argp, align);
485 	  memcpy (argp, avalue[i], size);
486 	  argp += size;
487 	}
488       else
489 	{
490 	  /* The argument is passed entirely in registers.  */
491 	  char *a = (char *) avalue[i];
492 	  int j;
493 
494 	  for (j = 0; j < n; j++, a += 8, size -= 8)
495 	    {
496 	      switch (classes[j])
497 		{
498 		case X86_64_INTEGER_CLASS:
499 		case X86_64_INTEGERSI_CLASS:
500 		  /* Sign-extend integer arguments passed in general
501 		     purpose registers, to cope with the fact that
502 		     LLVM incorrectly assumes that this will be done
503 		     (the x86-64 PS ABI does not specify this). */
504 		  switch (arg_types[i]->type)
505 		    {
506 		    case FFI_TYPE_SINT8:
507 		      *(SINT64 *)&reg_args->gpr[gprcount] = (SINT64) *((SINT8 *) a);
508 		      break;
509 		    case FFI_TYPE_SINT16:
510 		      *(SINT64 *)&reg_args->gpr[gprcount] = (SINT64) *((SINT16 *) a);
511 		      break;
512 		    case FFI_TYPE_SINT32:
513 		      *(SINT64 *)&reg_args->gpr[gprcount] = (SINT64) *((SINT32 *) a);
514 		      break;
515 		    default:
516 		      reg_args->gpr[gprcount] = 0;
517 		      memcpy (&reg_args->gpr[gprcount], a, size < 8 ? size : 8);
518 		    }
519 		  gprcount++;
520 		  break;
521 		case X86_64_SSE_CLASS:
522 		case X86_64_SSEDF_CLASS:
523 		  reg_args->sse[ssecount++].i64 = *(UINT64 *) a;
524 		  break;
525 		case X86_64_SSESF_CLASS:
526 		  reg_args->sse[ssecount++].i32 = *(UINT32 *) a;
527 		  break;
528 		default:
529 		  abort();
530 		}
531 	    }
532 	}
533     }
534 
535   ffi_call_unix64 (stack, cif->bytes + sizeof (struct register_args),
536 		   cif->flags, rvalue, fn, ssecount);
537 }
538 
539 
540 extern void ffi_closure_unix64(void);
541 
542 ffi_status
ffi_prep_closure_loc(ffi_closure * closure,ffi_cif * cif,void (* fun)(ffi_cif *,void *,void **,void *),void * user_data,void * codeloc)543 ffi_prep_closure_loc (ffi_closure* closure,
544 		      ffi_cif* cif,
545 		      void (*fun)(ffi_cif*, void*, void**, void*),
546 		      void *user_data,
547 		      void *codeloc)
548 {
549   volatile unsigned short *tramp;
550 
551   /* Sanity check on the cif ABI.  */
552   {
553     int abi = cif->abi;
554     if (UNLIKELY (! (abi > FFI_FIRST_ABI && abi < FFI_LAST_ABI)))
555       return FFI_BAD_ABI;
556   }
557 
558   tramp = (volatile unsigned short *) &closure->tramp[0];
559 
560   tramp[0] = 0xbb49;		/* mov <code>, %r11	*/
561   *((unsigned long long * volatile) &tramp[1])
562     = (unsigned long) ffi_closure_unix64;
563   tramp[5] = 0xba49;		/* mov <data>, %r10	*/
564   *((unsigned long long * volatile) &tramp[6])
565     = (unsigned long) codeloc;
566 
567   /* Set the carry bit iff the function uses any sse registers.
568      This is clc or stc, together with the first byte of the jmp.  */
569   tramp[10] = cif->flags & (1 << 11) ? 0x49f9 : 0x49f8;
570 
571   tramp[11] = 0xe3ff;			/* jmp *%r11    */
572 
573   closure->cif = cif;
574   closure->fun = fun;
575   closure->user_data = user_data;
576 
577   return FFI_OK;
578 }
579 
580 int
ffi_closure_unix64_inner(ffi_closure * closure,void * rvalue,struct register_args * reg_args,char * argp)581 ffi_closure_unix64_inner(ffi_closure *closure, void *rvalue,
582 			 struct register_args *reg_args, char *argp)
583 {
584   ffi_cif *cif;
585   void **avalue;
586   ffi_type **arg_types;
587   long i, avn;
588   int gprcount, ssecount, ngpr, nsse;
589   int ret;
590 
591   cif = closure->cif;
592   avalue = alloca(cif->nargs * sizeof(void *));
593   gprcount = ssecount = 0;
594 
595   ret = cif->rtype->type;
596   if (ret != FFI_TYPE_VOID)
597     {
598       enum x86_64_reg_class classes[MAX_CLASSES];
599       size_t n = examine_argument (cif->rtype, classes, 1, &ngpr, &nsse);
600       if (n == 0)
601 	{
602 	  /* The return value goes in memory.  Arrange for the closure
603 	     return value to go directly back to the original caller.  */
604 	  rvalue = (void *) (unsigned long) reg_args->gpr[gprcount++];
605 	  /* We don't have to do anything in asm for the return.  */
606 	  ret = FFI_TYPE_VOID;
607 	}
608       else if (ret == FFI_TYPE_STRUCT && n == 2)
609 	{
610 	  /* Mark which register the second word of the structure goes in.  */
611 	  _Bool sse0 = SSE_CLASS_P (classes[0]);
612 	  _Bool sse1 = SSE_CLASS_P (classes[1]);
613 	  if (!sse0 && sse1)
614 	    ret |= 1 << 8;
615 	  else if (sse0 && !sse1)
616 	    ret |= 1 << 9;
617 	}
618     }
619 
620   avn = cif->nargs;
621   arg_types = cif->arg_types;
622 
623   for (i = 0; i < avn; ++i)
624     {
625       enum x86_64_reg_class classes[MAX_CLASSES];
626       size_t n;
627 
628       n = examine_argument (arg_types[i], classes, 0, &ngpr, &nsse);
629       if (n == 0
630 	  || gprcount + ngpr > MAX_GPR_REGS
631 	  || ssecount + nsse > MAX_SSE_REGS)
632 	{
633 	  long align = arg_types[i]->alignment;
634 
635 	  /* Stack arguments are *always* at least 8 byte aligned.  */
636 	  if (align < 8)
637 	    align = 8;
638 
639 	  /* Pass this argument in memory.  */
640 	  argp = (void *) ALIGN (argp, align);
641 	  avalue[i] = argp;
642 	  argp += arg_types[i]->size;
643 	}
644       /* If the argument is in a single register, or two consecutive
645 	 integer registers, then we can use that address directly.  */
646       else if (n == 1
647 	       || (n == 2 && !(SSE_CLASS_P (classes[0])
648 			       || SSE_CLASS_P (classes[1]))))
649 	{
650 	  /* The argument is in a single register.  */
651 	  if (SSE_CLASS_P (classes[0]))
652 	    {
653 	      avalue[i] = &reg_args->sse[ssecount];
654 	      ssecount += n;
655 	    }
656 	  else
657 	    {
658 	      avalue[i] = &reg_args->gpr[gprcount];
659 	      gprcount += n;
660 	    }
661 	}
662       /* Otherwise, allocate space to make them consecutive.  */
663       else
664 	{
665 	  char *a = alloca (16);
666 	  int j;
667 
668 	  avalue[i] = a;
669 	  for (j = 0; j < n; j++, a += 8)
670 	    {
671 	      if (SSE_CLASS_P (classes[j]))
672 		memcpy (a, &reg_args->sse[ssecount++], 8);
673 	      else
674 		memcpy (a, &reg_args->gpr[gprcount++], 8);
675 	    }
676 	}
677     }
678 
679   /* Invoke the closure.  */
680   closure->fun (cif, rvalue, avalue, closure->user_data);
681 
682   /* Tell assembly how to perform return type promotions.  */
683   return ret;
684 }
685 
686 #endif /* __x86_64__ */
687