ffi.c

linux下的gcc编译器

	case FFI_TYPE_UINT64:
	case FFI_TYPE_SINT64:
	  /* 'long long' arguments are passed as two words, but
	     either both words must fit in registers or both go
	     on the stack.  If they go on the stack, they must
	     be 8-byte-aligned.  */
	  if (intarg_count == NUM_GPR_ARG_REGISTERS-1
	      || intarg_count >= NUM_GPR_ARG_REGISTERS && intarg_count%2 != 0)
	    intarg_count++;
	  intarg_count += 2;
	  break;

	case FFI_TYPE_STRUCT:
#if FFI_TYPE_LONGDOUBLE != FFI_TYPE_DOUBLE
	case FFI_TYPE_LONGDOUBLE:
#endif
	  /* We must allocate space for a copy of these to enforce
	     pass-by-value.  Pad the space up to a multiple of 16
	     bytes (the maximum alignment required for anything under
	     the SYSV ABI).  */
	  struct_copy_size += ((*ptr)->size + 15) & ~0xF;
	  /* Fall through (allocate space for the pointer).  */

	default:
	  /* Everything else is passed as a 4-byte word in a GPR, either
	     the object itself or a pointer to it.  */
	  intarg_count++;
	  break;
	}
    }

  if (fparg_count != 0)
    flags |= FLAG_FP_ARGUMENTS;
  if (intarg_count > 4)
    flags |= FLAG_4_GPR_ARGUMENTS;
  if (struct_copy_size != 0)
    flags |= FLAG_ARG_NEEDS_COPY;
  
  /* Space for the FPR registers, if needed.  */
  if (fparg_count != 0)
    bytes += NUM_FPR_ARG_REGISTERS * sizeof(double);

  /* Stack space.  */
  if (intarg_count > NUM_GPR_ARG_REGISTERS)
    bytes += (intarg_count - NUM_GPR_ARG_REGISTERS) * sizeof(int);
  if (fparg_count > NUM_FPR_ARG_REGISTERS)
    bytes += (fparg_count - NUM_FPR_ARG_REGISTERS) * sizeof(double);

  /* The stack space allocated needs to be a multiple of 16 bytes.  */
  bytes = (bytes + 15) & ~0xF;

  /* Add in the space for the copied structures.  */
  bytes += struct_copy_size;

  cif->flags = flags;
  cif->bytes = bytes;

  return FFI_OK;
}

/*@-declundef@*/
/*@-exportheader@*/
extern void ffi_call_SYSV(/*@out@*/ extended_cif *, 
			  unsigned, unsigned, 
			  /*@out@*/ unsigned *, 
			  void (*fn)());
/*@=declundef@*/
/*@=exportheader@*/

void ffi_call(/*@dependent@*/ ffi_cif *cif, 
	      void (*fn)(), 
	      /*@out@*/ void *rvalue, 
	      /*@dependent@*/ void **avalue)
{
  extended_cif ecif;

  ecif.cif = cif;
  ecif.avalue = avalue;
  
  /* If the return value is a struct and we don't have a return	*/
  /* value address then we need to make one		        */

  if ((rvalue == NULL) && 
      (cif->rtype->type == FFI_TYPE_STRUCT))
    {
      /*@-sysunrecog@*/
      ecif.rvalue = alloca(cif->rtype->size);
      /*@=sysunrecog@*/
    }
  else
    ecif.rvalue = rvalue;
    
  
  switch (cif->abi) 
    {
    case FFI_SYSV:
    case FFI_GCC_SYSV:
      /*@-usedef@*/
      ffi_call_SYSV(&ecif, -cif->bytes, 
		    cif->flags, ecif.rvalue, fn);
      /*@=usedef@*/
      break;
    default:
      FFI_ASSERT(0);
      break;
    }
}


static void flush_icache(char *, int);

ffi_status
ffi_prep_closure (ffi_closure* closure,
		  ffi_cif* cif,
		  void (*fun)(ffi_cif*, void*, void**, void*),
		  void *user_data)
{
  unsigned int *tramp;

  FFI_ASSERT (cif->abi == FFI_GCC_SYSV);

  tramp = (unsigned int *) &closure->tramp[0];
  tramp[0] = 0x7c0802a6;  /*   mflr    r0 */
  tramp[1] = 0x4800000d;  /*   bl      10 <trampoline_initial+0x10> */
  tramp[4] = 0x7d6802a6;  /*   mflr    r11 */
  tramp[5] = 0x7c0803a6;  /*   mtlr    r0 */
  tramp[6] = 0x800b0000;  /*   lwz     r0,0(r11) */
  tramp[7] = 0x816b0004;  /*   lwz     r11,4(r11) */
  tramp[8] = 0x7c0903a6;  /*   mtctr   r0 */
  tramp[9] = 0x4e800420;  /*   bctr */
  *(void **) &tramp[2] = (void *)ffi_closure_SYSV; /* function */
  *(void **) &tramp[3] = (void *)closure;          /* context */

  closure->cif = cif;
  closure->fun = fun;
  closure->user_data = user_data;

  /* Flush the icache.  */
  flush_icache(&closure->tramp[0],FFI_TRAMPOLINE_SIZE);

  return FFI_OK;
}


#define MIN_CACHE_LINE_SIZE 8

static void flush_icache(char * addr1, int size)
{
  int i;
  char * addr;
  for (i = 0; i < size; i += MIN_CACHE_LINE_SIZE) {
     addr = addr1 + i;
     __asm__ volatile ("icbi 0,%0;" "dcbf 0,%0;" : : "r"(addr) : "memory");
  }
  addr = addr1 + size - 1;
  __asm__ volatile ("icbi 0,%0;" "dcbf 0,%0;" "sync;" "isync;" : : "r"(addr) : "memory");
}


int ffi_closure_helper_SYSV (ffi_closure*, void*, unsigned long*, 
                                     unsigned long*, unsigned long*);

/* Basically the trampoline invokes ffi_closure_SYSV, and on 
 * entry, r11 holds the address of the closure.
 * After storing the registers that could possibly contain
 * parameters to be passed into the stack frame and setting
 * up space for a return value, ffi_closure_SYSV invokes the 
 * following helper function to do most of the work
 */

int
ffi_closure_helper_SYSV (ffi_closure* closure, void * rvalue, 
            unsigned long * pgr, unsigned long * pfr, 
            unsigned long * pst)
{
  /* rvalue is the pointer to space for return value in closure assembly */
  /* pgr is the pointer to where r3-r10 are stored in ffi_closure_SYSV */
  /* pfr is the pointer to where f1-f8 are stored in ffi_closure_SYSV  */
  /* pst is the pointer to outgoing parameter stack in original caller */

  void **          avalue;
  ffi_type **      arg_types;
  long             i, avn;
  long             nf;   /* number of floating registers already used */
  long             ng;   /* number of general registers already used */
  ffi_cif *        cif; 
  double           temp; 

  cif = closure->cif;
  avalue = alloca(cif->nargs * sizeof(void *));

  nf = 0;
  ng = 0;

  /* Copy the caller's structure return value address so that the closure
     returns the data directly to the caller.  */
  if (cif->rtype->type == FFI_TYPE_STRUCT)
    {
      rvalue = *pgr;
      ng++;
      pgr++;
    }

  i = 0;
  avn = cif->nargs;
  arg_types = cif->arg_types;
  
  /* Grab the addresses of the arguments from the stack frame.  */
  while (i < avn)
    {
      switch (arg_types[i]->type)
	{
	case FFI_TYPE_SINT8:
	case FFI_TYPE_UINT8:
	/* there are 8 gpr registers used to pass values */
          if (ng < 8) {
	     avalue[i] = (((char *)pgr)+3);
             ng++;
             pgr++;
          } else {
             avalue[i] = (((char *)pst)+3);
             pst++;
          }
	  break;
           
	case FFI_TYPE_SINT16:
	case FFI_TYPE_UINT16:
	/* there are 8 gpr registers used to pass values */
          if (ng < 8) {
	     avalue[i] = (((char *)pgr)+2);
             ng++;
             pgr++;
          } else {
             avalue[i] = (((char *)pst)+2);
             pst++;
          }
	  break;

	case FFI_TYPE_SINT32:
	case FFI_TYPE_UINT32:
	case FFI_TYPE_POINTER:
	case FFI_TYPE_STRUCT:
	/* there are 8 gpr registers used to pass values */
          if (ng < 8) {
	     avalue[i] = pgr;
             ng++;
             pgr++;
          } else {
             avalue[i] = pst;
             pst++;
          }
	  break;

	case FFI_TYPE_SINT64:
	case FFI_TYPE_UINT64:
	  /* passing long long ints are complex, they must
           * be passed in suitable register pairs such as
           * (r3,r4) or (r5,r6) or (r6,r7), or (r7,r8) or (r9,r10)
           * and if the entire pair aren't available then the outgoing
           * parameter stack is used for both but an alignment of 8
           * must will be kept.  So we must either look in pgr
           * or pst to find the correct address for this type
           * of parameter.
           */
           if (ng < 7) {
              if (ng & 0x01) {
		/* skip r4, r6, r8 as starting points */
                  ng++;
                  pgr++;
              }
              avalue[i] = pgr;
              ng+=2;
              pgr+=2;
           } else {
              if (((long)pst) & 4) pst++;
              avalue[i] = pst;
              pst+=2;
           }
           break;

	case FFI_TYPE_FLOAT:
	    /* unfortunately float values are stored as doubles
             * in the ffi_closure_SYSV code (since we don't check
             * the type in that routine).
             */

          /* there are 8 64bit floating point registers */

          if (nf < 8) {
             temp = *(double*)pfr;
             *(float*)pfr = (float)temp;
             avalue[i] = pfr;
             nf++;
             pfr+=2;
          } else {
	    /* FIXME? here we are really changing the values
             * stored in the original calling routines outgoing
             * parameter stack.  This is probably a really
             * naughty thing to do but...
             */
	     avalue[i] = pst;
             nf++;
             pst+=1;
          }
	  break;

	case FFI_TYPE_DOUBLE:
	  /* On the outgoing stack all values are aligned to 8 */
          /* there are 8 64bit floating point registers */

          if (nf < 8) {
	     avalue[i] = pfr;
             nf++;
             pfr+=2;
          } else {
	     if (((long)pst) & 4) pst++;
	     avalue[i] = pst;
             nf++;
             pst+=2;
          }
	  break;

	default:
	  FFI_ASSERT(0);
	}

      i++;
    }


  (closure->fun) (cif, rvalue, avalue, closure->user_data);

  /* Tell ffi_closure_osf how to perform return type promotions.  */
  return cif->rtype->type;

}