gcc/libgo/runtime/go-ffi.c

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/* go-ffi.c -- convert Go type description to libffi.
Copyright 2009 The Go Authors. All rights reserved.
Use of this source code is governed by a BSD-style
license that can be found in the LICENSE file. */
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include "runtime.h"
#include "go-alloc.h"
#include "go-assert.h"
#include "go-type.h"
#ifdef USE_LIBFFI
#include "ffi.h"
/* The functions in this file are only called from reflect_call and
reflect.ffi. As these functions call libffi functions, which will
be compiled without -fsplit-stack, they will always run with a
large stack. */
static ffi_type *go_array_to_ffi (const struct __go_array_type *)
__attribute__ ((no_split_stack));
static ffi_type *go_slice_to_ffi (const struct __go_slice_type *)
__attribute__ ((no_split_stack));
static ffi_type *go_struct_to_ffi (const struct __go_struct_type *)
__attribute__ ((no_split_stack));
static ffi_type *go_string_to_ffi (void) __attribute__ ((no_split_stack));
static ffi_type *go_interface_to_ffi (void) __attribute__ ((no_split_stack));
static ffi_type *go_complex_to_ffi (ffi_type *)
__attribute__ ((no_split_stack, unused));
static ffi_type *go_type_to_ffi (const struct __go_type_descriptor *)
__attribute__ ((no_split_stack));
static ffi_type *go_func_return_ffi (const struct __go_func_type *)
__attribute__ ((no_split_stack));
/* Return an ffi_type for a Go array type. The libffi library does
not have any builtin support for passing arrays as values. We work
around this by pretending that the array is a struct. */
static ffi_type *
go_array_to_ffi (const struct __go_array_type *descriptor)
{
ffi_type *ret;
uintptr_t len;
ffi_type *element;
uintptr_t i;
ret = (ffi_type *) __go_alloc (sizeof (ffi_type));
ret->type = FFI_TYPE_STRUCT;
len = descriptor->__len;
ret->elements = (ffi_type **) __go_alloc ((len + 1) * sizeof (ffi_type *));
element = go_type_to_ffi (descriptor->__element_type);
for (i = 0; i < len; ++i)
ret->elements[i] = element;
ret->elements[len] = NULL;
return ret;
}
/* Return an ffi_type for a Go slice type. This describes the
__go_open_array type defines in array.h. */
static ffi_type *
go_slice_to_ffi (
const struct __go_slice_type *descriptor __attribute__ ((unused)))
{
ffi_type *ret;
ffi_type *ffi_intgo;
ret = (ffi_type *) __go_alloc (sizeof (ffi_type));
ret->type = FFI_TYPE_STRUCT;
ret->elements = (ffi_type **) __go_alloc (4 * sizeof (ffi_type *));
ret->elements[0] = &ffi_type_pointer;
ffi_intgo = sizeof (intgo) == 4 ? &ffi_type_sint32 : &ffi_type_sint64;
ret->elements[1] = ffi_intgo;
ret->elements[2] = ffi_intgo;
ret->elements[3] = NULL;
return ret;
}
/* Return an ffi_type for a Go struct type. */
static ffi_type *
go_struct_to_ffi (const struct __go_struct_type *descriptor)
{
ffi_type *ret;
int field_count;
const struct __go_struct_field *fields;
int i;
field_count = descriptor->__fields.__count;
if (field_count == 0) {
return &ffi_type_void;
}
ret = (ffi_type *) __go_alloc (sizeof (ffi_type));
ret->type = FFI_TYPE_STRUCT;
fields = (const struct __go_struct_field *) descriptor->__fields.__values;
ret->elements = (ffi_type **) __go_alloc ((field_count + 1)
* sizeof (ffi_type *));
for (i = 0; i < field_count; ++i)
ret->elements[i] = go_type_to_ffi (fields[i].__type);
ret->elements[field_count] = NULL;
return ret;
}
/* Return an ffi_type for a Go string type. This describes the String
struct. */
static ffi_type *
go_string_to_ffi (void)
{
ffi_type *ret;
ffi_type *ffi_intgo;
ret = (ffi_type *) __go_alloc (sizeof (ffi_type));
ret->type = FFI_TYPE_STRUCT;
ret->elements = (ffi_type **) __go_alloc (3 * sizeof (ffi_type *));
ret->elements[0] = &ffi_type_pointer;
ffi_intgo = sizeof (intgo) == 4 ? &ffi_type_sint32 : &ffi_type_sint64;
ret->elements[1] = ffi_intgo;
ret->elements[2] = NULL;
return ret;
}
/* Return an ffi_type for a Go interface type. This describes the
__go_interface and __go_empty_interface structs. */
static ffi_type *
go_interface_to_ffi (void)
{
ffi_type *ret;
ret = (ffi_type *) __go_alloc (sizeof (ffi_type));
ret->type = FFI_TYPE_STRUCT;
ret->elements = (ffi_type **) __go_alloc (3 * sizeof (ffi_type *));
ret->elements[0] = &ffi_type_pointer;
ret->elements[1] = &ffi_type_pointer;
ret->elements[2] = NULL;
return ret;
}
/* Return an ffi_type for a Go complex type. */
static ffi_type *
go_complex_to_ffi (ffi_type *float_type)
{
ffi_type *ret;
ret = (ffi_type *) __go_alloc (sizeof (ffi_type));
ret->type = FFI_TYPE_STRUCT;
ret->elements = (ffi_type **) __go_alloc (3 * sizeof (ffi_type *));
ret->elements[0] = float_type;
ret->elements[1] = float_type;
ret->elements[2] = NULL;
return ret;
}
/* Return an ffi_type for a type described by a
__go_type_descriptor. */
static ffi_type *
go_type_to_ffi (const struct __go_type_descriptor *descriptor)
{
switch (descriptor->__code & GO_CODE_MASK)
{
case GO_BOOL:
if (sizeof (_Bool) == 1)
return &ffi_type_uint8;
else if (sizeof (_Bool) == sizeof (int))
return &ffi_type_uint;
abort ();
case GO_FLOAT32:
if (sizeof (float) == 4)
return &ffi_type_float;
abort ();
case GO_FLOAT64:
if (sizeof (double) == 8)
return &ffi_type_double;
abort ();
case GO_COMPLEX64:
#ifdef __alpha__
runtime_throw("the libffi library does not support Complex64 type with "
"reflect.Call or runtime.SetFinalizer");
#else
if (sizeof (float) == 4)
return go_complex_to_ffi (&ffi_type_float);
abort ();
#endif
case GO_COMPLEX128:
#ifdef __alpha__
runtime_throw("the libffi library does not support Complex128 type with "
"reflect.Call or runtime.SetFinalizer");
#else
if (sizeof (double) == 8)
return go_complex_to_ffi (&ffi_type_double);
abort ();
#endif
case GO_INT16:
return &ffi_type_sint16;
case GO_INT32:
return &ffi_type_sint32;
case GO_INT64:
return &ffi_type_sint64;
case GO_INT8:
return &ffi_type_sint8;
case GO_INT:
return sizeof (intgo) == 4 ? &ffi_type_sint32 : &ffi_type_sint64;
case GO_UINT16:
return &ffi_type_uint16;
case GO_UINT32:
return &ffi_type_uint32;
case GO_UINT64:
return &ffi_type_uint64;
case GO_UINT8:
return &ffi_type_uint8;
case GO_UINT:
return sizeof (uintgo) == 4 ? &ffi_type_uint32 : &ffi_type_uint64;
case GO_UINTPTR:
if (sizeof (void *) == 2)
return &ffi_type_uint16;
else if (sizeof (void *) == 4)
return &ffi_type_uint32;
else if (sizeof (void *) == 8)
return &ffi_type_uint64;
abort ();
case GO_ARRAY:
return go_array_to_ffi ((const struct __go_array_type *) descriptor);
case GO_SLICE:
return go_slice_to_ffi ((const struct __go_slice_type *) descriptor);
case GO_STRUCT:
return go_struct_to_ffi ((const struct __go_struct_type *) descriptor);
case GO_STRING:
return go_string_to_ffi ();
case GO_INTERFACE:
return go_interface_to_ffi ();
case GO_CHAN:
case GO_FUNC:
case GO_MAP:
case GO_PTR:
case GO_UNSAFE_POINTER:
/* These types are always pointers, and for FFI purposes nothing
else matters. */
return &ffi_type_pointer;
default:
abort ();
}
}
/* Return the return type for a function, given the number of out
parameters and their types. */
static ffi_type *
go_func_return_ffi (const struct __go_func_type *func)
{
int count;
const struct __go_type_descriptor **types;
ffi_type *ret;
int i;
count = func->__out.__count;
if (count == 0)
return &ffi_type_void;
types = (const struct __go_type_descriptor **) func->__out.__values;
if (count == 1)
{
#if defined (__i386__) && !defined (__x86_64__)
/* FFI does not support complex types. On 32-bit x86, a
complex64 will be returned in %eax/%edx. We normally tell
FFI that a complex64 is a struct of two floats. On 32-bit
x86 a struct of two floats is returned via a hidden first
pointer parameter. Fortunately we can make everything work
by pretending that complex64 is int64. */
if ((types[0]->__code & GO_CODE_MASK) == GO_COMPLEX64)
return &ffi_type_sint64;
#endif
return go_type_to_ffi (types[0]);
}
ret = (ffi_type *) __go_alloc (sizeof (ffi_type));
ret->type = FFI_TYPE_STRUCT;
ret->elements = (ffi_type **) __go_alloc ((count + 1) * sizeof (ffi_type *));
for (i = 0; i < count; ++i)
ret->elements[i] = go_type_to_ffi (types[i]);
ret->elements[count] = NULL;
return ret;
}
/* Build an ffi_cif structure for a function described by a
__go_func_type structure. */
void
__go_func_to_cif (const struct __go_func_type *func, _Bool is_interface,
_Bool is_method, ffi_cif *cif)
{
int num_params;
const struct __go_type_descriptor **in_types;
size_t num_args;
ffi_type **args;
int off;
int i;
ffi_type *rettype;
ffi_status status;
num_params = func->__in.__count;
in_types = ((const struct __go_type_descriptor **)
func->__in.__values);
num_args = num_params + (is_interface ? 1 : 0);
args = (ffi_type **) __go_alloc (num_args * sizeof (ffi_type *));
i = 0;
off = 0;
if (is_interface)
{
args[0] = &ffi_type_pointer;
off = 1;
}
else if (is_method)
{
args[0] = &ffi_type_pointer;
i = 1;
}
for (; i < num_params; ++i)
args[i + off] = go_type_to_ffi (in_types[i]);
rettype = go_func_return_ffi (func);
status = ffi_prep_cif (cif, FFI_DEFAULT_ABI, num_args, rettype, args);
__go_assert (status == FFI_OK);
}
#endif /* defined(USE_LIBFFI) */