gcc/libgo/runtime/go-reflect-call.c

526 lines
13 KiB
C

/* go-reflect-call.c -- call reflection support for Go.
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. As
reflect_call calls a libffi function, which will be compiled
without -fsplit-stack, it 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));
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));
static void go_func_to_cif (const struct __go_func_type *, _Bool, _Bool,
ffi_cif *)
__attribute__ ((no_split_stack));
static size_t go_results_size (const struct __go_func_type *)
__attribute__ ((no_split_stack));
static void go_set_results (const struct __go_func_type *, unsigned char *,
void **)
__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;
ret = (ffi_type *) __go_alloc (sizeof (ffi_type));
ret->type = FFI_TYPE_STRUCT;
field_count = descriptor->__fields.__count;
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:
if (sizeof (float) == 4)
return go_complex_to_ffi (&ffi_type_float);
abort ();
case GO_COMPLEX128:
if (sizeof (double) == 8)
return go_complex_to_ffi (&ffi_type_double);
abort ();
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)
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. */
static 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);
}
/* Get the total size required for the result parameters of a
function. */
static size_t
go_results_size (const struct __go_func_type *func)
{
int count;
const struct __go_type_descriptor **types;
size_t off;
size_t maxalign;
int i;
count = func->__out.__count;
if (count == 0)
return 0;
types = (const struct __go_type_descriptor **) func->__out.__values;
/* A single integer return value is always promoted to a full
word. */
if (count == 1)
{
switch (types[0]->__code & GO_CODE_MASK)
{
case GO_BOOL:
case GO_INT8:
case GO_INT16:
case GO_INT32:
case GO_UINT8:
case GO_UINT16:
case GO_UINT32:
case GO_INT:
case GO_UINT:
return sizeof (ffi_arg);
default:
break;
}
}
off = 0;
maxalign = 0;
for (i = 0; i < count; ++i)
{
size_t align;
align = types[i]->__field_align;
if (align > maxalign)
maxalign = align;
off = (off + align - 1) & ~ (align - 1);
off += types[i]->__size;
}
off = (off + maxalign - 1) & ~ (maxalign - 1);
return off;
}
/* Copy the results of calling a function via FFI from CALL_RESULT
into the addresses in RESULTS. */
static void
go_set_results (const struct __go_func_type *func, unsigned char *call_result,
void **results)
{
int count;
const struct __go_type_descriptor **types;
size_t off;
int i;
count = func->__out.__count;
if (count == 0)
return;
types = (const struct __go_type_descriptor **) func->__out.__values;
/* A single integer return value is always promoted to a full
word. */
if (count == 1)
{
switch (types[0]->__code & GO_CODE_MASK)
{
case GO_BOOL:
case GO_INT8:
case GO_INT16:
case GO_INT32:
case GO_UINT8:
case GO_UINT16:
case GO_UINT32:
case GO_INT:
case GO_UINT:
{
union
{
unsigned char buf[sizeof (ffi_arg)];
ffi_arg v;
} u;
ffi_arg v;
__builtin_memcpy (&u.buf, call_result, sizeof (ffi_arg));
v = u.v;
switch (types[0]->__size)
{
case 1:
{
uint8_t b;
b = (uint8_t) v;
__builtin_memcpy (results[0], &b, 1);
}
break;
case 2:
{
uint16_t s;
s = (uint16_t) v;
__builtin_memcpy (results[0], &s, 2);
}
break;
case 4:
{
uint32_t w;
w = (uint32_t) v;
__builtin_memcpy (results[0], &w, 4);
}
break;
case 8:
{
uint64_t d;
d = (uint64_t) v;
__builtin_memcpy (results[0], &d, 8);
}
break;
default:
abort ();
}
}
return;
default:
break;
}
}
off = 0;
for (i = 0; i < count; ++i)
{
size_t align;
size_t size;
align = types[i]->__field_align;
size = types[i]->__size;
off = (off + align - 1) & ~ (align - 1);
__builtin_memcpy (results[i], call_result + off, size);
off += size;
}
}
/* Call a function. The type of the function is FUNC_TYPE, and the
address is FUNC_ADDR. PARAMS is an array of parameter addresses.
RESULTS is an array of result addresses. */
void
reflect_call (const struct __go_func_type *func_type, const void *func_addr,
_Bool is_interface, _Bool is_method, void **params,
void **results)
{
ffi_cif cif;
unsigned char *call_result;
__go_assert ((func_type->__common.__code & GO_CODE_MASK) == GO_FUNC);
go_func_to_cif (func_type, is_interface, is_method, &cif);
call_result = (unsigned char *) malloc (go_results_size (func_type));
ffi_call (&cif, func_addr, call_result, params);
/* Some day we may need to free result values if RESULTS is
NULL. */
if (results != NULL)
go_set_results (func_type, call_result, results);
free (call_result);
}
#else /* !defined(USE_LIBFFI) */
void
reflect_call (const struct __go_func_type *func_type __attribute__ ((unused)),
const void *func_addr __attribute__ ((unused)),
_Bool is_interface __attribute__ ((unused)),
_Bool is_method __attribute__ ((unused)),
void **params __attribute__ ((unused)),
void **results __attribute__ ((unused)))
{
/* Without FFI there is nothing we can do. */
runtime_throw("libgo built without FFI does not support "
"reflect.Call or runtime.SetFinalizer");
}
#endif /* !defined(USE_LIBFFI) */