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/* go-fieldtrack.c -- structure field data analysis.
Copyright 2012 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 "runtime.h"
/* The compiler will track fields that have the tag go:"track". Any
function that refers to such a field will call this function with a
string
fieldtrack "package.type.field"
This function does not actually do anything. Instead, we gather
the field tracking information by looking for strings of that form
in the read-only data section. This is, of course, a horrible
hack, but it's good enough for now. We can improve it, e.g., by a
linker plugin, if this turns out to be useful. */
void
__go_fieldtrack (byte *p __attribute__ ((unused)))
{
}
/* A runtime function to add all the tracked fields to a
map[string]bool. */
extern void *mapassign (const struct maptype *, void *hmap, const void *key)
__asm__ (GOSYM_PREFIX "runtime.mapassign");
// The type descriptor for map[string] bool. */
extern const char map_string_bool[] __attribute__ ((weak));
extern const char map_string_bool[]
__asm__ (GOSYM_PREFIX "type..map_6string_7bool");
void runtime_Fieldtrack (void *) __asm__ (GOSYM_PREFIX "runtime.Fieldtrack");
void
runtime_Fieldtrack (void *m)
{
const char *p;
const char *pend;
const char *prefix;
size_t prefix_len;
if (map_string_bool == NULL)
return;
p = __data_start;
if (p == NULL)
p = __etext;
if (p == NULL)
p = _etext;
if (p == NULL)
return;
pend = __edata;
if (pend == NULL)
pend = _edata;
if (pend == NULL)
pend = __bss_start;
if (pend == NULL)
return;
prefix = "fieldtrack ";
prefix_len = __builtin_strlen (prefix);
while (p < pend)
{
const char *q1;
const char *q2;
q1 = __builtin_memchr (p + prefix_len, '"', pend - (p + prefix_len));
if (q1 == NULL)
break;
if (__builtin_memcmp (q1 - prefix_len, prefix, prefix_len) != 0)
{
p = q1 + 1;
continue;
}
q1++;
q2 = __builtin_memchr (q1, '"', pend - q1);
if (q2 == NULL)
break;
if (__builtin_memchr (q1, '\0', q2 - q1) == NULL)
{
String s;
void *p;
s.str = (const byte *) q1;
s.len = q2 - q1;
p = mapassign((const void*) map_string_bool, m, &s);
*(_Bool*)p = 1;
}
p = q2;
}
}
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