mirror of
https://github.com/jart/cosmopolitan.git
synced 2025-02-01 03:53:33 +00:00
67 lines
3.3 KiB
C
67 lines
3.3 KiB
C
|
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
|
||
|
|
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
|
||
|
|
╞══════════════════════════════════════════════════════════════════════════════╡
|
||
|
|
│ Copyright 2021 Justine Alexandra Roberts Tunney │
|
||
|
|
│ │
|
||
|
|
│ Permission to use, copy, modify, and/or distribute this software for │
|
||
|
|
│ any purpose with or without fee is hereby granted, provided that the │
|
||
|
|
│ above copyright notice and this permission notice appear in all copies. │
|
||
|
|
│ │
|
||
|
|
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
|
||
|
|
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
|
||
|
|
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
|
||
|
|
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
|
||
|
|
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
|
||
|
|
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
|
||
|
|
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
|
||
|
|
│ PERFORMANCE OF THIS SOFTWARE. │
|
||
|
|
╚─────────────────────────────────────────────────────────────────────────────*/
|
||
|
|
#include "libc/nexgen32e/stackframe.h"
|
||
|
|
#include "libc/runtime/gc.h"
|
||
|
|
#include "libc/runtime/runtime.h"
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Frees memory when function returns.
|
||
|
|
*
|
||
|
|
* This garbage collector overwrites the return address on the stack so
|
||
|
|
* that the RET instruction calls a trampoline which calls free(). It's
|
||
|
|
* loosely analogous to Go's defer keyword rather than a true cycle gc.
|
||
|
|
*
|
||
|
|
* const char *s = _gc(strdup("hello"));
|
||
|
|
* puts(s);
|
||
|
|
*
|
||
|
|
* This macro is equivalent to:
|
||
|
|
*
|
||
|
|
* _defer(free, ptr)
|
||
|
|
*
|
||
|
|
* @warning do not return a gc()'d pointer
|
||
|
|
* @warning do not realloc() with gc()'d pointer
|
||
|
|
* @warning be careful about static keyword due to impact of inlining
|
||
|
|
* @note you should use -fno-omit-frame-pointer
|
||
|
|
*/
|
||
|
|
void *(_gc)(void *thing) {
|
||
|
|
struct StackFrame *frame;
|
||
|
|
frame = __builtin_frame_address(0);
|
||
|
|
__deferer(frame->next, _weakfree, thing);
|
||
|
|
return thing;
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Calls fn(arg) when function returns.
|
||
|
|
*
|
||
|
|
* This garbage collector overwrites the return address on the stack so
|
||
|
|
* that the RET instruction calls a trampoline which calls free(). It's
|
||
|
|
* loosely analogous to Go's defer keyword rather than a true cycle gc.
|
||
|
|
*
|
||
|
|
* @warning do not return a gc()'d pointer
|
||
|
|
* @warning do not realloc() with gc()'d pointer
|
||
|
|
* @warning be careful about static keyword due to impact of inlining
|
||
|
|
* @note you should use -fno-omit-frame-pointer
|
||
|
|
*/
|
||
|
|
void *(_defer)(void *fn, void *arg) {
|
||
|
|
struct StackFrame *frame;
|
||
|
|
frame = __builtin_frame_address(0);
|
||
|
|
__deferer(frame->next, fn, arg);
|
||
|
|
return arg;
|
||
|
|
}
|