Ruby: wasm/setjmp.h Source File

Ruby 3.2.5p208 (2024-07-26 revision 31d0f1a2e7dbfb60731d1f05b868e1d578cda493)

setjmp.h
1#ifndef RB_WASM_SUPPORT_SETJMP_H
2#define RB_WASM_SUPPORT_SETJMP_H
3
4#include "ruby/internal/config.h"
5#include <stdbool.h>
6
7#ifndef WASM_SETJMP_STACK_BUFFER_SIZE
8# define WASM_SETJMP_STACK_BUFFER_SIZE 6144
9#endif
10
11 struct __rb_wasm_asyncify_jmp_buf {
12 void* top;
13 void* end;
14 char buffer[WASM_SETJMP_STACK_BUFFER_SIZE];
15};
16
17 typedef struct {
18 // Internal Asyncify buffer space to save execution context
19 struct __rb_wasm_asyncify_jmp_buf setjmp_buf;
20 // Internal Asyncify buffer space used while unwinding from longjmp
21 // but never used for rewinding.
22 struct __rb_wasm_asyncify_jmp_buf longjmp_buf;
23 // Used to save top address of Asyncify stack `setjmp_buf`, which is
24 // overwritten during first rewind.
25 void *dst_buf_top;
26 // A payload value given by longjmp and returned by setjmp for the second time
27 int payload;
28 // Internal state field
29 int state;
30} rb_wasm_jmp_buf;
31
32// noinline to avoid breaking Asyncify assumption
33NOINLINE(int _rb_wasm_setjmp(rb_wasm_jmp_buf *env));
34NOINLINE(void _rb_wasm_longjmp(rb_wasm_jmp_buf *env, int payload));
35
36#define rb_wasm_setjmp(env) ((env).state = 0, _rb_wasm_setjmp(&(env)))
37
38// NOTE: Why is `_rb_wasm_longjmp` not `noreturn`? Why put `unreachable` in the call site?
39// Asyncify expects that `_rb_wasm_longjmp` returns its control, and Asyncify inserts a return
40// for unwinding after the call. This means that "`_rb_wasm_longjmp` returns its control but the
41// next line in the caller (C level) won't be executed".
42// On the other hand, `noreturn` means the callee won't return its control to the caller,
43// so compiler can assume that a function with the attribute won't reach the end of the function.
44// Therefore `_rb_wasm_longjmp`'s semantics is not exactly same as `noreturn`.
45#define rb_wasm_longjmp(env, payload) (_rb_wasm_longjmp(&env, payload), __builtin_unreachable())
46
47// Returns the Asyncify buffer of next rewinding if unwound for setjmp capturing or longjmp.
48// Used by the top level Asyncify handling in wasm/runtime.c
49void *rb_wasm_handle_jmp_unwind(void);
50
51
52//
53// POSIX-compatible declarations
54//
55
56typedef rb_wasm_jmp_buf jmp_buf;
57
58#define setjmp(env) rb_wasm_setjmp(env)
59#define longjmp(env, payload) rb_wasm_longjmp(env, payload)
60
61
62typedef void (*rb_wasm_try_catch_func_t)(void *ctx);
63
64 struct rb_wasm_try_catch {
65 rb_wasm_try_catch_func_t try_f;
66 rb_wasm_try_catch_func_t catch_f;
67 void *context;
68 int state;
69};
70
71//
72// Lightweight try-catch API without unwinding to root frame.
73//
74
75void
76rb_wasm_try_catch_init(struct rb_wasm_try_catch *try_catch,
77 rb_wasm_try_catch_func_t try_f,
78 rb_wasm_try_catch_func_t catch_f,
79 void *context);
80
81// Run, catch longjmp thrown by run, and re-catch longjmp thrown by catch, ...
82//
83// 1. run try_f of try_catch struct
84// 2. catch longjmps with the given target jmp_buf or exit
85// 3. run catch_f if not NULL, otherwise exit
86// 4. catch longjmps with the given target jmp_buf or exit
87// 5. repeat from step 3
88//
89// NOTICE: This API assumes that all longjmp targeting the given jmp_buf are NOT called
90// after the function that called this function has exited.
91//
92void
93rb_wasm_try_catch_loop_run(struct rb_wasm_try_catch *try_catch, rb_wasm_jmp_buf *target);
94
95#endif
stdbool.h
C99 shim for <stdbool.h>
__rb_wasm_asyncify_jmp_buf
Definition setjmp.h:11
rb_wasm_jmp_buf
Definition setjmp.h:17
rb_wasm_try_catch
Definition setjmp.h:64