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ruby--ruby/mjit.c
Takashi Kokubun f6d569b7c0
Call appropriate hooks on MJIT's fork 
This takes care of signal_self_pipe and other things.
2022-09-04 18:22:25 -07:00

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/**********************************************************************
mjit.c - MRI method JIT compiler functions for Ruby's main thread
Copyright (C) 2017 Vladimir Makarov <vmakarov@redhat.com>.
**********************************************************************/
/* We utilize widely used C compilers (GCC and LLVM Clang) to
implement MJIT. We feed them a C code generated from ISEQ. The
industrial C compilers are slower than regular JIT engines.
Generated code performance of the used C compilers has a higher
priority over the compilation speed.
So our major goal is to minimize the ISEQ compilation time when we
use widely optimization level (-O2). It is achieved by
o Using a precompiled version of the header
o Keeping all files in `/tmp`. On modern Linux `/tmp` is a file
system in memory. So it is pretty fast
o Implementing MJIT as a multi-threaded code because we want to
compile ISEQs in parallel with iseq execution to speed up Ruby
code execution. MJIT has one thread (*worker*) to do
parallel compilations:
o It prepares a precompiled code of the minimized header.
It starts at the MRI execution start
o It generates PIC object files of ISEQs
o It takes one JIT unit from a priority queue unless it is empty.
o It translates the JIT unit ISEQ into C-code using the precompiled
header, calls CC and load PIC code when it is ready
o Currently MJIT put ISEQ in the queue when ISEQ is called
o MJIT can reorder ISEQs in the queue if some ISEQ has been called
many times and its compilation did not start yet
o MRI reuses the machine code if it already exists for ISEQ
o The machine code we generate can stop and switch to the ISEQ
interpretation if some condition is not satisfied as the machine
code can be speculative or some exception raises
o Speculative machine code can be canceled.
Here is a diagram showing the MJIT organization:
_______
|header |
|_______|
| MRI building
--------------|----------------------------------------
| MRI execution
|
_____________|_____
| | |
| ___V__ | CC ____________________
| | |----------->| precompiled header |
| | | | |____________________|
| | | | |
| | MJIT | | |
| | | | |
| | | | ____V___ CC __________
| |______|----------->| C code |--->| .so file |
| | |________| |__________|
| | |
| | |
| MRI machine code |<-----------------------------
|___________________| loading
*/
#include "ruby/internal/config.h" // defines USE_MJIT
#if USE_MJIT
#include "constant.h"
#include "id_table.h"
#include "internal.h"
#include "internal/class.h"
#include "internal/cmdlineopt.h"
#include "internal/cont.h"
#include "internal/file.h"
#include "internal/hash.h"
#include "internal/process.h"
#include "internal/warnings.h"
#include "vm_sync.h"
#include "ractor_core.h"
#ifdef __sun
#define __EXTENSIONS__ 1
#endif
#include "vm_core.h"
#include "vm_callinfo.h"
#include "mjit.h"
#include "mjit_unit.h"
#include "gc.h"
#include "ruby_assert.h"
#include "ruby/debug.h"
#include "ruby/thread.h"
#include "ruby/version.h"
#include "builtin.h"
#include "insns.inc"
#include "insns_info.inc"
#include "internal/compile.h"
#include <sys/wait.h>
#include <sys/time.h>
#include <dlfcn.h>
#include <errno.h>
#ifdef HAVE_FCNTL_H
#include <fcntl.h>
#endif
#ifdef HAVE_SYS_PARAM_H
# include <sys/param.h>
#endif
#include "dln.h"
#include "ruby/util.h"
#undef strdup // ruby_strdup may trigger GC
#ifndef MAXPATHLEN
# define MAXPATHLEN 1024
#endif
// Atomically set function pointer if possible.
#define MJIT_ATOMIC_SET(var, val) (void)ATOMIC_PTR_EXCHANGE(var, val)
#define MJIT_TMP_PREFIX "_ruby_mjit_"
// Linked list of struct rb_mjit_unit.
struct rb_mjit_unit_list {
struct ccan_list_head head;
int length; // the list length
};
extern void rb_native_mutex_lock(rb_nativethread_lock_t *lock);
extern void rb_native_mutex_unlock(rb_nativethread_lock_t *lock);
extern void rb_native_mutex_initialize(rb_nativethread_lock_t *lock);
extern void rb_native_mutex_destroy(rb_nativethread_lock_t *lock);
extern void rb_native_cond_initialize(rb_nativethread_cond_t *cond);
extern void rb_native_cond_destroy(rb_nativethread_cond_t *cond);
extern void rb_native_cond_signal(rb_nativethread_cond_t *cond);
extern void rb_native_cond_broadcast(rb_nativethread_cond_t *cond);
extern void rb_native_cond_wait(rb_nativethread_cond_t *cond, rb_nativethread_lock_t *mutex);
// process.c
extern void mjit_add_waiting_pid(rb_vm_t *vm, rb_pid_t pid);
// A copy of MJIT portion of MRI options since MJIT initialization. We
// need them as MJIT threads still can work when the most MRI data were
// freed.
struct mjit_options mjit_opts;
// true if MJIT is enabled.
bool mjit_enabled = false;
// true if JIT-ed code should be called. When `ruby_vm_event_enabled_global_flags & ISEQ_TRACE_EVENTS`
// and `mjit_call_p == false`, any JIT-ed code execution is cancelled as soon as possible.
bool mjit_call_p = false;
// Priority queue of iseqs waiting for JIT compilation.
// This variable is a pointer to head unit of the queue.
static struct rb_mjit_unit_list unit_queue = { CCAN_LIST_HEAD_INIT(unit_queue.head) };
// List of units which are successfully compiled.
static struct rb_mjit_unit_list active_units = { CCAN_LIST_HEAD_INIT(active_units.head) };
// List of compacted so files which will be cleaned up by `free_list()` in `mjit_finish()`.
static struct rb_mjit_unit_list compact_units = { CCAN_LIST_HEAD_INIT(compact_units.head) };
// List of units before recompilation and just waiting for dlclose().
static struct rb_mjit_unit_list stale_units = { CCAN_LIST_HEAD_INIT(stale_units.head) };
// The number of so far processed ISEQs, used to generate unique id.
static int current_unit_num;
// A mutex for conitionals and critical sections.
static rb_nativethread_lock_t mjit_engine_mutex;
// A thread conditional to wake up `mjit_finish` at the end of PCH thread.
static rb_nativethread_cond_t mjit_pch_wakeup;
// A thread conditional to wake up the client if there is a change in
// executed unit status.
static rb_nativethread_cond_t mjit_client_wakeup;
// A thread conditional to wake up a worker if there we have something
// to add or we need to stop MJIT engine.
static rb_nativethread_cond_t mjit_worker_wakeup;
// A thread conditional to wake up workers if at the end of GC.
static rb_nativethread_cond_t mjit_gc_wakeup;
// The times when unload_units is requested. unload_units is called after some requests.
static int unload_requests = 0;
// The total number of unloaded units.
static int total_unloads = 0;
// Set to true to stop worker.
static bool stop_worker_p;
// Set to true if worker is stopped.
static bool worker_stopped = true;
// Path of "/tmp", which is different on Windows or macOS. See: system_default_tmpdir()
static char *tmp_dir;
// Used C compiler path.
static const char *cc_path;
// Used C compiler flags.
static const char **cc_common_args;
// Used C compiler flags added by --mjit-debug=...
static char **cc_added_args;
// Name of the precompiled header file.
static char *pch_file;
// The process id which should delete the pch_file on mjit_finish.
static rb_pid_t pch_owner_pid;
// Status of the precompiled header creation. The status is
// shared by the workers and the pch thread.
static enum {PCH_NOT_READY, PCH_FAILED, PCH_SUCCESS} pch_status;
// The start timestamp of current compilation
static double current_cc_ms = 0.0; // TODO: make this part of unit?
// Currently compiling MJIT unit
static struct rb_mjit_unit *current_cc_unit = NULL;
// PID of currently running C compiler process. 0 if nothing is running.
static pid_t current_cc_pid = 0; // TODO: make this part of unit?
// Name of the header file.
static char *header_file;
#include "mjit_config.h"
#if defined(__GNUC__) && \
(!defined(__clang__) || \
(defined(__clang__) && (defined(__FreeBSD__) || defined(__GLIBC__))))
# define GCC_PIC_FLAGS "-Wfatal-errors", "-fPIC", "-shared", "-w", "-pipe",
# define MJIT_CFLAGS_PIPE 1
#else
# define GCC_PIC_FLAGS /* empty */
# define MJIT_CFLAGS_PIPE 0
#endif
// Use `-nodefaultlibs -nostdlib` for GCC where possible, which does not work on cygwin, AIX, and OpenBSD.
// This seems to improve MJIT performance on GCC.
#if defined __GNUC__ && !defined __clang__ && !defined(__CYGWIN__) && !defined(_AIX) && !defined(__OpenBSD__)
# define GCC_NOSTDLIB_FLAGS "-nodefaultlibs", "-nostdlib",
#else
# define GCC_NOSTDLIB_FLAGS // empty
#endif
static const char *const CC_COMMON_ARGS[] = {
MJIT_CC_COMMON MJIT_CFLAGS GCC_PIC_FLAGS
NULL
};
static const char *const CC_DEBUG_ARGS[] = {MJIT_DEBUGFLAGS NULL};
static const char *const CC_OPTIMIZE_ARGS[] = {MJIT_OPTFLAGS NULL};
static const char *const CC_LDSHARED_ARGS[] = {MJIT_LDSHARED MJIT_CFLAGS GCC_PIC_FLAGS NULL};
static const char *const CC_DLDFLAGS_ARGS[] = {MJIT_DLDFLAGS NULL};
// `CC_LINKER_ARGS` are linker flags which must be passed to `-c` as well.
static const char *const CC_LINKER_ARGS[] = {
#if defined __GNUC__ && !defined __clang__ && !defined(__OpenBSD__)
"-nostartfiles",
#endif
GCC_NOSTDLIB_FLAGS NULL
};
static const char *const CC_LIBS[] = {
#if defined(__CYGWIN__)
MJIT_LIBS // mswin, cygwin
#endif
#if defined __GNUC__ && !defined __clang__
"-lgcc", // cygwin, and GCC platforms using `-nodefaultlibs -nostdlib`
#endif
#if defined __ANDROID__
"-lm", // to avoid 'cannot locate symbol "modf" referenced by .../_ruby_mjit_XXX.so"'
#endif
NULL
};
#define CC_CODEFLAG_ARGS (mjit_opts.debug ? CC_DEBUG_ARGS : CC_OPTIMIZE_ARGS)
// Print the arguments according to FORMAT to stderr only if MJIT
// verbose option value is more or equal to LEVEL.
PRINTF_ARGS(static void, 2, 3)
verbose(int level, const char *format, ...)
{
if (mjit_opts.verbose >= level) {
va_list args;
size_t len = strlen(format);
char *full_format = alloca(sizeof(char) * (len + 2));
// Creating `format + '\n'` to atomically print format and '\n'.
memcpy(full_format, format, len);
full_format[len] = '\n';
full_format[len+1] = '\0';
va_start(args, format);
vfprintf(stderr, full_format, args);
va_end(args);
}
}
PRINTF_ARGS(static void, 1, 2)
mjit_warning(const char *format, ...)
{
if (mjit_opts.warnings || mjit_opts.verbose) {
va_list args;
fprintf(stderr, "MJIT warning: ");
va_start(args, format);
vfprintf(stderr, format, args);
va_end(args);
fprintf(stderr, "\n");
}
}
// Add unit node to the tail of doubly linked `list`. It should be not in
// the list before.
static void
add_to_list(struct rb_mjit_unit *unit, struct rb_mjit_unit_list *list)
{
(void)RB_DEBUG_COUNTER_INC_IF(mjit_length_unit_queue, list == &unit_queue);
(void)RB_DEBUG_COUNTER_INC_IF(mjit_length_active_units, list == &active_units);
(void)RB_DEBUG_COUNTER_INC_IF(mjit_length_compact_units, list == &compact_units);
(void)RB_DEBUG_COUNTER_INC_IF(mjit_length_stale_units, list == &stale_units);
ccan_list_add_tail(&list->head, &unit->unode);
list->length++;
}
static void
remove_from_list(struct rb_mjit_unit *unit, struct rb_mjit_unit_list *list)
{
#if USE_DEBUG_COUNTER
rb_debug_counter_add(RB_DEBUG_COUNTER_mjit_length_unit_queue, -1, list == &unit_queue);
rb_debug_counter_add(RB_DEBUG_COUNTER_mjit_length_active_units, -1, list == &active_units);
rb_debug_counter_add(RB_DEBUG_COUNTER_mjit_length_compact_units, -1, list == &compact_units);
rb_debug_counter_add(RB_DEBUG_COUNTER_mjit_length_stale_units, -1, list == &stale_units);
#endif
ccan_list_del(&unit->unode);
list->length--;
}
static void
remove_file(const char *filename)
{
if (remove(filename)) {
mjit_warning("failed to remove \"%s\": %s", filename, strerror(errno));
}
}
// This is called in the following situations:
// 1) On dequeue or `unload_units()`, associated ISeq is already GCed.
// 2) The unit is not called often and unloaded by `unload_units()`.
// 3) Freeing lists on `mjit_finish()`.
//
// `jit_func` value does not matter for 1 and 3 since the unit won't be used anymore.
// For the situation 2, this sets the ISeq's JIT state to NOT_COMPILED_JIT_ISEQ_FUNC
// to prevent the situation that the same methods are continuously compiled.
static void
free_unit(struct rb_mjit_unit *unit)
{
if (unit->iseq) { // ISeq is not GCed
ISEQ_BODY(unit->iseq)->jit_func = (mjit_func_t)NOT_COMPILED_JIT_ISEQ_FUNC;
ISEQ_BODY(unit->iseq)->jit_unit = NULL;
}
if (unit->cc_entries) {
void *entries = (void *)unit->cc_entries;
free(entries);
}
if (unit->handle && dlclose(unit->handle)) { // handle is NULL if it's in queue
mjit_warning("failed to close handle for u%d: %s", unit->id, dlerror());
}
free(unit);
}
// Start a critical section. Use message `msg` to print debug info at `level`.
static inline void
CRITICAL_SECTION_START(int level, const char *msg)
{
verbose(level, "Locking %s", msg);
rb_native_mutex_lock(&mjit_engine_mutex);
verbose(level, "Locked %s", msg);
}
// Finish the current critical section. Use message `msg` to print
// debug info at `level`.
static inline void
CRITICAL_SECTION_FINISH(int level, const char *msg)
{
verbose(level, "Unlocked %s", msg);
rb_native_mutex_unlock(&mjit_engine_mutex);
}
static pid_t mjit_pid = 0;
static int
sprint_uniq_filename(char *str, size_t size, unsigned long id, const char *prefix, const char *suffix)
{
return snprintf(str, size, "%s/%sp%"PRI_PIDT_PREFIX"uu%lu%s", tmp_dir, prefix, mjit_pid, id, suffix);
}
// Return time in milliseconds as a double.
#ifdef __APPLE__
double ruby_real_ms_time(void);
# define real_ms_time() ruby_real_ms_time()
#else
static double
real_ms_time(void)
{
# ifdef HAVE_CLOCK_GETTIME
struct timespec tv;
# ifdef CLOCK_MONOTONIC
const clockid_t c = CLOCK_MONOTONIC;
# else
const clockid_t c = CLOCK_REALTIME;
# endif
clock_gettime(c, &tv);
return tv.tv_nsec / 1000000.0 + tv.tv_sec * 1000.0;
# else
struct timeval tv;
gettimeofday(&tv, NULL);
return tv.tv_usec / 1000.0 + tv.tv_sec * 1000.0;
# endif
}
#endif
// Return the best unit from list. The best is the first
// high priority unit or the unit whose iseq has the biggest number
// of calls so far.
static struct rb_mjit_unit *
get_from_list(struct rb_mjit_unit_list *list)
{
// Find iseq with max total_calls
struct rb_mjit_unit *unit = NULL, *next, *best = NULL;
ccan_list_for_each_safe(&list->head, unit, next, unode) {
if (unit->iseq == NULL) { // ISeq is GCed.
remove_from_list(unit, list);
free_unit(unit);
continue;
}
if (best == NULL || ISEQ_BODY(best->iseq)->total_calls < ISEQ_BODY(unit->iseq)->total_calls) {
best = unit;
}
}
if (best) {
remove_from_list(best, list);
}
return best;
}
// Return length of NULL-terminated array `args` excluding the NULL marker.
static size_t
args_len(char *const *args)
{
size_t i;
for (i = 0; (args[i]) != NULL;i++)
;
return i;
}
// Concatenate `num` passed NULL-terminated arrays of strings, put the
// result (with NULL end marker) into the heap, and return the result.
static char **
form_args(int num, ...)
{
va_list argp;
size_t len, n;
int i;
char **args, **res, **tmp;
va_start(argp, num);
res = NULL;
for (i = len = 0; i < num; i++) {
args = va_arg(argp, char **);
n = args_len(args);
if ((tmp = (char **)realloc(res, sizeof(char *) * (len + n + 1))) == NULL) {
free(res);
res = NULL;
break;
}
res = tmp;
MEMCPY(res + len, args, char *, n + 1);
len += n;
}
va_end(argp);
return res;
}
COMPILER_WARNING_PUSH
#if __has_warning("-Wdeprecated-declarations") || RBIMPL_COMPILER_IS(GCC)
COMPILER_WARNING_IGNORED(-Wdeprecated-declarations)
#endif
// Start an OS process of absolute executable path with arguments `argv`.
// Return PID of the process.
static pid_t
start_process(const char *abspath, char *const *argv)
{
// Not calling non-async-signal-safe functions between vfork
// and execv for safety
int dev_null = rb_cloexec_open(ruby_null_device, O_WRONLY, 0);
if (dev_null < 0) {
verbose(1, "MJIT: Failed to open a null device: %s", strerror(errno));
return -1;
}
if (mjit_opts.verbose >= 2) {
const char *arg;
fprintf(stderr, "Starting process: %s", abspath);
for (int i = 0; (arg = argv[i]) != NULL; i++)
fprintf(stderr, " %s", arg);
fprintf(stderr, "\n");
}
pid_t pid;
if ((pid = vfork()) == 0) { /* TODO: reuse some function in process.c */
umask(0077);
if (mjit_opts.verbose == 0) {
// CC can be started in a thread using a file which has been
// already removed while MJIT is finishing. Discard the
// messages about missing files.
dup2(dev_null, STDERR_FILENO);
dup2(dev_null, STDOUT_FILENO);
}
(void)close(dev_null);
pid = execv(abspath, argv); // Pid will be negative on an error
// Even if we successfully found CC to compile PCH we still can
// fail with loading the CC in very rare cases for some reasons.
// Stop the forked process in this case.
verbose(1, "MJIT: Error in execv: %s", abspath);
_exit(1);
}
(void)close(dev_null);
return pid;
}
COMPILER_WARNING_POP
// Execute an OS process of executable PATH with arguments ARGV.
// Return -1 or -2 if failed to execute, otherwise exit code of the process.
// TODO: Use a similar function in process.c
static int
exec_process(const char *path, char *const argv[])
{
int stat, exit_code = -2;
pid_t pid = start_process(path, argv);
for (;pid > 0;) {
pid_t r = waitpid(pid, &stat, 0);
if (r == -1) {
if (errno == EINTR) continue;
fprintf(stderr, "[%"PRI_PIDT_PREFIX"d] waitpid(%lu): %s (SIGCHLD=%d,%u)\n",
getpid(), (unsigned long)pid, strerror(errno),
RUBY_SIGCHLD, SIGCHLD_LOSSY);
break;
}
else if (r == pid) {
if (WIFEXITED(stat)) {
exit_code = WEXITSTATUS(stat);
break;
}
else if (WIFSIGNALED(stat)) {
exit_code = -1;
break;
}
}
}
return exit_code;
}
static void
remove_so_file(const char *so_file, struct rb_mjit_unit *unit)
{
remove_file(so_file);
}
// Print _mjitX, but make a human-readable funcname when --mjit-debug is used
static void
sprint_funcname(char *funcname, const struct rb_mjit_unit *unit)
{
const rb_iseq_t *iseq = unit->iseq;
if (iseq == NULL || (!mjit_opts.debug && !mjit_opts.debug_flags)) {
sprintf(funcname, "_mjit%d", unit->id);
return;
}
// Generate a short path
const char *path = RSTRING_PTR(rb_iseq_path(iseq));
const char *lib = "/lib/";
const char *version = "/" STRINGIZE(RUBY_API_VERSION_MAJOR) "." STRINGIZE(RUBY_API_VERSION_MINOR) "." STRINGIZE(RUBY_API_VERSION_TEENY) "/";
while (strstr(path, lib)) // skip "/lib/"
path = strstr(path, lib) + strlen(lib);
while (strstr(path, version)) // skip "/x.y.z/"
path = strstr(path, version) + strlen(version);
// Annotate all-normalized method names
const char *method = RSTRING_PTR(ISEQ_BODY(iseq)->location.label);
if (!strcmp(method, "[]")) method = "AREF";
if (!strcmp(method, "[]=")) method = "ASET";
// Print and normalize
sprintf(funcname, "_mjit%d_%s_%s", unit->id, path, method);
for (size_t i = 0; i < strlen(funcname); i++) {
char c = funcname[i];
if (!(('a' <= c && c <= 'z') || ('A' <= c && c <= 'Z') || ('0' <= c && c <= '9') || c == '_')) {
funcname[i] = '_';
}
}
}
static const int c_file_access_mode =
#ifdef O_BINARY
O_BINARY|
#endif
O_WRONLY|O_EXCL|O_CREAT;
#define append_str2(p, str, len) ((char *)memcpy((p), str, (len))+(len))
#define append_str(p, str) append_str2(p, str, sizeof(str)-1)
#define append_lit(p, str) append_str2(p, str, rb_strlen_lit(str))
// The function producing the pre-compiled header.
static void
make_pch(void)
{
const char *rest_args[] = {
# ifdef __clang__
"-emit-pch",
"-c",
# endif
// -nodefaultlibs is a linker flag, but it may affect cc1 behavior on Gentoo, which should NOT be changed on pch:
// https://gitweb.gentoo.org/proj/gcc-patches.git/tree/7.3.0/gentoo/13_all_default-ssp-fix.patch
GCC_NOSTDLIB_FLAGS
"-o", pch_file, header_file,
NULL,
};
verbose(2, "Creating precompiled header");
char **args = form_args(4, cc_common_args, CC_CODEFLAG_ARGS, cc_added_args, rest_args);
if (args == NULL) {
mjit_warning("making precompiled header failed on forming args");
pch_status = PCH_FAILED;
return;
}
int exit_code = exec_process(cc_path, args);
free(args);
if (exit_code == 0) {
pch_status = PCH_SUCCESS;
}
else {
mjit_warning("Making precompiled header failed on compilation. Stopping MJIT worker...");
pch_status = PCH_FAILED;
}
}
static int
compile_c_to_so(const char *c_file, const char *so_file)
{
const char *so_args[] = {
"-o", so_file,
# ifdef __clang__
"-include-pch", pch_file,
# endif
c_file, NULL
};
# if defined(__MACH__)
extern VALUE rb_libruby_selfpath;
const char *loader_args[] = {"-bundle_loader", StringValuePtr(rb_libruby_selfpath), NULL};
# else
const char *loader_args[] = {NULL};
# endif
char **args = form_args(8, CC_LDSHARED_ARGS, CC_CODEFLAG_ARGS, cc_added_args,
so_args, loader_args, CC_LIBS, CC_DLDFLAGS_ARGS, CC_LINKER_ARGS);
if (args == NULL) return 1;
int exit_code = exec_process(cc_path, args);
if (!mjit_opts.save_temps)
remove_file(c_file);
free(args);
return exit_code;
}
static void compile_prelude(FILE *f);
// Compile all JIT code into a single .c file
static bool
mjit_compact(char* c_file)
{
FILE *f;
int fd = rb_cloexec_open(c_file, c_file_access_mode, 0600);
if (fd < 0 || (f = fdopen(fd, "w")) == NULL) {
int e = errno;
if (fd >= 0) (void)close(fd);
verbose(1, "Failed to fopen '%s', giving up JIT for it (%s)", c_file, strerror(e));
return false;
}
compile_prelude(f);
// This entire loop lock GC so that we do not need to consider a case that
// ISeq is GC-ed in a middle of re-compilation. It takes 3~4ms with 100 methods
// on my machine. It's not too bad compared to compilation time of C (7200~8000ms),
// but it might be larger if we use a larger --jit-max-cache.
//
// TODO: Consider using a more granular lock after we implement inlining across
// compacted functions (not done yet).
bool success = true;
struct rb_mjit_unit *child_unit = 0;
ccan_list_for_each(&active_units.head, child_unit, unode) {
if (!success) continue;
if (ISEQ_BODY(child_unit->iseq)->jit_unit == NULL) continue; // Sometimes such units are created. TODO: Investigate why
char funcname[MAXPATHLEN];
sprint_funcname(funcname, child_unit);
long iseq_lineno = 0;
if (FIXNUM_P(ISEQ_BODY(child_unit->iseq)->location.first_lineno))
// FIX2INT may fallback to rb_num2long(), which is a method call and dangerous in MJIT worker. So using only FIX2LONG.
iseq_lineno = FIX2LONG(ISEQ_BODY(child_unit->iseq)->location.first_lineno);
const char *sep = "@";
const char *iseq_label = RSTRING_PTR(ISEQ_BODY(child_unit->iseq)->location.label);
const char *iseq_path = RSTRING_PTR(rb_iseq_path(child_unit->iseq));
if (!iseq_label) iseq_label = sep = "";
fprintf(f, "\n/* %s%s%s:%ld */\n", iseq_label, sep, iseq_path, iseq_lineno);
success &= mjit_compile(f, child_unit->iseq, funcname, child_unit->id);
}
fclose(f);
return success;
}
// Compile all cached .c files and build a single .so file. Reload all JIT func from it.
// This improves the code locality for better performance in terms of iTLB and iCache.
static int
mjit_compact_unit(struct rb_mjit_unit *unit)
{
static const char c_ext[] = ".c";
static const char so_ext[] = DLEXT;
char c_file[MAXPATHLEN], so_file[MAXPATHLEN];
sprint_uniq_filename(c_file, (int)sizeof(c_file), unit->id, MJIT_TMP_PREFIX, c_ext);
sprint_uniq_filename(so_file, (int)sizeof(so_file), unit->id, MJIT_TMP_PREFIX, so_ext);
bool success = mjit_compact(c_file);
if (success) {
return compile_c_to_so(c_file, so_file);
}
return 1;
}
extern pid_t rb_mjit_fork();
static pid_t
start_mjit_compact(struct rb_mjit_unit *unit)
{
pid_t pid = rb_mjit_fork();
if (pid == 0) {
int exit_code = mjit_compact_unit(unit);
exit(exit_code);
}
else {
return pid;
}
}
static void
load_compact_funcs_from_so(struct rb_mjit_unit *unit, char *c_file, char *so_file)
{
struct rb_mjit_unit *cur = 0;
double end_time = real_ms_time();
void *handle = dlopen(so_file, RTLD_NOW);
if (handle == NULL) {
mjit_warning("failure in loading code from compacted '%s': %s", so_file, dlerror());
free(unit);
return;
}
unit->handle = handle;
// lazily dlclose handle (and .so file for win32) on `mjit_finish()`.
add_to_list(unit, &compact_units);
if (!mjit_opts.save_temps)
remove_so_file(so_file, unit);
ccan_list_for_each(&active_units.head, cur, unode) {
void *func;
char funcname[MAXPATHLEN];
sprint_funcname(funcname, cur);
if ((func = dlsym(handle, funcname)) == NULL) {
mjit_warning("skipping to reload '%s' from '%s': %s", funcname, so_file, dlerror());
continue;
}
if (cur->iseq) { // Check whether GCed or not
// Usage of jit_code might be not in a critical section.
MJIT_ATOMIC_SET(ISEQ_BODY(cur->iseq)->jit_func, (mjit_func_t)func);
}
}
verbose(1, "JIT compaction (%.1fms): Compacted %d methods %s -> %s", end_time - current_cc_ms, active_units.length, c_file, so_file);
}
static void *
load_func_from_so(const char *so_file, const char *funcname, struct rb_mjit_unit *unit)
{
void *handle, *func;
handle = dlopen(so_file, RTLD_NOW);
if (handle == NULL) {
mjit_warning("failure in loading code from '%s': %s", so_file, dlerror());
return (void *)NOT_COMPILED_JIT_ISEQ_FUNC;
}
func = dlsym(handle, funcname);
unit->handle = handle;
return func;
}
#ifndef __clang__
static const char *
header_name_end(const char *s)
{
const char *e = s + strlen(s);
# ifdef __GNUC__ // don't chomp .pch for mswin
static const char suffix[] = ".gch";
// chomp .gch suffix
if (e > s+sizeof(suffix)-1 && strcmp(e-sizeof(suffix)+1, suffix) == 0) {
e -= sizeof(suffix)-1;
}
# endif
return e;
}
#endif
// Print platform-specific prerequisites in generated code.
static void
compile_prelude(FILE *f)
{
#ifndef __clang__ // -include-pch is used for Clang
const char *s = pch_file;
const char *e = header_name_end(s);
fprintf(f, "#include \"");
// print pch_file except .gch for gcc, but keep .pch for mswin
for (; s < e; s++) {
switch (*s) {
case '\\': case '"':
fputc('\\', f);
}
fputc(*s, f);
}
fprintf(f, "\"\n");
#endif
}
// Compile ISeq in UNIT and return function pointer of JIT-ed code.
// It may return NOT_COMPILED_JIT_ISEQ_FUNC if something went wrong.
static int
mjit_compile_unit(struct rb_mjit_unit *unit)
{
static const char c_ext[] = ".c";
static const char so_ext[] = DLEXT;
char c_file[MAXPATHLEN], so_file[MAXPATHLEN], funcname[MAXPATHLEN];
sprint_uniq_filename(c_file, (int)sizeof(c_file), unit->id, MJIT_TMP_PREFIX, c_ext);
sprint_uniq_filename(so_file, (int)sizeof(so_file), unit->id, MJIT_TMP_PREFIX, so_ext);
sprint_funcname(funcname, unit);
FILE *f;
int fd = rb_cloexec_open(c_file, c_file_access_mode, 0600);
if (fd < 0 || (f = fdopen(fd, "w")) == NULL) {
int e = errno;
if (fd >= 0) (void)close(fd);
verbose(1, "Failed to fopen '%s', giving up JIT for it (%s)", c_file, strerror(e));
return 1;
}
// print #include of MJIT header, etc.
compile_prelude(f);
// To make MJIT worker thread-safe against GC.compact, copy ISeq values while `in_jit` is true.
long iseq_lineno = 0;
if (FIXNUM_P(ISEQ_BODY(unit->iseq)->location.first_lineno))
// FIX2INT may fallback to rb_num2long(), which is a method call and dangerous in MJIT worker. So using only FIX2LONG.
iseq_lineno = FIX2LONG(ISEQ_BODY(unit->iseq)->location.first_lineno);
char *iseq_label = alloca(RSTRING_LEN(ISEQ_BODY(unit->iseq)->location.label) + 1);
char *iseq_path = alloca(RSTRING_LEN(rb_iseq_path(unit->iseq)) + 1);
strcpy(iseq_label, RSTRING_PTR(ISEQ_BODY(unit->iseq)->location.label));
strcpy(iseq_path, RSTRING_PTR(rb_iseq_path(unit->iseq)));
verbose(2, "start compilation: %s@%s:%ld -> %s", iseq_label, iseq_path, iseq_lineno, c_file);
fprintf(f, "/* %s@%s:%ld */\n\n", iseq_label, iseq_path, iseq_lineno);
bool success = mjit_compile(f, unit->iseq, funcname, unit->id);
fclose(f);
if (!success) {
if (!mjit_opts.save_temps)
remove_file(c_file);
verbose(1, "JIT failure: %s@%s:%ld -> %s", iseq_label, iseq_path, iseq_lineno, c_file);
return 1;
}
return compile_c_to_so(c_file, so_file);
}
static pid_t
start_mjit_compile(struct rb_mjit_unit *unit)
{
pid_t pid = rb_mjit_fork();
if (pid == 0) {
int exit_code = mjit_compile_unit(unit);
exit(exit_code);
}
else {
return pid;
}
}
// Capture cc entries of `captured_iseq` and append them to `compiled_iseq->jit_unit->cc_entries`.
// This is needed when `captured_iseq` is inlined by `compiled_iseq` and GC needs to mark inlined cc.
//
// Index to refer to `compiled_iseq->jit_unit->cc_entries` is returned instead of the address
// because old addresses may be invalidated by `realloc` later. -1 is returned on failure.
//
// This assumes that it's safe to reference cc without acquiring GVL.
int
mjit_capture_cc_entries(const struct rb_iseq_constant_body *compiled_iseq, const struct rb_iseq_constant_body *captured_iseq)
{
VM_ASSERT(compiled_iseq != NULL);
VM_ASSERT(compiled_iseq->jit_unit != NULL);
VM_ASSERT(captured_iseq != NULL);
struct rb_mjit_unit *unit = compiled_iseq->jit_unit;
unsigned int new_entries_size = unit->cc_entries_size + captured_iseq->ci_size;
VM_ASSERT(captured_iseq->ci_size > 0);
// Allocate new cc_entries and append them to unit->cc_entries
const struct rb_callcache **cc_entries;
int cc_entries_index = unit->cc_entries_size;
if (unit->cc_entries_size == 0) {
VM_ASSERT(unit->cc_entries == NULL);
unit->cc_entries = cc_entries = malloc(sizeof(struct rb_callcache *) * new_entries_size);
if (cc_entries == NULL) return -1;
}
else {
void *cc_ptr = (void *)unit->cc_entries; // get rid of bogus warning by VC
cc_entries = realloc(cc_ptr, sizeof(struct rb_callcache *) * new_entries_size);
if (cc_entries == NULL) return -1;
unit->cc_entries = cc_entries;
cc_entries += cc_entries_index;
}
unit->cc_entries_size = new_entries_size;
// Capture cc to cc_enties
for (unsigned int i = 0; i < captured_iseq->ci_size; i++) {
cc_entries[i] = captured_iseq->call_data[i].cc;
}
return cc_entries_index;
}
// Set up field `used_code_p` for unit iseqs whose iseq on the stack of ec.
static void
mark_ec_units(rb_execution_context_t *ec)
{
const rb_control_frame_t *cfp;
if (ec->vm_stack == NULL)
return;
for (cfp = RUBY_VM_END_CONTROL_FRAME(ec) - 1; ; cfp = RUBY_VM_NEXT_CONTROL_FRAME(cfp)) {
const rb_iseq_t *iseq;
if (cfp->pc && (iseq = cfp->iseq) != NULL
&& imemo_type((VALUE) iseq) == imemo_iseq
&& (ISEQ_BODY(iseq)->jit_unit) != NULL) {
ISEQ_BODY(iseq)->jit_unit->used_code_p = true;
}
if (cfp == ec->cfp)
break; // reached the most recent cfp
}
}
// MJIT info related to an existing continutaion.
struct mjit_cont {
rb_execution_context_t *ec; // continuation ec
struct mjit_cont *prev, *next; // used to form lists
};
// Double linked list of registered continuations. This is used to detect
// units which are in use in unload_units.
static struct mjit_cont *first_cont;
// Unload JIT code of some units to satisfy the maximum permitted
// number of units with a loaded code.
static void
unload_units(void)
{
struct rb_mjit_unit *unit = 0, *next;
struct mjit_cont *cont;
int units_num = active_units.length;
// For now, we don't unload units when ISeq is GCed. We should
// unload such ISeqs first here.
ccan_list_for_each_safe(&active_units.head, unit, next, unode) {
if (unit->iseq == NULL) { // ISeq is GCed.
remove_from_list(unit, &active_units);
free_unit(unit);
}
}
// Detect units which are in use and can't be unloaded.
ccan_list_for_each(&active_units.head, unit, unode) {
VM_ASSERT(unit->iseq != NULL && unit->handle != NULL);
unit->used_code_p = false;
}
// All threads have a root_fiber which has a mjit_cont. Other normal fibers also
// have a mjit_cont. Thus we can check ISeqs in use by scanning ec of mjit_conts.
for (cont = first_cont; cont != NULL; cont = cont->next) {
mark_ec_units(cont->ec);
}
// TODO: check stale_units and unload unused ones! (note that the unit is not associated to ISeq anymore)
// Unload units whose total_calls is smaller than any total_calls in unit_queue.
// TODO: make the algorithm more efficient
long unsigned prev_queue_calls = -1;
while (true) {
// Calculate the next max total_calls in unit_queue
long unsigned max_queue_calls = 0;
ccan_list_for_each(&unit_queue.head, unit, unode) {
if (unit->iseq != NULL && max_queue_calls < ISEQ_BODY(unit->iseq)->total_calls
&& ISEQ_BODY(unit->iseq)->total_calls < prev_queue_calls) {
max_queue_calls = ISEQ_BODY(unit->iseq)->total_calls;
}
}
prev_queue_calls = max_queue_calls;
bool unloaded_p = false;
ccan_list_for_each_safe(&active_units.head, unit, next, unode) {
if (unit->used_code_p) // We can't unload code on stack.
continue;
if (max_queue_calls > ISEQ_BODY(unit->iseq)->total_calls) {
verbose(2, "Unloading unit %d (calls=%lu, threshold=%lu)",
unit->id, ISEQ_BODY(unit->iseq)->total_calls, max_queue_calls);
VM_ASSERT(unit->handle != NULL);
remove_from_list(unit, &active_units);
free_unit(unit);
unloaded_p = true;
}
}
if (!unloaded_p) break;
}
if (units_num > active_units.length) {
verbose(1, "Too many JIT code -- %d units unloaded", units_num - active_units.length);
total_unloads += units_num - active_units.length;
}
}
static void mjit_add_iseq_to_process(const rb_iseq_t *iseq, const struct rb_mjit_compile_info *compile_info, bool worker_p);
// Return an unique file name in /tmp with PREFIX and SUFFIX and
// number ID. Use getpid if ID == 0. The return file name exists
// until the next function call.
static char *
get_uniq_filename(unsigned long id, const char *prefix, const char *suffix)
{
char buff[70], *str = buff;
int size = sprint_uniq_filename(buff, sizeof(buff), id, prefix, suffix);
str = 0;
++size;
str = xmalloc(size);
if (size <= (int)sizeof(buff)) {
memcpy(str, buff, size);
}
else {
sprint_uniq_filename(str, size, id, prefix, suffix);
}
return str;
}
// Prohibit calling JIT-ed code and let existing JIT-ed frames exit before the next insn.
void
mjit_cancel_all(const char *reason)
{
if (!mjit_enabled)
return;
mjit_call_p = false;
if (mjit_opts.warnings || mjit_opts.verbose) {
fprintf(stderr, "JIT cancel: Disabled JIT-ed code because %s\n", reason);
}
}
// Deal with ISeq movement from compactor
void
mjit_update_references(const rb_iseq_t *iseq)
{
if (!mjit_enabled)
return;
CRITICAL_SECTION_START(4, "mjit_update_references");
if (ISEQ_BODY(iseq)->jit_unit) {
ISEQ_BODY(iseq)->jit_unit->iseq = (rb_iseq_t *)rb_gc_location((VALUE)ISEQ_BODY(iseq)->jit_unit->iseq);
// We need to invalidate JIT-ed code for the ISeq because it embeds pointer addresses.
// To efficiently do that, we use the same thing as TracePoint and thus everything is cancelled for now.
// See mjit.h and tool/ruby_vm/views/_mjit_compile_insn.erb for how `mjit_call_p` is used.
mjit_cancel_all("GC.compact is used"); // TODO: instead of cancelling all, invalidate only this one and recompile it with some threshold.
}
// Units in stale_units (list of over-speculated and invalidated code) are not referenced from
// `ISEQ_BODY(iseq)->jit_unit` anymore (because new one replaces that). So we need to check them too.
// TODO: we should be able to reduce the number of units checked here.
struct rb_mjit_unit *unit = NULL;
ccan_list_for_each(&stale_units.head, unit, unode) {
if (unit->iseq == iseq) {
unit->iseq = (rb_iseq_t *)rb_gc_location((VALUE)unit->iseq);
}
}
CRITICAL_SECTION_FINISH(4, "mjit_update_references");
}
// Iseqs can be garbage collected. This function should call when it
// happens. It removes iseq from the unit.
void
mjit_free_iseq(const rb_iseq_t *iseq)
{
if (!mjit_enabled)
return;
if (ISEQ_BODY(iseq)->jit_unit) {
// jit_unit is not freed here because it may be referred by multiple
// lists of units. `get_from_list` and `mjit_finish` do the job.
ISEQ_BODY(iseq)->jit_unit->iseq = NULL;
}
// Units in stale_units (list of over-speculated and invalidated code) are not referenced from
// `ISEQ_BODY(iseq)->jit_unit` anymore (because new one replaces that). So we need to check them too.
// TODO: we should be able to reduce the number of units checked here.
struct rb_mjit_unit *unit = NULL;
ccan_list_for_each(&stale_units.head, unit, unode) {
if (unit->iseq == iseq) {
unit->iseq = NULL;
}
}
}
// Free unit list. This should be called only when worker is finished
// because node of unit_queue and one of active_units may have the same unit
// during proceeding unit.
static void
free_list(struct rb_mjit_unit_list *list, bool close_handle_p)
{
struct rb_mjit_unit *unit = 0, *next;
ccan_list_for_each_safe(&list->head, unit, next, unode) {
ccan_list_del(&unit->unode);
if (!close_handle_p) unit->handle = NULL; /* Skip dlclose in free_unit() */
if (list == &stale_units) { // `free_unit(unit)` crashes after GC.compact on `stale_units`
/*
* TODO: REVERT THIS BRANCH
* Debug the crash on stale_units w/ GC.compact and just use `free_unit(unit)`!!
*/
if (unit->handle && dlclose(unit->handle)) {
mjit_warning("failed to close handle for u%d: %s", unit->id, dlerror());
}
free(unit);
}
else {
free_unit(unit);
}
}
list->length = 0;
}
// Register a new continuation with execution context `ec`. Return MJIT info about
// the continuation.
struct mjit_cont *
mjit_cont_new(rb_execution_context_t *ec)
{
struct mjit_cont *cont;
// We need to use calloc instead of something like ZALLOC to avoid triggering GC here.
// When this function is called from rb_thread_alloc through rb_threadptr_root_fiber_setup,
// the thread is still being prepared and marking it causes SEGV.
cont = calloc(1, sizeof(struct mjit_cont));
if (cont == NULL)
rb_memerror();
cont->ec = ec;
CRITICAL_SECTION_START(3, "in mjit_cont_new");
if (first_cont == NULL) {
cont->next = cont->prev = NULL;
}
else {
cont->prev = NULL;
cont->next = first_cont;
first_cont->prev = cont;
}
first_cont = cont;
CRITICAL_SECTION_FINISH(3, "in mjit_cont_new");
return cont;
}
// Unregister continuation `cont`.
void
mjit_cont_free(struct mjit_cont *cont)
{
CRITICAL_SECTION_START(3, "in mjit_cont_new");
if (cont == first_cont) {
first_cont = cont->next;
if (first_cont != NULL)
first_cont->prev = NULL;
}
else {
cont->prev->next = cont->next;
if (cont->next != NULL)
cont->next->prev = cont->prev;
}
CRITICAL_SECTION_FINISH(3, "in mjit_cont_new");
free(cont);
}
// Finish work with continuation info.
static void
finish_conts(void)
{
struct mjit_cont *cont, *next;
for (cont = first_cont; cont != NULL; cont = next) {
next = cont->next;
xfree(cont);
}
}
static void mjit_wait(struct rb_iseq_constant_body *body);
// Check the unit queue and start mjit_compile if nothing is in progress.
static void
check_unit_queue(void)
{
if (worker_stopped) return;
if (current_cc_pid != 0) return; // still compiling
// Run unload_units after it's requested `max_cache_size / 10` (default: 10) times.
// This throttles the call to mitigate locking in unload_units. It also throttles JIT compaction.
int throttle_threshold = mjit_opts.max_cache_size / 10;
if (unload_requests >= throttle_threshold) {
unload_units();
unload_requests = 0;
if (active_units.length == mjit_opts.max_cache_size && mjit_opts.wait) { // Sometimes all methods may be in use
mjit_opts.max_cache_size++; // avoid infinite loop on `rb_mjit_wait_call`. Note that --jit-wait is just for testing.
verbose(1, "No units can be unloaded -- incremented max-cache-size to %d for --jit-wait", mjit_opts.max_cache_size);
}
}
if (active_units.length >= mjit_opts.max_cache_size) return; // wait until unload_units makes a progress
// Dequeue a unit
struct rb_mjit_unit *unit = get_from_list(&unit_queue);
if (unit == NULL) return;
current_cc_ms = real_ms_time();
current_cc_unit = unit;
current_cc_pid = start_mjit_compile(unit);
// JIT failure
if (current_cc_pid == -1) {
current_cc_pid = 0;
current_cc_unit->iseq->body->jit_func = (mjit_func_t)NOT_COMPILED_JIT_ISEQ_FUNC; // TODO: consider unit->compact_p
current_cc_unit = NULL;
return;
}
if (mjit_opts.wait) {
mjit_wait(unit->iseq->body);
}
}
// Create unit for `iseq`. This function may be called from an MJIT worker.
static struct rb_mjit_unit*
create_unit(const rb_iseq_t *iseq)
{
// To prevent GC, don't use ZALLOC // TODO: just use ZALLOC
struct rb_mjit_unit *unit = calloc(1, sizeof(struct rb_mjit_unit));
if (unit == NULL)
return NULL;
unit->id = current_unit_num++;
if (iseq == NULL) { // Compact unit
unit->compact_p = true;
}
else { // Normal unit
unit->iseq = (rb_iseq_t *)iseq;
ISEQ_BODY(iseq)->jit_unit = unit;
}
return unit;
}
// Check if it should compact all JIT code and start it as needed
static void
check_compaction(void)
{
// Allow only `max_cache_size / 100` times (default: 100) of compaction.
// Note: GC of compacted code has not been implemented yet.
int max_compact_size = mjit_opts.max_cache_size / 100;
if (max_compact_size < 10) max_compact_size = 10;
// Run unload_units after it's requested `max_cache_size / 10` (default: 10) times.
// This throttles the call to mitigate locking in unload_units. It also throttles JIT compaction.
int throttle_threshold = mjit_opts.max_cache_size / 10;
if (compact_units.length < max_compact_size
&& ((!mjit_opts.wait && unit_queue.length == 0 && active_units.length > 1)
|| (active_units.length == mjit_opts.max_cache_size && compact_units.length * throttle_threshold <= total_unloads))) { // throttle compaction by total_unloads
struct rb_mjit_unit *unit = create_unit(NULL);
if (unit != NULL) {
// TODO: assert unit is null
current_cc_ms = real_ms_time();
current_cc_unit = unit;
current_cc_pid = start_mjit_compact(unit);
// TODO: check -1
}
}
}
// Check the current CC process if any, and start a next C compiler process as needed.
void
mjit_notify_waitpid(int status)
{
// TODO: check current_cc_pid?
current_cc_pid = 0;
// Delete .c file
char c_file[MAXPATHLEN];
sprint_uniq_filename(c_file, (int)sizeof(c_file), current_cc_unit->id, MJIT_TMP_PREFIX, ".c");
// Check the result
bool success = false;
if (WIFEXITED(status)) {
success = (WEXITSTATUS(status) == 0);
}
if (!success) {
verbose(2, "Failed to generate so");
if (!current_cc_unit->compact_p) {
current_cc_unit->iseq->body->jit_func = (mjit_func_t)NOT_COMPILED_JIT_ISEQ_FUNC;
}
free_unit(current_cc_unit);
current_cc_unit = NULL;
return;
}
// Load .so file
char so_file[MAXPATHLEN];
sprint_uniq_filename(so_file, (int)sizeof(so_file), current_cc_unit->id, MJIT_TMP_PREFIX, DLEXT);
if (current_cc_unit->compact_p) { // Compact unit
load_compact_funcs_from_so(current_cc_unit, c_file, so_file);
current_cc_unit = NULL;
}
else { // Normal unit
// Load the function from so
char funcname[MAXPATHLEN];
sprint_funcname(funcname, current_cc_unit);
void *func = load_func_from_so(so_file, funcname, current_cc_unit);
// Delete .so file
if (!mjit_opts.save_temps)
remove_file(so_file);
// Set the jit_func if successful
if (current_cc_unit->iseq != NULL) { // mjit_free_iseq could nullify this
rb_iseq_t *iseq = current_cc_unit->iseq;
if ((uintptr_t)func > (uintptr_t)LAST_JIT_ISEQ_FUNC) {
double end_time = real_ms_time();
verbose(1, "JIT success (%.1fms): %s@%s:%ld -> %s",
end_time - current_cc_ms, RSTRING_PTR(ISEQ_BODY(iseq)->location.label),
RSTRING_PTR(rb_iseq_path(iseq)), FIX2LONG(ISEQ_BODY(iseq)->location.first_lineno), c_file);
add_to_list(current_cc_unit, &active_units);
}
MJIT_ATOMIC_SET(ISEQ_BODY(iseq)->jit_func, func);
} // TODO: free unit on else?
current_cc_unit = NULL;
// Run compaction if it should
if (!stop_worker_p) {
check_compaction();
}
}
// Skip further compilation if mjit_finish is trying to stop it
if (!stop_worker_p) {
// Start the next one as needed
check_unit_queue();
}
}
// Return true if given ISeq body should be compiled by MJIT
static inline int
mjit_target_iseq_p(const rb_iseq_t *iseq)
{
struct rb_iseq_constant_body *body = ISEQ_BODY(iseq);
return (body->type == ISEQ_TYPE_METHOD || body->type == ISEQ_TYPE_BLOCK)
&& !body->builtin_inline_p
&& strcmp("<internal:mjit>", RSTRING_PTR(rb_iseq_path(iseq)));
}
// If recompile_p is true, the call is initiated by mjit_recompile.
// This assumes the caller holds CRITICAL_SECTION when recompile_p is true.
static void
mjit_add_iseq_to_process(const rb_iseq_t *iseq, const struct rb_mjit_compile_info *compile_info, bool recompile_p)
{
// TODO: Support non-main Ractors
if (!mjit_enabled || pch_status == PCH_FAILED || !rb_ractor_main_p())
return;
if (!mjit_target_iseq_p(iseq)) {
ISEQ_BODY(iseq)->jit_func = (mjit_func_t)NOT_COMPILED_JIT_ISEQ_FUNC; // skip mjit_wait
return;
}
RB_DEBUG_COUNTER_INC(mjit_add_iseq_to_process);
ISEQ_BODY(iseq)->jit_func = (mjit_func_t)NOT_READY_JIT_ISEQ_FUNC;
create_unit(iseq);
if (ISEQ_BODY(iseq)->jit_unit == NULL)
// Failure in creating the unit.
return;
if (compile_info != NULL)
ISEQ_BODY(iseq)->jit_unit->compile_info = *compile_info;
add_to_list(ISEQ_BODY(iseq)->jit_unit, &unit_queue);
if (active_units.length >= mjit_opts.max_cache_size) {
unload_requests++;
}
}
// Add ISEQ to be JITed in parallel with the current thread.
// Unload some JIT codes if there are too many of them.
void
rb_mjit_add_iseq_to_process(const rb_iseq_t *iseq)
{
mjit_add_iseq_to_process(iseq, NULL, false);
check_unit_queue();
}
// For this timeout seconds, --jit-wait will wait for JIT compilation finish.
#define MJIT_WAIT_TIMEOUT_SECONDS 60
static void
mjit_wait(struct rb_iseq_constant_body *body)
{
pid_t initial_pid = current_cc_pid;
struct timeval tv;
int tries = 0;
tv.tv_sec = 0;
tv.tv_usec = 1000;
while (body == NULL ? current_cc_pid == initial_pid : body->jit_func == (mjit_func_t)NOT_READY_JIT_ISEQ_FUNC) { // TODO: refactor this
tries++;
if (tries / 1000 > MJIT_WAIT_TIMEOUT_SECONDS || pch_status == PCH_FAILED) {
if (body != NULL) {
body->jit_func = (mjit_func_t) NOT_COMPILED_JIT_ISEQ_FUNC; // JIT worker seems dead. Give up.
}
mjit_warning("timed out to wait for JIT finish");
break;
}
rb_thread_wait_for(tv);
}
}
static void
mjit_wait_unit(struct rb_mjit_unit *unit)
{
if (unit->compact_p) {
mjit_wait(NULL);
}
else {
mjit_wait(current_cc_unit->iseq->body);
}
}
// Wait for JIT compilation finish for --jit-wait, and call the function pointer
// if the compiled result is not NOT_COMPILED_JIT_ISEQ_FUNC.
VALUE
rb_mjit_wait_call(rb_execution_context_t *ec, struct rb_iseq_constant_body *body)
{
if (worker_stopped)
return Qundef;
mjit_wait(body);
if ((uintptr_t)body->jit_func <= (uintptr_t)LAST_JIT_ISEQ_FUNC) {
return Qundef;
}
return body->jit_func(ec, ec->cfp);
}
struct rb_mjit_compile_info*
rb_mjit_iseq_compile_info(const struct rb_iseq_constant_body *body)
{
VM_ASSERT(body->jit_unit != NULL);
return &body->jit_unit->compile_info;
}
static void
mjit_recompile(const rb_iseq_t *iseq)
{
if ((uintptr_t)ISEQ_BODY(iseq)->jit_func <= (uintptr_t)LAST_JIT_ISEQ_FUNC)
return;
verbose(1, "JIT recompile: %s@%s:%d", RSTRING_PTR(ISEQ_BODY(iseq)->location.label),
RSTRING_PTR(rb_iseq_path(iseq)), FIX2INT(ISEQ_BODY(iseq)->location.first_lineno));
VM_ASSERT(ISEQ_BODY(iseq)->jit_unit != NULL);
mjit_add_iseq_to_process(iseq, &ISEQ_BODY(iseq)->jit_unit->compile_info, true);
check_unit_queue();
}
// Recompile iseq, disabling send optimization
void
rb_mjit_recompile_send(const rb_iseq_t *iseq)
{
rb_mjit_iseq_compile_info(ISEQ_BODY(iseq))->disable_send_cache = true;
mjit_recompile(iseq);
}
// Recompile iseq, disabling ivar optimization
void
rb_mjit_recompile_ivar(const rb_iseq_t *iseq)
{
rb_mjit_iseq_compile_info(ISEQ_BODY(iseq))->disable_ivar_cache = true;
mjit_recompile(iseq);
}
// Recompile iseq, disabling exivar optimization
void
rb_mjit_recompile_exivar(const rb_iseq_t *iseq)
{
rb_mjit_iseq_compile_info(ISEQ_BODY(iseq))->disable_exivar_cache = true;
mjit_recompile(iseq);
}
// Recompile iseq, disabling method inlining
void
rb_mjit_recompile_inlining(const rb_iseq_t *iseq)
{
rb_mjit_iseq_compile_info(ISEQ_BODY(iseq))->disable_inlining = true;
mjit_recompile(iseq);
}
// Recompile iseq, disabling getconstant inlining
void
rb_mjit_recompile_const(const rb_iseq_t *iseq)
{
rb_mjit_iseq_compile_info(ISEQ_BODY(iseq))->disable_const_cache = true;
mjit_recompile(iseq);
}
extern VALUE ruby_archlibdir_path, ruby_prefix_path;
// Initialize header_file, pch_file, libruby_pathflag. Return true on success.
static bool
init_header_filename(void)
{
int fd;
#ifdef LOAD_RELATIVE
// Root path of the running ruby process. Equal to RbConfig::TOPDIR.
VALUE basedir_val;
#endif
const char *basedir = "";
size_t baselen = 0;
char *p;
#ifdef LOAD_RELATIVE
basedir_val = ruby_prefix_path;
basedir = StringValuePtr(basedir_val);
baselen = RSTRING_LEN(basedir_val);
#else
if (getenv("MJIT_SEARCH_BUILD_DIR")) {
// This path is not intended to be used on production, but using build directory's
// header file here because people want to run `make test-all` without running
// `make install`. Don't use $MJIT_SEARCH_BUILD_DIR except for test-all.
struct stat st;
const char *hdr = dlsym(RTLD_DEFAULT, "MJIT_HEADER");
if (!hdr) {
verbose(1, "No MJIT_HEADER");
}
else if (hdr[0] != '/') {
verbose(1, "Non-absolute header file path: %s", hdr);
}
else if (stat(hdr, &st) || !S_ISREG(st.st_mode)) {
verbose(1, "Non-file header file path: %s", hdr);
}
else if ((st.st_uid != getuid()) || (st.st_mode & 022) ||
!rb_path_check(hdr)) {
verbose(1, "Unsafe header file: uid=%ld mode=%#o %s",
(long)st.st_uid, (unsigned)st.st_mode, hdr);
return FALSE;
}
else {
// Do not pass PRELOADENV to child processes, on
// multi-arch environment
verbose(3, "PRELOADENV("PRELOADENV")=%s", getenv(PRELOADENV));
// assume no other PRELOADENV in test-all
unsetenv(PRELOADENV);
verbose(3, "MJIT_HEADER: %s", hdr);
header_file = ruby_strdup(hdr);
if (!header_file) return false;
}
}
else
#endif
{
// A name of the header file included in any C file generated by MJIT for iseqs.
static const char header_name[] = MJIT_HEADER_INSTALL_DIR "/" MJIT_MIN_HEADER_NAME;
const size_t header_name_len = sizeof(header_name) - 1;
header_file = xmalloc(baselen + header_name_len + 1);
p = append_str2(header_file, basedir, baselen);
p = append_str2(p, header_name, header_name_len + 1);
if ((fd = rb_cloexec_open(header_file, O_RDONLY, 0)) < 0) {
verbose(1, "Cannot access header file: %s", header_file);
xfree(header_file);
header_file = NULL;
return false;
}
(void)close(fd);
}
pch_file = get_uniq_filename(0, MJIT_TMP_PREFIX "h", ".h.gch");
return true;
}
static char *
system_default_tmpdir(void)
{
// c.f. ext/etc/etc.c:etc_systmpdir()
#if defined _CS_DARWIN_USER_TEMP_DIR
char path[MAXPATHLEN];
size_t len = confstr(_CS_DARWIN_USER_TEMP_DIR, path, sizeof(path));
if (len > 0) {
char *tmpdir = xmalloc(len);
if (len > sizeof(path)) {
confstr(_CS_DARWIN_USER_TEMP_DIR, tmpdir, len);
}
else {
memcpy(tmpdir, path, len);
}
return tmpdir;
}
#endif
return 0;
}
static int
check_tmpdir(const char *dir)
{
struct stat st;
if (!dir) return FALSE;
if (stat(dir, &st)) return FALSE;
#ifndef S_ISDIR
# define S_ISDIR(m) (((m) & S_IFMT) == S_IFDIR)
#endif
if (!S_ISDIR(st.st_mode)) return FALSE;
#ifndef S_IWOTH
# define S_IWOTH 002
#endif
if (st.st_mode & S_IWOTH) {
#ifdef S_ISVTX
if (!(st.st_mode & S_ISVTX)) return FALSE;
#else
return FALSE;
#endif
}
if (access(dir, W_OK)) return FALSE;
return TRUE;
}
static char *
system_tmpdir(void)
{
char *tmpdir;
# define RETURN_ENV(name) \
if (check_tmpdir(tmpdir = getenv(name))) return ruby_strdup(tmpdir)
RETURN_ENV("TMPDIR");
RETURN_ENV("TMP");
tmpdir = system_default_tmpdir();
if (check_tmpdir(tmpdir)) return tmpdir;
return ruby_strdup("/tmp");
# undef RETURN_ENV
}
// Minimum value for JIT cache size.
#define MIN_CACHE_SIZE 10
// Default permitted number of units with a JIT code kept in memory.
#define DEFAULT_MAX_CACHE_SIZE 10000
// A default threshold used to add iseq to JIT.
#define DEFAULT_MIN_CALLS_TO_ADD 10000
// Start MJIT worker. Return TRUE if worker is successfully started.
static bool
start_worker(void)
{
stop_worker_p = false;
worker_stopped = false;
return true;
}
// There's no strndup on Windows
static char*
ruby_strndup(const char *str, size_t n)
{
char *ret = xmalloc(n + 1);
memcpy(ret, str, n);
ret[n] = '\0';
return ret;
}
// Convert "foo bar" to {"foo", "bar", NULL} array. Caller is responsible for
// freeing a returned buffer and its elements.
static char **
split_flags(const char *flags)
{
char *buf[MAXPATHLEN];
int i = 0;
char *next;
for (; flags != NULL; flags = next) {
next = strchr(flags, ' ');
if (next == NULL) {
if (strlen(flags) > 0)
buf[i++] = strdup(flags);
}
else {
if (next > flags)
buf[i++] = ruby_strndup(flags, next - flags);
next++; // skip space
}
}
char **ret = xmalloc(sizeof(char *) * (i + 1));
memcpy(ret, buf, sizeof(char *) * i);
ret[i] = NULL;
return ret;
}
#define opt_match_noarg(s, l, name) \
opt_match(s, l, name) && (*(s) ? (rb_warn("argument to --mjit-" name " is ignored"), 1) : 1)
#define opt_match_arg(s, l, name) \
opt_match(s, l, name) && (*(s) ? 1 : (rb_raise(rb_eRuntimeError, "--mjit-" name " needs an argument"), 0))
void
mjit_setup_options(const char *s, struct mjit_options *mjit_opt)
{
const size_t l = strlen(s);
if (l == 0) {
return;
}
else if (opt_match_noarg(s, l, "warnings")) {
mjit_opt->warnings = true;
}
else if (opt_match(s, l, "debug")) {
if (*s)
mjit_opt->debug_flags = strdup(s + 1);
else
mjit_opt->debug = true;
}
else if (opt_match_noarg(s, l, "wait")) {
mjit_opt->wait = true;
}
else if (opt_match_noarg(s, l, "save-temps")) {
mjit_opt->save_temps = true;
}
else if (opt_match(s, l, "verbose")) {
mjit_opt->verbose = *s ? atoi(s + 1) : 1;
}
else if (opt_match_arg(s, l, "max-cache")) {
mjit_opt->max_cache_size = atoi(s + 1);
}
else if (opt_match_arg(s, l, "min-calls")) {
mjit_opt->min_calls = atoi(s + 1);
}
else {
rb_raise(rb_eRuntimeError,
"invalid MJIT option `%s' (--help will show valid MJIT options)", s);
}
}
#define M(shortopt, longopt, desc) RUBY_OPT_MESSAGE(shortopt, longopt, desc)
const struct ruby_opt_message mjit_option_messages[] = {
M("--mjit-warnings", "", "Enable printing JIT warnings"),
M("--mjit-debug", "", "Enable JIT debugging (very slow), or add cflags if specified"),
M("--mjit-wait", "", "Wait until JIT compilation finishes every time (for testing)"),
M("--mjit-save-temps", "", "Save JIT temporary files in $TMP or /tmp (for testing)"),
M("--mjit-verbose=num", "", "Print JIT logs of level num or less to stderr (default: 0)"),
M("--mjit-max-cache=num", "", "Max number of methods to be JIT-ed in a cache (default: "
STRINGIZE(DEFAULT_MAX_CACHE_SIZE) ")"),
M("--mjit-min-calls=num", "", "Number of calls to trigger JIT (for testing, default: "
STRINGIZE(DEFAULT_MIN_CALLS_TO_ADD) ")"),
{0}
};
#undef M
// Initialize MJIT. Start a thread creating the precompiled header and
// processing ISeqs. The function should be called first for using MJIT.
// If everything is successful, MJIT_INIT_P will be TRUE.
void
mjit_init(const struct mjit_options *opts)
{
mjit_opts = *opts;
mjit_enabled = true;
mjit_call_p = true;
mjit_pid = getpid();
// Normalize options
if (mjit_opts.min_calls == 0)
mjit_opts.min_calls = DEFAULT_MIN_CALLS_TO_ADD;
if (mjit_opts.max_cache_size <= 0)
mjit_opts.max_cache_size = DEFAULT_MAX_CACHE_SIZE;
if (mjit_opts.max_cache_size < MIN_CACHE_SIZE)
mjit_opts.max_cache_size = MIN_CACHE_SIZE;
// Initialize variables for compilation
pch_status = PCH_NOT_READY;
cc_path = CC_COMMON_ARGS[0];
verbose(2, "MJIT: CC defaults to %s", cc_path);
cc_common_args = xmalloc(sizeof(CC_COMMON_ARGS));
memcpy((void *)cc_common_args, CC_COMMON_ARGS, sizeof(CC_COMMON_ARGS));
cc_added_args = split_flags(opts->debug_flags);
xfree(opts->debug_flags);
#if MJIT_CFLAGS_PIPE
// eliminate a flag incompatible with `-pipe`
for (size_t i = 0, j = 0; i < sizeof(CC_COMMON_ARGS) / sizeof(char *); i++) {
if (CC_COMMON_ARGS[i] && strncmp("-save-temps", CC_COMMON_ARGS[i], strlen("-save-temps")) == 0)
continue; // skip -save-temps flag
cc_common_args[j] = CC_COMMON_ARGS[i];
j++;
}
#endif
tmp_dir = system_tmpdir();
verbose(2, "MJIT: tmp_dir is %s", tmp_dir);
if (!init_header_filename()) {
mjit_enabled = false;
verbose(1, "Failure in MJIT header file name initialization\n");
return;
}
pch_owner_pid = getpid();
// Initialize mutex
rb_native_mutex_initialize(&mjit_engine_mutex);
rb_native_cond_initialize(&mjit_pch_wakeup);
rb_native_cond_initialize(&mjit_client_wakeup);
rb_native_cond_initialize(&mjit_worker_wakeup);
rb_native_cond_initialize(&mjit_gc_wakeup);
// Make sure the saved_ec of the initial thread's root_fiber is scanned by mark_ec_units.
//
// rb_threadptr_root_fiber_setup for the initial thread is called before mjit_init,
// meaning mjit_cont_new is skipped for the root_fiber. Therefore we need to call
// rb_fiber_init_mjit_cont again with mjit_enabled=true to set the root_fiber's mjit_cont.
rb_fiber_init_mjit_cont(GET_EC()->fiber_ptr);
// Initialize worker thread
start_worker();
// TODO: Consider running C compiler asynchronously
make_pch();
}
static void
stop_worker(void)
{
stop_worker_p = true;
if (current_cc_unit != NULL) {
mjit_wait_unit(current_cc_unit);
}
worker_stopped = true;
}
// Stop JIT-compiling methods but compiled code is kept available.
VALUE
mjit_pause(bool wait_p)
{
if (!mjit_enabled) {
rb_raise(rb_eRuntimeError, "MJIT is not enabled");
}
if (worker_stopped) {
return Qfalse;
}
// Flush all queued units with no option or `wait: true`
if (wait_p) {
while (current_cc_unit != NULL) {
mjit_wait_unit(current_cc_unit);
}
}
stop_worker();
return Qtrue;
}
// Restart JIT-compiling methods after mjit_pause.
VALUE
mjit_resume(void)
{
if (!mjit_enabled) {
rb_raise(rb_eRuntimeError, "MJIT is not enabled");
}
if (!worker_stopped) {
return Qfalse;
}
if (!start_worker()) {
rb_raise(rb_eRuntimeError, "Failed to resume MJIT worker");
}
return Qtrue;
}
// This is called after fork initiated by Ruby's method to launch MJIT worker thread
// for child Ruby process.
//
// In multi-process Ruby applications, child Ruby processes do most of the jobs.
// Thus we want child Ruby processes to enqueue ISeqs to MJIT worker's queue and
// call the JIT-ed code.
//
// But unfortunately current MJIT-generated code is process-specific. After the fork,
// JIT-ed code created by parent Ruby process cannot be used in child Ruby process
// because the code could rely on inline cache values (ivar's IC, send's CC) which
// may vary between processes after fork or embed some process-specific addresses.
//
// So child Ruby process can't request parent process to JIT an ISeq and use the code.
// Instead of that, MJIT worker thread is created for all child Ruby processes, even
// while child processes would end up with compiling the same ISeqs.
void
mjit_child_after_fork(void)
{
if (!mjit_enabled)
return;
/* MJIT worker thread is not inherited on fork. Start it for this child process. */
start_worker();
}
// Edit 0 to 1 to enable this feature for investigating hot methods
#define MJIT_COUNTER 0
#if MJIT_COUNTER
static void
mjit_dump_total_calls(void)
{
struct rb_mjit_unit *unit;
fprintf(stderr, "[MJIT_COUNTER] total_calls of active_units:\n");
ccan_list_for_each(&active_units.head, unit, unode) {
const rb_iseq_t *iseq = unit->iseq;
fprintf(stderr, "%8ld: %s@%s:%d\n", ISEQ_BODY(iseq)->total_calls, RSTRING_PTR(ISEQ_BODY(iseq)->location.label),
RSTRING_PTR(rb_iseq_path(iseq)), FIX2INT(ISEQ_BODY(iseq)->location.first_lineno));
}
}
#endif
// Finish the threads processing units and creating PCH, finalize
// and free MJIT data. It should be called last during MJIT
// life.
//
// If close_handle_p is true, it calls dlclose() for JIT-ed code. So it should be false
// if the code can still be on stack. ...But it means to leak JIT-ed handle forever (FIXME).
void
mjit_finish(bool close_handle_p)
{
if (!mjit_enabled)
return;
// Stop worker
verbose(2, "Stopping worker thread");
stop_worker();
rb_native_mutex_destroy(&mjit_engine_mutex);
rb_native_cond_destroy(&mjit_pch_wakeup);
rb_native_cond_destroy(&mjit_client_wakeup);
rb_native_cond_destroy(&mjit_worker_wakeup);
rb_native_cond_destroy(&mjit_gc_wakeup);
#if MJIT_COUNTER
mjit_dump_total_calls();
#endif
if (!mjit_opts.save_temps && getpid() == pch_owner_pid)
remove_file(pch_file);
xfree(header_file); header_file = NULL;
xfree((void *)cc_common_args); cc_common_args = NULL;
for (char **flag = cc_added_args; *flag != NULL; flag++)
xfree(*flag);
xfree((void *)cc_added_args); cc_added_args = NULL;
xfree(tmp_dir); tmp_dir = NULL;
xfree(pch_file); pch_file = NULL;
mjit_call_p = false;
free_list(&unit_queue, close_handle_p);
free_list(&active_units, close_handle_p);
free_list(&compact_units, close_handle_p);
free_list(&stale_units, close_handle_p);
finish_conts();
mjit_enabled = false;
verbose(1, "Successful MJIT finish");
}
// Called by rb_vm_mark().
//
// Mark active_units so that we do not GC ISeq which may still be
// referenced by mjit_recompile() or mjit_compact().
void
mjit_mark(void)
{
if (!mjit_enabled)
return;
RUBY_MARK_ENTER("mjit");
struct rb_mjit_unit *unit = NULL;
ccan_list_for_each(&active_units.head, unit, unode) {
rb_gc_mark((VALUE)unit->iseq);
}
RUBY_MARK_LEAVE("mjit");
}
// Called by rb_iseq_mark() to mark cc_entries captured for MJIT
void
mjit_mark_cc_entries(const struct rb_iseq_constant_body *const body)
{
const struct rb_callcache **cc_entries;
if (body->jit_unit && (cc_entries = body->jit_unit->cc_entries) != NULL) {
// It must be `body->jit_unit->cc_entries_size` instead of `body->ci_size` to mark children's cc_entries
for (unsigned int i = 0; i < body->jit_unit->cc_entries_size; i++) {
const struct rb_callcache *cc = cc_entries[i];
if (cc != NULL && vm_cc_markable(cc)) {
// Pin `cc` and `cc->cme` against GC.compact as their addresses may be written in JIT-ed code.
rb_gc_mark((VALUE)cc);
rb_gc_mark((VALUE)vm_cc_cme(cc));
}
}
}
}
#include "mjit.rbinc"
#endif // USE_MJIT
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