Add low-overhead profiler. Part 1: interpreter, low-level C API.
This commit is contained in:
Mike Pall
274
src/lj_profile.c
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274
src/lj_profile.c
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/*
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** Low-overhead profiling.
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** Copyright (C) 2005-2013 Mike Pall. See Copyright Notice in luajit.h
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*/
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#define lj_profile_c
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#define LUA_CORE
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#include "lj_obj.h"
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#if LJ_HASPROFILE
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#include "lj_buf.h"
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#include "lj_frame.h"
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#include "lj_debug.h"
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#include "lj_dispatch.h"
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#include "lj_profile.h"
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#include "luajit.h"
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#if LJ_PROFILE_SIGPROF
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#include <sys/time.h>
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#include <signal.h>
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#elif LJ_PROFILE_PTHREAD
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#include <pthread.h>
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#elif LJ_PROFILE_WTHREAD
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#define WIN32_LEAN_AND_MEAN
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#include <windows.h>
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typedef unsigned int (WINAPI *WMM_TPFUNC)(unsigned int);
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#endif
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/* Profiler state. */
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typedef struct ProfileState {
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global_State *g; /* VM state that started the profiler. */
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luaJIT_profile_callback cb; /* Profiler callback. */
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void *data; /* Profiler callback data. */
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SBuf sb; /* String buffer for stack dumps. */
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int interval; /* Sample interval in milliseconds. */
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int samples; /* Number of samples for next callback. */
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int vmstate; /* VM state when profile timer triggered. */
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#if LJ_PROFILE_SIGPROF
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struct sigaction oldsa; /* Previous SIGPROF state. */
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#elif LJ_PROFILE_PTHREAD
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pthread_t thread; /* Timer thread. */
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int abort; /* Abort timer thread. */
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#elif LJ_PROFILE_WTHREAD
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HINSTANCE wmm; /* WinMM library handle. */
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WMM_TPFUNC wmm_tbp; /* WinMM timeBeginPeriod function. */
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WMM_TPFUNC wmm_tep; /* WinMM timeEndPeriod function. */
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HANDLE thread; /* Timer thread. */
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int abort; /* Abort timer thread. */
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#endif
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} ProfileState;
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/* Sadly, we have to use a static profiler state.
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**
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** The SIGPROF variant needs a static pointer to the global state, anyway.
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** And it would be hard to extend for multiple threads. You can still use
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** multiple VMs in multiple threads, but only profile one at a time.
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*/
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static ProfileState profile_state;
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/* Default sample interval in milliseconds. */
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#define LJ_PROFILE_INTERVAL_DEFAULT 10
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/* -- Profile callbacks --------------------------------------------------- */
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/* Callback from profile hook (HOOK_PROFILE already cleared). */
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void LJ_FASTCALL lj_profile_interpreter(lua_State *L)
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{
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ProfileState *ps = &profile_state;
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int samples = ps->samples;
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ps->samples = 0;
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ps->cb(ps->data, L, samples, ps->vmstate); /* Invoke user callback. */
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}
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/* Trigger profile hook. Asynchronous call from OS-specific profile timer. */
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static void profile_trigger(ProfileState *ps)
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{
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global_State *g = ps->g;
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uint8_t mask;
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ps->samples++; /* Always increment number of samples. */
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mask = g->hookmask;
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if (!(mask & HOOK_PROFILE)) { /* Set profile hook, unless already set. */
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int st = g->vmstate;
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ps->vmstate = st >= 0 ? 'N' :
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st == ~LJ_VMST_INTERP ? 'I' :
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st == ~LJ_VMST_C ? 'C' :
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st == ~LJ_VMST_GC ? 'G' : 'J';
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g->hookmask = (mask | HOOK_PROFILE);
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lj_dispatch_update(g);
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}
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}
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/* -- OS-specific profile timer handling ---------------------------------- */
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#if LJ_PROFILE_SIGPROF
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/* SIGPROF handler. */
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static void profile_signal(int sig)
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{
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UNUSED(sig);
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profile_trigger(&profile_state);
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}
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/* Start profiling timer. */
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static void profile_timer_start(ProfileState *ps)
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{
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int interval = ps->interval;
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struct itimerval tm;
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struct sigaction sa;
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tm.it_value.tv_sec = tm.it_interval.tv_sec = interval / 1000;
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tm.it_value.tv_usec = tm.it_interval.tv_usec = (interval % 1000) * 1000;
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setitimer(ITIMER_PROF, &tm, NULL);
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sa.sa_flags = SA_RESTART;
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sa.sa_handler = profile_signal;
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sigemptyset(&sa.sa_mask);
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sigaction(SIGPROF, &sa, &ps->oldsa);
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}
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/* Stop profiling timer. */
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static void profile_timer_stop(ProfileState *ps)
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{
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struct itimerval tm;
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tm.it_value.tv_sec = tm.it_interval.tv_sec = 0;
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tm.it_value.tv_usec = tm.it_interval.tv_usec = 0;
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setitimer(ITIMER_PROF, &tm, NULL);
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sigaction(SIGPROF, &ps->oldsa, NULL);
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}
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#elif LJ_PROFILE_PTHREAD
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/* POSIX timer thread. */
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static void *profile_thread(ProfileState *ps)
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{
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int interval = ps->interval;
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struct timespec ts;
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ts.tv_sec = interval / 1000;
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ts.tv_nsec = (interval % 1000) * 1000000;
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while (1) {
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nanosleep(&ts, NULL);
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if (ps->abort) break;
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profile_trigger(ps);
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}
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return NULL;
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}
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/* Start profiling timer thread. */
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static void profile_timer_start(ProfileState *ps)
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{
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ps->abort = 0;
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pthread_create(&ps->thread, NULL, (void *(*)(void *))profile_thread, ps);
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}
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/* Stop profiling timer thread. */
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static void profile_timer_stop(ProfileState *ps)
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{
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ps->abort = 1;
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pthread_join(ps->thread, NULL);
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}
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#elif LJ_PROFILE_WTHREAD
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/* Windows timer thread. */
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static DWORD WINAPI profile_thread(void *psx)
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{
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ProfileState *ps = (ProfileState *)psx;
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int interval = ps->interval;
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ps->wmm_tbp(1);
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while (1) {
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Sleep(interval);
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if (ps->abort) break;
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profile_trigger(ps);
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}
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ps->wmm_tep(1);
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return 0;
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}
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/* Start profiling timer thread. */
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static void profile_timer_start(ProfileState *ps)
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{
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if (!ps->wmm) { /* Load WinMM library on-demand. */
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ps->wmm = LoadLibraryA("winmm.dll");
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if (ps->wmm) {
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ps->wmm_tbp = (WMM_TPFUNC)GetProcAddress(ps->wmm, "timeBeginPeriod");
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ps->wmm_tep = (WMM_TPFUNC)GetProcAddress(ps->wmm, "timeEndPeriod");
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if (!ps->wmm_tbp || !ps->wmm_tep) {
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ps->wmm = NULL;
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return;
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}
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}
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}
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ps->abort = 0;
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ps->thread = CreateThread(NULL, 0, profile_thread, ps, 0, NULL);
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}
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/* Stop profiling timer thread. */
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static void profile_timer_stop(ProfileState *ps)
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{
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ps->abort = 1;
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WaitForSingleObject(ps->thread, INFINITE);
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}
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#endif
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/* -- Public profiling API ------------------------------------------------ */
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/* Start profiling. */
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LUA_API void luaJIT_profile_start(lua_State *L, const char *mode,
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luaJIT_profile_callback cb, void *data)
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{
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ProfileState *ps = &profile_state;
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int interval = LJ_PROFILE_INTERVAL_DEFAULT;
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while (*mode) {
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switch (*mode++) {
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case 'i':
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interval = 0;
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while (*mode >= '0' && *mode <= '9')
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interval = interval * 10 + (*mode++ - '0');
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if (interval <= 0) interval = 1;
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break;
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default: /* Ignore unknown mode chars. */
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break;
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}
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}
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if (ps->g) {
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luaJIT_profile_stop(L);
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if (ps->g) return; /* Profiler in use by another VM. */
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}
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ps->g = G(L);
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ps->interval = interval;
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ps->cb = cb;
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ps->data = data;
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ps->samples = 0;
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lj_buf_init(L, &ps->sb);
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profile_timer_start(ps);
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}
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/* Stop profiling. */
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LUA_API void luaJIT_profile_stop(lua_State *L)
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{
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ProfileState *ps = &profile_state;
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global_State *g = ps->g;
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if (G(L) == g) { /* Only stop profiler if started by this VM. */
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profile_timer_stop(ps);
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g->hookmask &= ~HOOK_PROFILE;
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lj_dispatch_update(g);
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lj_buf_free(g, &ps->sb);
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setmref(ps->sb.b, NULL);
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setmref(ps->sb.e, NULL);
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ps->g = NULL;
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}
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}
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/* Return a compact stack dump. */
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LUA_API const char *luaJIT_profile_dumpstack(lua_State *L, const char *fmt,
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int depth, size_t *len)
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{
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ProfileState *ps = &profile_state;
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SBuf *sb = &ps->sb;
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setsbufL(sb, L);
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lj_buf_reset(sb);
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lj_debug_dumpstack(L, sb, fmt, depth);
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*len = (size_t)sbuflen(sb);
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return sbufB(sb);
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}
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#endif
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