Added LUAJIT_VMPROFILE: new profiler backend

src/Makefile

@@ -481,7 +481,7 @@ LJLIB_C= $(LJLIB_O:.o=.c)
 LJCORE_O= lj_gc.o lj_err.o lj_char.o lj_bc.o lj_obj.o lj_buf.o \
  lj_str.o lj_tab.o lj_func.o lj_udata.o lj_meta.o lj_debug.o \
  lj_state.o lj_dispatch.o lj_vmevent.o lj_vmmath.o lj_strscan.o \
- lj_strfmt.o lj_strfmt_num.o lj_api.o lj_profile.o \
+ lj_strfmt.o lj_strfmt_num.o lj_api.o lj_profile.o lj_vmprofile.o \
  lj_lex.o lj_parse.o lj_bcread.o lj_bcwrite.o lj_load.o \
  lj_ir.o lj_opt_mem.o lj_opt_fold.o lj_opt_narrow.o \
  lj_opt_dce.o lj_opt_loop.o lj_opt_split.o lj_opt_sink.o \

src/lib_jit.c

@@ -630,6 +630,34 @@ static int luaopen_jit_profile(lua_State *L)
 
 #endif
 
+/* -- jit.vmprofile module ----------------------------------------------- */
+
+#ifdef LUAJIT_VMPROFILE
+
+#define LJLIB_MODULE_jit_vmprofile
+
+LJLIB_CF(jit_vmprofile_start)
+{
+ luaJIT_vmprofile_start(L);
+ return 0;
+}
+
+LJLIB_CF(jit_vmprofile_stop)
+{
+ luaJIT_vmprofile_stop(L);
+ return 0;
+}
+
+#include "lj_libdef.h"
+
+static int luaopen_jit_vmprofile(lua_State *L)
+{
+ LJ_LIB_REG(L, NULL, jit_vmprofile);
+ return 1;
+}
+
+#endif
+
 /* -- JIT compiler initialization ----------------------------------------- */
 
 #if LJ_HASJIT
@@ -765,6 +793,10 @@ LUALIB_API int luaopen_jit(lua_State *L)
  lj_lib_prereg(L, LUA_JITLIBNAME ".profile", luaopen_jit_profile,
  tabref(L->env));
 #endif
+#ifdef LUAJIT_VMPROFILE
+ lj_lib_prereg(L, LUA_JITLIBNAME ".vmprofile", luaopen_jit_vmprofile,
+ tabref(L->env));
+#endif
 #ifndef LUAJIT_DISABLE_JITUTIL
  lj_lib_prereg(L, LUA_JITLIBNAME ".util", luaopen_jit_util, tabref(L->env));
 #endif

src/lj_vmprofile.c

@@ -0,0 +1,113 @@
+/*
+** VM profiling.
+** Copyright (C) 2016 Luke Gorrie. See Copyright Notice in luajit.h
+*/
+
+#define lj_vmprofile_c
+#define LUA_CORE
+
+#ifdef LUAJIT_VMPROFILE
+
+#define _GNU_SOURCE 1
+#include <stdio.h>
+#include <assert.h>
+#include <sys/time.h>
+#include <stdint.h>
+#include <signal.h>
+#include <ucontext.h>
+#undef _GNU_SOURCE
+
+#include "lj_obj.h"
+#include "lj_dispatch.h"
+#include "lj_jit.h"
+#include "lj_trace.h"
+#include "lj_vmprofile.h"
+
+static struct {
+ global_State *g;
+ struct sigaction oldsa;
+} state;
+
+/* -- State that the application can manage via FFI ----------------------- */
+
+static VMProfile *profile; /* Current counters */
+
+/* How much memory to allocate for profiler counters. */
+int vmprofile_get_profile_size() {
+ return sizeof(VMProfile);
+}
+
+/* Set the memory where the next samples will be counted. 
+ Size of the memory must match vmprofile_get_profile_size(). */
+void vmprofile_set_profile(void *counters) {
+ profile = (VMProfile*)counters;
+ profile->magic = 0x1d50f007;
+ profile->major = 1;
+ profile->minor = 0;
+}
+
+/* -- Signal handler ------------------------------------------------------ */
+
+/* Signal handler: bumps one counter. */
+static void vmprofile_signal(int sig, siginfo_t *si, void *data)
+{
+ if (profile != NULL) {
+ lua_State *L = gco2th(gcref(state.g->cur_L));
+ int vmstate = state.g->vmstate;
+ /* Not in a trace */
+ if (vmstate < 0) {
+ profile->vm[~vmstate]++;
+ } else {
+ int bucket = vmstate > LJ_VMPROFILE_TRACE_MAX ? 0 : vmstate;
+ VMProfileTraceCount *count = &profile->trace[bucket];
+ GCtrace *T = traceref(L2J(L), (TraceNo)vmstate);
+ intptr_t ip = (intptr_t)((ucontext_t*)data)->uc_mcontext.gregs[REG_RIP];
+ ptrdiff_t mcposition = ip - (intptr_t)T->mcode;
+ if ((mcposition < 0) || (mcposition >= T->szmcode)) {
+ count->other++;
+ } else if ((T->mcloop != 0) && (mcposition >= T->mcloop)) {
+ count->loop++;
+ } else {
+ count->head++;
+ }
+ }
+ }
+}
+
+static void start_timer(int interval)
+{
+ struct itimerval tm;
+ struct sigaction sa;
+ tm.it_value.tv_sec = tm.it_interval.tv_sec = interval / 1000;
+ tm.it_value.tv_usec = tm.it_interval.tv_usec = (interval % 1000) * 1000;
+ setitimer(ITIMER_PROF, &tm, NULL);
+ sa.sa_flags = SA_SIGINFO | SA_RESTART;
+ sa.sa_sigaction = vmprofile_signal;
+ sigemptyset(&sa.sa_mask);
+ sigaction(SIGPROF, &sa, &state.oldsa);
+}
+
+static void stop_timer()
+{
+ struct itimerval tm;
+ tm.it_value.tv_sec = tm.it_interval.tv_sec = 0;
+ tm.it_value.tv_usec = tm.it_interval.tv_usec = 0;
+ setitimer(ITIMER_PROF, &tm, NULL);
+ sigaction(SIGPROF, NULL, &state.oldsa);
+}
+
+/* -- Lua API ------------------------------------------------------------- */
+
+LUA_API void luaJIT_vmprofile_start(lua_State *L)
+{
+ memset(&state, 0, sizeof(state));
+ state.g = G(L);
+ start_timer(1); /* Sample every 1ms */
+}
+
+LUA_API void luaJIT_vmprofile_stop(lua_State *L)
+{
+ stop_timer();
+}
+
+#endif

src/lj_vmprofile.h

@@ -0,0 +1,37 @@
+/*
+** Virtual machine profiling.
+** Copyright (C) 2017 Luke Gorrie. See Copyright Notice in luajit.h
+*/
+
+#ifndef _LJ_VMPROFILE_H
+#define _LJ_VMPROFILE_H
+
+
+/* Counters are 64-bit to avoid overflow even in long running processes. */
+typedef uint64_t VMProfileCount;
+
+/* Maximum trace number for distinct counter buckets. Traces with
+ higher numbers will be counted together in bucket zero. */
+#define LJ_VMPROFILE_TRACE_MAX 4096
+
+/* Traces have separate counters for different machine code regions. */
+typedef struct VMProfileTraceCount {
+ VMProfileCount head; /* Head of the trace (non-looping part) */
+ VMProfileCount loop; /* Loop of the trace */
+ VMProfileCount other; /* Outside the trace mcode (unidentified) */
+} VMProfileTraceCount;
+
+/* Complete set of counters for VM and traces. */
+typedef struct VMProfile {
+ uint32_t magic; /* 0x1d50f007 */
+ uint16_t major, minor; /* 1, 0 */
+ VMProfileCount vm[LJ_VMST__MAX];
+ VMProfileTraceCount trace[LJ_VMPROFILE_TRACE_MAX+1];
+} VMProfile;
+
+/* Functions that should be accessed via FFI. */
+
+void vmprofile_set_profile(void *counters);
+int vmprofile_get_profile_size();
+
+#endif

src/luajit.h

@@ -73,6 +73,10 @@ LUA_API void luaJIT_profile_stop(lua_State *L);
 LUA_API const char *luaJIT_profile_dumpstack(lua_State *L, const char *fmt,
  int depth, size_t *len);
 
+/* VM profiling API. */
+LUA_API void luaJIT_vmprofile_start(lua_State *L);
+LUA_API void luaJIT_vmprofile_stop(lua_State *L);
+
 /* Enforce (dynamic) linker error for version mismatches. Call from main. */
 LUA_API void LUAJIT_VERSION_SYM(void);