core: introduce various platform metrics

This patch introduces the following counters:
  - overall amount of allocated tables, cdata and udata objects
  - number of incremental GC steps grouped by GC state
  - number of string hashes hits and misses
  - amount of allocated and freed memory
  - number of trace aborts, number of traces and restored snapshots

Also this patch fixes alignment for 64-bit architectures.

NB: MSize and BCIns are the only fixed types that equal 32 bits. GCRef,
MRef and GCSize sizes depend on LJ_GC64 define.

struct GCState is terminated by three fields: GCSize estimate, MSize
stepmul and MSize pause, which are aligned. The introduced size_t
fields do not violate the alignment too.

vmstate 32-bit field goes right after GCState field within global_State
structure. The next field tmpbuf consists of several MRef fields that
have 64-bit size each. This issue can be solved by moving vmstate field
below. However DynASM doesn't work well with unaligned memory access on
64-bit bigendian MIPS, so vmstate should be aligned to a 64-bit
boundary.

Furthermore field order has been changed to be able to compile code by
DynASM for 32-bit ARM too (see also
openresty/luajit2#37 (comment)).

Interfaces to obtain these metrics via both Lua and C API are
introduced in the next patch.

Part of tarantool/tarantool#5187

src/lj_asm_arm.h

@@ -1257,9 +1257,16 @@ static void asm_cnew(ASMState *as, IRIns *ir)
   {
     uint32_t k = emit_isk12(ARMI_MOV, id);
     Reg r = k ? RID_R1 : ra_allock(as, id, allow);
+    allow = rset_exclude(allow, r);
+    Reg gr = ra_allock(as, i32ptr(J2G(as->J)), allow);
     emit_lso(as, ARMI_STRB, RID_TMP, RID_RET, offsetof(GCcdata, gct));
     emit_lsox(as, ARMI_STRH, r, RID_RET, offsetof(GCcdata, ctypeid));
     emit_d(as, ARMI_MOV|ARMI_K12|~LJ_TCDATA, RID_TMP);
+    emit_lso(as, ARMI_STR, RID_TMP, gr,
+	     (int32_t)offsetof(global_State, gc.cdatanum));
+    emit_dn(as, ARMI_ADD|ARMI_K12|1, RID_TMP, RID_TMP);
+    emit_lso(as, ARMI_LDR, RID_TMP, gr,
+	     (int32_t)offsetof(global_State, gc.cdatanum));
     if (k) emit_d(as, ARMI_MOV^k, RID_R1);
   }
   args[0] = ASMREF_L;     /* lua_State *L */

src/lj_asm_arm64.h

@@ -1220,9 +1220,16 @@ static void asm_cnew(ASMState *as, IRIns *ir)
   /* Initialize gct and ctypeid. lj_mem_newgco() already sets marked. */
   {
     Reg r = (id < 65536) ? RID_X1 : ra_allock(as, id, allow);
+    allow = rset_exclude(allow, r);
+    Reg gr = ra_allock(as, i64ptr(J2G(as->J)), allow);
     emit_lso(as, A64I_STRB, RID_TMP, RID_RET, offsetof(GCcdata, gct));
     emit_lso(as, A64I_STRH, r, RID_RET, offsetof(GCcdata, ctypeid));
     emit_d(as, A64I_MOVZw | A64F_U16(~LJ_TCDATA), RID_TMP);
+    emit_lso(as, A64I_STRx, RID_TMP, gr,
+	     (int32_t)offsetof(global_State, gc.cdatanum));
+    emit_dn(as, (A64I_ADDx^A64I_K12) | A64F_U12(1), RID_TMP, RID_TMP);
+    emit_lso(as, A64I_LDRx, RID_TMP, gr,
+	     (int32_t)offsetof(global_State, gc.cdatanum));
     if (id < 65536) emit_d(as, A64I_MOVZw | A64F_U16(id), RID_X1);
   }
   args[0] = ASMREF_L;     /* lua_State *L */

src/lj_asm_mips.h

@@ -1430,7 +1430,9 @@ static void asm_cnew(ASMState *as, IRIns *ir)
   CTInfo info = lj_ctype_info(cts, id, &sz);
   const CCallInfo *ci = &lj_ir_callinfo[IRCALL_lj_mem_newgco];
   IRRef args[4];
+  RegSet allow = (RSET_GPR & ~RSET_SCRATCH);
   RegSet drop = RSET_SCRATCH;
+  Reg tmp;
   lua_assert(sz != CTSIZE_INVALID || (ir->o == IR_CNEW && ir->op2 != REF_NIL));
 
   as->gcsteps++;
@@ -1442,7 +1444,6 @@ static void asm_cnew(ASMState *as, IRIns *ir)
 
   /* Initialize immutable cdata object. */
   if (ir->o == IR_CNEWI) {
-    RegSet allow = (RSET_GPR & ~RSET_SCRATCH);
 #if LJ_32
     int32_t ofs = sizeof(GCcdata);
     if (sz == 8) {
@@ -1473,11 +1474,16 @@ static void asm_cnew(ASMState *as, IRIns *ir)
     return;
   }
 
+  tmp = ra_scratch(as, allow);
+  /* Code incrementing cdatanum is sparse to avoid mips data hazards. */
+  emit_setgl(as, tmp, gc.cdatanum);
   /* Initialize gct and ctypeid. lj_mem_newgco() already sets marked. */
   emit_tsi(as, MIPSI_SB, RID_RET+1, RID_RET, offsetof(GCcdata, gct));
   emit_tsi(as, MIPSI_SH, RID_TMP, RID_RET, offsetof(GCcdata, ctypeid));
+  emit_tsi(as, MIPSI_AADDIU, tmp, tmp, 1);
   emit_ti(as, MIPSI_LI, RID_RET+1, ~LJ_TCDATA);
   emit_ti(as, MIPSI_LI, RID_TMP, id); /* Lower 16 bit used. Sign-ext ok. */
+  emit_getgl(as, tmp, gc.cdatanum);
   args[0] = ASMREF_L;     /* lua_State *L */
   args[1] = ASMREF_TMP1;  /* MSize size   */
   asm_gencall(as, ci, args);

src/lj_asm_ppc.h

@@ -1057,6 +1057,9 @@ static void asm_cnew(ASMState *as, IRIns *ir)
     return;
   }
 
+  emit_setgl(as, RID_TMP, gc.cdatanum);
+  emit_tai(as, PPCI_ADDIC, RID_TMP, RID_TMP, 1);
+  emit_getgl(as, RID_TMP, gc.cdatanum);
   /* Initialize gct and ctypeid. lj_mem_newgco() already sets marked. */
   emit_tai(as, PPCI_STB, RID_RET+1, RID_RET, offsetof(GCcdata, gct));
   emit_tai(as, PPCI_STH, RID_TMP, RID_RET, offsetof(GCcdata, ctypeid));

src/lj_asm_x86.h

@@ -1835,6 +1835,10 @@ static void asm_cnew(ASMState *as, IRIns *ir)
     return;
   }
 
+  /* Increment cdatanum counter by address directly. */
+  emit_i8(as, 1);
+  emit_rmro(as, XO_ARITHi8, XOg_ADD, RID_NONE,
+	    ptr2addr(&J2G(as->J)->gc.cdatanum));
   /* Combine initialization of marked, gct and ctypeid. */
   emit_movtomro(as, RID_ECX, RID_RET, offsetof(GCcdata, marked));
   emit_gri(as, XG_ARITHi(XOg_OR), RID_ECX,

src/lj_cdata.c

@@ -46,6 +46,7 @@ GCcdata *lj_cdata_newv(lua_State *L, CTypeID id, CTSize sz, CTSize align)
   cd->marked |= 0x80;
   cd->gct = ~LJ_TCDATA;
   cd->ctypeid = id;
+  g->gc.cdatanum++;
   return cd;
 }
 
@@ -82,6 +83,7 @@ void LJ_FASTCALL lj_cdata_free(global_State *g, GCcdata *cd)
   } else {
     lj_mem_free(g, memcdatav(cd), sizecdatav(cd));
   }
+  g->gc.cdatanum--;
 }
 
 void lj_cdata_setfin(lua_State *L, GCcdata *cd, GCobj *obj, uint32_t it)

src/lj_cdata.h

@@ -45,6 +45,7 @@ static LJ_AINLINE GCcdata *lj_cdata_new(CTState *cts, CTypeID id, CTSize sz)
   cd = (GCcdata *)lj_mem_newgco(cts->L, sizeof(GCcdata) + sz);
   cd->gct = ~LJ_TCDATA;
   cd->ctypeid = ctype_check(cts, id);
+  G(cts->L)->gc.cdatanum++;
   return cd;
 }
 
@@ -54,6 +55,7 @@ static LJ_AINLINE GCcdata *lj_cdata_new_(lua_State *L, CTypeID id, CTSize sz)
   GCcdata *cd = (GCcdata *)lj_mem_newgco(L, sizeof(GCcdata) + sz);
   cd->gct = ~LJ_TCDATA;
   cd->ctypeid = id;
+  G(L)->gc.cdatanum++;
   return cd;
 }
 

src/lj_gc.c

@@ -634,6 +634,7 @@ static void atomic(global_State *g, lua_State *L)
 static size_t gc_onestep(lua_State *L)
 {
   global_State *g = G(L);
+  g->gc.state_count[g->gc.state]++;
   switch (g->gc.state) {
   case GCSpause:
     gc_mark_start(g);  /* Start a new GC cycle by marking all GC roots. */
@@ -857,6 +858,8 @@ void *lj_mem_realloc(lua_State *L, void *p, GCSize osz, GCSize nsz)
   lua_assert((nsz == 0) == (p == NULL));
   lua_assert(checkptrGC(p));
   g->gc.total = (g->gc.total - osz) + nsz;
+  g->gc.allocated += nsz;
+  g->gc.freed += osz;
   return p;
 }
 
@@ -869,6 +872,7 @@ void * LJ_FASTCALL lj_mem_newgco(lua_State *L, GCSize size)
     lj_err_mem(L);
   lua_assert(checkptrGC(o));
   g->gc.total += size;
+  g->gc.allocated += size;
   setgcrefr(o->gch.nextgc, g->gc.root);
   setgcref(g->gc.root, o);
   newwhite(g, o);

src/lj_gc.h

@@ -8,11 +8,6 @@
 
 #include "lj_obj.h"
 
-/* Garbage collector states. Order matters. */
-enum {
-  GCSpause, GCSpropagate, GCSatomic, GCSsweepstring, GCSsweep, GCSfinalize
-};
-
 /* Bitmasks for marked field of GCobj. */
 #define LJ_GC_WHITE0	0x01
 #define LJ_GC_WHITE1	0x02
@@ -117,6 +112,7 @@ LJ_FUNC void *lj_mem_grow(lua_State *L, void *p,
 static LJ_AINLINE void lj_mem_free(global_State *g, void *p, size_t osize)
 {
   g->gc.total -= (GCSize)osize;
+  g->gc.freed += osize;
   g->allocf(g->allocd, p, osize, 0);
 }
 

src/lj_jit.h

@@ -474,6 +474,9 @@ typedef struct jit_State {
   MCode *mcbot;		/* Bottom of current mcode area. */
   size_t szmcarea;	/* Size of current mcode area. */
   size_t szallmcarea;	/* Total size of all allocated mcode areas. */
+  size_t tracenum;	/* Overall number of traces. */
+  size_t nsnaprestore;	/* Overall number of snap restores. */
+  size_t ntraceabort;	/* Overall number of abort traces. */
 
   TValue errinfo;	/* Additional info element for trace errors. */
 

src/lj_obj.h

@@ -571,6 +571,17 @@ typedef enum {
 #define basemt_obj(g, o)	((g)->gcroot[GCROOT_BASEMT+itypemap(o)])
 #define mmname_str(g, mm)	(strref((g)->gcroot[GCROOT_MMNAME+(mm)]))
 
+/* Garbage collector states. Order matters. */
+enum {
+  GCSpause,		/* Start a GC cycle and mark the root set.*/
+  GCSpropagate,		/* One gray object is processed. */
+  GCSatomic,		/* Atomic transition from mark to sweep phase. */
+  GCSsweepstring,	/* Sweep one chain of strings. */
+  GCSsweep,		/* Sweep few objects from root. */
+  GCSfinalize,		/* Finalize one userdata or cdata object. */
+  GCSmax
+};
+
 typedef struct GCState {
   GCSize total;		/* Memory currently allocated. */
   GCSize threshold;	/* Memory threshold. */
@@ -589,6 +600,15 @@ typedef struct GCState {
   GCSize estimate;	/* Estimate of memory actually in use. */
   MSize stepmul;	/* Incremental GC step granularity. */
   MSize pause;		/* Pause between successive GC cycles. */
+
+  size_t freed;		/* Total amount of freed memory. */
+  size_t allocated;	/* Total amount of allocated memory. */
+  size_t state_count[GCSmax]; /* Count of incremental GC steps per state. */
+  size_t tabnum;	/* Amount of allocated table objects. */
+  size_t udatanum;	/* Amount of allocated udata objects. */
+#ifdef LJ_HASFFI
+  size_t cdatanum;	/* Amount of allocated cdata objects. */
+#endif
 } GCState;
 
 /* Global state, shared by all threads of a Lua universe. */
@@ -602,22 +622,24 @@ typedef struct global_State {
     BloomFilter next[2];
   } strbloom;
 #endif
+  size_t strhash_hit;	/* Strings amount found in string hash. */
+  size_t strhash_miss;	/* Strings amount allocated and put into string hash. */
   lua_Alloc allocf;	/* Memory allocator. */
   void *allocd;		/* Memory allocator data. */
   GCState gc;		/* Garbage collector. */
-  volatile int32_t vmstate;  /* VM state or current JIT code trace number. */
   SBuf tmpbuf;		/* Temporary string buffer. */
   GCstr strempty;	/* Empty string. */
   uint8_t stremptyz;	/* Zero terminator of empty string. */
   uint8_t hookmask;	/* Hook mask. */
   uint8_t dispatchmode;	/* Dispatch mode. */
   uint8_t vmevmask;	/* VM event mask. */
+  int32_t hookcount;	/* Instruction hook countdown. */
   GCRef mainthref;	/* Link to main thread. */
   TValue registrytv;	/* Anchor for registry. */
-  TValue tmptv, tmptv2;	/* Temporary TValues. */
+  TValue tmptv2, tmptv;	/* Temporary TValues. */
   Node nilnode;		/* Fallback 1-element hash part (nil key and value). */
   GCupval uvhead;	/* Head of double-linked list of all open upvalues. */
-  int32_t hookcount;	/* Instruction hook countdown. */
+  volatile int32_t vmstate;  /* VM state or current JIT code trace number. */
   int32_t hookcstart;	/* Start count for instruction hook counter. */
   lua_Hook hookf;	/* Hook function. */
   lua_CFunction wrapf;	/* Wrapper for C function calls. */

src/lj_snap.c

@@ -904,6 +904,7 @@ const BCIns *lj_snap_restore(jit_State *J, void *exptr)
     L->top = frame + snap->nslots;
     break;
   }
+  J->nsnaprestore++;
   return pc;
 }
 

src/lj_state.c

@@ -214,7 +214,7 @@ LUA_API lua_State *lua_newstate(lua_Alloc f, void *ud)
   g->gc.state = GCSpause;
   setgcref(g->gc.root, obj2gco(L));
   setmref(g->gc.sweep, &g->gc.root);
-  g->gc.total = sizeof(GG_State);
+  g->gc.allocated = g->gc.total = sizeof(GG_State);
   g->gc.pause = LUAI_GCPAUSE;
   g->gc.stepmul = LUAI_GCMUL;
   lj_dispatch_init((GG_State *)L);

src/lj_str.c

@@ -222,6 +222,7 @@ GCstr *lj_str_new(lua_State *L, const char *str, size_t lenx)
                       str_fastcmp(str, strdata(sx), len) == 0) {
 	/* Resurrect if dead. Can only happen with fixstring() (keywords). */
 	if (isdead(g, o)) flipwhite(o);
+	g->strhash_hit++;
 	return sx;  /* Return existing string. */
       }
       o = gcnext(o);
@@ -234,6 +235,7 @@ GCstr *lj_str_new(lua_State *L, const char *str, size_t lenx)
                       memcmp(str, strdata(sx), len) == 0) {
 	/* Resurrect if dead. Can only happen with fixstring() (keywords). */
 	if (isdead(g, o)) flipwhite(o);
+	g->strhash_hit++;
 	return sx;  /* Return existing string. */
       }
       o = gcnext(o);
@@ -266,6 +268,7 @@ GCstr *lj_str_new(lua_State *L, const char *str, size_t lenx)
 	    if (sx->hash == fh && sx->len == len && str_fastcmp(str, strdata(sx), len) == 0) {
 	      /* Resurrect if dead. Can only happen with fixstring() (keywords). */
 	      if (isdead(g, o)) flipwhite(o);
+	      g->strhash_hit++;
 	      return sx;  /* Return existing string. */
 	    }
 	    o = gcnext(o);
@@ -276,6 +279,7 @@ GCstr *lj_str_new(lua_State *L, const char *str, size_t lenx)
 	    if (sx->hash == fh && sx->len == len && memcmp(str, strdata(sx), len) == 0) {
 	      /* Resurrect if dead. Can only happen with fixstring() (keywords). */
 	      if (isdead(g, o)) flipwhite(o);
+	      g->strhash_hit++;
 	      return sx;  /* Return existing string. */
 	    }
 	    o = gcnext(o);
@@ -293,6 +297,7 @@ GCstr *lj_str_new(lua_State *L, const char *str, size_t lenx)
     }
   }
 #endif
+  g->strhash_miss++;
   /* Nope, create a new string. */
   s = lj_mem_newt(L, sizeof(GCstr)+len+1, GCstr);
   newwhite(g, s);

src/lj_tab.c

@@ -141,6 +141,7 @@ static GCtab *newtab(lua_State *L, uint32_t asize, uint32_t hbits)
   }
   if (hbits)
     newhpart(L, t, hbits);
+  G(L)->gc.tabnum++;
   return t;
 }
 
@@ -240,6 +241,7 @@ void LJ_FASTCALL lj_tab_free(global_State *g, GCtab *t)
     lj_mem_free(g, t, sizetabcolo((uint32_t)t->colo & 0x7f));
   else
     lj_mem_freet(g, t);
+  g->gc.tabnum--;
 }
 
 /* -- Table resizing ------------------------------------------------------ */

src/lj_trace.c

@@ -136,6 +136,7 @@ GCtrace * LJ_FASTCALL lj_trace_alloc(lua_State *L, GCtrace *T)
   T2->nsnap = T->nsnap;
   T2->nsnapmap = T->nsnapmap;
   memcpy(p, T->ir + T->nk, szins);
+  L2J(L)->tracenum++;
   return T2;
 }
 
@@ -176,6 +177,7 @@ void LJ_FASTCALL lj_trace_free(global_State *g, GCtrace *T)
   lj_mem_free(g, T,
     ((sizeof(GCtrace)+7)&~7) + (T->nins-T->nk)*sizeof(IRIns) +
     T->nsnap*sizeof(SnapShot) + T->nsnapmap*sizeof(SnapEntry));
+  J->tracenum--;
 }
 
 /* Re-enable compiling a prototype by unpatching any modified bytecode. */
@@ -538,8 +540,10 @@ static int trace_downrec(jit_State *J)
   /* Restart recording at the return instruction. */
   lua_assert(J->pt != NULL);
   lua_assert(bc_isret(bc_op(*J->pc)));
-  if (bc_op(*J->pc) == BC_RETM)
+  if (bc_op(*J->pc) == BC_RETM) {
+    J->ntraceabort++;
     return 0;  /* NYI: down-recursion with RETM. */
+  }
   J->parent = 0;
   J->exitno = 0;
   J->state = LJ_TRACE_RECORD;
@@ -616,6 +620,7 @@ static int trace_abort(jit_State *J)
     return trace_downrec(J);
   else if (e == LJ_TRERR_MCODEAL)
     lj_trace_flushall(L);
+  J->ntraceabort++;
   return 0;
 }
 

src/lj_udata.c

@@ -24,11 +24,13 @@ GCudata *lj_udata_new(lua_State *L, MSize sz, GCtab *env)
   /* Chain to userdata list (after main thread). */
   setgcrefr(ud->nextgc, mainthread(g)->nextgc);
   setgcref(mainthread(g)->nextgc, obj2gco(ud));
+  g->gc.udatanum++;
   return ud;
 }
 
 void LJ_FASTCALL lj_udata_free(global_State *g, GCudata *ud)
 {
+  g->gc.udatanum--;
   lj_mem_free(g, ud, sizeudata(ud));
 }