hash_sparse: change length checks

dont early return on 0 len, let it be the falltrough case, this seems to help branch prediction

src/blua/lauxlib.c

@@ -20,6 +20,7 @@
 #define lauxlib_c
 #define LUA_LIB
 
+#include "ldebug.h"
 #include "lua.h"
 
 #include "lauxlib.h"
@@ -468,8 +469,19 @@ LUALIB_API char *luaL_prepbuffer (luaL_Buffer *B) {
 
 
 LUALIB_API void luaL_addlstring (luaL_Buffer *B, const char *s, size_t l) {
-  while (l--)
+ while (l) {
-    luaL_addchar(B, *s++);
+    size_t space = bufffree(B);
+    if (space == 0) {
+      luaL_prepbuffer(B);
+      lua_assert(bufffree(B) == LUAL_BUFFERSIZE);
+      space = LUAL_BUFFERSIZE;
+    }
+    if (space > l) space = l;
+    memcpy(B->p, s, space);
+    B->p += space;
+    s += space;
+    l -= space;
+  }
 }
 
 
@@ -686,6 +698,6 @@ static int panic (lua_State *L) {
 
 LUALIB_API lua_State *luaL_newstate (void) {
   lua_State *L = lua_newstate(l_alloc, NULL);
-  if (L) lua_atpanic(L, &panic);
+  if (l_likely(L)) lua_atpanic(L, &panic);
   return L;
 }

src/blua/lcode.c

@@ -790,18 +790,19 @@ void luaK_posfix (FuncState *fs, BinOpr op, expdesc *e1, expdesc *e2) {
     case OPR_BXOR: codearith(fs, OP_BXOR, e1, e2); break;
     case OPR_BSHL: codearith(fs, OP_BSHL, e1, e2); break;
     case OPR_BSHR: codearith(fs, OP_BSHR, e1, e2); break;
-    case OPR_ADD: codearith(fs, OP_ADD, e1, e2); break;
+    case OPR_ADD: case OPR_SUB: case OPR_MUL: case OPR_DIV:
-    case OPR_SUB: codearith(fs, OP_SUB, e1, e2); break;
+    case OPR_MOD: case OPR_POW: {
-    case OPR_MUL: codearith(fs, OP_MUL, e1, e2); break;
+      codearith(fs, op - OPR_ADD + OP_ADD, e1, e2);
-    case OPR_DIV: codearith(fs, OP_DIV, e1, e2); break;
+      break;
-    case OPR_MOD: codearith(fs, OP_MOD, e1, e2); break;
+    }
-    case OPR_POW: codearith(fs, OP_POW, e1, e2); break;
+    case OPR_EQ: case OPR_LT: case OPR_LE: {
-    case OPR_EQ: codecomp(fs, OP_EQ, 1, e1, e2); break;
+      codecomp(fs, op - OPR_EQ + OP_EQ, 1, e1, e2);
-    case OPR_NE: codecomp(fs, OP_EQ, 0, e1, e2); break;
+      break;
-    case OPR_LT: codecomp(fs, OP_LT, 1, e1, e2); break;
+    }
-    case OPR_LE: codecomp(fs, OP_LE, 1, e1, e2); break;
+    case OPR_NE: case OPR_GT: case OPR_GE: {
-    case OPR_GT: codecomp(fs, OP_LT, 0, e1, e2); break;
+      codecomp(fs, op - OPR_NE + OP_EQ, 0, e1, e2);
-    case OPR_GE: codecomp(fs, OP_LE, 0, e1, e2); break;
+      break;
+    }
     default: lua_assert(0);
   }
 }

src/blua/lcode.h

@@ -21,13 +21,13 @@
 
 
 /*
-** grep "ORDER OPR" if you change these enums
+** grep "ORDER OPR" if you change these enums  (ORDER OP)
 */
 typedef enum BinOpr {
   OPR_ADD, OPR_SUB, OPR_MUL, OPR_DIV, OPR_MOD, OPR_POW,
   OPR_CONCAT,
-  OPR_NE, OPR_EQ,
+  OPR_EQ, OPR_LT, OPR_LE,
-  OPR_LT, OPR_LE, OPR_GT, OPR_GE,
+  OPR_NE, OPR_GT, OPR_GE,
   OPR_AND, OPR_OR,
   OPR_BAND, OPR_BOR, OPR_BXOR,
   OPR_BSHL, OPR_BSHR,

src/blua/ldebug.c

@@ -542,16 +542,39 @@ static const char *getobjname (lua_State *L, CallInfo *ci, int stackpos,
 
 
 static const char *getfuncname (lua_State *L, CallInfo *ci, const char **name) {
+  TMS tm = 0;
   Instruction i;
   if ((isLua(ci) && ci->tailcalls > 0) || !isLua(ci - 1))
     return NULL;  /* calling function is not Lua (or is unknown) */
   ci--;  /* calling function */
   i = ci_func(ci)->l.p->code[currentpc(L, ci)];
-  if (GET_OPCODE(i) == OP_CALL || GET_OPCODE(i) == OP_TAILCALL ||
+  switch (GET_OPCODE(i)) {
-      GET_OPCODE(i) == OP_TFORLOOP)
+    case OP_CALL:
-    return getobjname(L, ci, GETARG_A(i), name);
+    case OP_TAILCALL:
-  else
+    case OP_TFORLOOP:
-    return NULL;  /* no useful name can be found */
+      return getobjname(L, ci, GETARG_A(i), name);
+    case OP_GETGLOBAL:
+    case OP_SELF:
+    case OP_GETTABLE: tm = TM_INDEX; break;
+    case OP_SETGLOBAL:
+    case OP_SETTABLE: tm = TM_NEWINDEX; break;
+    case OP_EQ: tm = TM_EQ; break;
+    case OP_ADD: tm = TM_ADD; break;
+    case OP_SUB: tm = TM_SUB; break;
+    case OP_MUL: tm = TM_MUL; break;
+    case OP_DIV: tm = TM_DIV; break;
+    case OP_MOD: tm = TM_MOD; break;
+    case OP_POW: tm = TM_POW; break;
+    case OP_UNM: tm = TM_UNM; break;
+    case OP_LEN: tm = TM_LEN; break;
+    case OP_LT: tm = TM_LT; break;
+    case OP_LE: tm = TM_LE; break;
+    case OP_CONCAT: tm = TM_CONCAT; break;
+    default:
+      return NULL;  /* else no useful name can be found */
+  }
+  *name = getstr(G(L)->tmname[tm]);
+  return "metamethod";
 }
 
 

src/blua/ldo.c

@@ -164,7 +164,7 @@ void luaD_reallocCI (lua_State *L, int newsize) {
 
 
 void luaD_growstack (lua_State *L, int n) {
-  if (l_likely(n <= L->stacksize))  /* double size is enough? */
+  if (n <= L->stacksize)  /* double size is enough? */
     luaD_reallocstack(L, 2*L->stacksize);
   else
     luaD_reallocstack(L, L->stacksize + n);
@@ -318,7 +318,7 @@ int luaD_precall (lua_State *L, StkId func, int nresults) {
     ci->top = L->top + LUA_MINSTACK;
     lua_assert(ci->top <= L->stack_last);
     ci->nresults = nresults;
-    if (L->hookmask & LUA_MASKCALL)
+    if (l_unlikely(L->hookmask & LUA_MASKCALL))
       luaD_callhook(L, LUA_HOOKCALL, -1);
     lua_unlock(L);
     n = (*curr_func(L)->c.f)(L);  /* do the actual call */

src/blua/liolib.c

@@ -356,20 +356,21 @@ static int read_line (lua_State *L, FILE *f) {
 
 
 static int read_chars (lua_State *L, FILE *f, size_t n) {
-  size_t rlen;  /* how much to read */
+  size_t tbr = n;  /* number of chars to be read */
-  size_t nr;  /* number of chars actually read */
+  size_t rlen;  /* how much to read in each cycle */
+  size_t nr;  /* number of chars actually read in each cycle */
   luaL_Buffer b;
   luaL_buffinit(L, &b);
   rlen = LUAL_BUFFERSIZE;  /* try to read that much each time */
   do {
     char *p = luaL_prepbuffer(&b);
-    if (rlen > n) rlen = n;  /* cannot read more than asked */
+    if (rlen > tbr) rlen = tbr;  /* cannot read more than asked */
     nr = fread(p, sizeof(char), rlen, f);
     luaL_addsize(&b, nr);
-    n -= nr;  /* still have to read `n' chars */
+    tbr -= nr;  /* still have to read 'tbr' chars */
-  } while (n > 0 && nr == rlen);  /* until end of count or eof */
+  } while (tbr > 0 && nr == rlen);  /* until end of count or eof */
   luaL_pushresult(&b);  /* close buffer */
-  return (n == 0 || lua_objlen(L, -1) > 0);
+  return (tbr == 0 || tbr < n);  /* true iff read something */
 }
 
 
@@ -432,13 +433,13 @@ static int f_read (lua_State *L) {
 
 static int io_readline (lua_State *L) {
   FILE *f = *(FILE **)lua_touserdata(L, lua_upvalueindex(1));
-  int sucess;
+  int success;
   if (f == NULL)  /* file is already closed? */
     luaL_error(L, "file is already closed");
-  sucess = read_line(L, f);
+  success = read_line(L, f);
   if (ferror(f))
     return luaL_error(L, "%s", strerror(errno));
-  if (sucess) return 1;
+  if (success) return 1;
   else {  /* EOF */
     if (lua_toboolean(L, lua_upvalueindex(2))) {  /* generator created file? */
       lua_settop(L, 0);

src/blua/lparser.c

@@ -881,10 +881,10 @@ static const struct {
   lu_byte right; /* right priority */
 } priority[] = {  /* ORDER OPR */
    {6, 6}, {6, 6}, {7, 7}, {7, 7}, {7, 7},  /* `+' `-' `/' `%' */
-   {10, 9}, {5, 4},                 /* power and concat (right associative) */
+   {10, 9}, {5, 4},                 /* ^, .. (right associative) */
-   {3, 3}, {3, 3},                  /* equality and inequality */
+   {3, 3}, {3, 3}, {3, 3},          /* ==, <, <= */
-   {3, 3}, {3, 3}, {3, 3}, {3, 3},  /* order */
+   {3, 3}, {3, 3}, {3, 3},          /* ~=, >, >= */
-   {2, 2}, {1, 1}                   /* logical (and/or) */
+   {2, 2}, {1, 1}                   /* and, or */
    ,{6, 6}, {6, 6}, {6, 6},           /* bit-wise (band/bor/bxor) */
    {7, 7}, {7, 7}		    /* shl/shr */
 };

src/blua/lstring.c

@@ -51,7 +51,7 @@ static TString *newlstr (lua_State *L, const char *str, size_t l,
                                        unsigned int h) {
   TString *ts;
   stringtable *tb;
-  if (l+1 > (MAX_SIZET - sizeof(TString))/sizeof(char))
+  if (l_unlikely(l+1 > (MAX_SIZET - sizeof(TString))/sizeof(char)))
     luaM_toobig(L);
   ts = cast(TString *, luaM_malloc(L, (l+1)*sizeof(char)+sizeof(TString)));
   ts->tsv.len = l;
@@ -72,18 +72,72 @@ static TString *newlstr (lua_State *L, const char *str, size_t l,
 }
 
 
-TString *luaS_newlstr (lua_State *L, const char *str, size_t l) {
+// string hash taken from luaJIT
-  GCObject *o;
+
+/* Unaligned load of uint32_t. */
+static inline __attribute__((always_inline)) uint32_t getu32(const void* ptr)
+{
+  uint32_t result;
+  memcpy(&result, ptr, 4);
+  return result;
+}
+
+// smol macro to look a little less messy lul
+#define getu8(p) *cast(const uint8_t *, p)
+
+/* Keyed sparse ARX string hash. Constant time. */
+static unsigned hash_sparse(const char *str, size_t len)
+{
+  /* Constants taken from lookup3 hash by Bob Jenkins. */
+  unsigned int a, b, h = cast(unsigned int, len);
+#define rol(x, n) (((x)<<(n)) | ((x)>>(-cast(int, n)&(8*sizeof(x)-1))))
+  if (len >= 4) {  /* Caveat: unaligned access! */
+    a  = getu32(str);
+    h ^= getu32(str+len-4);
+    b  = getu32(str+(len>>1)-2);
+    h ^= b; h -= rol(b, 14);
+    b += getu32(str+(len>>2)-1);
+  } else if (len > 0) {
+    a  = getu8(str);
+    h ^= getu8(str+len-1);
+    b  = getu8(str+(len>>1));
+    h ^= b; h -= rol(b, 14);
+  } else {
+    return 0;
+  }
+  a ^= h; a -= rol(h, 11);
+  b ^= a; b -= rol(a, 25);
+  h ^= b; h -= rol(b, 16);
+#undef rol
+  return h;
+}
+
+#undef getu8
+
+
+static inline __attribute__((always_inline)) unsigned luaS_hash (const char *str, size_t l) {
+#if 0
   unsigned int h = cast(unsigned int, l);  /* seed */
   size_t step = (l>>5)+1;  /* if string is too long, don't hash all its chars */
   size_t l1;
   for (l1=l; l1>=step; l1-=step)  /* compute hash */
     h = h ^ ((h<<5)+(h>>2)+cast(unsigned char, str[l1-1]));
+  return h;
+#else
+  return hash_sparse(str, l);
+#endif
+}
+
+TString *luaS_newlstr (lua_State *L, const char *str, size_t l) {
+  GCObject *o;
+  unsigned int h = luaS_hash(str, l);
   for (o = G(L)->strt.hash[lmod(h, G(L)->strt.size)];
        o != NULL;
        o = o->gch.next) {
     TString *ts = rawgco2ts(o);
-    if (l_unlikely(ts->tsv.len == l && (memcmp(str, getstr(ts), l) == 0))) {
+    if (ts->tsv.hash == h &&
+        ts->tsv.len == l &&
+       (memcmp(str, getstr(ts), l) == 0)) {
       /* string may be dead */
       if (isdead(G(L), o)) changewhite(o);
       return ts;

src/blua/lvm.c

@@ -28,7 +28,7 @@
 
 
 
-/* limit for table tag-method chains (to avoid loops) */
+/* limit for table tag-method chains (to avoid infinite loops) */
 #define MAXTAGLOOP	100
 
 
@@ -366,6 +366,7 @@ static void Arith (lua_State *L, StkId ra, TValue *rb,
 
 
 #define arith_op(op,tm) { \
+        StkId ra = RA(i); \
         TValue *rb = RKB(i); \
         TValue *rc = RKC(i); \
         if (ttisnumber(rb) && ttisnumber(rc)) { \
@@ -392,7 +393,6 @@ void luaV_execute (lua_State *L, int nexeccalls) {
   /* main loop of interpreter */
   for (;;) {
     const Instruction i = *pc++;
-    StkId ra;
     if ((L->hookmask & (LUA_MASKLINE | LUA_MASKCOUNT)) &&
         (--L->hookcount == 0 || L->hookmask & LUA_MASKLINE)) {
       traceexec(L, pc);
@@ -402,26 +402,28 @@ void luaV_execute (lua_State *L, int nexeccalls) {
       }
       base = L->base;
     }
-    /* warning!! several calls may realloc the stack and invalidate `ra' */
-    ra = RA(i);
     lua_assert(base == L->base && L->base == L->ci->base);
     lua_assert(base <= L->top && L->top <= L->stack + L->stacksize);
     lua_assert(L->top == L->ci->top || luaG_checkopenop(i));
     switch (GET_OPCODE(i)) {
       case OP_MOVE: {
+        StkId ra = RA(i);
         setobjs2s(L, ra, RB(i));
         continue;
       }
       case OP_LOADK: {
+        StkId ra = RA(i);
         setobj2s(L, ra, KBx(i));
         continue;
       }
       case OP_LOADBOOL: {
+        StkId ra = RA(i);
         setbvalue(ra, GETARG_B(i));
         if (GETARG_C(i)) pc++;  /* skip next instruction (if C) */
         continue;
       }
       case OP_LOADNIL: {
+        StkId ra = RA(i);
         TValue *rb = RB(i);
         do {
           setnilvalue(rb--);
@@ -429,11 +431,13 @@ void luaV_execute (lua_State *L, int nexeccalls) {
         continue;
       }
       case OP_GETUPVAL: {
+        StkId ra = RA(i);
         int b = GETARG_B(i);
         setobj2s(L, ra, cl->upvals[b]->v);
         continue;
       }
       case OP_GETGLOBAL: {
+        StkId ra = RA(i);
         TValue g;
         TValue *rb = KBx(i);
         sethvalue(L, &g, cl->env);
@@ -442,10 +446,14 @@ void luaV_execute (lua_State *L, int nexeccalls) {
         continue;
       }
       case OP_GETTABLE: {
-        Protect(luaV_gettable(L, RB(i), RKC(i), ra));
+        StkId ra = RA(i);
+        StkId rb = RB(i);
+        TValue *rc = RKC(i);
+        Protect(luaV_gettable(L, rb, rc, ra));
         continue;
       }
       case OP_SETGLOBAL: {
+        StkId ra = RA(i);
         TValue g;
         sethvalue(L, &g, cl->env);
         lua_assert(ttisstring(KBx(i)));
@@ -453,16 +461,21 @@ void luaV_execute (lua_State *L, int nexeccalls) {
         continue;
       }
       case OP_SETUPVAL: {
+        StkId ra = RA(i);
         UpVal *uv = cl->upvals[GETARG_B(i)];
         setobj(L, uv->v, ra);
         luaC_barrier(L, uv, ra);
         continue;
       }
       case OP_SETTABLE: {
-        Protect(luaV_settable(L, ra, RKB(i), RKC(i)));
+        StkId ra = RA(i);
+        TValue *rb = RKB(i);
+        TValue *rc = RKC(i);
+        Protect(luaV_settable(L, ra, rb, rc));
         continue;
       }
       case OP_NEWTABLE: {
+        StkId ra = RA(i);
         int b = GETARG_B(i);
         int c = GETARG_C(i);
         sethvalue(L, ra, luaH_new(L, luaO_fb2int(b), luaO_fb2int(c)));
@@ -470,6 +483,7 @@ void luaV_execute (lua_State *L, int nexeccalls) {
         continue;
       }
       case OP_SELF: {
+        StkId ra = RA(i);
         StkId rb = RB(i);
         setobjs2s(L, ra+1, rb);
         Protect(luaV_gettable(L, rb, RKC(i), ra));
@@ -488,6 +502,7 @@ void luaV_execute (lua_State *L, int nexeccalls) {
         continue;
       }
       case OP_DIV: {
+        StkId ra = RA(i);
         TValue *rb = RKB(i);
         TValue *rc = RKC(i);
         if (ttisnumber(rb) && ttisnumber(rc)) {
@@ -503,6 +518,7 @@ void luaV_execute (lua_State *L, int nexeccalls) {
         continue;
       }
       case OP_MOD: {
+        StkId ra = RA(i);
         TValue *rb = RKB(i);
         TValue *rc = RKC(i);
         if (ttisnumber(rb) && ttisnumber(rc)) {
@@ -522,26 +538,27 @@ void luaV_execute (lua_State *L, int nexeccalls) {
         continue;
       }
       case OP_BAND: {
-	arith_op(luai_numand, TM_AND);
+        arith_op(luai_numand, TM_AND);
-	continue;
+        continue;
       }
       case OP_BOR: {
-	arith_op(luai_numor, TM_OR);
+        arith_op(luai_numor, TM_OR);
-	continue;
+        continue;
       }
       case OP_BXOR: {
-	arith_op(luai_numxor, TM_XOR);
+        arith_op(luai_numxor, TM_XOR);
-	continue;
+        continue;
       }
       case OP_BSHL: {
-	arith_op(luai_numshl, TM_SHL);
+        arith_op(luai_numshl, TM_SHL);
-	continue;
+        continue;
       }
       case OP_BSHR: {
-	arith_op(luai_numshr, TM_SHR);
+        arith_op(luai_numshr, TM_SHR);
-	continue;
+        continue;
       }
       case OP_BNOT: {
+        StkId ra = RA(i);
         TValue *rb = RB(i);
         if (ttisnumber(rb)) {
           lua_Number nb = nvalue(rb);
@@ -553,6 +570,7 @@ void luaV_execute (lua_State *L, int nexeccalls) {
         continue;
       }
       case OP_UNM: {
+        StkId ra = RA(i);
         TValue *rb = RB(i);
         if (ttisnumber(rb)) {
           lua_Number nb = nvalue(rb);
@@ -564,11 +582,13 @@ void luaV_execute (lua_State *L, int nexeccalls) {
         continue;
       }
       case OP_NOT: {
+        StkId ra = RA(i);
         int res = l_isfalse(RB(i));  /* next assignment may change this value */
         setbvalue(ra, res);
         continue;
       }
       case OP_LEN: {
+        StkId ra = RA(i);
         TValue *rb = RB(i);
         switch (ttype(rb)) {
           case LUA_TTABLE: {
@@ -626,12 +646,14 @@ void luaV_execute (lua_State *L, int nexeccalls) {
         continue;
       }
       case OP_TEST: {
+        StkId ra = RA(i);
         if (l_isfalse(ra) != GETARG_C(i))
           dojump(L, pc, GETARG_sBx(*pc));
         pc++;
         continue;
       }
       case OP_TESTSET: {
+        StkId ra = RA(i);
         TValue *rb = RB(i);
         if (l_isfalse(rb) != GETARG_C(i)) {
           setobjs2s(L, ra, rb);
@@ -641,6 +663,7 @@ void luaV_execute (lua_State *L, int nexeccalls) {
         continue;
       }
       case OP_CALL: {
+        StkId ra = RA(i);
         int b = GETARG_B(i);
         int nresults = GETARG_C(i) - 1;
         if (b != 0) L->top = ra+b;  /* else previous instruction set top */
@@ -662,6 +685,7 @@ void luaV_execute (lua_State *L, int nexeccalls) {
         }
       }
       case OP_TAILCALL: {
+        StkId ra = RA(i);
         int b = GETARG_B(i);
         if (b != 0) L->top = ra+b;  /* else previous instruction set top */
         L->savedpc = pc;
@@ -694,6 +718,7 @@ void luaV_execute (lua_State *L, int nexeccalls) {
         }
       }
       case OP_RETURN: {
+        StkId ra = RA(i);
         int b = GETARG_B(i);
         if (b != 0) L->top = ra+b-1;
         if (L->openupval) luaF_close(L, base);
@@ -709,6 +734,7 @@ void luaV_execute (lua_State *L, int nexeccalls) {
         }
       }
       case OP_FORLOOP: {
+        StkId ra = RA(i);
         lua_Number step = nvalue(ra+2);
         lua_Number idx = luai_numadd(nvalue(ra), step); /* increment index */
         lua_Number limit = nvalue(ra+1);
@@ -721,6 +747,7 @@ void luaV_execute (lua_State *L, int nexeccalls) {
         continue;
       }
       case OP_FORPREP: {
+        StkId ra = RA(i);
         const TValue *init = ra;
         const TValue *plimit = ra+1;
         const TValue *pstep = ra+2;
@@ -737,6 +764,7 @@ void luaV_execute (lua_State *L, int nexeccalls) {
         continue;
       }
       case OP_TFORLOOP: {
+        StkId ra = RA(i);
         StkId cb = ra + 3;  /* call base */
         setobjs2s(L, cb+2, ra+2);
         setobjs2s(L, cb+1, ra+1);
@@ -753,6 +781,7 @@ void luaV_execute (lua_State *L, int nexeccalls) {
         continue;
       }
       case OP_SETLIST: {
+        StkId ra = RA(i);
         int n = GETARG_B(i);
         int c = GETARG_C(i);
         int last;
@@ -775,10 +804,12 @@ void luaV_execute (lua_State *L, int nexeccalls) {
         continue;
       }
       case OP_CLOSE: {
+        StkId ra = RA(i);
         luaF_close(L, ra);
         continue;
       }
       case OP_CLOSURE: {
+        StkId ra = RA(i);
         Proto *p;
         Closure *ncl;
         int nup, j;
@@ -799,6 +830,7 @@ void luaV_execute (lua_State *L, int nexeccalls) {
         continue;
       }
       case OP_VARARG: {
+        StkId ra = RA(i);
         int b = GETARG_B(i) - 1;
         int j;
         CallInfo *ci = L->ci;