implementation of fast track for gettable operations

1 files changed, 25 insertions, 3 deletions

diff --git a/lvm.h b/lvm.h
index a50fb981..9f7d028f 100644
--- a/lvm.h
+++ b/lvm.h
@@ -1,5 +1,5 @@
 /*
-** $Id: lvm.h,v 2.34 2014/08/01 17:24:02 roberto Exp roberto $
+** $Id: lvm.h,v 2.35 2015/02/20 14:27:53 roberto Exp roberto $
 ** Lua virtual machine
 ** See Copyright Notice in lua.h
 */
@@ -48,13 +48,35 @@
 #define luaV_rawequalobj(t1,t2)         luaV_equalobj(NULL,t1,t2)
 
 
+/*
+** fast track for 'gettable': 1 means 'aux' points to resulted value;
+** 0 means 'aux' is metamethod (if 't' is a table) or NULL. 'f' is
+** the raw get function to use.
+*/
+#define luaV_fastget(L,t,k,aux,f) \
+  (!ttistable(t)  \
+   ? (aux = NULL, 0)  /* not a table; 'aux' is NULL and result is 0 */  \
+   : (aux = f(hvalue(t), k),  /* else, do raw access */  \
+      !ttisnil(aux) ? 1  /* result not nil? 'aux' has it */  \
+      : (aux = fasttm(L, hvalue(t)->metatable, TM_INDEX),  /* get metamethod */\
+         aux != NULL  ? 0  /* has metamethod? must call it */  \
+         : (aux = luaO_nilobject, 1))))  /* else, final result is nil */
+
+/*
+** standard implementation for 'gettable'
+*/
+#define luaV_gettable(L,t,k,v) { const TValue *aux; \
+  if (luaV_fastget(L,t,k,aux,luaH_get)) { setobj2s(L, v, aux); } \
+  else luaV_finishget(L,t,k,v,aux); }
+
+
 LUAI_FUNC int luaV_equalobj (lua_State *L, const TValue *t1, const TValue *t2);
 LUAI_FUNC int luaV_lessthan (lua_State *L, const TValue *l, const TValue *r);
 LUAI_FUNC int luaV_lessequal (lua_State *L, const TValue *l, const TValue *r);
 LUAI_FUNC int luaV_tonumber_ (const TValue *obj, lua_Number *n);
 LUAI_FUNC int luaV_tointeger (const TValue *obj, lua_Integer *p, int mode);
-LUAI_FUNC void luaV_gettable (lua_State *L, const TValue *t, TValue *key,
-                                            StkId val);
+LUAI_FUNC void luaV_finishget (lua_State *L, const TValue *t, TValue *key,
+                               StkId val, const TValue *tm);
 LUAI_FUNC void luaV_settable (lua_State *L, const TValue *t, TValue *key,
                                             StkId val);
 LUAI_FUNC void luaV_finishOp (lua_State *L);