issue #60 improve parsing of table get access with short strings

src/lcode.c

@@ -422,6 +422,18 @@ void luaK_setoneret (FuncState *fs, expdesc *e) {
   }
 }
 
+/**
+ * Is the operand a reference to a short string constant?
+ */
+static int isshortstr(FuncState *fs, int kk) {
+  if (ISK(kk)) {
+    Proto *f = fs->f;
+    kk = INDEXK(kk);
+    lua_assert(kk >= 0 && kk < f->sizek);
+    return ttisshrstring(&f->k[kk]);
+  }
+  return 0;
+}
 
 void luaK_dischargevars (FuncState *fs, expdesc *e) {
   switch (e->k) {
@@ -441,12 +453,14 @@ void luaK_dischargevars (FuncState *fs, expdesc *e) {
       freereg(fs, e->u.ind.idx);
       if (e->u.ind.vt == VLOCAL) {  /* 't' is in a register? */
         freereg(fs, e->u.ind.t);
+        /* TODO we should do this for upvalues too */
         /* table access - set specialized op codes if array types are detected */
         if (e->ravi_type == RAVI_TARRAYFLT && e->u.ind.key_type == RAVI_TNUMINT)
           op = OP_RAVI_GETTABLE_AF;
         else if (e->ravi_type == RAVI_TARRAYINT && e->u.ind.key_type == RAVI_TNUMINT)
           op = OP_RAVI_GETTABLE_AI;
-        else if (e->ravi_type == RAVI_TTABLE && e->u.ind.key_type == RAVI_TSTRING)
+        /* Check that we have a short string constant */
+        else if (e->ravi_type == RAVI_TTABLE && e->u.ind.key_type == RAVI_TSTRING && isshortstr(fs, e->u.ind.idx))
           op = OP_RAVI_GETTABLE_S;
         else if (e->ravi_type == RAVI_TTABLE && e->u.ind.key_type == RAVI_TNUMINT)
           op = OP_RAVI_GETTABLE_I;

src/lvm.c

@@ -886,17 +886,10 @@ newframe:  /* reentry point when frame changes (call/return) */
       break;
     }
     case OP_RAVI_GETTABLE_S: {
-      if (ISK(GETARG_C(i))) {
-        TValue *kv = k + INDEXK(GETARG_C(i));
-        TString *key = tsvalue(kv);
-        if (key->tt == LUA_TSHRSTR) {
-          const TValue *v = luaH_getstr(hvalue(RB(i)), key);
-          setobj2s(L, ra, v);
-        }
-        else
-          goto l_gettable;
-      } else
-        goto l_gettable;
+      TValue *kv = k + INDEXK(GETARG_C(i));
+      TString *key = tsvalue(kv);
+      const TValue *v = luaH_getstr(hvalue(RB(i)), key);
+      setobj2s(L, ra, v);
       /*
       if (ISK(GETARG_C(i))) {
         TValue *kv = k + INDEXK(GETARG_C(i));

src/ravi_llvmcodegen.cpp

@@ -1550,17 +1550,11 @@ void RaviCodeGenerator::compile(lua_State *L, Proto *p,
     case OP_RAVI_GETTABLE_S: {
       int C = GETARG_C(i);
       int B = GETARG_B(i);
-      if (ISK(C)) {
-        TValue *kv = k + INDEXK(C);
-        TString *key = tsvalue(kv);
-        if (key->tt == LUA_TSHRSTR) {
-          emit_GETTABLE_S(def, A, B, C, pc, key);
-        } else {
-          emit_GETTABLE(def, A, B, C, pc);
-        }
-      } else {
-        emit_GETTABLE(def, A, B, C, pc);
-      }
+      lua_assert(ISK(C));
+      TValue *kv = k + INDEXK(C);
+      TString *key = tsvalue(kv);
+      lua_assert(key->tt == LUA_TSHRSTR);
+      emit_GETTABLE_S(def, A, B, C, pc, key);
     } break;
     case OP_RAVI_GETTABLE_I: {
       int B = GETARG_B(i);