shithub: libmujs

Info  •  Files  •  Log  •  Branches

Issue #120: Optimize array construction bytecode.

Use a specialized array initializer that pushes values to the end
of the array instead of using a lot of setprop. This avoids the need
to create a lot of number constants for the array indices.

--- a/jscompile.c

+++ b/jscompile.c

@@ -302,17 +302,10 @@

 static void carray(JF, js_Ast *list)

 {

-	int i = 0;

 	while (list) {

-		if (list->a->type != EXP_UNDEF) {

-			emitline(J, F, list->a);

-			emitnumber(J, F, i++);

-			cexp(J, F, list->a);

-			emitline(J, F, list->a);

-			emit(J, F, OP_INITPROP);

-		} else {

-			++i;

-		}

+		emitline(J, F, list->a);

+		cexp(J, F, list->a);

+		emit(J, F, OP_INITARRAY);

 		list = list->b;

 	}

 }

--- a/jscompile.h

+++ b/jscompile.h

@@ -38,6 +38,7 @@

 	OP_IN,		/* <name> <obj> -- <exists?> */

+	OP_INITARRAY,	/* <obj> <val> -- <obj> */

 	OP_INITPROP,	/* <obj> <key> <val> -- <obj> */

 	OP_INITGETTER,	/* <obj> <key> <closure> -- <obj> */

 	OP_INITSETTER,	/* <obj> <key> <closure> -- <obj> */

--- a/jsrun.c

+++ b/jsrun.c

@@ -1438,6 +1438,10 @@

 			js_pushboolean(J, b);

 			break;

+		case OP_INITARRAY:

+			js_setindex(J, -2, js_getlength(J, -2));

+			break;

+

 		case OP_INITPROP:

 			obj = js_toobject(J, -3);

 			str = js_tostring(J, -2);

--- a/opnames.h

+++ b/opnames.h

@@ -25,6 +25,7 @@

 "setvar",

 "delvar",

 "in",

+"initarray",

 "initprop",

 "initgetter",

 "initsetter",