411175 - TT: add obox!, sbox!, dbox!, nsbox! when boxed value is known not-null or not-NaN

Status: VERIFIED FIXED

(Tamarin Graveyard :: Virtual Machine, defect)

Description

[Edwin Smith]

add dedicated boxing primitives for use in Forth when the value being boxed is known not-null and/or not-NaN

eliminates null pointer checks and/or CMOV for common code paths.

e.g.

SUPER: setrawboxtypeornull (( i i -- x ))
	OVER NOT INEG | setrawboxtype ;
: obox  ( obj -- x ) BoxedObj setrawboxtypeornull ;
: obox! ( obj -- x ) BoxedObj setrawboxtype ;

Comment 1

[Steven Johnson]

How frequently do such occurrences actually happen? (ie do you already have a list of candidate words that would benefit from this optimization)

Comment 2

[Edwin Smith]

sure, any time we box a string constant, for example, or any time we box a new object we just created.  (OP_newobject, OP_newarray, result of constructing an object, etc).  I dont have a concrete list however.  

Comment 3

[Steven Johnson]

Attachment: Patch

add sbox!/obox!/nsbox! and appropriate usage.

Comment 4

[Edwin Smith]

Comment on attachment 296173 [details] [diff] [review]
Patch

did this help performance at all?

Comment 5

[Steven Johnson]

Not measurably on the AS3Chess test, no, it's within the noise level at this point. But it's definitely fewer ops in a lot of places and so worth doing.

Comment 6

[Steven Johnson]

pushed as changeset:   279:101e97c2d1c5

Comment 7

[Chris Peyer]

Closing out all TT: transfer bugs that are resolved fixed.