459240 - Off-by-one error breaks right shift operator for shift of 32

Status: RESOLVED INVALID

(Rhino Graveyard :: Core, defect)

Description

[Dave Baggett]

User-Agent:       Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.5; en-US; rv:1.9.0.3) Gecko/2008092414 Firefox/3.0.3
Build Identifier: rhino1_7R1

x >> 32 should return 0, but returns x


Reproducible: Always

Steps to Reproduce:
% java org.mozilla.javascript.tools.shell.Main -e "print (0xFFFFFFFF >> 32)"
4294967295
% java org.mozilla.javascript.tools.shell.Main -e "print (0xFFFFFFFF >>> 32)"
4294967295

Actual Results:  
(x >> 32) == x
(x >>> 32) == x

(x >> y) appears to be interpreted as (x >> (y % 32)) -- same for (x >>> y)


Expected Results:  
(x >> 32) == 0
(x >>> 32) == 0

(x >> y) should be interpreted as (x >> (y % 33))
(x >>> y) should be interpreted as (x >>> (y % 33))

Comment 1

[Attila Szegedi]

This is conformant to the ECMA-262 spec, sections 11.7.2 "The Signed Right Shift Operator" and 11.7.3. "The Unsigned Right Shift Operator". Both specify:

"7. Mask out all but the least significant 5 bits of Result(6), that is, compute Result(6) & 0x1F"

Where Result(6) refers to the shift offset value. This is effectively indeed making it modulo 32.