On Thu, May 06, 2021 at 04:33:55PM -0700, tim Rowledge wrote:
> I was just about to say something about Chris'question and tried 
> 
> 2 raisedTo: 63
> 
> in a Workspace. I was a little surprised to see '0' returned.
> 
> On my Mac 64 I get the right answer. On the Pi I get the right(ish) answer if I substitute 2.0. To make things weirder if I debug, the end value of 'result' in Number>>#raisedToInteger: is correct. The value of 'stack top' in its sender #raisedTo: is the same correct value.
> 
> Gronk? It's clearly not a problem with printing the value since I see the correct value. If I try 
> (2 raisedTo: 63)  / 64.0
> to check what number is actually there... I get 0. Implying there is really 0. Debug it and.. yup 0. What? It looks like somewhere the LPI instance is getting mishandled but where?
>

Whatever the issue turns out to be, we need to turn it into a unit
test in trunk. It's a serious failure that is very easy to overlook.

It only takes 8 passes through the look in Number>>raisedToInteger:
to get to the solution, so you should be able to use a debugger to
see where things are going wrong. Or print to Transcript and see
where it fails.

For example if I use this:

Number>>raisedToInteger: anInteger
	"The 0 raisedToInteger: 0 is an special case. In some contexts must be 1 and in others must
	be handled as an indeterminate form.
	I take the first context because that's the way that was previously handled.
	Maybe further discussion is required on this topic."
	
	| bitProbe result |
	anInteger negative ifTrue: [^(self raisedToInteger: anInteger negated) reciprocal].
	bitProbe := 1 bitShift: anInteger highBit - 1.
	result := self class one.
	[
		Transcript showln: 'TOP LOOP ', result asString, ' BITPROBE ', bitProbe asString.
		(anInteger bitAnd: bitProbe) > 0 ifTrue: [ result := result * self ].
		(bitProbe := bitProbe bitShift: -1) > 0 ]
		whileTrue: [ result := result squared .
			Transcript showln: 'INNER LOOP ', result asString].
	^result


Then the (good) output on the Transcript is:

  TOP LOOP 1 BITPROBE 32
  INNER LOOP 4
  TOP LOOP 4 BITPROBE 16
  INNER LOOP 64
  TOP LOOP 64 BITPROBE 8
  INNER LOOP 16384
  TOP LOOP 16384 BITPROBE 4
  INNER LOOP 1073741824
  TOP LOOP 1073741824 BITPROBE 2
  TOP LOOP 1 BITPROBE 8
  INNER LOOP 100
  TOP LOOP 100 BITPROBE 4
  INNER LOOP 10000
  TOP LOOP 10000 BITPROBE 2
  INNER LOOP 100000000
  TOP LOOP 100000000 BITPROBE 1
  INNER LOOP 4611686018427387904
  TOP LOOP 1 BITPROBE 8
  INNER LOOP 100
  TOP LOOP 100 BITPROBE 4
  INNER LOOP 10000
  TOP LOOP 10000 BITPROBE 2
  INNER LOOP 100000000
  TOP LOOP 100000000 BITPROBE 1
  TOP LOOP 4611686018427387904 BITPROBE 1

If you run the same thing on the Pi VM, I expect you will see something quite different.

Dave