Fix #22663: Fix sign extension for bool bitfields

[bscuron]

#22663

true = -1
false = 0

!true case:
-1 & 1 => 1
1 ^ 1 => 0

!false case:
0 & 1 => 0
0 ^ 1 => 1

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[dkorpel]

This looks like the wrong place to fix. TYbool is supposed to be a 1-bit integer. If accessing a bool bitfield somehow generates a value of 0b11111111 or -1 then the masking should happen before it gets into an expression. Otherwise we need to check the logic for all TYbool operations (not just 'logical not') to handle arbitrary bit patterns, which generates more bytes of code even in cases where it's not necessary.

[thewilsonator]

TYbool is supposed to be a 1-bit integer.

I still think that is a really stupid idea.

[bscuron]

Did some more testing and the bug does not occur if optimizations are enabled:

[bscuron]

This looks like the wrong place to fix. TYbool is supposed to be a 1-bit integer. If accessing a bool bitfield somehow generates a value of 0b11111111 or -1 then the masking should happen before it gets into an expression. Otherwise we need to check the logic for all TYbool operations (not just 'logical not') to handle arbitrary bit patterns, which generates more bytes of code even in cases where it's not necessary.

@dkorpel I have made the update. Please let me know if this is still incorrect. Thank you!

[dkorpel]

Code change looks good to me. Why did you remove the test case?