On Thu, 25 Oct 2018 17:16:49 -0400, Tony Harminc wrote:
>
>> (In debug mode, the compiler generated STH; LH of a halfword variable not
>> otherwise referenced, truncating an invalid halfword value. Even before
>> that,
>> I had felt that by design STH should program check on such a condition.)
>
>What halfword value is invalid? Surely by definition...
>
>Oh - you mean silent truncation of a larger value into a halfword?
>What does the language (what language?) definition say about this?
>And what did the optimized code do that failed?
>
Mainsail, one of my most enjoyable programming experiences:
https://en.wikipedia.org/wiki/SAIL_(programming_language)
An embryonic attempt at O-O. Alas, several years ago the vendor's web
site was for sale.
"Machine independent". The data type was not "halfword", but "int", defined
as [-32768,32767] and stated that the effect of assigning a larger value was
undefined. Debugger should have enforced.
The optimized code simply omitted the STH which debugger used only to
examine a value at breakpoint and the LH which allowed debugging to
modify that value. Optimized code kept the value in a GR.
-- gil
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