On Sat, 15 Oct 2016 22:50:11 +0000, Robert Prins wrote:
>
>Programs compiled with different optimization levels (and sometimes even other
>compiler options) are not the same program! Period. Full stop. End of story!
>
Many possibilities.  A race condition might be won by the wrong path when
optimized; the desired path when not optimized.  But beware of processor
upgrades.

I once had a program in a little-known langage from a vendor other than IBM
which program checked when optimized; at the debug levei it operated as I
had intended.  Reported.  Vendor replied (correctly) that I had (unwittingly)
used a construct clearly documented as undefined; unpredictable; NAPWAD.
(Not timing-dependent nor resource constrained.)  I seethed that the object
of debugging mode is to report as many or more errors, not fewer.  Vendor
remained adamant.  it had been:

    STH    Removed ...
    LH         ... when optmized.
    SLA ..,3  Fixed point overflow when optimized

-- gil

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