Re: [RFC 06/12] entryval: Display @entry parameters in bt full

Jakub Jelinek
2011-07-19T17:04:35Z

On Tue, Jul 19, 2011 at 07:38:41PM +0300, Eli Zaretskii wrote:
> > 4) only current value is known, entry value isn't provided (the value
> > passed to the function in the caller wasn't saved in any call saved
> > register or memory slot and wasn't constant, or the compiler didn't
> > provide call site info for it)
>
> Show "optimized out" in calls and backtraces, the current value in
> response to "print foo".

This is IMHO a bad idea, the current value is still far better than
"optimized out", at least when it is obvious from the backtrace which one is
which. All -O0 compiled code would show just "optimized out" in backtraces
for all arguments, similarly all code compiled by older compilers.
And, even for -O2 -g code the entry value will be available in roughly 50%
of cases at most. The lack of entry value being provided doesn't mean
that the current value isn't the same as the value on entry, just that it
wasn't proved.

Jakub