Re: Dwarf unwinder problems with store.exp and preserved regs

Richard Henderson
2003-07-02T21:33:12Z

On Wed, Jul 02, 2003 at 03:19:07PM -0400, Daniel Jacobowitz wrote:
> So if the initial row assumes all registers are valid, we'd print out a
> value in the caller's $eax incorrectly.

Ok, so? Except you forget that variables that are live across
that call are either (1) in call saved registers or (2) on the
stack. So I don't see that the problem will actually affect
folk debugging real programs.

The only time you get a false positive is when the variable is
dead at the call site. And the results you get there will be
no different than when the variable is dead and the register
gets re-used /in the same function/ without location expressions
to note the exact time of death.

The best argument, IMO, is that if you switch the default from
undefined to samevalue, then you'll get useful information some
of the time as opposed to none of the time.

r~