Re: Patch to block removal optimization

[Mark Mitchell <mark at codesourcery dot com>]

>>>>> "Jason" == Jason Merrill <jason@cygnus.com> writes:

    Jason> Well, yes; when you pack all the notes together at the
    Jason> start of the basic block, it looks like a bunch of empty
    Jason> blocks.  So the debugging info shrinks because we don't
    Jason> know what code goes with what blocks.  Kind of a Pyrrhic
    Jason> optimization...

I understand your point -- namely, that the scheduler is squishing
blocks even though in reality they're still there.  So, a better
scheduler will make the debugging optimization less valuable.   But ...

    >> what good does it do to output block data for that?  There are
    >> no points in the debugger when you can print the value of the
    >> local variables in there anyhow -- you're never in their scope.

    Jason> Hmm, good point.  

... I'm glad you also agree with me that given that there's little
point in keeping the information.

    Jason> It seems that the reason this change was
    Jason> useful is that the optimization was removing the outermost
    Jason> block of a function (the one with __FUNCTION__ et al),
    Jason> which is always in scope.  I'll change it to test that
    Jason> instead.

Seems reasonable.  Thanks!

--
Mark Mitchell                   mark@codesourcery.com
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