Re: On killing SAVE_EXPR

[Richard Henderson <rth at redhat dot com>]

On Tue, Feb 13, 2001 at 05:28:37PM -0500, Richard Kenner wrote:
>     The instance I'm most familiar is in tail-call elimination.  Here we
>     generate two code sequences -- one as a normal call and one as a
>     tail-call or tail-recursion.  At some point later we'll select one
>     sequence or the other depending on whether the tail-call sequence is
>     actually legitimate.
> 
> Well that one isn't a problem since you'll only select one to generate
> code for.

Incorrect.  We generate code for both cases, and discard one
sequence later.  It _is_ a problem.  Look near calls.c:2486
for what is done to address this problem.

>     A third instance involves inlining at the tree level.  In this case
>     we've spliced one function into others, potentially many times.
>     Naturally all copies are present in the output.
> 
> Don't we *copy* trees in that case?

Apparently.  I hadn't recalled that.  Though apparently we go
through some effort to make sure that we dtrt with save_expr.


r~