middle-end/9997: Coelesce stack slots for disjoint scopes.

[rth@redhat.com]

>Number:         9997
>Category:       middle-end
>Synopsis:       Coelesce stack slots for disjoint scopes.
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          change-request
>Submitter-Id:   net
>Arrival-Date:   Sat Mar 08 01:06:00 UTC 2003
>Closed-Date:
>Last-Modified:
>Originator:     Richard Henderson
>Release:        all
>Organization:
>Environment:
any
>Description:
Given

struct big { char x[1024]; };
extern void bar(struct big *);

void foo(void)
{
  {
    struct big one;
    bar(&one);
  }
  {
    struct big one;
    bar(&one);
  }
}

we should allocate only one structure on the stack.
>How-To-Repeat:

>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted: