error in `expand_expr', at expr.c:6388

[craig@jcb-sc.com]

>This is caused by operations on freed memory.  We call ffeste_R819B
>(why is it named this?) to generate RTL for the DO WHILE conditional.

It's named that because R819B was the "name" for the rule in the syntax
specifications in the F90 draft I was working from, some ten years ago
while writing g77.  I'll probably pick better names for the rewrite,
if it gets far enough into st[bcde].c.

The bug was that the `result' tree was overwritten by the tree to
modify the temporary variable containing the result.

Surprisingly (*very* ;-), the code-generation issues here actually
are documented, under "Transforming DO WHILE", in the g77 docs.
The source is in ffe.texi.

        tq vm, (burley)