[m-dev.] for review: fix bug with quantification & instmap deltas

[Fergus Henderson]

On 10-Jun-1999, Simon Taylor <stayl at cs.mu.OZ.AU> wrote:
> 
> > Estimated hours taken: 1
> > 
> > Fix a bug that caused a variable not found error when compiling
> > library/term_io.m with intermodule optimization in my local version
> > of the Mercury compiler (which has various changes for existential types).
> > The problem was that when liveness.m calls requantify_proc,
> > quantification.m discovers that a variable is now local to a subgoal,
> > but leaves the instmap delta on the containing goal unchanged, still
> > containing a (now bogus) entry for that variable.
> > I think the same problem could occur without my existential types changes,
[...]
> The alias branch will need a different
> fix because instmap_delta_restrict doesn't work with aliasing. It's probably 
> necessary to run recompute_instmap_delta every time a goal is requantified
> after mode analysis.

Ouch -- that sounds expensive.

Could you remind me why instmap_delta_restrict doesn't work with aliasing?

-- 
Fergus Henderson <fjh at cs.mu.oz.au>  |  "I have always known that the pursuit
WWW: <http://www.cs.mu.oz.au/~fjh>  |  of excellence is a lethal habit"
PGP: finger fjh at 128.250.37.3        |     -- the last words of T. S. Garp.
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