variable not found bug

[Fergus Henderson]

Hi,

Anyone want to have a look at the following bug?  Tom?  Zoltan?
The Mercury compiler dies with a "variable not found"
error, apparently while computing liveness.
(The program compiles fine with `--no-inlining').

> From fjh at murlibobo.cs.mu.OZ.AU Wed Nov 27 02:35:07 1996
> From: Fergus Henderson <fjh at cs.mu.oz.au>
> Message-Id: <199611261535.CAA17845 at murlibobo.cs.mu.OZ.AU>
> Subject: variable not found bug
> To: mercury-bugs at cs.mu.oz.au
> Date: Wed, 27 Nov 1996 02:35:04 +1100 (EST)
> X-Mailer: ELM [version 2.4 PL24]
> Content-Type: text
> 
> /*
> $ mc bug2
> bug2.m:009: Warning: incorrect module name in `:- module' declaration.
> bug2.m:034: In `error(in) = out':
> bug2.m:034:   warning: determinism declaration could be tighter.
> bug2.m:034:   Declared `det', inferred `erroneous'.
> Software error: variable V_32 not found
> */
> :- module change.
> :- interface.
> :- import_module io.
> 
> :- pred main(io__state::di, io__state::uo) is det.
> 
> :- implementation.
> :- import_module int, require, time, string.
> 
> :- func first_denomination(int) = int.
> first_denomination(Kinds_of_coins) =
>   (if (Kinds_of_coins = 1) then
>     1
>   else if (Kinds_of_coins = 2) then
>     5
>   else if (Kinds_of_coins = 3) then
>     10
>   else if (Kinds_of_coins = 4) then
>     25
>   else if (Kinds_of_coins = 5) then
>     50
>   else
>     error("wrong kind of coin")
>   ).
> 
> :- func error(string) = _.
> error(S) = _ :-
>   error(S).
> 
> :- func cc_tail(int, int, int) = int.
> cc_tail(Amount, Kinds_of_coins, Count) =
>   (if (Amount = 0) then
>     Count + 1
>   else if (Amount < 0 ; Kinds_of_coins = 0) then
>     Count
>   else
>     cc_tail(Amount - first_denomination(Kinds_of_coins),
>                    Kinds_of_coins,
>                    cc_tail(Amount, Kinds_of_coins - 1, Count))
>   ).
> 
> :- func count_change(int) = int.
> count_change(Amount) =
>   cc_tail(Amount, 5, 0).
> 
> :- pred do_count_change(int::in, int::out) is det.
> do_count_change(Amount, Result) :- Result = count_change(Amount).
> 
> main -->
>   io__command_line_arguments(Args),
>   (if { Args = [Num] } then
>     (if { string__to_int(Num, N), N >= 0 } then
>       { benchmark_det(do_count_change, N, Answer, 1, Time) },
>       { string__format("Answer = %d, Time = %d milliseconds\n",
> 		[i(Answer),i(Time)], Message) },
>       io__write_string(Message)
>     else
>       io__write_string("invalid argument\n")
>     )
>   else
>     io__write_string("wrong number of arguments\n")
>   ).

-- 
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.