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https://github.com/Mercury-Language/mercury.git
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89 lines
2.4 KiB
Mathematica
89 lines
2.4 KiB
Mathematica
%---------------------------------------------------------------------------%
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% vim: ts=4 sw=4 et ft=mercury
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%---------------------------------------------------------------------------%
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%
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% This program used to get a compiler abort in hlc.gc.
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% This happened because find_int_lookup_switch_params in switch_util.m
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% said that the inner switch on Thing in classify/2 below needed a bit vector
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% check. It said so because the inner switch does not cover Thing = nothing.
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% However, it does not *need* to cover Thing = nothing, because the inner
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% switch is reached only in the arm of the outer switch that is not taken
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% when Thing = nothing.
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% In general, cannot_fail switches should not need either bit vector
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% or range checks. The compiler abort happensed because the MLDS code generator
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% had sanity checks (assertions) to this effect. The LLDS code generator
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% just silently generated an unnecessary bit vector check, which would execute
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% incorrect code if the check failed; however, for these cannot_fail switches,
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% the check could never fail.
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%
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:- module bug452.
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:- interface.
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:- import_module io.
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:- pred main(io::di, io::uo) is det.
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:- implementation.
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:- import_module list.
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main(!IO) :-
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list.foldl(test_thing, [thing1, thing2, nothing, thing3, thing4], !IO).
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:- pred test_thing(thing::in, io::di, io::uo) is det.
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test_thing(Thing, !IO) :-
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list.foldl(test_category(Thing), [cat1, cat2, nocat], !IO),
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io.nl(!IO).
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:- pred test_category(thing::in, category::in, io::di, io::uo) is det.
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test_category(Thing, Cat0, !IO) :-
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Cat = classify(Cat0, Thing),
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io.write(Thing, !IO),
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io.write_string(" ", !IO),
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io.write(Cat0, !IO),
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io.write_string(" -> ", !IO),
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io.write(Cat, !IO),
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io.nl(!IO).
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:- type thing
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---> thing1
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; thing2
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; nothing
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; thing3
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; thing4.
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:- type category
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---> cat1
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; cat2
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; nocat.
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:- func classify(category, thing) = category.
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:- pragma no_inline(classify/2).
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classify(Cat0, Thing) = Cat :-
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(
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( Thing = thing1
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; Thing = thing2
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; Thing = thing3
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; Thing = thing4
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),
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(
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( Thing = thing1
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; Thing = thing2
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),
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Cat = cat1
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;
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( Thing = thing3
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; Thing = thing4
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),
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Cat = cat2
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)
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;
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Thing = nothing,
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Cat = Cat0
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).
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