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2466524308
This fixes github issue #64. compiler/cse_detection.m: When pulling a unification X = f(Y1, ..., Yn) out of an arm of a disjunction, switch or if-then-else, require the instantiation state of X to be free of unique or mostly_unique components. Put the requirements on X's inst into a single predicate. Add a mechanism to make debugging similar issues easier. tests/valid/cse_unique.m: A suitably modified form of the test program on github. tests/valid/Mmakefile: Enable the new test case.
48 lines
1.7 KiB
Mathematica
48 lines
1.7 KiB
Mathematica
%---------------------------------------------------------------------------%
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% vim: ft=mercury ts=4 sw=4 et
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%---------------------------------------------------------------------------%
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% Any copyright is dedicated to the Public Domain.
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% http://creativecommons.org/publicdomain/zero/1.0/
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% Released by Transnat Games for testing purposes.
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%---------------------------------------------------------------------------%
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%
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% This regression test used to cause this Mercury compiler abort:
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% Software Error: check_hlds.cse_detection: predicate
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% `check_hlds.cse_detection.detect_cse_in_proc'/4:
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% Unexpected: mode check fails when repeated.
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% This is Github issue #64.
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%
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% The cause was that the deconstruction of D in get_directions was pulled
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% out of the switch on the first argument even though its inst contained
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% unique components. Mode analysis can track uniqueness through the
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% original form of the switch, but not through its transformed form,
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% which is more complicated and has longer chains of unifications.
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%
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%---------------------------------------------------------------------------%
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:- module cse_unique.
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:- interface.
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:- type direction
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---> left
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; right.
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:- type directions(T)
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---> directions(on_left::T, on_right::T).
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%---------------------------------------------------------------------------%
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:- func get_directions(direction, directions(T)) = T.
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:- mode get_directions(in, in) = (out) is det.
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:- mode get_directions(in, di) = (uo) is det.
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%---------------------------------------------------------------------------%
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:- implementation.
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get_directions(left, D) = D ^ on_left.
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get_directions(right, D) = D ^ on_right.
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%---------------------------------------------------------------------------%
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