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d5c08567e4
compiler/simplify_proc.m:
If a first attempt to analyse and optimize format calls fails
due to insufficient information about format strings and/or values,
then try the whole process again after pushing copies of the format calls,
and the conjuncts that precede them, into the last preceding branched
control structure (disjunction, switch, or if-then-else). This will
fix the problem if each branch does construct known format strings
and/or values, and is harmless if this is not the case.
tests/valid/format_after_switch.m:
A test case for the new capability.
tests/valid/Mmakefile:
tests/valid/Mercury.options:
Enable the new test case.
90 lines
3.0 KiB
Mathematica
90 lines
3.0 KiB
Mathematica
%---------------------------------------------------------------------------%
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% vim: ft=mercury ts=4 sw=4 et
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%---------------------------------------------------------------------------%
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%
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% The first predicate in this test case is a simplified version of
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% the message_type_to_string predicate in deep_profiler/message.m
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% (as of 2025 nov 13).
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%
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% This test predicate looks at what happens when switch detection converts
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% that predicate's nested disjunction not into a three-way switch
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% (its traditional output) but into two nested switches, with each switch
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% replacing one of the original disjunctions. (The outer switch having
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% two arms, the first arm handling both msg_a and msg_b, with the second arm
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% handling msg_c, and the inner switch having two arms for msg_a and msg_b
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% respectively.)
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%
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% Both translations are valid, and in almost all situations, they are
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% indistinguishable. The one exception found by a bootcheck was this predicate.
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% The issue is that with the two-switch version, the call to string.format
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% is *outside* the inner switch, meaning it has to handle both the msg_a
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% and msg_b cases. These have different format strings, so the result is
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% this message:
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%
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% Warning: unknown format string in call to predicate `string.format'/3.
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%
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% and the inability of opt_format_call.m to optimize the call.
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%
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% The second predicate tests a different instance of the same problem,
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% an instance that was raised during the discussion of the problem on m-dev.
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% This version always got a warning from the compiler, with or without
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% the recent change to switch_detection.m. This warning was shut up
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% by the commit that added this test case.
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%
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%---------------------------------------------------------------------------%
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:- module format_after_switch.
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:- interface.
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:- import_module cord.
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%---------------------------------------------------------------------------%
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:- type message_type
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---> msg_a(int)
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; msg_b(int)
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; msg_c.
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:- func message_type_to_string_a(message_type) = cord(string).
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:- func message_type_to_string_b(message_type) = cord(string).
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%---------------------------------------------------------------------------%
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:- implementation.
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:- import_module list.
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:- import_module string.
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message_type_to_string_a(MessageType) = Cord :-
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(
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(
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MessageType = msg_a(Num),
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Template = "A %d"
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;
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MessageType = msg_b(Num),
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Template = "B %d"
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),
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string.format(Template, [i(Num)], Str)
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;
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MessageType = msg_c,
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Str = "C"
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),
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Cord = singleton(Str).
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message_type_to_string_b(MessageType) = Cord :-
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(
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MessageType = msg_a(Num),
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Template = "A %d"
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;
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MessageType = msg_b(Num),
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Template = "B %d"
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;
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MessageType = msg_c,
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Num = 42,
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Template = "C %d"
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),
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string.format(Template, [i(Num)], Str),
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Cord = singleton(Str).
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%---------------------------------------------------------------------------%
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