70 lines
3.6 KiB
OCaml
70 lines
3.6 KiB
OCaml
(**************************************************************************)
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(* *)
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(* OCaml *)
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(* *)
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(* Pierre Chambart, OCamlPro *)
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(* Mark Shinwell and Leo White, Jane Street Europe *)
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(* *)
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(* Copyright 2013--2016 OCamlPro SAS *)
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(* Copyright 2014--2016 Jane Street Group LLC *)
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(* *)
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(* All rights reserved. This file is distributed under the terms of *)
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(* the GNU Lesser General Public License version 2.1, with the *)
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(* special exception on linking described in the file LICENSE. *)
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(* *)
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(**************************************************************************)
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[@@@ocaml.warning "+a-4-9-30-40-41-42"]
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(** Description of the semantics of primitives, to be used for optimization
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purposes.
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"No effects" means that the primitive does not change the observable state
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of the world. For example, it must not write to any mutable storage,
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call arbitrary external functions or change control flow (e.g. by raising
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an exception). Note that allocation is not "No effects" (see below).
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It is assumed in the compiler that applications of primitives with no
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effects, whose results are not used, may be eliminated. It is further
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assumed that applications of primitives with no effects may be
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duplicated (and thus possibly executed more than once).
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(Exceptions arising from allocation points, for example "out of memory" or
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exceptions propagated from finalizers or signal handlers, are treated as
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"effects out of the ether" and thus ignored for our determination here
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of effectfulness. The same goes for floating point operations that may
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cause hardware traps on some platforms.)
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"Only generative effects" means that a primitive does not change the
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observable state of the world save for possibly affecting the state of
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the garbage collector by performing an allocation. Applications of
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primitives that only have generative effects and whose results are unused
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may be eliminated by the compiler. However, unlike "No effects"
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primitives, such applications will never be eligible for duplication.
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"Arbitrary effects" covers all other primitives.
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"No coeffects" means that the primitive does not observe the effects (in
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the sense described above) of other expressions. For example, it must not
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read from any mutable storage or call arbitrary external functions.
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It is assumed in the compiler that, subject to data dependencies,
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expressions with neither effects nor coeffects may be reordered with
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respect to other expressions.
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*)
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type effects = No_effects | Only_generative_effects | Arbitrary_effects
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type coeffects = No_coeffects | Has_coeffects
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(** Describe the semantics of a primitive. This does not take into account of
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the (non-)(co)effectfulness of the arguments in a primitive application.
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To determine whether such an application is (co)effectful, the arguments
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must also be analysed. *)
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val for_primitive: Clambda_primitives.primitive -> effects * coeffects
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type return_type =
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| Float
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| Other
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val return_type_of_primitive: Clambda_primitives.primitive -> return_type
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