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(**************************************************************************)
(* *)
(* OCaml *)
(* *)
(* Xavier Leroy, projet Cristal, INRIA Rocquencourt *)
(* Mark Shinwell, Jane Street Europe *)
(* *)
(* Copyright 2015 Institut National de Recherche en Informatique et *)
(* en Automatique. *)
(* *)
(* All rights reserved. This file is distributed under the terms of *)
(* the GNU Lesser General Public License version 2.1, with the *)
(* special exception on linking described in the file LICENSE. *)
(* *)
(**************************************************************************)
module type S = sig
(* The distance between two instructions, in arbitrary units (typically
the natural word size of instructions). *)
type distance = int
module Cond_branch : sig
(* The various types of conditional branches for a given target that
may require relaxation. *)
type t
(* All values of type [t] that the emitter may produce. *)
val all : t list
(* If [max_displacement branch] is [n] then [branch] is assumed to
reach any address in the range [pc - n, pc + n] (inclusive), after
the [pc] of the branch has been adjusted by [offset_pc_at_branch]
(see below). *)
val max_displacement : t -> distance
(* Which variety of conditional branch may be produced by the emitter for a
given instruction description. For the moment we assume that only one
such variety per instruction description is needed.
N.B. The only instructions supported are the following:
- Lop (Ialloc _)
- Lop (Iintop Icheckbound)
- Lop (Iintop_imm (Icheckbound, _))
- Lop (Ispecific _)
- Lcondbranch (_, _)
- Lcondbranch3 (_, _, _)
[classify_instr] is expected to return [None] when called on any
instruction not in this list. *)
val classify_instr : Linearize.instruction_desc -> t option
end
(* The value to be added to the program counter (in [distance] units)
when it is at a branch instruction, prior to calculating the distance
to a branch target. *)
val offset_pc_at_branch : distance
(* The maximum size of a given instruction. *)
val instr_size : Linearize.instruction_desc -> distance
(* Insertion of target-specific code to relax operations that cannot be
relaxed generically. It is assumed that these rewrites do not change
the size of out-of-line code (cf. branch_relaxation.mli). *)
val relax_allocation
: num_words:int
-> label_after_call_gc:Cmm.label option
-> Linearize.instruction_desc
val relax_intop_checkbound
: label_after_error:Cmm.label option
-> Linearize.instruction_desc
val relax_intop_imm_checkbound
: bound:int
-> label_after_error:Cmm.label option
-> Linearize.instruction_desc
val relax_specific_op : Arch.specific_operation -> Linearize.instruction_desc
end
|
