flambda-backend: Add ocamlcfg (ocaml#34)

* Import the code of ocamlcfg.

* Fix imported code.

* Optionally go through ocamlcfg.

* Merge in the latest CFG version

* Fix compilation warning 18.

* Add copyright header to cfg files.

The head is a copy of the LICENSE file at the root of ocamlcfg library

Co-authored-by: xclerc <xclerc@janestreet.com>

Author: 2 people

driver/compenv.ml

@@ -371,6 +371,8 @@ let read_one_param ppf position name v =
       set "flambda-invariants" [ flambda_invariant_checks ] v
   | "linscan" ->
       set "linscan" [ use_linscan ] v
+  | "ocamlcfg" ->
+      set "ocamlcfg" [ use_ocamlcfg ] v
   | "insn-sched" -> set "insn-sched" [ insn_sched ] v
   | "no-insn-sched" -> clear "insn-sched" [ insn_sched ] v
 

driver/main_args.ml

@@ -328,6 +328,10 @@ let mk_linscan f =
   "-linscan", Arg.Unit f, " Use the linear scan register allocator"
 ;;
 
+let mk_ocamlcfg f =
+  "-ocamlcfg", Arg.Unit f, " Use ocamlcfg"
+;;
+
 let mk_make_runtime f =
   "-make-runtime", Arg.Unit f,
   " Build a runtime system with given C objects and libraries"
@@ -1092,6 +1096,7 @@ module type Optcommon_options = sig
   val _insn_sched : unit -> unit
   val _no_insn_sched : unit -> unit
   val _linscan : unit -> unit
+  val _ocamlcfg : unit -> unit
   val _no_float_const_prop : unit -> unit
 
   val _clambda_checks : unit -> unit
@@ -1393,6 +1398,7 @@ struct
     mk_alias_deps F._alias_deps;
     mk_no_alias_deps F._no_alias_deps;
     mk_linscan F._linscan;
+    mk_ocamlcfg F._ocamlcfg;
     mk_app_funct F._app_funct;
     mk_no_app_funct F._no_app_funct;
     mk_no_float_const_prop F._no_float_const_prop;
@@ -1522,6 +1528,7 @@ module Make_opttop_options (F : Opttop_options) = struct
     mk_alias_deps F._alias_deps;
     mk_no_alias_deps F._no_alias_deps;
     mk_linscan F._linscan;
+    mk_ocamlcfg F._ocamlcfg;
     mk_app_funct F._app_funct;
     mk_no_app_funct F._no_app_funct;
     mk_no_float_const_prop F._no_float_const_prop;
@@ -1824,6 +1831,7 @@ module Default = struct
     let _insn_sched = set insn_sched
     let _no_insn_sched = clear insn_sched
     let _linscan = set use_linscan
+    let _ocamlcfg = set use_ocamlcfg
     let _no_float_const_prop = clear float_const_prop
     let _no_unbox_free_vars_of_closures = clear unbox_free_vars_of_closures
     let _no_unbox_specialised_args = clear unbox_specialised_args

driver/main_args.mli

@@ -192,6 +192,7 @@ module type Optcommon_options = sig
   val _insn_sched : unit -> unit
   val _no_insn_sched : unit -> unit
   val _linscan : unit -> unit
+  val _ocamlcfg : unit -> unit
   val _no_float_const_prop : unit -> unit
 
   val _clambda_checks : unit -> unit

utils/clflags.ml

@@ -52,6 +52,7 @@ and debug = ref false                   (* -g *)
 and debug_full = ref false              (* For full DWARF support *)
 and unsafe = ref false                  (* -unsafe *)
 and use_linscan = ref false             (* -linscan *)
+and use_ocamlcfg = ref false            (* -ocamlcfg *)
 and link_everything = ref false         (* -linkall *)
 and custom_runtime = ref false          (* -custom *)
 and no_check_prims = ref false          (* -no-check-prims *)

utils/clflags.mli

@@ -79,6 +79,7 @@ val debug : bool ref
 val debug_full : bool ref
 val unsafe : bool ref
 val use_linscan : bool ref
+val use_ocamlcfg : bool ref
 val link_everything : bool ref
 val custom_runtime : bool ref
 val no_check_prims : bool ref