Move Cmm builtin translation code

Makefile

@@ -93,6 +93,7 @@ fmt:
 	  $$(find backend/debug \
 	    \( -name "*.ml" -or -name "*.mli" \))
 	ocamlformat -i backend/cmm_helpers.ml{,i}
+	ocamlformat -i backend/cmm_builtins.ml{,i}
 	ocamlformat -i backend/checkmach.ml{,i}
 	ocamlformat -i tools/merge_archives.ml
 	ocamlformat -i \
@@ -111,6 +112,7 @@ check-fmt:
            [ "$$(git status --porcelain backend/asm_targets)" != "" ] || \
            [ "$$(git status --porcelain backend/debug)" != "" ] || \
            [ "$$(git status --porcelain backend/cmm_helpers.ml{,i})" != "" ] || \
+           [ "$$(git status --porcelain backend/cmm_builtins.ml{,i})" != "" ] || \
            [ "$$(git status --porcelain backend/checkmach.ml{,i})" != "" ] || \
            [ "$$(git status --porcelain tools/merge_archives.ml)" != "" ] || \
            [ "$$(git status --porcelain utils)" != "" ]; then \
@@ -126,6 +128,7 @@ check-fmt:
            [ "$$(git diff backend/asm_targets)" != "" ] || \
            [ "$$(git diff backend/debug)" != "" ] || \
            [ "$$(git diff backend/cmm_helpers.ml{,i})" != "" ] || \
+           [ "$$(git diff backend/cmm_builtins.ml{,i})" != "" ] || \
            [ "$$(git diff backend/checkmach.ml{,i})" != "" ] || \
            [ "$$(git diff tools/merge_archives.ml)" != "" ] || \
            [ "$$(git diff utils)" != "" ]; then \

backend/.ocamlformat-enable

@@ -1,5 +1,7 @@
 cmm_helpers.ml
 cmm_helpers.mli
+cmm_builtins.ml
+cmm_builtins.mli
 internal_assembler/*.ml
 internal_assembler/*.mli
 checkmach.ml

backend/cmm_builtins.mli

@@ -0,0 +1,40 @@
+(**************************************************************************)
+(*                                                                        *)
+(*                                 OCaml                                  *)
+(*                                                                        *)
+(*             Xavier Leroy, projet Cristal, INRIA Rocquencourt           *)
+(*                                                                        *)
+(*   Copyright 1996 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.          *)
+(*                                                                        *)
+(**************************************************************************)
+
+open Cmm
+
+(** Create a C function call. *)
+val extcall :
+  dbg:Debuginfo.t ->
+  returns:bool ->
+  alloc:bool ->
+  is_c_builtin:bool ->
+  ty_args:exttype list ->
+  string ->
+  machtype ->
+  expression list ->
+  expression
+
+(** [cextcall prim args dbg type_of_result] returns Cextcall operation that
+    corresponds to [prim]. If [prim] is a C builtin supported on the target,
+    returns [Cmm.operation] variant for [prim]'s intrinsics. *)
+val cextcall :
+  Primitive.description ->
+  expression list ->
+  Debuginfo.t ->
+  machtype ->
+  exttype list ->
+  bool ->
+  expression