Implement memoization for expand_module to improve performance

git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@13240 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02

3 files changed, 32 insertions, 11 deletions

diff --git a/ocamlbuild/my_std.ml b/ocamlbuild/my_std.ml
index aa25ecb13..764341b71 100644
--- a/ocamlbuild/my_std.ml
+++ b/ocamlbuild/my_std.ml
@@ -403,3 +403,19 @@ let memo f =
     with Not_found ->
       let res = f x in
       (Hashtbl.add cache x res; res)
+
+let memo2 f =
+  let cache = Hashtbl.create 103 in
+  fun x y ->
+    try Hashtbl.find cache (x,y)
+    with Not_found ->
+      let res = f x y in
+      (Hashtbl.add cache (x,y) res; res)
+
+let memo3 f =
+  let cache = Hashtbl.create 103 in
+  fun x y z ->
+    try Hashtbl.find cache (x,y,z)
+    with Not_found ->
+      let res = f x y z in
+      (Hashtbl.add cache (x,y,z) res; res)
diff --git a/ocamlbuild/ocaml_utils.ml b/ocamlbuild/ocaml_utils.ml
index dd74e1048..b35ad679e 100644
--- a/ocamlbuild/ocaml_utils.ml
+++ b/ocamlbuild/ocaml_utils.ml
@@ -65,17 +65,18 @@ let path_importance path x =
   end
   else if ignore_stdlib x then `just_try else `mandatory
 
-let expand_module include_dirs module_name exts =
-  let dirname = Pathname.dirname module_name in
-  let basename = Pathname.basename module_name in
-  let module_name_cap = dirname/(String.capitalize basename) in
-  let module_name_uncap = dirname/(String.uncapitalize basename) in
-  List.fold_right begin fun include_dir ->
-    List.fold_right begin fun ext acc ->
-      include_dir/(module_name_uncap-.-ext) ::
-      include_dir/(module_name_cap-.-ext) :: acc
-    end exts
-  end include_dirs []
+let expand_module =
+  memo3 (fun include_dirs module_name exts ->
+    let dirname = Pathname.dirname module_name in
+    let basename = Pathname.basename module_name in
+    let module_name_cap = dirname/(String.capitalize basename) in
+    let module_name_uncap = dirname/(String.uncapitalize basename) in
+    List.fold_right begin fun include_dir ->
+      List.fold_right begin fun ext acc ->
+        include_dir/(module_name_uncap-.-ext) ::
+          include_dir/(module_name_cap-.-ext) :: acc
+      end exts
+    end include_dirs [])
 
 let string_list_of_file file =
   with_input_file file begin fun ic ->
diff --git a/ocamlbuild/signatures.mli b/ocamlbuild/signatures.mli
index f1b038857..42590a00d 100644
--- a/ocamlbuild/signatures.mli
+++ b/ocamlbuild/signatures.mli
@@ -348,6 +348,10 @@ module type MISC = sig
   val ( @:= ) : 'a list ref -> 'a list -> unit
 
   val memo : ('a -> 'b) -> ('a -> 'b)
+
+  val memo2 : ('a -> 'b -> 'c) -> ('a -> 'b -> 'c)
+
+  val memo3 : ('a -> 'b -> 'c -> 'd) -> ('a -> 'b -> 'c -> 'd)
 end
 
 module type OPTIONS = sig