Inline uncurried application when it is safe

CHANGELOG.md

@@ -22,7 +22,7 @@ subset of the arguments, and return a curried type with the remaining ones https
 - Add support for uncurried externals https://github.com/rescript-lang/rescript-compiler/pull/5815 https://github.com/rescript-lang/rescript-compiler/pull/5819 https://github.com/rescript-lang/rescript-compiler/pull/5830
 - Parser/Printer: unify uncurried functions of arity 0, and of arity 1 taking unit. There's now only arity 1 in the source language. https://github.com/rescript-lang/rescript-compiler/pull/5825
 - Add support for default arguments in uncurried functions https://github.com/rescript-lang/rescript-compiler/pull/5835
-
+- Inline uncurried application when it is safe https://github.com/rescript-lang/rescript-compiler/pull/5847
 
 #### :boom: Breaking Change
 

jscomp/core/lam_pass_remove_alias.ml

@@ -64,6 +64,49 @@ let simplify_alias (meta : Lam_stats.t) (lam : Lam.t) : Lam.t =
         | Some (OptionalBlock (l, _)) -> l
         | _ -> if p = Pval_from_option_not_nest then lvar else x)
     | Lglobal_module _ -> lam
+    | Lprim { primitive = Pfull_apply; args = Lvar v :: ap_args as args; loc }
+      -> (
+        (* Inline uncurried application when safe *)
+        let normal () =
+          Lam.prim ~primitive:Pfull_apply ~args:(Ext_list.map args simpl) loc
+        in
+        let ap_args = Ext_list.map ap_args simpl in
+        match Hash_ident.find_opt meta.ident_tbl v with
+        | Some
+            (FunctionId
+              {
+                lambda =
+                  Some
+                    ( Lfunction
+                        ({ params; body; attr = { is_a_functor = false } } as m),
+                      rec_flag );
+              })
+          when Ext_list.same_length ap_args params
+               && Lam_analysis.lfunction_can_be_beta_reduced m
+               && Lam_analysis.ok_to_inline_fun_when_app m ap_args -> (
+            let param_map =
+              Lam_closure.is_closed_with_map meta.export_idents params body
+            in
+            let is_export_id = Set_ident.mem meta.export_idents v in
+            match (is_export_id, param_map) with
+            | false, (_, param_map) | true, (true, param_map) -> (
+                match rec_flag with
+                | Lam_rec ->
+                    Lam_beta_reduce.propagate_beta_reduce_with_map meta
+                      param_map params body ap_args
+                | Lam_self_rec -> normal ()
+                | Lam_non_rec ->
+                    if
+                      Ext_list.exists ap_args (fun lam ->
+                          Lam_hit.hit_variable v lam)
+                      (*avoid nontermination, e.g, `g(g)`*)
+                    then normal ()
+                    else
+                      simpl
+                        (Lam_beta_reduce.propagate_beta_reduce_with_map meta
+                           param_map params body ap_args))
+            | _ -> normal ())
+        | _ -> normal ())
     | Lprim { primitive; args; loc } ->
         Lam.prim ~primitive ~args:(Ext_list.map args simpl) loc
     | Lifthenelse
@@ -160,8 +203,9 @@ let simplify_alias (meta : Lam_stats.t) (lam : Lam.t) : Lam.t =
                   Some
                     ( Lfunction ({ params; body; attr = { is_a_functor } } as m),
                       rec_flag );
-              }) when Lam_analysis.lfunction_can_be_beta_reduced m ->
-            if Ext_list.same_length ap_args params (* && false *) then
+              })
+          when Lam_analysis.lfunction_can_be_beta_reduced m ->
+            if Ext_list.same_length ap_args params then
               if
                 is_a_functor
                 (* && (Set_ident.mem v meta.export_idents) && false *)
@@ -211,8 +255,14 @@ let simplify_alias (meta : Lam_stats.t) (lam : Lam.t) : Lam.t =
               else normal ()
             else normal ()
         | Some _ | None -> normal ())
-    | Lapply { ap_func = Lfunction ({ params; body } as lfunction); ap_args = args; _ }
-      when Ext_list.same_length params args && Lam_analysis.lfunction_can_be_beta_reduced lfunction ->
+    | Lapply
+        {
+          ap_func = Lfunction ({ params; body } as lfunction);
+          ap_args = args;
+          _;
+        }
+      when Ext_list.same_length params args
+           && Lam_analysis.lfunction_can_be_beta_reduced lfunction ->
         simpl (Lam_beta_reduce.propagate_beta_reduce meta params body args)
     (* | Lapply{ fn = Lfunction{function_kind =  Tupled;  params; body};  *)
     (*          args = [Lprim {primitive = Pmakeblock _; args; _}]; _} *)

jscomp/test/arity_deopt.js

@@ -1,7 +1,6 @@
 'use strict';
 
 var Mt = require("./mt.js");
-var Curry = require("../../lib/js/curry.js");
 
 var suites = {
   contents: /* [] */0
@@ -50,13 +49,13 @@ function f3(x) {
   };
 }
 
-eq("File \"arity_deopt.ml\", line 45, characters 7-14", 6, f0(1, 2, 3));
+eq("File \"arity_deopt.ml\", line 45, characters 7-14", 6, 6);
 
 eq("File \"arity_deopt.ml\", line 46, characters 11-18", 6, (function (y, z) {
           return (1 + y | 0) + z | 0;
         })(2, 3));
 
-eq("File \"arity_deopt.ml\", line 47, characters 15-22", 6, Curry._1(f2(1, 2), 3));
+eq("File \"arity_deopt.ml\", line 47, characters 15-22", 6, 6);
 
 eq("File \"arity_deopt.ml\", line 48, characters 15-22", 6, (function (y, z) {
           return (1 + y | 0) + z | 0;

jscomp/test/async_inline.js

@@ -31,9 +31,41 @@ async function broken$1(someAsyncFunction) {
 
 var broken$2 = broken$1;
 
+function curriedId(x) {
+  return x;
+}
+
+async function curriedIdAsync(x) {
+  return x;
+}
+
+function uncurriedId(x) {
+  return x;
+}
+
+async function uncurriedIdAsync(x) {
+  return x;
+}
+
+var tcia = curriedIdAsync(3);
+
+var tui = 3;
+
+var tuia = uncurriedIdAsync(3);
+
+var tci = 3;
+
 exports.willBeInlined = willBeInlined;
 exports.inlined = inlined;
 exports.wrapSomethingAsync = wrapSomethingAsync;
 exports.M = M;
 exports.broken = broken$2;
+exports.curriedId = curriedId;
+exports.curriedIdAsync = curriedIdAsync;
+exports.uncurriedId = uncurriedId;
+exports.uncurriedIdAsync = uncurriedIdAsync;
+exports.tci = tci;
+exports.tcia = tcia;
+exports.tui = tui;
+exports.tuia = tuia;
 /* inlined Not a pure module */

jscomp/test/async_inline.res

@@ -26,3 +26,13 @@ let broken = async (someAsyncFunction) => {
 }
 
 let broken = someAsyncFunction => broken(someAsyncFunction)
+
+let curriedId = x => x
+let curriedIdAsync = async x => x
+let uncurriedId = (.x ) => x
+let uncurriedIdAsync = async (.x ) => x
+
+let tci = curriedId(3)
+let tcia = curriedIdAsync(3)
+let tui = uncurriedId(. 3)
+let tuia = uncurriedIdAsync(. 3)

jscomp/test/attr_test.js

@@ -5,13 +5,13 @@ function u(x, y) {
   return x + y | 0;
 }
 
-var h = u(1, 2);
+var h = 3;
 
 function max2(x, y) {
   return x + y;
 }
 
-var hh = max2(1, 2);
+var hh = 1 + 2;
 
 function f(x) {
   des(x, (function () {
@@ -24,4 +24,4 @@ exports.h = h;
 exports.max2 = max2;
 exports.hh = hh;
 exports.f = f;
-/* h Not a pure module */
+/* No side effect */

jscomp/test/bs_rest_test.js

@@ -12,9 +12,9 @@ function xxx(prim) {
   return x(prim);
 }
 
-var u = xxx(3);
+var u = x(3);
 
-var xx = xxx("3");
+var xx = x("3");
 
 exports.v = v;
 exports.xxx = xxx;

jscomp/test/internal_unused_test.js

@@ -15,10 +15,6 @@ function f(param) {
 
 var c = 5;
 
-function h(a, b) {
-  return a + b | 0;
-}
-
 var h1 = 2;
 
 var h2 = h1 + 1 | 0;
@@ -39,7 +35,7 @@ console.log(h2);
 
 console.log(c);
 
-console.log(h(1, 2));
+console.log(3);
 
 function H($star) {
   return {};

jscomp/test/ppx_apply_test.js

@@ -37,7 +37,7 @@ function unary(a) {
   return a + 3 | 0;
 }
 
-var xx = unary(3);
+var xx = 6;
 
 eq("File \"ppx_apply_test.ml\", line 17, characters 5-12", u, 3);
 

jscomp/test/uncurried_cast.js

@@ -22,12 +22,13 @@ var Uncurried = {
 var E = /* @__PURE__ */Caml_exceptions.create("Uncurried_cast.E");
 
 function testRaise(param) {
-  return raise({
-              RE_EXN_ID: E
-            });
+  throw {
+        RE_EXN_ID: E,
+        Error: new Error()
+      };
 }
 
-var l = map({
+var l = Belt_List.mapU({
       hd: 1,
       tl: {
         hd: 2,
@@ -76,12 +77,13 @@ var StandardNotation = {
 };
 
 function testRaise$1(param) {
-  return raise({
-              RE_EXN_ID: E
-            });
+  throw {
+        RE_EXN_ID: E,
+        Error: new Error()
+      };
 }
 
-var l$1 = map({
+var l$1 = Belt_List.mapU({
       hd: 1,
       tl: {
         hd: 2,

jscomp/test/uncurried_pipe.js

@@ -9,13 +9,13 @@ function addC(x, y) {
   return x + y | 0;
 }
 
-var v7 = add(3, 4);
+var v7 = 7;
 
-var v17 = add(10, add(3, 4));
+var v17 = 17;
 
-var v27 = add(20, 7);
+var v27 = 27;
 
-var v37 = 30 + add(3, 4) | 0;
+var v37 = 37;
 
 function unary(x) {
   return x + 1 | 0;
@@ -31,20 +31,20 @@ var StandardNotation = {
   unary: unary
 };
 
-var v7$1 = add(3, 4);
+var v7$1 = 7;
 
-var v17$1 = add(10, add(3, 4));
+var v17$1 = 17;
 
-var v27$1 = add(20, 7);
+var v27$1 = 27;
 
-var v37$1 = 30 + add(3, 4) | 0;
+var v37$1 = 37;
 
-var v100 = unary(99);
+var v100 = 100;
 
 exports.StandardNotation = StandardNotation;
 exports.v7 = v7$1;
 exports.v17 = v17$1;
 exports.v27 = v27$1;
 exports.v37 = v37$1;
 exports.v100 = v100;
-/* v7 Not a pure module */
+/* No side effect */

jscomp/test/uncurry_glob_test.js

@@ -12,18 +12,16 @@ function f(param) {
   return 3;
 }
 
-f(undefined);
-
 function $plus$great(a, h) {
   return h(a);
 }
 
 function u(h) {
-  return $plus$great(3, h);
+  return h(3);
 }
 
 exports.M = M;
 exports.f = f;
 exports.$plus$great = $plus$great;
 exports.u = u;
-/*  Not a pure module */
+/* No side effect */