Option optimization: do not create redundant local vars

Author: cknitt

compiler/core/lam_util.ml

@@ -93,6 +93,9 @@ let refine_let
         since function evaluation is always delayed
     *)
     Lam.let_ Alias param arg l
+  | (Strict | StrictOpt),
+    ( Lprim {primitive = Psome_not_nest; _} as prim ), _ ->
+    Lam.let_ Alias param prim l
   | ( (Strict | StrictOpt ) ), (Lfunction _ ), _ ->
     (*It can be promoted to [Alias], however, 
         we don't want to do this, since we don't want the 

packages/@rescript/runtime/lib/es6/Belt_internalAVLset.js

@@ -741,15 +741,13 @@ function rotateWithRightChild(k1) {
 
 function doubleWithLeftChild(k3) {
   let k3l = k3.l;
-  let v = rotateWithRightChild(k3l);
-  k3.l = v;
+  k3.l = rotateWithRightChild(k3l);
   return rotateWithLeftChild(k3);
 }
 
 function doubleWithRightChild(k2) {
   let k2r = k2.r;
-  let v = rotateWithLeftChild(k2r);
-  k2.r = v;
+  k2.r = rotateWithLeftChild(k2r);
   return rotateWithRightChild(k2);
 }
 

packages/@rescript/runtime/lib/js/Belt_internalAVLset.js

@@ -741,15 +741,13 @@ function rotateWithRightChild(k1) {
 
 function doubleWithLeftChild(k3) {
   let k3l = k3.l;
-  let v = rotateWithRightChild(k3l);
-  k3.l = v;
+  k3.l = rotateWithRightChild(k3l);
   return rotateWithLeftChild(k3);
 }
 
 function doubleWithRightChild(k2) {
   let k2r = k2.r;
-  let v = rotateWithLeftChild(k2r);
-  k2.r = v;
+  k2.r = rotateWithLeftChild(k2r);
   return rotateWithRightChild(k2);
 }
 

tests/gentype_tests/typescript-react-example/src/nested/Types.res.js

@@ -3,9 +3,7 @@
 import * as Primitive_option from "@rescript/runtime/lib/es6/Primitive_option.js";
 
 function boolean(val1, val2) {
-  let a = val1;
-  let b = val2;
-  if (b || a) {
+  if (val2 || val1) {
     return "a";
   } else {
     return "b";
@@ -33,8 +31,7 @@ function constant() {
 }
 
 function param(opt) {
-  let x = opt;
-  console.log(x);
+  console.log(opt);
 }
 
 export {

tests/tests/src/option_optimisation.mjs

@@ -8,6 +8,25 @@ let x6 = {
   x: 42
 };
 
+let x10 = null;
+
+let x11 = Primitive_option.some(undefined);
+
+let x1 = "hello";
+
+let x2 = 1;
+
+let x3 = {
+  TAG: "Ok",
+  _0: "hi"
+};
+
+let x4 = "polyvar";
+
+let x5 = {
+  x: 42
+};
+
 let x7 = [
   1,
   2,
@@ -16,9 +35,7 @@ let x7 = [
 
 let x8 = () => {};
 
-let x10 = null;
-
-let x11 = Primitive_option.some(undefined);
+let x12 = "test";
 
 let x20 = null;
 
@@ -68,36 +85,19 @@ let x42 = new Intl.PluralRules();
 
 let x43 = new Intl.Locale("en");
 
-let x45 = Promise.resolve(true);
-
-let x47 = {};
-
-let x48 = Stdlib_Lazy.make(() => true);
-
-let x1 = "hello";
-
-let x2 = 1;
-
-let x3 = {
-  TAG: "Ok",
-  _0: "hi"
-};
-
-let x4 = "polyvar";
-
-let x5 = {
-  x: 42
-};
-
-let x12 = "test";
-
 let x44 = [
   1,
   2
 ];
 
+let x45 = Promise.resolve(true);
+
 let x46 = /* [] */0;
 
+let x47 = {};
+
+let x48 = Stdlib_Lazy.make(() => true);
+
 export {
   x1,
   x2,

tests/tests/src/option_wrapping_test.mjs

@@ -92,17 +92,6 @@ function wrapReasonForJs(component, jsPropsToReason) {
 let dummyInteropComponent = basicComponent("interop");
 
 function wrapJsForReason(reactClass, props, children) {
-  let jsElementWrapped = (extra, extra$1) => {
-    let props$1 = Object.assign(Object.assign({}, props), {
-      ref: extra$1,
-      key: extra
-    });
-    let varargs = Js_array.concat(children, [
-      reactClass,
-      props$1
-    ]);
-    return React.createElement.apply(null, varargs);
-  };
   return {
     debugName: dummyInteropComponent.debugName,
     reactClassInternal: dummyInteropComponent.reactClassInternal,
@@ -117,7 +106,17 @@ function wrapJsForReason(reactClass, props, children) {
     initialState: dummyInteropComponent.initialState,
     retainedProps: dummyInteropComponent.retainedProps,
     reducer: dummyInteropComponent.reducer,
-    jsElementWrapped: jsElementWrapped
+    jsElementWrapped: (extra, extra$1) => {
+      let props$1 = Object.assign(Object.assign({}, props), {
+        ref: extra$1,
+        key: extra
+      });
+      let varargs = Js_array.concat(children, [
+        reactClass,
+        props$1
+      ]);
+      return React.createElement.apply(null, varargs);
+    }
   };
 }