Simplify conditionals codegen + add missing side effects checks.

CHANGELOG.md

@@ -63,6 +63,7 @@
 - Improve pattern matching on optional fields. https://github.com/rescript-lang/rescript-compiler/pull/7143 https://github.com/rescript-lang/rescript-compiler/pull/7144
 - Optimize compilation of switch statements for untagged variants when there are no literal cases. https://github.com/rescript-lang/rescript-compiler/pull/7135
 - Further improve boolean optimizations. https://github.com/rescript-lang/rescript-compiler/pull/7149
+- Simplify code generated forconditionals. https://github.com/rescript-lang/rescript-compiler/pull/7151
 
 
 #### :house: Internal

compiler/core/js_exp_make.ml

@@ -702,7 +702,7 @@ let rec push_negation (e : t) : t option =
   Basic simplification rules:
   - [false && e] -> [false]
   - [true && e] -> [e] 
-  - [e && false] -> [false]
+  - [e && false] -> [false] If [e] has no side effects
   - [e && true] -> [e]
   - [(a && b) && e] -> If either [a && e] or [b && e] can be simplified, 
                        creates new AND expression with simplified parts: [(a' && b')]
@@ -743,7 +743,7 @@ let rec simplify_and ~n (e1 : t) (e2 : t) : t option =
   let res =
     match (e1.expression_desc, e2.expression_desc) with
     | Bool false, _ -> Some false_
-    | _, Bool false -> Some false_
+    | _, Bool false when no_side_effect e1 -> Some false_
     | Bool true, _ -> Some e2
     | _, Bool true -> Some e1
     | Bin (And, a, b), _ -> (
@@ -997,7 +997,7 @@ let rec simplify_and ~n (e1 : t) (e2 : t) : t option =
              _ ) as is_array) )
       when Js_op_util.same_vident ia ib ->
       Some {expression_desc = is_array; comment = None}
-    | x, y when x = y -> Some e1
+    | _ when Js_analyzer.eq_expression e1 e2 -> Some e1
     | ( Bin
           ( EqEqEq,
             {expression_desc = Var ia},
@@ -1022,7 +1022,9 @@ let rec simplify_and ~n (e1 : t) (e2 : t) : t option =
             ({expression_desc = Bool _ | Null | Undefined _ | Number _ | Str _}
              as v2) ) )
       when Js_op_util.same_vident ia ib && op1 != op2 ->
-      if v1 = v2 then Some false_ else if op1 = EqEqEq then Some e1 else Some e2
+      if Js_analyzer.eq_expression v1 v2 then Some false_
+      else if op1 = EqEqEq then Some e1
+      else Some e2
     | _ -> None
   in
   (if debug then
@@ -1138,14 +1140,22 @@ let not (e : t) : t =
   | Bin (Ge, a, b) -> {e with expression_desc = Bin (Lt, a, b)}
   | Bin (Le, a, b) -> {e with expression_desc = Bin (Gt, a, b)}
   | Bin (Gt, a, b) -> {e with expression_desc = Bin (Le, a, b)}
-  | _ -> {expression_desc = Js_not e; comment = None}
+  | _ -> (
+    match push_negation e with
+    | Some e_ -> e_
+    | None -> {expression_desc = Js_not e; comment = None})
 
 let not_empty_branch (x : t) =
   match x.expression_desc with
   | Number (Int {i = 0l}) | Undefined _ -> false
   | _ -> true
 
 let rec econd ?comment (pred : t) (ifso : t) (ifnot : t) : t =
+  let default () =
+    if Js_analyzer.eq_expression ifso ifnot then
+      if no_side_effect pred then ifso else seq ?comment pred ifso
+    else {expression_desc = Cond (pred, ifso, ifnot); comment}
+  in
   match (pred.expression_desc, ifso.expression_desc, ifnot.expression_desc) with
   | Bool false, _, _ -> ifnot
   | Number (Int {i = 0l; _}), _, _ -> ifnot
@@ -1179,10 +1189,15 @@ let rec econd ?comment (pred : t) (ifso : t) (ifnot : t) : t =
       Seq (a, {expression_desc = Undefined _}),
       Seq (b, {expression_desc = Undefined _}) ) ->
     seq (econd ?comment pred a b) undefined
-  | _ ->
-    if Js_analyzer.eq_expression ifso ifnot then
-      if no_side_effect pred then ifso else seq ?comment pred ifso
-    else {expression_desc = Cond (pred, ifso, ifnot); comment}
+  | _, _, Bool false -> (
+    match simplify_and ~n:0 pred ifso with
+    | Some e -> e
+    | None -> default ())
+  | _, Bool false, _ -> (
+    match simplify_and ~n:0 (not pred) ifnot with
+    | Some e -> e
+    | None -> default ())
+  | _ -> default ()
 
 let rec float_equal ?comment (e0 : t) (e1 : t) : t =
   match (e0.expression_desc, e1.expression_desc) with

lib/es6/Belt_List.js

@@ -988,11 +988,7 @@ function eq(_l1, _l2, p) {
     let l2 = _l2;
     let l1 = _l1;
     if (!l1) {
-      if (l2) {
-        return false;
-      } else {
-        return true;
-      }
+      return !l2;
     }
     if (!l2) {
       return false;

lib/es6/Belt_Result.js

@@ -57,11 +57,7 @@ function isOk(x) {
 }
 
 function isError(x) {
-  if (x.TAG === "Ok") {
-    return false;
-  } else {
-    return true;
-  }
+  return x.TAG !== "Ok";
 }
 
 function eq(a, b, f) {
@@ -71,10 +67,8 @@ function eq(a, b, f) {
     } else {
       return false;
     }
-  } else if (b.TAG === "Ok") {
-    return false;
   } else {
-    return true;
+    return b.TAG !== "Ok";
   }
 }
 

lib/es6/List.js

@@ -1000,11 +1000,7 @@ function equal(_l1, _l2, p) {
     let l2 = _l2;
     let l1 = _l1;
     if (!l1) {
-      if (l2) {
-        return false;
-      } else {
-        return true;
-      }
+      return !l2;
     }
     if (!l2) {
       return false;

lib/es6/Primitive_option.js

@@ -44,7 +44,7 @@ function fromNull(x) {
 }
 
 function valFromOption(x) {
-  if (!(x !== null && x.BS_PRIVATE_NESTED_SOME_NONE !== undefined)) {
+  if (x === null || x.BS_PRIVATE_NESTED_SOME_NONE === undefined) {
     return x;
   }
   let depth = x.BS_PRIVATE_NESTED_SOME_NONE;

lib/es6/Result.js

@@ -51,11 +51,7 @@ function isOk(x) {
 }
 
 function isError(x) {
-  if (x.TAG === "Ok") {
-    return false;
-  } else {
-    return true;
-  }
+  return x.TAG !== "Ok";
 }
 
 function equal(a, b, f) {
@@ -65,10 +61,8 @@ function equal(a, b, f) {
     } else {
       return false;
     }
-  } else if (b.TAG === "Ok") {
-    return false;
   } else {
-    return true;
+    return b.TAG !== "Ok";
   }
 }
 

lib/js/Belt_List.js

@@ -988,11 +988,7 @@ function eq(_l1, _l2, p) {
     let l2 = _l2;
     let l1 = _l1;
     if (!l1) {
-      if (l2) {
-        return false;
-      } else {
-        return true;
-      }
+      return !l2;
     }
     if (!l2) {
       return false;

lib/js/Belt_Result.js

@@ -57,11 +57,7 @@ function isOk(x) {
 }
 
 function isError(x) {
-  if (x.TAG === "Ok") {
-    return false;
-  } else {
-    return true;
-  }
+  return x.TAG !== "Ok";
 }
 
 function eq(a, b, f) {
@@ -71,10 +67,8 @@ function eq(a, b, f) {
     } else {
       return false;
     }
-  } else if (b.TAG === "Ok") {
-    return false;
   } else {
-    return true;
+    return b.TAG !== "Ok";
   }
 }
 

lib/js/List.js

@@ -1000,11 +1000,7 @@ function equal(_l1, _l2, p) {
     let l2 = _l2;
     let l1 = _l1;
     if (!l1) {
-      if (l2) {
-        return false;
-      } else {
-        return true;
-      }
+      return !l2;
     }
     if (!l2) {
       return false;

lib/js/Primitive_option.js

@@ -44,7 +44,7 @@ function fromNull(x) {
 }
 
 function valFromOption(x) {
-  if (!(x !== null && x.BS_PRIVATE_NESTED_SOME_NONE !== undefined)) {
+  if (x === null || x.BS_PRIVATE_NESTED_SOME_NONE === undefined) {
     return x;
   }
   let depth = x.BS_PRIVATE_NESTED_SOME_NONE;

lib/js/Result.js

@@ -51,11 +51,7 @@ function isOk(x) {
 }
 
 function isError(x) {
-  if (x.TAG === "Ok") {
-    return false;
-  } else {
-    return true;
-  }
+  return x.TAG !== "Ok";
 }
 
 function equal(a, b, f) {
@@ -65,10 +61,8 @@ function equal(a, b, f) {
     } else {
       return false;
     }
-  } else if (b.TAG === "Ok") {
-    return false;
   } else {
-    return true;
+    return b.TAG !== "Ok";
   }
 }
 

tests/tests/src/UntaggedVariants.mjs

@@ -234,7 +234,7 @@ let TrickyNested = {
 };
 
 function checkEnum(e) {
-  if (!(e === "One" || e === "Three" || e === "Two")) {
+  if (e !== "One" && e !== "Three" && e !== "Two") {
     return "Something else..." + e;
   }
   switch (e) {
@@ -252,7 +252,7 @@ let OverlapString = {
 };
 
 function checkEnum$1(e) {
-  if (!(e === 1.0 || e === "Three" || e === "Two")) {
+  if (e !== 1.0 && e !== "Three" && e !== "Two") {
     return "Something else...";
   }
   switch (e) {
@@ -270,7 +270,7 @@ let OverlapNumber = {
 };
 
 function checkEnum$2(e) {
-  if (!(e === null || typeof e !== "object")) {
+  if (e !== null && typeof e === "object") {
     return "Object...";
   }
   switch (e) {

tests/tests/src/bdd.mjs

@@ -363,10 +363,8 @@ function random_vars(n) {
 function bool_equal(a, b) {
   if (a) {
     return b;
-  } else if (b) {
-    return false;
   } else {
-    return true;
+    return !b;
   }
 }
 

tests/tests/src/bs_poly_map_test.mjs

@@ -210,21 +210,21 @@ let match$1 = match[0];
 
 let match$2 = Belt_Map.get(v3, 10);
 
-b("File \"bs_poly_map_test.res\", line 155, characters 4-11", match$2 !== undefined ? match$2 === 11 : false);
+b("File \"bs_poly_map_test.res\", line 155, characters 4-11", match$2 === 11);
 
 let match$3 = Belt_Map.get(v3, -10);
 
 b("File \"bs_poly_map_test.res\", line 162, characters 4-11", match$3 === undefined);
 
 let match$4 = Belt_Map.get(v4, -10);
 
-b("File \"bs_poly_map_test.res\", line 169, characters 4-11", match$4 !== undefined ? match$4 === 0 : false);
+b("File \"bs_poly_map_test.res\", line 169, characters 4-11", match$4 === 0);
 
 b("File \"bs_poly_map_test.res\", line 175, characters 4-11", Belt_Map.isEmpty(Belt_Map.remove(Belt_Map.make(Icmp), 0)));
 
 b("File \"bs_poly_map_test.res\", line 176, characters 4-11", Belt_Map.isEmpty(Belt_Map.removeMany(Belt_Map.make(Icmp), [0])));
 
-b("File \"bs_poly_map_test.res\", line 178, characters 4-11", pres !== undefined ? pres === 5000 : false);
+b("File \"bs_poly_map_test.res\", line 178, characters 4-11", pres === 5000);
 
 b("File \"bs_poly_map_test.res\", line 184, characters 4-11", Belt_Array.eq(Belt_Map.keysToArray(match$1[0]), Belt_Array.makeBy(5000, i => i), (prim0, prim1) => prim0 === prim1));
 

tests/tests/src/complex_while_loop.mjs

@@ -5,10 +5,10 @@ function f() {
   let n = 0;
   while ((() => {
       let fib = x => {
-        if (x === 0 || x === 1) {
-          return 1;
-        } else {
+        if (x !== 0 && x !== 1) {
           return fib(x - 1 | 0) + fib(x - 2 | 0) | 0;
+        } else {
+          return 1;
         }
       };
       return fib(n) > 10;

tests/tests/src/core/Core_NullableTests.mjs

@@ -7,7 +7,7 @@ function shouldHandleNullableValues() {
   let tUndefined = undefined;
   let tValue = "hello";
   let tmp;
-  tmp = (tNull == null) ? tNull === null : false;
+  tmp = tNull === null;
   Test.run([
     [
       "Core_NullableTests.res",
@@ -29,7 +29,7 @@ function shouldHandleNullableValues() {
     "Should handle undefined"
   ], tmp$1, (prim0, prim1) => prim0 === prim1, true);
   let tmp$2;
-  tmp$2 = (tValue == null) ? false : tValue === "hello";
+  tmp$2 = tValue === "hello";
   Test.run([
     [
       "Core_NullableTests.res",

tests/tests/src/demo_page.mjs

@@ -4,10 +4,10 @@ import * as React from "react";
 import * as ReactDom from "react-dom";
 
 function fib(x) {
-  if (x === 2 || x === 1) {
-    return 1;
-  } else {
+  if (x !== 2 && x !== 1) {
     return fib(x - 1 | 0) + fib(x - 2 | 0) | 0;
+  } else {
+    return 1;
   }
 }
 

tests/tests/src/exception_rebound_err_test.mjs

@@ -52,7 +52,7 @@ function test_js_error4() {
       }
     } else if (e.RE_EXN_ID === B) {
       return 5;
-    } else if (e.RE_EXN_ID === C && !(e._1 !== 1 || e._2 !== 2)) {
+    } else if (e.RE_EXN_ID === C && e._1 === 1 && e._2 === 2) {
       return 6;
     } else {
       return 7;

tests/tests/src/fib.mjs

@@ -2,10 +2,10 @@
 
 
 function fib(x) {
-  if (x === 0 || x === 1) {
-    return 1;
-  } else {
+  if (x !== 0 && x !== 1) {
     return fib(x - 1 | 0) + fib(x - 2 | 0) | 0;
+  } else {
+    return 1;
   }
 }