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small simplifications #7141

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merged 3 commits into from
Nov 1, 2024
Merged

small simplifications #7141

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1cf77a4
small simplification: null or undefined
cristianoc Oct 31, 2024
c1b266f
Simplifications for string and number constants.
cristianoc Oct 31, 2024
529d960
Update CHANGELOG.md
cristianoc Oct 31, 2024
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1 change: 1 addition & 0 deletions CHANGELOG.md
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Expand Up @@ -55,6 +55,7 @@
- Improve error message when passing an object where a record is expected. https://github.com/rescript-lang/rescript-compiler/pull/7101
- Improve code generation or pattern matching of untagged variants. https://github.com/rescript-lang/rescript-compiler/pull/7128
- Improve negation handling in combination with and/or to simplify generated code (especially coming out of pattern matching). https://github.com/rescript-lang/rescript-compiler/pull/7138
- optimize JavaScript code generation by using x == null checks and improving type-based optimizations for string/number literals. https://github.com/rescript-lang/rescript-compiler/pull/7141


#### :house: Internal
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10 changes: 10 additions & 0 deletions compiler/core/js_dump.ml
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Expand Up @@ -700,6 +700,16 @@ and expression_desc cxt ~(level : int) f x : cxt =
| Float _ -> "- "
| _ -> "-");
expression ~level:13 cxt f e)
| Bin
( Or,
{expression_desc = Bin (EqEqEq, e1, {expression_desc = Null})},
{expression_desc = Bin (EqEqEq, e2, {expression_desc = Undefined _})} )
| Bin
( Or,
{expression_desc = Bin (EqEqEq, e1, {expression_desc = Undefined _})},
{expression_desc = Bin (EqEqEq, e2, {expression_desc = Null})} )
when e1 = e2 ->
expression_desc cxt ~level:(level : int) f (Is_null_or_undefined e1)
| Bin (op, e1, e2) ->
let out, lft, rght = Js_op_util.op_prec op in
let need_paren =
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87 changes: 71 additions & 16 deletions compiler/core/js_exp_make.ml
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Expand Up @@ -711,16 +711,20 @@ let rec push_negation (e : t) : t option =

Type check optimizations:
- [(typeof x === "boolean") && (x === true/false)] -> [x === true/false]
- [(typeof x ==="boolean" | "string" | "number") && (x === boolean/null/undefined)] -> [false]
- [(Array.isArray(x)) && (x === boolean/null/undefined)] -> [false]
- [(typeof x === "string") && (x === "abc")] -> [x === "abc"]
- [(typeof x === "number") && (x === 123)] -> [x === 123]
- [(typeof x === "boolean" | "string" | "number") && (x === boolean/null/undefined/123/"hello")] -> [false]
- [(Array.isArray(x)) && (x === boolean/null/undefined/123/"hello")] -> [false]

- [(typeof x === "boolean") && (x !== true/false)] -> unchanged
- [(typeof x === "boolean" | "string" | "number") && (x !== boolean/null/undefined)] -> [typeof x === ...]
- [(Array.isArray(x)) && (x !== boolean/null/undefined)] -> [Array.isArray(x)]
- [(typeof x === "string") && (x !== "abc")] -> unchanged
- [(typeof x === "number") && (x !== 123)] -> unchanged
- [(typeof x === "boolean" | "string" | "number") && (x !== boolean/null/undefined/123/"hello")] -> [typeof x === ...]
- [(Array.isArray(x)) && (x !== boolean/null/undefined/123/"hello")] -> [Array.isArray(x)]

Equality optimizations:
- [e && e] -> [e]
- [(x === boolean/null/undefined) && (x === boolean/null/undefined)] -> [false] (when not equal)
- [(x === boolean/null/undefined/123/"hello") && (x === boolean/null/undefined/123/"hello")] -> [false] (when not equal)

Note: The function preserves the semantics of the original expression while
attempting to reduce it to a simpler form. If no simplification is possible,
Expand Down Expand Up @@ -778,24 +782,51 @@ let rec simplify_and (e1 : t) (e2 : t) : t option =
{expression_desc = Str {txt = "boolean"}} ) )
when Js_op_util.same_vident ia ib ->
Some {expression_desc = b; comment = None}
| ( Bin
( EqEqEq,
{expression_desc = Typeof {expression_desc = Var ia}},
{expression_desc = Str {txt = "string"}} ),
(Bin (EqEqEq, {expression_desc = Var ib}, {expression_desc = Str _}) as s)
)
| ( (Bin (EqEqEq, {expression_desc = Var ib}, {expression_desc = Str _}) as s),
Bin
( EqEqEq,
{expression_desc = Typeof {expression_desc = Var ia}},
{expression_desc = Str {txt = "string"}} ) )
when Js_op_util.same_vident ia ib ->
Some {expression_desc = s; comment = None}
| ( Bin
( EqEqEq,
{expression_desc = Typeof {expression_desc = Var ia}},
{expression_desc = Str {txt = "number"}} ),
(Bin (EqEqEq, {expression_desc = Var ib}, {expression_desc = Number _}) as
i) )
| ( (Bin (EqEqEq, {expression_desc = Var ib}, {expression_desc = Number _}) as
i),
Bin
( EqEqEq,
{expression_desc = Typeof {expression_desc = Var ia}},
{expression_desc = Str {txt = "number"}} ) )
when Js_op_util.same_vident ia ib ->
Some {expression_desc = i; comment = None}
| ( Bin
( EqEqEq,
{expression_desc = Typeof {expression_desc = Var ia}},
{expression_desc = Str {txt = "boolean" | "string" | "number"}} ),
Bin
( EqEqEq,
{expression_desc = Var ib},
{expression_desc = Bool _ | Null | Undefined _} ) )
{expression_desc = Bool _ | Null | Undefined _ | Number _ | Str _} ) )
| ( Bin
( EqEqEq,
{expression_desc = Var ib},
{expression_desc = Bool _ | Null | Undefined _} ),
{expression_desc = Bool _ | Null | Undefined _ | Number _ | Str _} ),
Bin
( EqEqEq,
{expression_desc = Typeof {expression_desc = Var ia}},
{expression_desc = Str {txt = "boolean" | "string" | "number"}} ) )
when Js_op_util.same_vident ia ib ->
(* Note: case boolean / Bool _ is handled above *)
(* Note: cases boolean / Bool _, number / Number _, string / Str _ are handled above *)
Some false_
| ( Call
( {expression_desc = Str {txt = "Array.isArray"}},
Expand All @@ -804,11 +835,11 @@ let rec simplify_and (e1 : t) (e2 : t) : t option =
Bin
( EqEqEq,
{expression_desc = Var ib},
{expression_desc = Bool _ | Null | Undefined _} ) )
{expression_desc = Bool _ | Null | Undefined _ | Number _ | Str _} ) )
| ( Bin
( EqEqEq,
{expression_desc = Var ib},
{expression_desc = Bool _ | Null | Undefined _} ),
{expression_desc = Bool _ | Null | Undefined _ | Number _ | Str _} ),
Call
( {expression_desc = Str {txt = "Array.isArray"}},
[{expression_desc = Var ia}],
Expand All @@ -827,6 +858,30 @@ let rec simplify_and (e1 : t) (e2 : t) : t option =
{expression_desc = Str {txt = "boolean"}} ) )
when Js_op_util.same_vident ia ib ->
None
| ( Bin
( EqEqEq,
{expression_desc = Typeof {expression_desc = Var ia}},
{expression_desc = Str {txt = "string"}} ),
Bin (NotEqEq, {expression_desc = Var ib}, {expression_desc = Str _}) )
| ( Bin (NotEqEq, {expression_desc = Var ib}, {expression_desc = Str _}),
Bin
( EqEqEq,
{expression_desc = Typeof {expression_desc = Var ia}},
{expression_desc = Str {txt = "string"}} ) )
when Js_op_util.same_vident ia ib ->
None
| ( Bin
( EqEqEq,
{expression_desc = Typeof {expression_desc = Var ia}},
{expression_desc = Str {txt = "number"}} ),
Bin (NotEqEq, {expression_desc = Var ib}, {expression_desc = Number _}) )
| ( Bin (NotEqEq, {expression_desc = Var ib}, {expression_desc = Number _}),
Bin
( EqEqEq,
{expression_desc = Typeof {expression_desc = Var ia}},
{expression_desc = Str {txt = "number"}} ) )
when Js_op_util.same_vident ia ib ->
None
| ( (Bin
( EqEqEq,
{expression_desc = Typeof {expression_desc = Var ia}},
Expand All @@ -835,7 +890,7 @@ let rec simplify_and (e1 : t) (e2 : t) : t option =
Bin
( NotEqEq,
{expression_desc = Var ib},
{expression_desc = Bool _ | Null | Undefined _} ) )
{expression_desc = Bool _ | Null | Undefined _ | Number _ | Str _} ) )
| ( Bin
( NotEqEq,
{expression_desc = Var ib},
Expand All @@ -846,7 +901,7 @@ let rec simplify_and (e1 : t) (e2 : t) : t option =
{expression_desc = Str {txt = "boolean" | "string" | "number"}} ) as
typeof) )
when Js_op_util.same_vident ia ib ->
(* Note: case boolean / Bool _ is handled above *)
(* Note: cases boolean / Bool _, number / Number _, string / Str _ are handled above *)
Some {expression_desc = typeof; comment = None}
| ( (Call
( {expression_desc = Str {txt = "Array.isArray"}},
Expand All @@ -855,11 +910,11 @@ let rec simplify_and (e1 : t) (e2 : t) : t option =
Bin
( NotEqEq,
{expression_desc = Var ib},
{expression_desc = Bool _ | Null | Undefined _} ) )
{expression_desc = Bool _ | Null | Undefined _ | Number _ | Str _} ) )
| ( Bin
( NotEqEq,
{expression_desc = Var ib},
{expression_desc = Bool _ | Null | Undefined _} ),
{expression_desc = Bool _ | Null | Undefined _ | Number _ | Str _} ),
(Call
( {expression_desc = Str {txt = "Array.isArray"}},
[{expression_desc = Var ia}],
Expand All @@ -870,11 +925,11 @@ let rec simplify_and (e1 : t) (e2 : t) : t option =
| ( Bin
( EqEqEq,
{expression_desc = Var ia},
{expression_desc = Bool _ | Null | Undefined _} ),
{expression_desc = Bool _ | Null | Undefined _ | Number _ | Str _} ),
Bin
( EqEqEq,
{expression_desc = Var ib},
{expression_desc = Bool _ | Null | Undefined _} ) )
{expression_desc = Bool _ | Null | Undefined _ | Number _ | Str _} ) )
when Js_op_util.same_vident ia ib ->
(* Note: case x = y is handled above *)
Some false_
Expand Down
4 changes: 2 additions & 2 deletions tests/tests/src/UntaggedVariants.mjs
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Expand Up @@ -80,7 +80,7 @@ let Truthy = {
};

function classify$1(x) {
if (x === null || x === undefined) {
if (x == null) {
if (x === null) {
return "null";
} else {
Expand Down Expand Up @@ -404,7 +404,7 @@ function check$1(s) {
console.log("Nope...");
return;
}
if (typeof match$3 === "string" && match$3 === "My name is") {
if (match$3 === "My name is") {
let match$4 = match$2[1];
if (match$4 === undefined || match$4 === null || match$4 === false || match$4 === true) {
console.log("Nope...");
Expand Down
6 changes: 3 additions & 3 deletions tests/tests/src/core/Core_NullableTests.mjs
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Expand Up @@ -7,7 +7,7 @@ function shouldHandleNullableValues() {
let tUndefined = undefined;
let tValue = "hello";
let tmp;
tmp = tNull === null || tNull === undefined ? tNull === null : false;
tmp = (tNull == null) ? tNull === null : false;
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Could be simplified to tNull === null.

Test.run([
[
"Core_NullableTests.res",
Expand All @@ -18,7 +18,7 @@ function shouldHandleNullableValues() {
"Should handle null"
], tmp, (prim0, prim1) => prim0 === prim1, true);
let tmp$1;
tmp$1 = (tUndefined === null || tUndefined === undefined) && tUndefined !== null;
tmp$1 = (tUndefined == null) && tUndefined !== null;
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@cknitt cknitt Oct 31, 2024 •
edited
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Could be simplified to tUndefined === undefined.

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

Test.run([
[
"Core_NullableTests.res",
Expand Down
6 changes: 3 additions & 3 deletions tests/tests/src/variantsMatching.mjs
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Expand Up @@ -216,17 +216,17 @@ function isUndefined$1(x) {
}

function plus$2(x, y) {
if (x === null || x === undefined) {
if (x == null) {
return y;
} else if (y === null || y === undefined) {
} else if (y == null) {
return x;
} else {
return x + y | 0;
}
}

function kind(x) {
if (x === null || x === undefined) {
if (x == null) {
if (x === null) {
return "null";
} else {
Expand Down