feat(minifier): constant fold small integer multiplication (n <= 255) (#12236)

ref: evanw/esbuild@492e299

Author: Boshen

crates/oxc_minifier/src/peephole/fold_constants.rs

@@ -336,6 +336,12 @@ impl<'a> PeepholeOptimizations {
                         || *right == 0.0
                         || right.is_nan()
                         || right.is_infinite()
+                        // Small number multiplication.
+                        || (e.operator == BinaryOperator::Multiplication
+                            && left.abs() <= 255.0
+                            && left.fract() == 0.0
+                            && right.abs() <= 255.0
+                            && right.fract() == 0.0)
                 })
                 .and_then(|_| ctx.eval_binary(e)),
             BinaryOperator::Division => Self::extract_numeric_values(e)
@@ -1751,6 +1757,12 @@ mod test {
         // test("x = (null + 1) * 2", "x = 2");
         // test("x = y + (z * 24 * 60 * 60 * 1000)", "x = y + z * 864E5");
         fold("x = y + (z & 24 & 60 & 60 & 1000)", "x = y + (z & 8)");
+        fold("x = -1 * -1", "x = 1");
+        fold("x = 1 * -1", "x = -1");
+        fold("x = 255 * 255", "x = 65025");
+        fold("x = -255 * 255", "x = -65025");
+        fold("x = -255 * -255", "x = 65025");
+        fold_same("x = 256 * 255");
     }
 
     #[test]

crates/oxc_minifier/tests/peephole/esbuild.rs

@@ -901,7 +901,7 @@ fn constant_evaluation_test() {
     test("x = +{valueOf:()=>1}", "x = +{ valueOf: () => 1 };");
     test("x = 3 + 6", "x = 9;");
     test("x = 3 - 6", "x = -3;");
-    test("x = 3 * 6", "x = 3 * 6;");
+    test("x = 3 * 6", "x = 18;");
     test("x = 3 / 6", "x = 3 / 6;");
     test("x = 3 % 6", "x = 3 % 6;");
     test("x = 3 ** 6", "x = 3 ** 6;");

tasks/minsize/minsize.snap

@@ -3,7 +3,7 @@ Original   | minified   | minified   | gzip       | gzip       | Fixture
 -------------------------------------------------------------------------------------
 72.14 kB   | 23.49 kB   | 23.70 kB   | 8.47 kB    | 8.54 kB    | react.development.js
 
-173.90 kB  | 59.52 kB   | 59.82 kB   | 19.18 kB   | 19.33 kB   | moment.js 
+173.90 kB  | 59.51 kB   | 59.82 kB   | 19.18 kB   | 19.33 kB   | moment.js 
 
 287.63 kB  | 89.33 kB   | 90.07 kB   | 30.95 kB   | 31.95 kB   | jquery.js 
 
@@ -15,7 +15,7 @@ Original   | minified   | minified   | gzip       | gzip       | Fixture
 
 1.01 MB    | 440.17 kB  | 458.89 kB  | 122.37 kB  | 126.71 kB  | bundle.min.js
 
-1.25 MB    | 647.00 kB  | 646.76 kB  | 160.28 kB  | 163.73 kB  | three.js  
+1.25 MB    | 647 kB     | 646.76 kB  | 160.28 kB  | 163.73 kB  | three.js  
 
 2.14 MB    | 716.13 kB  | 724.14 kB  | 161.80 kB  | 181.07 kB  | victory.js