fix(es/minifier): Fix panic in bitwise logic and incorrect values

crates/swc_ecma_transforms_optimization/src/simplify/expr/mod.rs

@@ -633,13 +633,6 @@ impl SimplifyExpr {
 
             // Bit shift operations
             op!("<<") | op!(">>") | op!(">>>") => {
-                /// Uses a method for treating a double as 32bits that is
-                /// equivalent to how JavaScript would convert a
-                /// number before applying a bit operation.
-                fn js_convert_double_to_bits(d: f64) -> i32 {
-                    ((d.floor() as i64) & 0xffff_ffff) as i32
-                }
-
                 fn try_fold_shift(
                     ctx: &ExprCtx,
                     op: BinaryOp,
@@ -654,38 +647,12 @@ impl SimplifyExpr {
                         (Known(lv), Known(rv)) => (lv, rv),
                         _ => unreachable!(),
                     };
-
-                    // only the lower 5 bits are used when shifting, so don't do anything
-                    // if the shift amount is outside [0,32)
-                    if !(0.0..32.0).contains(&rv) {
-                        return Unknown;
-                    }
-
-                    let rv_int = rv as i32;
-                    if rv_int as f64 != rv {
-                        unimplemented!("error reporting: FRACTIONAL_BITWISE_OPERAND")
-                        // report(FRACTIONAL_BITWISE_OPERAND, right.span());
-                        // return n;
-                    }
-
-                    if lv.floor() != lv {
-                        unimplemented!("error reporting: FRACTIONAL_BITWISE_OPERAND")
-                        // report(FRACTIONAL_BITWISE_OPERAND, left.span());
-                        // return n;
-                    }
-
-                    let bits = js_convert_double_to_bits(lv);
+                    let (lv, rv) = (JsNumber::from(lv), JsNumber::from(rv));
 
                     Known(match op {
-                        op!("<<") => (bits << rv_int) as f64,
-                        op!(">>") => (bits >> rv_int) as f64,
-                        op!(">>>") => {
-                            let res = bits as u32 >> rv_int as u32;
-                            // JavaScript always treats the result of >>> as unsigned.
-                            // We must force Java to do the same here.
-                            // unimplemented!(">>> (Zerofill rshift)")
-                            res as f64
-                        }
+                        op!("<<") => *(lv << rv),
+                        op!(">>") => *(lv >> rv),
+                        op!(">>>") => *(lv.unsigned_shr(rv)),
 
                         _ => unreachable!("Unknown bit operator {:?}", op),
                     })

crates/swc_ecma_transforms_optimization/src/simplify/expr/tests.rs

@@ -659,6 +659,27 @@ fn test_fold_bitwise_op2() {
     fold("x = 12 | NaN", "x=12");
 }
 
+#[test]
+fn test_issue_9256() {
+    // Returns -2 prior to fix (Number.MAX_VALUE)
+    fold("1.7976931348623157e+308 << 1", "0");
+
+    // Isn't changed prior to fix
+    fold("1.7976931348623157e+308 << 1.7976931348623157e+308", "0");
+    fold("1.7976931348623157e+308 >> 1.7976931348623157e+308", "0");
+
+    // Panics prior to fix (Number.MIN_VALUE)
+    fold("5e-324 >> 5e-324", "0");
+    fold("5e-324 << 5e-324", "0");
+    fold("5e-324 << 0", "0");
+    fold("0 << 5e-324", "0");
+
+    // Wasn't broken prior, used to ensure overflows are handled correctly
+    fold("1 << 31", "-2147483648");
+    fold("-8 >> 2", "-2");
+    fold("-8 >>> 2", "1073741822");
+}
+
 #[test]
 #[ignore]
 fn test_folding_mix_types_early() {
@@ -726,9 +747,9 @@ fn test_fold_bit_shifts() {
 
     fold("x = 0xffffffff << 0", "x = -1");
     fold("x = 0xffffffff << 4", "x = -16");
-    fold_same("1 << 32");
-    fold_same("1 << -1");
-    fold_same("1 >> 32");
+    fold("1 << 32", "1");
+    fold("1 << -1", "-2147483648");
+    fold("1 >> 32", "1");
 }
 
 #[test]

crates/swc_ecma_utils/src/number.rs

@@ -36,11 +36,7 @@ impl std::ops::Deref for JsNumber {
 impl JsNumber {
     // https://tc39.es/ecma262/#sec-toint32
     fn as_int32(&self) -> i32 {
-        if !self.0.is_finite() {
-            return 0;
-        }
-
-        self.0.trunc() as i32
+        self.as_uint32() as i32
     }
 
     // https://tc39.es/ecma262/#sec-touint32
@@ -49,7 +45,8 @@ impl JsNumber {
             return 0;
         }
 
-        self.0.trunc() as u32
+        // pow(2, 32) = 4294967296
+        self.0.trunc().rem_euclid(4294967296.0) as u32
     }
 }
 
@@ -211,6 +208,7 @@ mod test_js_number {
         assert_eq!(JsNumber(-0.0).as_uint32(), 0);
         assert_eq!(JsNumber(f64::INFINITY).as_uint32(), 0);
         assert_eq!(JsNumber(f64::NEG_INFINITY).as_uint32(), 0);
+        assert_eq!(JsNumber(-8.0).as_uint32(), 4294967288);
     }
 
     #[test]