perf(common): Improve StringInput#bump_bytes (#11230)

Author: kdy1

.changeset/tiny-eyes-knock.md

@@ -0,0 +1,7 @@
+---
+swc_common: patch
+swc_ecma_parser: patch
+swc_core: patch
+---
+
+perf(common): Improve `StringInput#bump_bytes`

crates/swc_common/src/input.rs

@@ -75,9 +75,19 @@ impl<'a> StringInput<'a> {
 
     #[inline]
     pub fn bump_bytes(&mut self, n: usize) {
-        unsafe {
-            // Safety: We only proceed, not go back.
-            self.reset_to(self.last_pos + BytePos(n as u32));
+        let s = self.iter.as_str();
+        self.iter = unsafe { s.get_unchecked(n..) }.chars();
+        self.last_pos.0 += n as u32;
+    }
+
+    #[inline]
+    pub fn bump_one(&mut self) {
+        if self.iter.next().is_some() {
+            self.last_pos.0 += 1;
+        } else {
+            unsafe {
+                debug_unreachable!("bump should not be called when cur() == None");
+            }
         }
     }
 

crates/swc_ecma_parser/src/lexer/table.rs

@@ -341,7 +341,7 @@ const PIP: ByteHandler = |lexer| lexer.read_token_logical::<b'|'>();
 macro_rules! single_char {
     ($name:ident, $c:literal, $token:ident) => {
         const $name: ByteHandler = |lexer| {
-            lexer.input.bump_bytes(1);
+            lexer.input.bump_one();
             Ok(Token::$token)
         };
     };
@@ -368,9 +368,9 @@ single_char!(BEC, b'}', RBrace);
 /// `^`
 const CRT: ByteHandler = |lexer| {
     // Bitwise xor
-    lexer.input.bump_bytes(1);
+    lexer.input.bump_one();
     Ok(if lexer.input.cur_as_ascii() == Some(b'=') {
-        lexer.input.bump_bytes(1);
+        lexer.input.bump_one();
         Token::BitXorEq
     } else {
         Token::Caret