cleanup and minor optimization by updating TapeTagKind

.gitignore

@@ -5,8 +5,8 @@
 flamegraph.svg
 perf.data
 perf.data.old
-callgrind.out.*
-cachegrind.out.*
+callgrind.out*
+cachegrind.out*
 
 # sometimes i make these files when benchmarking, don't want to accidentally commit them
 benchmark_result.txt

simdnbt/src/borrow/compound.rs

@@ -328,12 +328,6 @@ pub(crate) fn read_tag<'a>(
     stack: &mut ParsingStack,
     tag_type: u8,
 ) -> Result<(), NonRootError> {
-    match tag_type {
-        COMPOUND_ID => return NbtCompound::read(data, tapes, stack),
-        LIST_ID => return NbtList::read(data, tapes, stack),
-        _ => {}
-    }
-
     let pushing_element = match tag_type {
         BYTE_ID => {
             let byte = data.read_i8()?;
@@ -376,6 +370,8 @@ pub(crate) fn read_tag<'a>(
 
             TapeElement::new_with_ptr(TapeTagKind::String, string_ptr)
         }
+        COMPOUND_ID => return NbtCompound::read(data, tapes, stack),
+        LIST_ID => return NbtList::read(data, tapes, stack),
         INT_ARRAY_ID => {
             let int_array_ptr = data.cur;
             read_int_array(data)?;

simdnbt/src/borrow/list.rs

@@ -1,4 +1,4 @@
-use std::{hint::unreachable_unchecked, marker::PhantomData};
+use std::{hint::unreachable_unchecked, marker::PhantomData, mem};
 
 use crate::{
     common::{
@@ -810,7 +810,7 @@ where
     let length = unsafe { u32::from(*ptr) };
     #[cfg(target_endian = "little")]
     let length = length.swap_bytes();
-    let length_in_bytes = length as usize * std::mem::size_of::<T>();
+    let length_in_bytes = length as usize * mem::size_of::<T>();
     let array_be = unsafe { std::slice::from_raw_parts(ptr.add(1) as *const u8, length_in_bytes) };
     Some(RawList::new(array_be))
 }

simdnbt/src/borrow/tape.rs

@@ -226,6 +226,9 @@ impl From<UnalignedU16> for u16 {
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
 #[repr(u8)]
 pub enum TapeTagKind {
+    // putting this at the start makes it slightly faster
+    EmptyList = 0,
+
     Byte = BYTE_ID,
     Short = SHORT_ID,
     Int = INT_ID,
@@ -238,7 +241,6 @@ pub enum TapeTagKind {
     IntArray = INT_ARRAY_ID,
     LongArray = LONG_ARRAY_ID,
 
-    EmptyList,
     ByteList,
     ShortList,
     IntList,

simdnbt/src/reader.rs

@@ -1,6 +1,7 @@
 use std::{
     io::Cursor,
     marker::PhantomData,
+    mem,
     ops::{Deref, DerefMut},
 };
 
@@ -33,14 +34,15 @@ impl<'a> Reader<'a> {
         }
     }
 
+    #[inline]
     pub unsafe fn unchecked_read_type<T>(&mut self) -> T {
         let value = unsafe { self.cur.cast::<T>().read_unaligned() };
-        self.cur = unsafe { self.cur.add(std::mem::size_of::<T>()) };
+        self.cur = unsafe { self.cur.add(mem::size_of::<T>()) };
         value
     }
 
     pub fn read_type<T: Copy>(&mut self) -> Result<T, UnexpectedEofError> {
-        self.ensure_can_read(std::mem::size_of::<T>())?;
+        self.ensure_can_read(mem::size_of::<T>())?;
         Ok(unsafe { self.unchecked_read_type() })
     }