deflate::Window: cleanup unused fields

Author: folkertdev

zlib-rs/src/deflate.rs

@@ -1650,7 +1650,6 @@ pub(crate) fn read_buf_window(stream: &mut DeflateStream, offset: usize, size: u
         // we likely cannot fuse the crc32 and the copy here because the input can be changed by
         // a concurrent thread. Therefore it cannot be converted into a slice!
         let window = &mut stream.state.window;
-        window.initialize_at_least(offset + len);
         // SAFETY: len is bounded by avail_in, so this copy is in bounds.
         unsafe { window.copy_and_initialize(offset..offset + len, stream.next_in) };
 
@@ -1660,15 +1659,13 @@ pub(crate) fn read_buf_window(stream: &mut DeflateStream, offset: usize, size: u
         // we likely cannot fuse the adler32 and the copy here because the input can be changed by
         // a concurrent thread. Therefore it cannot be converted into a slice!
         let window = &mut stream.state.window;
-        window.initialize_at_least(offset + len);
         // SAFETY: len is bounded by avail_in, so this copy is in bounds.
         unsafe { window.copy_and_initialize(offset..offset + len, stream.next_in) };
 
         let data = &stream.state.window.filled()[offset..][..len];
         stream.adler = adler32(stream.adler as u32, data) as _;
     } else {
         let window = &mut stream.state.window;
-        window.initialize_at_least(offset + len);
         // SAFETY: len is bounded by avail_in, so this copy is in bounds.
         unsafe { window.copy_and_initialize(offset..offset + len, stream.next_in) };
     }
@@ -1742,7 +1739,6 @@ pub(crate) fn fill_window(stream: &mut DeflateStream) {
             // explicitly initialize them with zeros.
             //
             // see also the "fill_window_out_of_bounds" test.
-            state.window.initialize_at_least(2 * wsize);
             state.window.filled_mut().copy_within(wsize..2 * wsize, 0);
 
             if state.match_start >= wsize {
@@ -1811,11 +1807,6 @@ pub(crate) fn fill_window(stream: &mut DeflateStream) {
         }
     }
 
-    // initialize some memory at the end of the (filled) window, so SIMD operations can go "out of
-    // bounds" without violating any requirements. The window allocation is already slightly bigger
-    // to allow for this.
-    stream.state.window.initialize_out_of_bounds();
-
     assert!(
         stream.state.strstart <= stream.state.window_size - MIN_LOOKAHEAD,
         "not enough room for search"

zlib-rs/src/deflate/window.rs

@@ -6,12 +6,7 @@ pub struct Window<'a> {
     // perform bounds checks.
     buf: WeakSliceMut<'a, u8>,
 
-    // number of initialized bytes
-    filled: usize,
-
     window_bits: usize,
-
-    high_water: usize,
 }
 
 impl<'a> Window<'a> {
@@ -21,12 +16,7 @@ impl<'a> Window<'a> {
         // SAFETY: freshly allocated buffer
         let buf = unsafe { WeakSliceMut::from_raw_parts_mut(ptr, len) };
 
-        Some(Self {
-            buf,
-            filled: len,
-            window_bits,
-            high_water: len,
-        })
+        Some(Self { buf, window_bits })
     }
 
     pub fn clone_in(&self, alloc: &Allocator<'a>) -> Option<Self> {
@@ -36,8 +26,6 @@ impl<'a> Window<'a> {
             .buf
             .as_mut_slice()
             .copy_from_slice(self.buf.as_slice());
-        clone.filled = self.filled;
-        clone.high_water = self.high_water;
 
         Some(clone)
     }
@@ -60,14 +48,14 @@ impl<'a> Window<'a> {
     #[inline]
     pub fn filled(&self) -> &[u8] {
         // SAFETY: `self.buf` has been initialized for at least `filled` elements
-        unsafe { core::slice::from_raw_parts(self.buf.as_ptr().cast(), self.filled) }
+        unsafe { core::slice::from_raw_parts(self.buf.as_ptr().cast(), self.buf.len()) }
     }
 
     /// Returns a mutable reference to the filled portion of the buffer.
     #[inline]
     pub fn filled_mut(&mut self) -> &mut [u8] {
         // SAFETY: `self.buf` has been initialized for at least `filled` elements
-        unsafe { core::slice::from_raw_parts_mut(self.buf.as_mut_ptr().cast(), self.filled) }
+        unsafe { core::slice::from_raw_parts_mut(self.buf.as_mut_ptr().cast(), self.buf.len()) }
     }
 
     /// # Safety
@@ -78,23 +66,8 @@ impl<'a> Window<'a> {
 
         let dst = self.buf.as_mut_slice()[range].as_mut_ptr() as *mut u8;
         unsafe { core::ptr::copy_nonoverlapping(src, dst, end - start) };
-
-        if start >= self.filled {
-            self.filled = Ord::max(self.filled, end);
-        }
-
-        self.high_water = Ord::max(self.high_water, self.filled);
     }
 
-    // this library has many functions that operated in a chunked fashion on memory. For
-    // performance, we want to minimize bounds checks. Therefore we reserve initialize some extra
-    // memory at the end of the window so that chunked operations can use the whole buffer. If they
-    // go slightly over `self.capacity` that's okay, we account for that here by making sure the
-    // memory there is initialized!
-    pub fn initialize_out_of_bounds(&mut self) {}
-
-    pub fn initialize_at_least(&mut self, at_least: usize) {}
-
     // padding required so that SIMD operations going out-of-bounds are not a problem
     pub fn padding() -> usize {
         if crate::cpu_features::is_enabled_pclmulqdq() {