Revert changes

Author: tibvdm

sa-index/src/sa_searcher.rs

@@ -426,23 +426,9 @@ impl Searcher {
             if let BoundSearchResult::SearchResult((min_bound, max_bound)) = search_bound_result {
                 // try all the partially matched suffixes and store the matching suffixes in an
                 // array (stop when our max number of matches is reached)
-                const ITER_PREFETCH_DISTANCE: usize = 16;
                 let mut sa_index = min_bound;
                 let t_iter = Instant::now();
                 while sa_index < max_bound {
-                    // Text reads only occur when skip > 0 (check_prefix is called).
-                    // When skip == 0 the prefix check is short-circuited and there are
-                    // no random text accesses to hide, so we skip the extra sa.get() cost.
-                    if skip > 0 {
-                        let future_sa_index = sa_index + ITER_PREFETCH_DISTANCE;
-                        if future_sa_index < max_bound {
-                            let future_suffix = self.sa.get(future_sa_index) as usize;
-                            if future_suffix >= skip {
-                                self.proteins.text().prefetch(future_suffix - skip);
-                            }
-                        }
-                    }
-
                     let suffix = self.sa.get(sa_index) as usize;
 
                     if suffix >= skip {

text-compression/src/lib.rs

@@ -16,18 +16,6 @@ pub use traits::{WriteBinary, ReadBinary, ReadBinaryMmap};
 /// The 5-bit-to-char lookup table for mmap-backed ProteinText.
 const BIT5_TO_CHAR: &[u8; 27] = b"ABCDEFGHIKLMNOPQRSTUVWXYZ-$";
 
-/// Non-blocking hardware prefetch hint: move the cache line containing `ptr` into L1.
-/// No-op on unsupported architectures.
-#[inline(always)]
-fn prefetch_read(ptr: *const u8) {
-    #[cfg(target_arch = "x86_64")]
-    unsafe { std::arch::x86_64::_mm_prefetch(ptr as *const i8, std::arch::x86_64::_MM_HINT_T0) }
-    #[cfg(target_arch = "aarch64")]
-    unsafe { std::arch::asm!("prfm pldl1keep, [{p}]", p = in(reg) ptr, options(nostack, preserves_flags, readonly)) }
-    #[cfg(not(any(target_arch = "x86_64", target_arch = "aarch64")))]
-    let _ = ptr;
-}
-
 /// Returns the number of bytes the BitArray data occupies for a given text length at 5 bits/value.
 pub fn bit_array_byte_size(text_length: usize) -> usize {
     let extra = if (text_length * 5).is_multiple_of(64) { 0 } else { 1 };
@@ -200,20 +188,6 @@ impl ProteinText {
         ProteinTextSlice::new(self, start, end)
     }
 
-    /// Non-blocking hardware prefetch hint for the cache line covering character `index`.
-    /// At 5 bits/char a 64-byte cache line holds 102 characters, so a single hint covers
-    /// the entire peptide window starting at `index`.
-    /// No-op for in-memory text and on unsupported platforms.
-    #[inline]
-    pub fn prefetch(&self, index: usize) {
-        if let ProteinText::MmapBacked { mmap, data_offset, .. } = self {
-            let byte_off = data_offset + (index * 5 / 64) * 8;
-            if byte_off + 8 <= mmap.len() {
-                prefetch_read(&mmap[byte_off] as *const u8);
-            }
-        }
-    }
-
 }
 
 impl WriteBinary for ProteinText {