From 62f5a5501f70f544689423a7c1b8a5113bed1924 Mon Sep 17 00:00:00 2001
From: real-eren <erenalpkahriman@gmail.com>
Date: Thu, 20 Feb 2025 16:04:02 -0500
Subject: [PATCH] Use `as_chunks` in `analyze_source_file_sse2`

---
 compiler/rustc_span/src/analyze_source_file.rs | 11 ++++-------
 compiler/rustc_span/src/lib.rs                 |  1 +
 2 files changed, 5 insertions(+), 7 deletions(-)

diff --git a/compiler/rustc_span/src/analyze_source_file.rs b/compiler/rustc_span/src/analyze_source_file.rs
index a39bb884faadc..141d261b5f015 100644
--- a/compiler/rustc_span/src/analyze_source_file.rs
+++ b/compiler/rustc_span/src/analyze_source_file.rs
@@ -68,9 +68,7 @@ cfg_match! {
 
             const CHUNK_SIZE: usize = 16;
 
-            let src_bytes = src.as_bytes();
-
-            let chunk_count = src.len() / CHUNK_SIZE;
+            let (chunks, tail) = src.as_bytes().as_chunks::<CHUNK_SIZE>();
 
             // This variable keeps track of where we should start decoding a
             // chunk. If a multi-byte character spans across chunk boundaries,
@@ -78,11 +76,10 @@ cfg_match! {
             // handled it.
             let mut intra_chunk_offset = 0;
 
-            for chunk_index in 0..chunk_count {
-                let ptr = src_bytes.as_ptr() as *const __m128i;
+            for (chunk_index, chunk) in chunks.iter().enumerate() {
                 // We don't know if the pointer is aligned to 16 bytes, so we
                 // use `loadu`, which supports unaligned loading.
-                let chunk = unsafe { _mm_loadu_si128(ptr.add(chunk_index)) };
+                let chunk = unsafe { _mm_loadu_si128(chunk.as_ptr() as *const __m128i) };
 
                 // For character in the chunk, see if its byte value is < 0, which
                 // indicates that it's part of a UTF-8 char.
@@ -123,7 +120,7 @@ cfg_match! {
             }
 
             // There might still be a tail left to analyze
-            let tail_start = chunk_count * CHUNK_SIZE + intra_chunk_offset;
+            let tail_start = src.len() - tail.len() + intra_chunk_offset;
             if tail_start < src.len() {
                 analyze_source_file_generic(
                     &src[tail_start..],
diff --git a/compiler/rustc_span/src/lib.rs b/compiler/rustc_span/src/lib.rs
index c09669d959c93..bca9323a50d4c 100644
--- a/compiler/rustc_span/src/lib.rs
+++ b/compiler/rustc_span/src/lib.rs
@@ -31,6 +31,7 @@
 #![feature(round_char_boundary)]
 #![feature(rustc_attrs)]
 #![feature(rustdoc_internals)]
+#![feature(slice_as_chunks)]
 #![warn(unreachable_pub)]
 // tidy-alphabetical-end